1
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Kazanietz MG, Cooke M. Protein kinase C signaling "in" and "to" the nucleus: Master kinases in transcriptional regulation. J Biol Chem 2024; 300:105692. [PMID: 38301892 PMCID: PMC10907189 DOI: 10.1016/j.jbc.2024.105692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 02/03/2024] Open
Abstract
PKC is a multifunctional family of Ser-Thr kinases widely implicated in the regulation of fundamental cellular functions, including proliferation, polarity, motility, and differentiation. Notwithstanding their primary cytoplasmic localization and stringent activation by cell surface receptors, PKC isozymes impel prominent nuclear signaling ultimately impacting gene expression. While transcriptional regulation may be wielded by nuclear PKCs, it most often relies on cytoplasmic phosphorylation events that result in nuclear shuttling of PKC downstream effectors, including transcription factors. As expected from the unique coupling of PKC isozymes to signaling effector pathways, glaring disparities in gene activation/repression are observed upon targeting individual PKC family members. Notably, specific PKCs control the expression and activation of transcription factors implicated in cell cycle/mitogenesis, epithelial-to-mesenchymal transition and immune function. Additionally, PKCs isozymes tightly regulate transcription factors involved in stepwise differentiation of pluripotent stem cells toward specific epithelial, mesenchymal, and hematopoietic cell lineages. Aberrant PKC expression and/or activation in pathological conditions, such as in cancer, leads to profound alterations in gene expression, leading to an extensive rewiring of transcriptional networks associated with mitogenesis, invasiveness, stemness, and tumor microenvironment dysregulation. In this review, we outline the current understanding of PKC signaling "in" and "to" the nucleus, with significant focus on established paradigms of PKC-mediated transcriptional control. Dissecting these complexities would allow the identification of relevant molecular targets implicated in a wide spectrum of diseases.
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Affiliation(s)
- Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
| | - Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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2
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Aquino A, Bianchi N, Terrazzan A, Franzese O. Protein Kinase C at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response. BIOLOGY 2023; 12:1047. [PMID: 37626933 PMCID: PMC10451643 DOI: 10.3390/biology12081047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023]
Abstract
The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms.
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Affiliation(s)
- Angelo Aquino
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Nicoletta Bianchi
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (N.B.); (A.T.)
| | - Anna Terrazzan
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (N.B.); (A.T.)
- Laboratory for Advanced Therapy Technologies (LTTA), University of Ferrara, 44121 Ferrara, Italy
| | - Ornella Franzese
- Department of Systems Medicine, University of Rome Tor Vergata, 00133 Rome, Italy;
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3
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Crossay E, Jullian V, Trinel M, Sagnat D, Hamel D, Groppi E, Rolland C, Stigliani JL, Mejia K, Cabanillas BJ, Alric L, Buscail E, El Kalamouni C, Mavingui P, Deraison C, Racaud-Sultan C, Fabre N. Daphnanes diterpenes from the latex of Hura crepitans L. and their PKCζ-dependent anti-proliferative activity on colorectal cancer cells. Bioorg Med Chem 2023; 90:117366. [PMID: 37329676 DOI: 10.1016/j.bmc.2023.117366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/04/2023] [Accepted: 05/30/2023] [Indexed: 06/19/2023]
Abstract
Hura crepitans L. (Euphorbiaceae) is a thorn-covered tree widespread in South America, Africa and Asia which produces an irritating milky latex containing numerous secondary metabolites, notably daphnane-type diterpenes known as Protein Kinase C activators. Fractionation of a dichloromethane extract of the latex led to the isolation of five new daphnane diterpenes (1-5), along with two known analogs (6-7) including huratoxin. Huratoxin (6) and 4',5'-epoxyhuratoxin (4) were found to exhibit significant and selective cell growth inhibition against colorectal cancer cell line Caco-2 and primary colorectal cancer cells cultured as colonoids. The underlying mechanism of 4 and 6 was further investigated revealing the involvement of PKCζ in the cytostatic activity.
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Affiliation(s)
- Elise Crossay
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | | | - Manon Trinel
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | - David Sagnat
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; Toulouse Organoids Platform, Institut de Recherche en Santé Digestive, INSERM, Toulouse, France
| | - Dimitri Hamel
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Emie Groppi
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France
| | - Corinne Rolland
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France
| | | | - Kember Mejia
- Instituto de Investigaciones de la Amazonia Peruana (IIAP), Iquitos, Peru
| | - Billy Joel Cabanillas
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima 15102, Peru
| | - Laurent Alric
- Pole Digestif, Centre Hospitalier Universitaire, Toulouse, France
| | - Etienne Buscail
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France; Département de Chirurgie Digestive, Unité de Chirurgie Colorectale, Centre Hospitalier Universitaire, Toulouse, France
| | - Chaker El Kalamouni
- UMR PIMIT, Université de La Réunion, INSERM U1187, CNRS 9192, IRD 249, La Réunion, France
| | - Patrick Mavingui
- UMR PIMIT, Université de La Réunion, INSERM U1187, CNRS 9192, IRD 249, La Réunion, France
| | - Céline Deraison
- IRSD, Université de Toulouse, INSERM, INRAE, ENVT, UPS, France
| | | | - Nicolas Fabre
- UMR 152 PharmaDev, Université de Toulouse, IRD, UPS, France.
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4
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Somadder PD, Hossain MA, Ahsan A, Sultana T, Soikot SH, Rahman MM, Ibrahim SM, Ahmed K, Bui FM. Drug Repurposing and Systems Biology approaches of Enzastaurin can target potential biomarkers and critical pathways in Colorectal Cancer. Comput Biol Med 2023; 155:106630. [PMID: 36774894 DOI: 10.1016/j.compbiomed.2023.106630] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 01/28/2023] [Accepted: 02/04/2023] [Indexed: 02/10/2023]
Abstract
Colorectal cancer (CRC) is a severe health concern that results from a cocktail of genetic, epigenetic, and environmental abnormalities. Because it is the second most lethal malignancy in the world and the third-most common malignant tumor, but the treatment is unavailable. The goal of the current study was to use bioinformatics and systems biology techniques to determine the pharmacological mechanism underlying putative important genes and linked pathways in early-onset CRC. Computer-aided methods were used to uncover similar biological targets and signaling pathways associated with CRC, along with bioinformatics and network pharmacology techniques to assess the effects of enzastaurin on CRC. The KEGG and gene ontology (GO) pathway analysis revealed several significant pathways including in positive regulation of protein phosphorylation, negative regulation of the apoptotic process, nucleus, nucleoplasm, protein tyrosine kinase activity, PI3K-Akt signaling pathway, pathways in cancer, focal adhesion, HIF-1 signaling pathway, and Rap1 signaling pathway. Later, the hub protein module identified from the protein-protein interactions (PPIs) network, molecular docking and molecular dynamics simulation represented that enzastaurin showed strong binding interaction with two hub proteins including CASP3 (-8.6 kcal/mol), and MCL1 (-8.6 kcal/mol), which were strongly implicated in CRC management than other the five hub proteins. Moreover, the pharmacokinetic features of enzastaurin revealed that it is an effective therapeutic agent with minimal adverse effects. Enzastaurin may inhibit the potential biological targets that are thought to be responsible for the advancement of CRC and this study suggests a potential novel therapeutic target for CRC.
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Affiliation(s)
- Pratul Dipta Somadder
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Md Arju Hossain
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Asif Ahsan
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Tayeba Sultana
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Sadat Hossain Soikot
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Md Masuder Rahman
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Tangail, 1092, Bangladesh.
| | - Sobhy M Ibrahim
- Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh, 11451, Saudi Arabia.
| | - Kawsar Ahmed
- Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9, Canada; Group of Biophotomatiχ, Department of Information and Communication Technology, Mawlana Bhashani Science and Technology University, Santosh, Tangail, 1902, Bangladesh.
| | - Francis M Bui
- Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK, S7N 5A9, Canada.
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5
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Li X, Kaur N, Albahrani M, Karpf AR, Black AR, Black JD. Crosstalk between protein kinase C α and transforming growth factor β signaling mediated by Runx2 in intestinal epithelial cells. J Biol Chem 2023; 299:103017. [PMID: 36791912 PMCID: PMC10036670 DOI: 10.1016/j.jbc.2023.103017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 02/15/2023] Open
Abstract
Tight coordination of growth regulatory signaling is required for intestinal epithelial homeostasis. Protein kinase C α (PKCα) and transforming growth factor β (TGFβ) are negative regulators of proliferation with tumor suppressor properties in the intestine. Here, we identify novel crosstalk between PKCα and TGFβ signaling. RNA-Seq analysis of nontransformed intestinal crypt-like cells and colorectal cancer cells identified TGFβ receptor 1 (TGFβR1) as a target of PKCα signaling. RT-PCR and immunoblot analysis confirmed that PKCα positively regulates TGFβR1 mRNA and protein expression in these cells. Effects on TGFβR1 were dependent on Ras-extracellular signal-regulated kinase 1/2 (ERK) signaling. Nascent RNA and promoter-reporter analysis indicated that PKCα induces TGFβR1 transcription, and Runx2 was identified as an essential mediator of the effect. PKCα promoted ERK-mediated activating phosphorylation of Runx2, which preceded transcriptional activation of the TGFβR1 gene and induction of Runx2 expression. Thus, we have identified a novel PKCα→ERK→Runx2→TGFβR1 signaling axis. In further support of a link between PKCα and TGFβ signaling, PKCα knockdown reduced the ability of TGFβ to induce SMAD2 phosphorylation and cell cycle arrest, and inhibition of TGFβR1 decreased PKCα-induced upregulation of p21Cip1 and p27Kip1 in intestinal cells. The physiological relevance of these findings is also supported by The Cancer Genome Atlas data showing correlation between PKCα, Runx2, and TGFβR1 mRNA expression in human colorectal cancer. PKCα also regulated TGFβR1 in endometrial cancer cells, and PKCα, Runx2, and TGFβR1 expression correlates in uterine tumors, indicating that crosstalk between PKCα and TGFβ signaling may be a common mechanism in diverse epithelial tissues.
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Affiliation(s)
- Xinyue Li
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Navneet Kaur
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Mustafa Albahrani
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Adam R Karpf
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, USA.
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6
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Kawano T, Inokuchi J, Eto M, Murata M, Kang JH. Protein Kinase C (PKC) Isozymes as Diagnostic and Prognostic Biomarkers and Therapeutic Targets for Cancer. Cancers (Basel) 2022; 14:5425. [PMID: 36358843 PMCID: PMC9658272 DOI: 10.3390/cancers14215425] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/02/2022] [Accepted: 11/02/2022] [Indexed: 08/05/2023] Open
Abstract
Protein kinase C (PKC) is a large family of calcium- and phospholipid-dependent serine/threonine kinases that consists of at least 11 isozymes. Based on their structural characteristics and mode of activation, the PKC family is classified into three subfamilies: conventional or classic (cPKCs; α, βI, βII, and γ), novel or non-classic (nPKCs; δ, ε, η, and θ), and atypical (aPKCs; ζ, ι, and λ) (PKCλ is the mouse homolog of PKCι) PKC isozymes. PKC isozymes play important roles in proliferation, differentiation, survival, migration, invasion, apoptosis, and anticancer drug resistance in cancer cells. Several studies have shown a positive relationship between PKC isozymes and poor disease-free survival, poor survival following anticancer drug treatment, and increased recurrence. Furthermore, a higher level of PKC activation has been reported in cancer tissues compared to that in normal tissues. These data suggest that PKC isozymes represent potential diagnostic and prognostic biomarkers and therapeutic targets for cancer. This review summarizes the current knowledge and discusses the potential of PKC isozymes as biomarkers in the diagnosis, prognosis, and treatment of cancers.
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Affiliation(s)
- Takahito Kawano
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Junichi Inokuchi
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masatoshi Eto
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
- Department of Urology, Graduate School of Medical Sciences, Kyushu University, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masaharu Murata
- Center for Advanced Medical Innovation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Jeong-Hun Kang
- Division of Biopharmaceutics and Pharmacokinetics, National Cerebral and Cardiovascular Center Research Institute, 6-1 Shinmachi, Kishibe, Suita, Osaka 564-8565, Japan
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7
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A simplified analog of debromoaplysiatoxin lacking the B-ring of spiroketal moiety retains protein kinase C-binding and antiproliferative activities. Bioorg Med Chem 2022; 73:116988. [DOI: 10.1016/j.bmc.2022.116988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 11/20/2022]
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8
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Black JD, Affandi T, Black AR, Reyland ME. PKCα and PKCδ: Friends and Rivals. J Biol Chem 2022; 298:102194. [PMID: 35760100 PMCID: PMC9352922 DOI: 10.1016/j.jbc.2022.102194] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/13/2022] [Accepted: 06/21/2022] [Indexed: 01/06/2023] Open
Abstract
PKC comprises a large family of serine/threonine kinases that share a requirement for allosteric activation by lipids. While PKC isoforms have significant homology, functional divergence is evident among subfamilies and between individual PKC isoforms within a subfamily. Here, we highlight these differences by comparing the regulation and function of representative PKC isoforms from the conventional (PKCα) and novel (PKCδ) subfamilies. We discuss how unique structural features of PKCα and PKCδ underlie differences in activation and highlight the similar, divergent, and even opposing biological functions of these kinases. We also consider how PKCα and PKCδ can contribute to pathophysiological conditions and discuss challenges to targeting these kinases therapeutically.
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Affiliation(s)
- Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE.
| | - Trisiani Affandi
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus
| | - Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE
| | - Mary E Reyland
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus.
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9
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Cooke M, Kazanietz MG. Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity. Sci Signal 2022; 15:eabo0264. [PMID: 35412850 DOI: 10.1126/scisignal.abo0264] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell-directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.
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Affiliation(s)
- Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Department of Medicine, Einstein Medical Center Philadelphia, Philadelphia, PA 19141, USA
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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10
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Black AR, Black JD. The complexities of PKCα signaling in cancer. Adv Biol Regul 2021; 80:100769. [PMID: 33307285 PMCID: PMC8141086 DOI: 10.1016/j.jbior.2020.100769] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 11/15/2020] [Indexed: 01/06/2023]
Abstract
Protein kinase C α (PKCα) is a ubiquitously expressed member of the PKC family of serine/threonine kinases with diverse functions in normal and neoplastic cells. Early studies identified anti-proliferative and differentiation-inducing functions for PKCα in some normal tissues (e.g., regenerating epithelia) and pro-proliferative effects in others (e.g., cells of the hematopoietic system, smooth muscle cells). Additional well documented roles of PKCα signaling in normal cells include regulation of the cytoskeleton, cell adhesion, and cell migration, and PKCα can function as a survival factor in many contexts. While a majority of tumors lose expression of PKCα, others display aberrant overexpression of the enzyme. Cancer-related mutations in PKCα are uncommon, but rare examples of driver mutations have been detected in certain cancer types (e. g., choroid gliomas). Here we review the role of PKCα in various cancers, describe mechanisms by which PKCα affects cancer-related cell functions, and discuss how the diverse functions of PKCα contribute to tumor suppressive and tumor promoting activities of the enzyme. We end the discussion by addressing mutations and expression of PKCα in tumors and the clinical relevance of these findings.
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Affiliation(s)
- Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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11
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PHLPPing the balance: restoration of protein kinase C in cancer. Biochem J 2021; 478:341-355. [PMID: 33502516 DOI: 10.1042/bcj20190765] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/22/2020] [Accepted: 01/04/2021] [Indexed: 12/28/2022]
Abstract
Protein kinase signalling, which transduces external messages to mediate cellular growth and metabolism, is frequently deregulated in human disease, and specifically in cancer. As such, there are 77 kinase inhibitors currently approved for the treatment of human disease by the FDA. Due to their historical association as the receptors for the tumour-promoting phorbol esters, PKC isozymes were initially targeted as oncogenes in cancer. However, a meta-analysis of clinical trials with PKC inhibitors in combination with chemotherapy revealed that these treatments were not advantageous, and instead resulted in poorer outcomes and greater adverse effects. More recent studies suggest that instead of inhibiting PKC, therapies should aim to restore PKC function in cancer: cancer-associated PKC mutations are generally loss-of-function and high PKC protein is protective in many cancers, including most notably KRAS-driven cancers. These recent findings have reframed PKC as having a tumour suppressive function. This review focusses on a potential new mechanism of restoring PKC function in cancer - through targeting of its negative regulator, the Ser/Thr protein phosphatase PHLPP. This phosphatase regulates PKC steady-state levels by regulating the phosphorylation of a key site, the hydrophobic motif, whose phosphorylation is necessary for the stability of the enzyme. We also consider whether the phosphorylation of the potent oncogene KRAS provides a mechanism by which high PKC expression may be protective in KRAS-driven human cancers.
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12
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Parker PJ, Brown SJ, Calleja V, Chakravarty P, Cobbaut M, Linch M, Marshall JJT, Martini S, McDonald NQ, Soliman T, Watson L. Equivocal, explicit and emergent actions of PKC isoforms in cancer. Nat Rev Cancer 2021; 21:51-63. [PMID: 33177705 DOI: 10.1038/s41568-020-00310-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 01/02/2023]
Abstract
The maturing mutational landscape of cancer genomes, the development and application of clinical interventions and evolving insights into tumour-associated functions reveal unexpected features of the protein kinase C (PKC) family of serine/threonine protein kinases. These advances include recent work showing gain or loss-of-function mutations relating to driver or bystander roles, how conformational constraints and plasticity impact this class of proteins and how emergent cancer-associated properties may offer opportunities for intervention. The profound impact of the tumour microenvironment, reflected in the efficacy of immune checkpoint interventions, further prompts to incorporate PKC family actions and interventions in this ecosystem, informed by insights into the control of stromal and immune cell functions. Drugging PKC isoforms has offered much promise, but when and how is not obvious.
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Affiliation(s)
- Peter J Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK.
- School of Cancer and Pharmaceutical Sciences, King's College London, Guy's Campus, London, UK.
| | - Sophie J Brown
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Veronique Calleja
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | | | - Mathias Cobbaut
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Mark Linch
- UCL Cancer Institute, University College London, London, UK
| | | | - Silvia Martini
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
| | - Neil Q McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, London, UK
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, UK
| | - Tanya Soliman
- Centre for Cancer Genomics and Computational Biology, Bart's Cancer Institute, London, UK
| | - Lisa Watson
- Protein Phosphorylation Laboratory, Francis Crick Institute, London, UK
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13
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Leitges M. Investigations of mouse models during tumorigenesis revealed essential but distinct in vivo functions among the PKC family. Adv Biol Regul 2020; 78:100756. [PMID: 32992232 DOI: 10.1016/j.jbior.2020.100756] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/11/2020] [Accepted: 09/18/2020] [Indexed: 10/25/2022]
Abstract
PKC isozymes have been put in place as oncoproteins since the discovery that they can function as receptors for potent tumor-promoting phorbol esters in the 1980s. Despite nearly two decades of research, a clear in vivo proof of that concept was missing. The availability of so-called knock out mouse lines of individual PKC genes provided a tool to investigate isozyme specific in vivo functions in the context of tumor initiation, development and progression. This review aims to provide a limited overview of how the application of these mouse lines in combination with a cancer mouse model helped to understand PKC's in vivo function during tumorigenesis. The focus of this review will be on skin, colon and lung cancer.
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Affiliation(s)
- Michael Leitges
- Division of BioMedical Sciences, Faculty of Medicine, Craig L. Dobbin Genetics Research Centre, Memorial University of Newfoundland, Health Science Centre, 300 Prince Philip Drive, St. John's, NL, A1B 3V6, Canada.
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14
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The PKC universe keeps expanding: From cancer initiation to metastasis. Adv Biol Regul 2020; 78:100755. [PMID: 33017725 DOI: 10.1016/j.jbior.2020.100755] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 02/08/2023]
Abstract
Classical and novel protein kinase C (PKC) isozymes (c/nPKCs), members of the PKC family that become activated by the lipid second messenger diacylglycerol (DAG) and phorbol esters, exert a myriad of cellular effects that impact proliferative and motile cellular responses. While c/nPKCs have been indisputably associated with tumor promotion, their roles exceed by far their sole involvement as promoter kinases. Indeed, this original dogma has been subsequently redefined by the introduction of several new concepts: the identification of tumor suppressing roles for c/nPKCs, and their participation in early and late stages of carcinogenesis. This review dives deep into the intricate roles of c/nPKCs in cancer initiation as well as in the different stages of the metastatic cascade, with great emphasis in their involvement in cancer cell motility via regulation of small Rho GTPases, the production of extracellular matrix (ECM)-degrading proteases, and the epithelial-to-mesenchymal transition (EMT) program required for the acquisition of highly invasive traits. Here, we highlight functional interplays between either PKCα or PKCε and mesenchymal features that may ultimately contribute to anticancer drug resistance in cellular and animal models. We also introduce the novel hypothesis that c/nPKCs may be implicated in the control of immune evasion through the regulation of immune checkpoint protein expression. In summary, dissecting the colossal complexity of c/nPKC signaling in the wide spectrum of cancer progression may bring new opportunities for the development of meaningful tools aiding for cancer prognosis and therapy.
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15
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Hermyt E, Zmarzły N, Grabarek B, Kruszniewska-Rajs C, Gola J, Jęda-Golonka A, Szczepanek K, Mazurek U, Witek A. Interplay between miRNAs and Genes Associated with Cell Proliferation in Endometrial Cancer. Int J Mol Sci 2019; 20:ijms20236011. [PMID: 31795319 PMCID: PMC6928856 DOI: 10.3390/ijms20236011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 11/20/2019] [Accepted: 11/27/2019] [Indexed: 12/11/2022] Open
Abstract
Endometrial cancer develops as a result of abnormal cell growth associated with uncontrolled cell proliferation, excessive activation of signaling pathways and miRNA activity. The aim of this study was to determine the expression profile of genes associated with cell proliferation and to assess which miRNAs can participate in the regulation of their expression. The study enrolled 40 patients with endometrial cancer and 10 patients without neoplastic changes. The expression profile of genes associated with cell proliferation and the expression profile of miRNAs were assessed using microarrays. RT-qPCR was performed to validate mRNA microarray results. The mirTAR tool was used to identify miRNAs that regulate the activity of genes associated with cell proliferation. Decreased expression of IGF1 and MYLK, as well as SOD2 overexpression, were observed in endometrial cancer using both mRNA microarrays and RT-qPCR. Microarray analysis showed low levels of NES and PRKCA, but this was only partially validated using RT-qPCR. Reduced activity of MYLK may be caused by increased miR-200c, miR-155 and miR-200b expression. Cell proliferation is disturbed in endometrial cancer, which may be associated with an overexpression of miR-200a, miR-200c, and miR-155, making it a potential diagnostic marker.
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Affiliation(s)
- Ewelina Hermyt
- Department of Gynecology and Obstetrics, Faculty of Medical Sciences in Katowice, Medical University of Silesia in Katowice, Medyków 14, 40-752 Katowice, Poland; (E.H.); (A.J.-G.); (K.S.); (A.W.)
| | - Nikola Zmarzły
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Jedności 8, 41-200 Sosnowiec, Poland; (B.G.); (C.K.-R.); (J.G.)
- Department of Histology, Faculty of Medicine, University of Technology, Park Hutniczy 3-5, 41-800 Zabrze, Poland
- Correspondence:
| | - Beniamin Grabarek
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Jedności 8, 41-200 Sosnowiec, Poland; (B.G.); (C.K.-R.); (J.G.)
- Department of Histology, Faculty of Medicine, University of Technology, Park Hutniczy 3-5, 41-800 Zabrze, Poland
- Center of Oncology, M. Sklodowska-Curie Memorial Institute, Cracow Branch, Garncarska 11, 31-115 Kraków, Poland
| | - Celina Kruszniewska-Rajs
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Jedności 8, 41-200 Sosnowiec, Poland; (B.G.); (C.K.-R.); (J.G.)
| | - Joanna Gola
- Department of Molecular Biology, Faculty of Pharmaceutical Sciences in Sosnowiec, Medical University of Silesia in Katowice, Jedności 8, 41-200 Sosnowiec, Poland; (B.G.); (C.K.-R.); (J.G.)
| | - Agnieszka Jęda-Golonka
- Department of Gynecology and Obstetrics, Faculty of Medical Sciences in Katowice, Medical University of Silesia in Katowice, Medyków 14, 40-752 Katowice, Poland; (E.H.); (A.J.-G.); (K.S.); (A.W.)
| | - Katarzyna Szczepanek
- Department of Gynecology and Obstetrics, Faculty of Medical Sciences in Katowice, Medical University of Silesia in Katowice, Medyków 14, 40-752 Katowice, Poland; (E.H.); (A.J.-G.); (K.S.); (A.W.)
| | - Urszula Mazurek
- Jozef Tyszkiewicz Higher School in Bielsko-Biała, Nadbrzeżna 12, 43-300 Bielsko-Biała, Poland;
| | - Andrzej Witek
- Department of Gynecology and Obstetrics, Faculty of Medical Sciences in Katowice, Medical University of Silesia in Katowice, Medyków 14, 40-752 Katowice, Poland; (E.H.); (A.J.-G.); (K.S.); (A.W.)
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16
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Shatnawi A, Malkaram SA, Fandy T, Tsouko E. Identification of the inhibitor of growth protein 4 (ING4) as a potential target in prostate cancer therapy. Mol Cell Biochem 2019; 464:153-167. [PMID: 31773467 DOI: 10.1007/s11010-019-03657-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 11/16/2019] [Indexed: 02/02/2023]
Abstract
INhibitor of Growth protein 4 (ING4) is a potential chromatin modifier that has been implicated in several cancer-related processes. However, the role of ING4 in prostate cancer (PC) is largely unknown. This study aimed to assess ING4's role in global transcriptional regulation in PC cells to identify potential cellular processes associated with ING4 loss. RNA-Seq using next-generation sequencing (NGS) was used to identify altered genes in LNCaP PC cells following ING4 depletion. Ingenuity pathways analysis (IPA®) was applied to the data to highlight candidates, ING4-regulated pathways, networks and cellular processes. Selected genes were validated using RT-qPCR. RNA-Seq of LNCaP cells revealed a total of 159 differentially expressed genes (fold change ≥ 1.5 or ≤ - 1.5, FDR ≤ 0.05) following ING4 knockdown. RT-qPCR used to validate the expression level of selected genes was in agreement with RNA-Seq results. Key genes, unique pathways, and biological networks were identified using IPA® analysis. This is the first report of global gene regulation in PC cells by ING4. The resultant differential expression profile revealed the potential role of ING4 in PC pathogenesis possibly through modulation of key genes, pathways and biological networks that are central drivers of the disease. Collectively, these findings shed light on a novel transcriptional regulator of PC that ultimately may influence the disease progression and as a potential target in the disease therapy.
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Affiliation(s)
- Aymen Shatnawi
- Department of Pharmaceutical and Administrative Sciences, University of Charleston School of Pharmacy, 2300 MacCorkle Ave SE, Charleston, WV, 25304, USA.
| | - Sridhar A Malkaram
- Department of Mathematics and Computer Sciences, West Virginia State University, W729, Wallace Hall, Institute, WV, 25112, USA
| | - Tamer Fandy
- Department of Pharmaceutical and Administrative Sciences, University of Charleston School of Pharmacy, 2300 MacCorkle Ave SE, Charleston, WV, 25304, USA
| | - Efrosini Tsouko
- Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX, 77030, USA
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Salama MF, Liu M, Clarke CJ, Espaillat MP, Haley JD, Jin T, Wang D, Obeid LM, Hannun YA. PKCα is required for Akt-mTORC1 activation in non-small cell lung carcinoma (NSCLC) with EGFR mutation. Oncogene 2019; 38:7311-7328. [PMID: 31420605 PMCID: PMC6883150 DOI: 10.1038/s41388-019-0950-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 12/29/2022]
Abstract
Mutational activation of the epidermal growth factor receptor (EGFR) is a major player in the pathogenesis of non-small cell lung cancer (NSCLC). NSCLC patients with constitutively active EGFR mutations eventually develop drug resistance against EGFR tyrosine-kinase inhibitors; therefore, better understandings of key components of mutant EGFR (mtEGFR) signaling are required. Here, we initially observed aberrantly high expression of protein kinase Cα (PKCα) in lung adenocarcinomas, especially those with EGFR mutations, and proceeded to examine the role of PKCα in the regulation of the signaling pathways downstream of mtEGFR. The results showed that NSCLC cell lines with constitutively active EGFR mutations tend to have very or moderately high PKCα levels. Furthermore, PKCα was constitutively activated in HCC827 and H4006 cells which have an EGFR deletion mutation in exon 19. Interestingly, mtEGFR was not required for the induction of PKCα at protein and message levels suggesting that the increased levels of PKCα are due to independent selection. On the other hand, mtEGFR activity was required for robust activation of PKCα. Loss of functions studies revealed that the NSCLC cells rely heavily on PKCα for the activation of the mTORC1 signaling pathway. Unexpectedly, the results demonstrated that PKCα was required for activation of Akt upstream of mTOR but only in cells with the mtEGFR and with the increased expression of PKCα. Functionally, inhibition of PKCα in HCC827 led to caspase-3-dependent apoptosis and a significant decrease in cell survival in response to cellular stress induced by serum starvation. In summary, the results identified important roles of PKCα in regulating mTORC1 activity in lung cancer cells, whereby a primary switching occurs from PKCα-independent to PKCα-dependent signaling in the presence of EGFR mutations. The results present PKCα as a potential synergistic target of personalized treatment for NSCLC with constitutively active mutant forms of EGFR and constitutively active PKCα.
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Affiliation(s)
- Mohamed F Salama
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA
- Department of Biochemistry, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt
| | - Mengling Liu
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA
- Department of Immuno-Oncology, HD Biosciences Inc, San Diego, CA, 92121, USA
| | - Christopher J Clarke
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA
| | - Mel Pilar Espaillat
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA
| | - John D Haley
- Departments of Biochemistry and Pathology, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Ting Jin
- Department of Biomedical Informatics, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Daifeng Wang
- Department of Biomedical Informatics, Stony Brook University, Stony Brook, NY, 11794, USA
- Department of Biostatistics and Medical Informatics and Waisman Center, University of Wisconsin-Madison, Madison, WI, 53792, USA
| | - Lina M Obeid
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA
| | - Yusuf A Hannun
- Department of Medicine, Stony Brook University, Stony Brook, NY, 11794, USA.
- Stony Brook Cancer Center, Stony Brook University Hospital, Stony Brook, NY, 11794, USA.
- Departments of Biochemistry and Pathology, Stony Brook University, Stony Brook, NY, 11794, USA.
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18
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Reina-Campos M, Diaz-Meco MT, Moscat J. The Dual Roles of the Atypical Protein Kinase Cs in Cancer. Cancer Cell 2019; 36:218-235. [PMID: 31474570 PMCID: PMC6751000 DOI: 10.1016/j.ccell.2019.07.010] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/24/2019] [Accepted: 07/30/2019] [Indexed: 02/08/2023]
Abstract
Atypical protein kinase C (aPKC) isozymes, PKCλ/ι and PKCζ, are now considered fundamental regulators of tumorigenesis. However, the specific separation of functions that determine their different roles in cancer is still being unraveled. Both aPKCs have pleiotropic context-dependent functions that can translate into tumor-promoter or -suppressive functions. Here, we review early and more recent literature to discuss how the different tumor types, and their microenvironments, might account for the selective signaling of each aPKC isotype. This is of clinical relevance because a better understanding of the roles of these kinases is essential for the design of new anti-cancer treatments.
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Affiliation(s)
- Miguel Reina-Campos
- Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Maria T Diaz-Meco
- Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jorge Moscat
- Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA.
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19
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Nam TW, Park SY, Lee JH, Roh JI, Lee HW. Effect of EI24 expression on the tumorigenesis of Apc Min/+ colorectal cancer mouse model. Biochem Biophys Res Commun 2019; 514:1087-1092. [PMID: 31097220 DOI: 10.1016/j.bbrc.2019.04.186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 04/27/2019] [Indexed: 12/14/2022]
Abstract
Etoposide-induced 2.4 kb transcript (EI24, also known as PIG8) is a p53 target gene involved in cell growth suppression and apoptosis and known to be frequently altered in human cancers. Although EI24 expression is decreased in various cancers and is associated with colorectal cancer progression and metastasis, the physiological function of EI24 in colorectal cancer is yet unclear. We generated an Ei24 conditional transgenic (Tg) mouse to study the therapeutic effects of Ei24 in vivo and evaluated whether Ei24 plays a role of a tumor suppressor using Ei24 Tg mouse crossed with ApcMin/+ mouse, which develops multiple intestinal adenomas. The overexpression of Ei24 failed to cause any notable difference in the number of polyps, lengths of the intestine and spleen, and survival rate between ApcMin/+ and ApcMin/+Ei24 Tg mice. Ei24 plays no significant role in colon cancer caused by the substitutional mutation of Apc in mice. Therefore, our result dismisses the hypothesized direct link between ApcMin/+ mutation and Ei24 expression in colorectal cancer model.
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Affiliation(s)
- Tae Wook Nam
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Song Yi Park
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Jae Hoon Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Jae Il Roh
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea
| | - Han-Woong Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Republic of Korea.
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20
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Dupasquier S, Blache P, Picque Lasorsa L, Zhao H, Abraham JD, Haigh JJ, Ychou M, Prévostel C. Modulating PKCα Activity to Target Wnt/β-Catenin Signaling in Colon Cancer. Cancers (Basel) 2019; 11:cancers11050693. [PMID: 31109112 PMCID: PMC6563011 DOI: 10.3390/cancers11050693] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/15/2019] [Accepted: 05/16/2019] [Indexed: 12/20/2022] Open
Abstract
Inactivating mutations of the tumor suppressor Adenomatosis Polyposis Coli (APC), which are found in familial adenomatosis polyposis and in 80% of sporadic colorectal cancers (CRC), result in constitutive activation of the Wnt/β-catenin pathway and tumor development in the intestine. These mutations disconnect the Wnt/β-catenin pathway from its Wnt extracellular signal by inactivating the APC/GSK3-β/axin destruction complex of β-catenin. This results in sustained nuclear accumulation of β-catenin, followed by β-catenin-dependent co-transcriptional activation of Wnt/β-catenin target genes. Thus, mechanisms acting downstream of APC, such as those controlling β-catenin stability and/or co-transcriptional activity, are attractive targets for CRC treatment. Protein Kinase C-α (PKCα) phosphorylates the orphan receptor RORα that then inhibits β-catenin co-transcriptional activity. PKCα also phosphorylates β-catenin, leading to its degradation by the proteasome. Here, using both in vitro (DLD-1 cells) and in vivo (C57BL/6J mice) PKCα knock-in models, we investigated whether enhancing PKCα function could be beneficial in CRC treatment. We found that PKCα is infrequently mutated in CRC samples, and that inducing PKCα function is not deleterious for the normal intestinal epithelium. Conversely, di-terpene ester-induced PKCα activity triggers CRC cell death. Together, these data indicate that PKCα is a relevant drug target for CRC treatment.
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Affiliation(s)
| | - Philippe Blache
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
| | - Laurence Picque Lasorsa
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
| | - Han Zhao
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
| | - Jean-Daniel Abraham
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
| | - Jody J Haigh
- Research Institute in Oncology and Hematology, University of Manitoba, Winnipeg, MB R3E 0V9, Canada.
| | - Marc Ychou
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
| | - Corinne Prévostel
- Campus Val d'Aurelle-Research team "Integrative cancer research for personalized medicine in digestive oncology", IRCM U1194, University of Montpellier, ICM, CNRS, CHU, 34298 Montpellier, France.
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21
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Blache P, Canterel-Thouennon L, Busson M, Verdié P, Subra G, Ychou M, Prévostel C. A Short SOX9 Peptide Mimics SOX9 Tumor Suppressor Activity and Is Sufficient to Inhibit Colon Cancer Cell Growth. Mol Cancer Ther 2019; 18:1386-1395. [DOI: 10.1158/1535-7163.mct-18-1149] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 02/14/2019] [Accepted: 05/09/2019] [Indexed: 11/16/2022]
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22
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Dükel M, Tavsan Z, Erdogan D, Erkan Gök D, Ayar Kayali H. Protein kinase C Inhibitors selectively modulate dynamics of cell adhesion molecules and cell death in human colon cancer cells. Cell Adh Migr 2018; 13:83-97. [PMID: 30289336 PMCID: PMC6527378 DOI: 10.1080/19336918.2018.1530933] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
During development of colon cancer, Protein Kinase Cs (PKCs) are involved in regulation of many genes controlling several cellular mechanisms. Here, we examined the changes in cell adhesion molecules and PKCs for colorectal cancer progression. We identified that PKCs affected expression of EpCAM, claudins, tetraspanins. Treatment with low concentrations of PKC inhibitors resulted in decreased cell viability. In addition, immunoblotting and qRT-PCR analysis showed that apoptosis was inhibited while autophagy was induced by PKC inhibition in colon cancer cells. Furthermore, we observed decreased levels of intracellular Reactive Oxygen Species (ROS), lipid peroxidation and protein carbonyl, confirming the ROS-induced apoptosis. Taken together, our results reveal that PKC signalling modulates not only cell adhesion dynamics but also cell death-related mechanisms. Abbreviations: PKC: Protein Kinase C; EpCAM: Epithelial cell adhesion molecule; FBS: fetal bovine serum; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide); CAM: cell adhesion molecule; ROS: reactive oxygen species.
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Affiliation(s)
- Muzaffer Dükel
- a Moleculer Biology and Genetic Department, Faculty of Art and Science , Mehmet Akif Ersoy University , Burdur , Turkey.,b Izmir Biomedicine and Genome Center , Izmir , Turkey
| | - Zehra Tavsan
- b Izmir Biomedicine and Genome Center , Izmir , Turkey
| | - Duygu Erdogan
- c Izmir International Biomedicine and Genome Institute , Dokuz Eylül University , Izmir , Turkey
| | | | - Hulya Ayar Kayali
- b Izmir Biomedicine and Genome Center , Izmir , Turkey.,d Biochemistry Division, Chemistry Department, Science Faculty , Dokuz Eylul University , Izmir , Turkey
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23
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Yu S, Yin Y, Wang Q, Wang L. Dual gene deficient models of Apc Min/+ mouse in assessing molecular mechanisms of intestinal carcinogenesis. Biomed Pharmacother 2018; 108:600-609. [PMID: 30243094 DOI: 10.1016/j.biopha.2018.09.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/08/2018] [Accepted: 09/11/2018] [Indexed: 02/07/2023] Open
Abstract
The ApcMin/+ mouse, carrying an inactivated allele of the adenomatous polyposis coli (Apc) gene, is a widely used animal model of human colorectal tumorigenesis. While crossed with other gene knockout or knock-in mice, these mice possess advantages in investigation of human intestinal tumorigenesis. Intestinal tumor pathogenesis involves multiple gene alterations; thus, various double gene deficiency models could provide novel insights into molecular mechanisms of tumor biology, as well as gene-gene interactions involved in intestinal tumor development and assessment of novel strategies for preventing and treating intestinal cancer. This review discusses approximately 100 double gene deficient mice and their associated intestinal tumor development and progression phenotypes. The dual gene knockouts based on the Apc mutation background consist of inflammation and immune-related, cell cycle-related, Wnt/β-catenin signaling-related, tumor growth factor (TGF)-signaling-related, drug metabolism-related, and transcription factor genes, as well as some oncogenes and tumor suppressors. Future studies should focus on conditional or inducible dual or multiple mouse gene knockout models to investigate the molecular mechanisms underlying intestinal tumor development, as well as potential drug targets.
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Affiliation(s)
- Shuwen Yu
- Department of Pharmacy, Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong, China.
| | - Yanhui Yin
- Department of Pharmacy, Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Qian Wang
- Department of Pharmacy, Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Lu Wang
- Department of Pharmacy, Jinan Central Hospital Affiliated to Shandong University, Jinan, Shandong, China.
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24
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Hsu AH, Lum MA, Shim KS, Frederick PJ, Morrison CD, Chen B, Lele SM, Sheinin YM, Daikoku T, Dey SK, Leone G, Black AR, Black JD. Crosstalk between PKCα and PI3K/AKT Signaling Is Tumor Suppressive in the Endometrium. Cell Rep 2018; 24:655-669. [PMID: 30021163 PMCID: PMC6118133 DOI: 10.1016/j.celrep.2018.06.067] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 04/25/2018] [Accepted: 06/13/2018] [Indexed: 11/17/2022] Open
Abstract
Protein kinase C (PKC) isozymes are commonly recognized as oncoproteins based on their activation by tumor-promoting phorbol esters. However, accumulating evidence indicates that PKCs can be inhibitory in some cancers, with recent findings propelling a shift in focus to understanding tumor suppressive functions of these enzymes. Here, we report that PKCα acts as a tumor suppressor in PI3K/AKT-driven endometrial cancer. Transcriptional suppression of PKCα is observed in human endometrial tumors in association with aggressive disease and poor prognosis. In murine models, loss of PKCα is rate limiting for endometrial tumor initiation. PKCα tumor suppression involves PP2A-family-dependent inactivation of AKT, which can occur even in the context of genetic hyperactivation of PI3K/AKT signaling by coincident mutations in PTEN, PIK3CA, and/or PIK3R1. Together, our data point to PKCα as a crucial tumor suppressor in the endometrium, with deregulation of a PKCα→PP2A/PP2A-like phosphatase signaling axis contributing to robust AKT activation and enhanced endometrial tumorigenesis.
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Affiliation(s)
- Alice H Hsu
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Michelle A Lum
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kang-Sup Shim
- Department of Molecular Virology, Immunology, and Medical Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Peter J Frederick
- Department of Gynecologic Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA
| | - Carl D Morrison
- Department of Pathology and Laboratory Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA
| | - Baojiang Chen
- Department of Biostatistics, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Subodh M Lele
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yuri M Sheinin
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Takiko Daikoku
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Sudhansu K Dey
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Gustavo Leone
- Department of Molecular Virology, Immunology, and Medical Genetics, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jennifer D Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198, USA.
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Protein kinase Cα gain-of-function variant in Alzheimer's disease displays enhanced catalysis by a mechanism that evades down-regulation. Proc Natl Acad Sci U S A 2018; 115:E5497-E5505. [PMID: 29844158 DOI: 10.1073/pnas.1805046115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Conventional protein kinase C (PKC) family members are reversibly activated by binding to the second messengers Ca2+ and diacylglycerol, events that break autoinhibitory constraints to allow the enzyme to adopt an active, but degradation-sensitive, conformation. Perturbing these autoinhibitory constraints, resulting in protein destabilization, is one of many mechanisms by which PKC function is lost in cancer. Here, we address how a gain-of-function germline mutation in PKCα in Alzheimer's disease (AD) enhances signaling without increasing vulnerability to down-regulation. Biochemical analyses of purified protein demonstrate that this mutation results in an ∼30% increase in the catalytic rate of the activated enzyme, with no changes in the concentrations of Ca2+ or lipid required for half-maximal activation. Molecular dynamics simulations reveal that this mutation has both localized and allosteric effects, most notably decreasing the dynamics of the C-helix, a key determinant in the catalytic turnover of kinases. Consistent with this mutation not altering autoinhibitory constraints, live-cell imaging studies reveal that the basal signaling output of PKCα-M489V is unchanged. However, the mutant enzyme in cells displays increased sensitivity to an inhibitor that is ineffective toward scaffolded PKC, suggesting the altered dynamics of the kinase domain may influence protein interactions. Finally, we show that phosphorylation of a key PKC substrate, myristoylated alanine-rich C-kinase substrate, is increased in brains of CRISPR-Cas9 genome-edited mice containing the PKCα-M489V mutation. Our results unveil how an AD-associated mutation in PKCα permits enhanced agonist-dependent signaling via a mechanism that evades the cell's homeostatic down-regulation of constitutively active PKCα.
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26
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Cheng Y, Zhu Y, Xu W, Xu J, Yang M, Chen P, Zhao J, Geng L, Gong S. PKCα in colon cancer cells promotes M1 macrophage polarization via MKK3/6-P38 MAPK pathway. Mol Carcinog 2018; 57:1017-1029. [PMID: 29637628 DOI: 10.1002/mc.22822] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 03/17/2018] [Accepted: 04/04/2018] [Indexed: 01/19/2023]
Abstract
Tumor associated macrophages are potential targets of the immune therapy for patients with colon cancer. PKCα acts as a tumor suppressor in the intestine. However, the correlation between PKCα expressed in colon cancer cells and tumor associated macrophages polarization has never been detected. In the present study, the correlation between PKCα expression and level of M1 macrophages was evaluated in human colon cancer tissues. A xenograft mouse model of colon cancer cells with different PKCα expression level was constructed to evaluate the effect of PKCα on M1 macrophages polarization in vivo. Co-culture of colon cancer cells and differentiated macrophages was used to detect the potential interplay in vitro. PKCα regulated production of cytokines which correlated with macrophage polarization and the underlying mechanism was further explored. Our study showed that high PKCα expression in human colon cancer tissues correlated with better prognosis and high M1 macrophage content. PKCα expressed in colon cancer cells inhibited the growth of colon cancer in mice model. PKCα induced macrophages polarized to the M1-like phenotype both in vitro and in vivo. Mechanistically, PKCα targeted P38 via MKK3/6 to promote IL12 and GM-CSF expression which further enhanced M1-like macrophages polarization. In conclusion, this study provided evidence for the first time that PKCα in colon cancer cells play an anticancer action by inducing the polarization of tumor associated macrophages to M1-like phenotype in the tumor microenvironment. PKCα promoted IL12/GM-CSF-mediated M1 polarization through MKK3/6-P38 signaling pathway. Our investigation suggested that modulation of the PKCα signaling pathway might serve as a novel strategy for colon cancer therapy.
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Affiliation(s)
- Yang Cheng
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Yun Zhu
- Liver Tumor Center, Department of Infectious Diseases and Hepatology Unit, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
| | - Wanfu Xu
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Jiajia Xu
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Min Yang
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Peiyu Chen
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Junhong Zhao
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Lanlan Geng
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Sitang Gong
- Department of Digestive, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, China
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Singh RK, Kumar S, Gautam PK, Tomar MS, Verma PK, Singh SP, Kumar S, Acharya A. Protein kinase C-α and the regulation of diverse cell responses. Biomol Concepts 2018; 8:143-153. [PMID: 28841566 DOI: 10.1515/bmc-2017-0005] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/18/2017] [Indexed: 11/15/2022] Open
Abstract
Protein kinase C (PKC) comprises a family of lipid-sensitive enzymes that have been involved in a broad range of cellular functions. PKC-α is a member of classical PKC with ubiquitous expression and different cellular localization. This unique PKC isoform is activated by various signals which evoke lipid hydrolysis, after activation it interacts with various adapter proteins and is localized to specific cellular compartments where it is devised to work. The universal expression and activation by various stimuli make it a perfect player in uncountable cellular functions including differentiation, proliferation, apoptosis, cellular transformation, motility, adhesion and so on. However, these functions are not intrinsic properties of PKC-α, but depend on cell types and conditions. The activities of PKC-α are managed by the various pharmacological activators/inhibitors and antisense oligonucleotides. The aim of this review is to elaborate the structural feature, and provide an insight into the mechanism of PKC-α activation and regulation of its key biological functions in different cellular compartments to develop an effective pharmacological approach to regulate the PKC-α signal array.
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Lee KH, Jeong WJ, Cha PH, Lee SK, Min DS, Choi KY. Stabilization of Sur8 via PKCα/δ degradation promotes transformation and migration of colorectal cancer cells. Oncotarget 2017; 8:115596-115608. [PMID: 29383184 PMCID: PMC5777796 DOI: 10.18632/oncotarget.23313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 12/03/2017] [Indexed: 12/23/2022] Open
Abstract
Scaffold proteins of the mitogen activated protein kinase (MAPK) pathway recruit protein kinase cascades to confer context-specificity to cellular signaling. Varying concentrations of scaffold proteins determine different aspects of signaling outputs. However, regulatory mechanisms of scaffold proteins are poorly understood. Sur8, a scaffold protein in the Ras-MAPK pathway, is known to be involved in cell transformation and migration, and is increased in human colorectal cancer (CRC) patient tissue. Here we determine that regulation of Sur8 stability mediates transformation and migration of CRC cells. Fibroblast growth factor 2 (FGF2) is identified as an external regulator that stabilizes Sur8. Protein kinase C-alpha and -delta (PKCα/δ) are also identified as specific mediators of FGF2 regulation of Sur8 stability. PKCα/δ phosphorylate Sur8 at Thr-71 and Ser-297, respectively. This phosphorylation is essential for polyubiquitin-dependent degradation of Sur8. Sur8 mutations, which mimic phosphorylation by PKCα/δ and destabilized Sur8, suppress the FGF2-induced transformation and migration of CRC cells. The clinical relevance of Sur8 regulation by PKCα/δ is indicated by the inverse relationship between PKCα/δ and Sur8 expression in human CRC patient tissues. Overall, our findings demonstrate for the first time a regulatory mechanism of Sur8 stability involving cellular transformation and migration in CRC.
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Affiliation(s)
- Kug Hwa Lee
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Woo-Jeong Jeong
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Pu-Hyeon Cha
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Sang-Kyu Lee
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Do Sik Min
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Molecular Biology, College of Natural Science, Pusan National University, Pusan, South Korea
| | - Kang-Yell Choi
- Translational Research Center for Protein Function Control, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
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Zhang J, Wang Y, Duan Y, Fan D, Zhou Z, Huang J, Wei R, Shen L. PKCα promotes local advancement via its dual roles in nasopharyngeal carcinoma. Acta Otolaryngol 2017; 137:662-667. [PMID: 28084179 DOI: 10.1080/00016489.2016.1269195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CONCLUSION In patients with nasopharyngeal carcinoma (NPC), PKCα is linked to local advancement and plays dual roles in tumorigenesis. Moreover, positive PKCα is associated with 2-year overall survival of NPC. OBJECTIVE This study seeks to investigate the role of PKCα to identify different sub-types in NPC. METHODS PKCα expression levels were detected in a collection of NPC samples. CT and MRI scans of the corresponding patients were used to assess adjacent tissue invasion and lymph node metastasis. The correlation of tumour invasion and PKCα levels was evaluated by statistical analysis. The correlation between expression level of PKCα and 2-year overall survival was analysed by the Kaplan-Meier curves. Moreover, a multivariate Cox proportional hazard regression analysis was used to identify the independent prognostic factors for NPC. RESULTS PKCα is linked to the invasion of adjacent tissues, especially in the skull base. However, down-regulation of PKCα is a risk factor for regional lymph node metastasis. The 2-year overall survival of the PKCα negative group is better than that of the PKCα positive group (PKCα negative group 100%, PKCα positive group 88.5%, p = 0.034). Based on the multivariate Cox proportional hazard regression analysis, age was identified as a risk factor.
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Affiliation(s)
- Jing Zhang
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, PR China
| | - Ying Wang
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, PR China
| | - Yumei Duan
- Department of Pathology, Xiangya Hospital, Central South University, Changsha, PR China
| | - Dan Fan
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, PR China
| | - Zhijiao Zhou
- Department of Pathology, The Third Xiangya Hospital, Central South University, Changsha, PR China
| | - Jianghai Huang
- Department of Pathology, The Second Xiangya Hospital, Central South University, Changsha, PR China
| | - Rui Wei
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, PR China
| | - Liangfang Shen
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, PR China
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30
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Protein kinase C as a tumor suppressor. Semin Cancer Biol 2017; 48:18-26. [PMID: 28476658 DOI: 10.1016/j.semcancer.2017.04.017] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 03/31/2017] [Accepted: 04/28/2017] [Indexed: 01/01/2023]
Abstract
Protein kinase C (PKC) has historically been considered an oncoprotein. This stems in large part from the discovery in the early 1980s that PKC is directly activated by tumor-promoting phorbol esters. Yet three decades of clinical trials using PKC inhibitors in cancer therapies not only failed, but in some cases worsened patient outcome. Why has targeting PKC in cancer eluded successful therapies? Recent studies looking at the disease for insight provide an explanation: cancer-associated mutations in PKC are generally loss-of-function (LOF), supporting an unexpected function as tumor suppressors. And, contrasting with LOF mutations in cancer, germline mutations that enhance the activity of some PKC isozymes are associated with degenerative diseases such as Alzheimer's disease. This review provides a background on the diverse mechanisms that ensure PKC is only active when, where, and for the appropriate duration needed and summarizes recent findings converging on a paradigm reversal: PKC family members generally function by suppressing, rather than promoting, survival signaling.
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31
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Newton AC, Brognard J. Reversing the Paradigm: Protein Kinase C as a Tumor Suppressor. Trends Pharmacol Sci 2017; 38:438-447. [PMID: 28283201 PMCID: PMC5403564 DOI: 10.1016/j.tips.2017.02.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 02/02/2017] [Accepted: 02/03/2017] [Indexed: 12/20/2022]
Abstract
The discovery in the 1980s that protein kinase C (PKC) is a receptor for the tumor-promoting phorbol esters fueled the dogma that PKC is an oncoprotein. Yet 30+ years of clinical trials for cancer using PKC inhibitors not only failed, but in some instances worsened patient outcome. The recent analysis of cancer-associated mutations, from diverse cancers and throughout the PKC family, revealed that PKC isozymes are generally inactivated in cancer, supporting a tumor suppressive function. In keeping with a bona fide tumor suppressive role, germline causal loss-of-function (LOF) mutations in one isozyme have recently been identified in lymphoproliferative disorders. Thus, strategies in cancer treatment should focus on restoring rather than inhibiting PKC.
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Affiliation(s)
- Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92093-0721, USA.
| | - John Brognard
- Laboratory of Cell and Developmental Signaling, National Cancer Institute at Frederick, Frederick, MD 21702, USA; Cancer Research UK Manchester Institute, Manchester, UK.
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32
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Cooke M, Magimaidas A, Casado-Medrano V, Kazanietz MG. Protein kinase C in cancer: The top five unanswered questions. Mol Carcinog 2017; 56:1531-1542. [PMID: 28112438 DOI: 10.1002/mc.22617] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 01/04/2017] [Accepted: 01/20/2017] [Indexed: 12/29/2022]
Abstract
Few kinases have been studied as extensively as protein kinase C (PKC), particularly in the context of cancer. As major cellular targets for the phorbol ester tumor promoters and diacylglycerol (DAG), a second messenger generated by stimulation of membrane receptors, PKC isozymes play major roles in the control of signaling pathways associated with proliferation, migration, invasion, tumorigenesis, and metastasis. However, despite decades of research, fundamental questions remain to be answered or are the subject of intense controversy. Primary among these unresolved issues are the role of PKC isozymes as either tumor promoter or tumor suppressor kinases and the incomplete understanding on isozyme-specific substrates and effectors. The involvement of PKC isozymes in cancer progression needs to be reassessed in the context of specific oncogenic and tumor suppressing alterations. In addition, there are still major hurdles in addressing isozyme-specific function due to the limited specificity of most pharmacological PKC modulators and the lack of validated predictive biomarkers for response, which impacts the translation of these agents to the clinic. In this review we focus on key controversial issues and upcoming challenges, with the expectation that understanding the intricacies of PKC function will help fulfill the yet unsuccessful promise of targeting PKCs for cancer therapeutics.
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Affiliation(s)
- Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Andrew Magimaidas
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Victoria Casado-Medrano
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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33
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Chen S, Wang Y, Zhang Y, Wan Y. Low expression of PKCα and high expression of KRAS predict poor prognosis in patients with colorectal cancer. Oncol Lett 2016; 12:1655-1660. [PMID: 27602102 PMCID: PMC4998155 DOI: 10.3892/ol.2016.4845] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 03/08/2016] [Indexed: 01/13/2023] Open
Abstract
The current study aimed to determine the association between protein kinase Cα (PKCα) and Kirsten rat sarcoma viral oncogene homolog (KRAS) expression and the response to folinic acid, 5-fluorouracil and oxaliplatin (FOLFOX regimen) in patients with colorectal cancer (CRC). The protein levels of PKCα and KRAS were analyzed by immunohistochemistry in tissue samples from patients with CRC and in non-cancerous tissues, including 152 cases of colorectal adenocarcinoma, 30 cases of colorectal adenoma and 20 normal colonic mucosa samples. The association between PKCα and KRAS expression and clinicopathological features was analyzed. The rates of positive PKCα protein expression in patients with poorly, moderately and well-differentiated adenocarcinoma were 16.7% (6/36), 40.0% (24/60), and 57.1% (32/56), respectively (P<0.013). The rate of positive KRAS expression in CRC patients was significantly higher than in patients with colon adenoma and normal colon mucosa (P<0.001). Expression levels of KRAS were associated with the degree of differentiation of CRC (P<0.001). Expression of PKCα was negatively correlated with KRAS expression in CRC tissues. The mean progression-free survival (PFS) times in patients with high and low expression of PKCα were 43.9 and 38.8 months, respectively (P<0.001). The mean PFS times were 38.5 and 45.5 months in patients with high and low expression of KRAS, respectively (P=0.001). In conclusion, low PKCα and high KRAS expression predicted relatively poor prognosis in patients with CRC.
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Affiliation(s)
- Suxian Chen
- Department of Pathology, The Third Affiliated Hospital of Liaoning Medical College, Jinzhou, Liaoning 121002, P.R. China
| | - Yadi Wang
- Department of Oncology, The Third Affiliated Hospital of Liaoning Medical College, Jinzhou, Liaoning 121002, P.R. China
| | - Yun Zhang
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Liaoning Medical College, Jinzhou, Liaoning 121002, P.R. China
| | - Yizeng Wan
- Department of Pathology, The Third Affiliated Hospital of Liaoning Medical College, Jinzhou, Liaoning 121002, P.R. China
- Correspondence to: Dr Yizeng Wan, Department of Pathology, The Third Affiliated Hospital of Liaoning Medical College, 2 Heping Road Section 5, Linghe, Jinzhou, Liaoning 121002, P.R. China, E-mail:
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Redox Homeostasis and Cellular Antioxidant Systems: Crucial Players in Cancer Growth and Therapy. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:6235641. [PMID: 27418953 PMCID: PMC4932173 DOI: 10.1155/2016/6235641] [Citation(s) in RCA: 188] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/18/2016] [Indexed: 02/07/2023]
Abstract
Reactive oxygen species (ROS) and their products are components of cell signaling pathways and play important roles in cellular physiology and pathophysiology. Under physiological conditions, cells control ROS levels by the use of scavenging systems such as superoxide dismutases, peroxiredoxins, and glutathione that balance ROS generation and elimination. Under oxidative stress conditions, excessive ROS can damage cellular proteins, lipids, and DNA, leading to cell damage that may contribute to carcinogenesis. Several studies have shown that cancer cells display an adaptive response to oxidative stress by increasing expression of antioxidant enzymes and molecules. As a double-edged sword, ROS influence signaling pathways determining beneficial or detrimental outcomes in cancer therapy. In this review, we address the role of redox homeostasis in cancer growth and therapy and examine the current literature regarding the redox regulatory systems that become upregulated in cancer and their role in promoting tumor progression and resistance to chemotherapy.
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Lum MA, Barger CJ, Hsu AH, Leontieva OV, Black AR, Black JD. Protein Kinase Cα (PKCα) Is Resistant to Long Term Desensitization/Down-regulation by Prolonged Diacylglycerol Stimulation. J Biol Chem 2016; 291:6331-46. [PMID: 26769967 DOI: 10.1074/jbc.m115.696211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 11/06/2022] Open
Abstract
Sustained activation of PKCα is required for long term physiological responses, such as growth arrest and differentiation. However, studies with pharmacological agonists (e.g. phorbol 12-myristate 13-acetate (PMA)) indicate that prolonged stimulation leads to PKCα desensitization via dephosphorylation and/or degradation. The current study analyzed effects of chronic stimulation with the physiological agonist diacylglycerol. Repeated addition of 1,2-dioctanoyl-sn-glycerol (DiC8) resulted in sustained plasma membrane association of PKCα in a pattern comparable with that induced by PMA. However, although PMA potently down-regulated PKCα, prolonged activation by DiC8 failed to engage known desensitization mechanisms, with the enzyme remaining membrane-associated and able to support sustained downstream signaling. DiC8-activated PKCα did not undergo dephosphorylation, ubiquitination, or internalization, early events in PKCα desensitization. Although DiC8 efficiently down-regulated novel PKCs PKCδ and PKCϵ, differences in Ca(2+) sensitivity and diacylglycerol affinity were excluded as mediators of the selective resistance of PKCα. Roles for Hsp/Hsc70 and Hsp90 were also excluded. PMA, but not DiC8, targeted PKCα to detergent-resistant membranes, and disruption of these domains with cholesterol-binding agents demonstrated a role for differential membrane compartmentalization in selective agonist-induced degradation. Chronic DiC8 treatment failed to desensitize PKCα in several cell types and did not affect PKCβI; thus, conventional PKCs appear generally insensitive to desensitization by sustained diacylglycerol stimulation. Consistent with this conclusion, prolonged (several-day) membrane association/activation of PKCα is seen in self-renewing epithelium of the intestine, cervix, and skin. PKCα deficiency affects gene expression, differentiation, and tumorigenesis in these tissues, highlighting the importance of mechanisms that protect PKCα from desensitization in vivo.
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Affiliation(s)
- Michelle A Lum
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Carter J Barger
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Alice H Hsu
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and
| | - Olga V Leontieva
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Adrian R Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Jennifer D Black
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950 and the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
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36
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Antal CE, Hudson AM, Kang E, Zanca C, Wirth C, Stephenson NL, Trotter EW, Gallegos LL, Miller CJ, Furnari FB, Hunter T, Brognard J, Newton AC. Cancer-associated protein kinase C mutations reveal kinase's role as tumor suppressor. Cell 2015; 160:489-502. [PMID: 25619690 PMCID: PMC4313737 DOI: 10.1016/j.cell.2015.01.001] [Citation(s) in RCA: 247] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/12/2014] [Accepted: 12/24/2014] [Indexed: 12/24/2022]
Abstract
Protein kinase C (PKC) isozymes have remained elusive cancer targets despite the unambiguous tumor promoting function of their potent ligands, phorbol esters, and the prevalence of their mutations. We analyzed 8% of PKC mutations identified in human cancers and found that, surprisingly, most were loss of function and none were activating. Loss-of-function mutations occurred in all PKC subgroups and impeded second-messenger binding, phosphorylation, or catalysis. Correction of a loss-of-function PKCβ mutation by CRISPR-mediated genome editing in a patient-derived colon cancer cell line suppressed anchorage-independent growth and reduced tumor growth in a xenograft model. Hemizygous deletion promoted anchorage-independent growth, revealing that PKCβ is haploinsufficient for tumor suppression. Several mutations were dominant negative, suppressing global PKC signaling output, and bioinformatic analysis suggested that PKC mutations cooperate with co-occurring mutations in cancer drivers. These data establish that PKC isozymes generally function as tumor suppressors, indicating that therapies should focus on restoring, not inhibiting, PKC activity.
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Affiliation(s)
- Corina E Antal
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Andrew M Hudson
- Signalling Networks in Cancer Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK
| | - Emily Kang
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA
| | - Ciro Zanca
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA
| | - Christopher Wirth
- Applied Computational Biology and Bioinformatics Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK
| | - Natalie L Stephenson
- Signalling Networks in Cancer Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK
| | - Eleanor W Trotter
- Signalling Networks in Cancer Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK
| | - Lisa L Gallegos
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA; Biomedical Sciences Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Crispin J Miller
- Applied Computational Biology and Bioinformatics Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK
| | - Frank B Furnari
- Ludwig Institute for Cancer Research, University of California at San Diego, La Jolla, CA 92093, USA
| | | | - John Brognard
- Signalling Networks in Cancer Group, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, UK.
| | - Alexandra C Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093, USA.
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37
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Nakagawa R, Vukovic M, Tarafdar A, Cosimo E, Dunn K, McCaig AM, Holroyd A, McClanahan F, Ramsay AG, Gribben JG, Michie AM. Generation of a poor prognostic chronic lymphocytic leukemia-like disease model: PKCα subversion induces up-regulation of PKCβII expression in B lymphocytes. Haematologica 2015; 100:499-510. [PMID: 25616575 DOI: 10.3324/haematol.2014.112276] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Overwhelming evidence identifies the microenvironment as a critical factor in the development and progression of chronic lymphocytic leukemia, underlining the importance of developing suitable translational models to study the pathogenesis of the disease. We previously established that stable expression of kinase dead protein kinase C alpha in hematopoietic progenitor cells resulted in the development of a chronic lymphocytic leukemia-like disease in mice. Here we demonstrate that this chronic lymphocytic leukemia model resembles the more aggressive subset of chronic lymphocytic leukemia, expressing predominantly unmutated immunoglobulin heavy chain genes, with upregulated tyrosine kinase ZAP-70 expression and elevated ERK-MAPK-mTor signaling, resulting in enhanced proliferation and increased tumor load in lymphoid organs. Reduced function of PKCα leads to an up-regulation of PKCβII expression, which is also associated with a poor prognostic subset of human chronic lymphocytic leukemia samples. Treatment of chronic lymphocytic leukemia-like cells with the selective PKCβ inhibitor enzastaurin caused cell cycle arrest and apoptosis both in vitro and in vivo, and a reduction in the leukemic burden in vivo. These results demonstrate the importance of PKCβII in chronic lymphocytic leukemia-like disease progression and suggest a role for PKCα subversion in creating permissive conditions for leukemogenesis.
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Affiliation(s)
- Rinako Nakagawa
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow The Babraham Institute, Cambridge
| | - Milica Vukovic
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow MRC Centre for Regenerative Medicine, University of Edinburgh
| | - Anuradha Tarafdar
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
| | - Emilio Cosimo
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
| | - Karen Dunn
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
| | - Alison M McCaig
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
| | - Ailsa Holroyd
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
| | - Fabienne McClanahan
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London
| | - Alan G Ramsay
- Department of Haemato-Oncology, King's College London, UK
| | - John G Gribben
- Centre for Haemato-Oncology, Barts Cancer Institute, Queen Mary University of London
| | - Alison M Michie
- Institute of Cancer Sciences, College of Medical, Veterinary & Life Sciences, University of Glasgow
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Garg R, Benedetti LG, Abera MB, Wang H, Abba M, Kazanietz MG. Protein kinase C and cancer: what we know and what we do not. Oncogene 2014; 33:5225-37. [PMID: 24336328 DOI: 10.1038/onc.2013.524] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/20/2013] [Accepted: 10/20/2013] [Indexed: 02/08/2023]
Abstract
Since their discovery in the late 1970s, protein kinase C (PKC) isozymes represent one of the most extensively studied signaling kinases. PKCs signal through multiple pathways and control the expression of genes relevant for cell cycle progression, tumorigenesis and metastatic dissemination. Despite the vast amount of information concerning the mechanisms that control PKC activation and function in cellular models, the relevance of individual PKC isozymes in the progression of human cancer is still a matter of controversy. Although the expression of PKC isozymes is altered in multiple cancer types, the causal relationship between such changes and the initiation and progression of the disease remains poorly defined. Animal models developed in the last years helped to better understand the involvement of individual PKCs in various cancer types and in the context of specific oncogenic alterations. Unraveling the enormous complexity in the mechanisms by which PKC isozymes have an impact on tumorigenesis and metastasis is key for reassessing their potential as pharmacological targets for cancer treatment.
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Affiliation(s)
- R Garg
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - L G Benedetti
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M B Abera
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - H Wang
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Abba
- Centro de Investigaciones Inmunológicas Básicas y Aplicadas (CINIBA), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M G Kazanietz
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Galea GL, Meakin LB, Williams CM, Hulin-Curtis SL, Lanyon LE, Poole AW, Price JS. Protein kinase Cα (PKCα) regulates bone architecture and osteoblast activity. J Biol Chem 2014; 289:25509-22. [PMID: 25070889 PMCID: PMC4162157 DOI: 10.1074/jbc.m114.580365] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bones' strength is achieved and maintained through adaptation to load bearing. The role of the protein kinase PKCα in this process has not been previously reported. However, we observed a phenotype in the long bones of Prkca−/− female but not male mice, in which bone tissue progressively invades the medullary cavity in the mid-diaphysis. This bone deposition progresses with age and is prevented by disuse but unaffected by ovariectomy. Castration of male Prkca−/− but not WT mice results in the formation of small amounts of intramedullary bone. Osteoblast differentiation markers and Wnt target gene expression were up-regulated in osteoblast-like cells derived from cortical bone of female Prkca−/− mice compared with WT. Additionally, although osteoblastic cells derived from WT proliferate following exposure to estradiol or mechanical strain, those from Prkca−/− mice do not. Female Prkca−/− mice develop splenomegaly and reduced marrow GBA1 expression reminiscent of Gaucher disease, in which PKC involvement has been suggested previously. From these data, we infer that in female mice, PKCα normally serves to prevent endosteal bone formation stimulated by load bearing. This phenotype appears to be suppressed by testicular hormones in male Prkca−/− mice. Within osteoblastic cells, PKCα enhances proliferation and suppresses differentiation, and this regulation involves the Wnt pathway. These findings implicate PKCα as a target gene for therapeutic approaches in low bone mass conditions.
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Affiliation(s)
- Gabriel L Galea
- From the School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom and
| | - Lee B Meakin
- From the School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom and
| | - Christopher M Williams
- the School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Sarah L Hulin-Curtis
- From the School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom and
| | - Lance E Lanyon
- From the School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom and
| | - Alastair W Poole
- the School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Joanna S Price
- From the School of Veterinary Sciences, University of Bristol, Bristol BS2 8EJ, United Kingdom and
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Pysz MA, Hao F, Hizli AA, Lum MA, Swetzig WM, Black AR, Black JD. Differential regulation of cyclin D1 expression by protein kinase C α and ϵ signaling in intestinal epithelial cells. J Biol Chem 2014; 289:22268-83. [PMID: 24914206 DOI: 10.1074/jbc.m114.571554] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Cellular accumulation of cyclin D1, a key regulator of cell proliferation and tumorigenesis, is subject to tight control. Our previous studies have identified PKCα as a negative regulator of cyclin D1 in the intestinal epithelium. However, treatment of non-transformed IEC-18 ileal crypt cells with PKC agonists has a biphasic effect on cyclin D1 expression. Initial PKCα-mediated down-regulation is followed by recovery and subsequent accumulation of the cyclin to levels markedly higher than those seen in untreated cells. Using protein overexpression strategies, siRNA, and pharmacological inhibitors, we now demonstrate that the recovery and hyperinduction of cyclin D1 reflect the combined effects of (a) loss of negative signals from PKCα due to agonist-induced PKCα down-regulation and (b) positive effects of PKCϵ. PKCϵ-mediated up-regulation of cyclin D1 requires sustained ERK stimulation and transcriptional activation of the proximal cyclin D1 (CCDN1) promoter, without apparent involvement of changes in protein stability or translation. PKCϵ also up-regulates cyclin D1 expression in colon cancer cells, through mechanisms that parallel those in IEC-18 cells. Although induction of cyclin D1 by PKCϵ is dependent on non-canonical NF-κB activation, the NF-κB site in the proximal promoter is not required. Instead, cyclin D1 promoter activity is regulated by a novel interaction between NF-κB and factors that associate with the cyclic AMP-response element adjacent to the NF-κB site. The differential effects of PKCα and PKCϵ on cyclin D1 accumulation are likely to contribute to the opposing tumor-suppressive and tumor-promoting activities of these PKC family members in the intestinal epithelium.
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Affiliation(s)
- Marybeth A Pysz
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Fang Hao
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - A Asli Hizli
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Michelle A Lum
- From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198 and
| | - Wendy M Swetzig
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263
| | - Adrian R Black
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198 and
| | - Jennifer D Black
- the Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263From the Eppley Institute for Research in Cancer and Allied Diseases and the Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska 68198 and
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Abstract
Protein kinase C (PKC) is a family of phospholipid-dependent serine/threonine kinases, which can be further classified into three PKC isozymes subfamilies: conventional or classic, novel or nonclassic, and atypical. PKC isozymes are known to be involved in cell proliferation, survival, invasion, migration, apoptosis, angiogenesis, and drug resistance. Because of their key roles in cell signaling, PKC isozymes also have the potential to be promising therapeutic targets for several diseases, such as cardiovascular diseases, immune and inflammatory diseases, neurological diseases, metabolic disorders, and multiple types of cancer. This review primarily focuses on the activation, mechanism, and function of PKC isozymes during cancer development and progression.
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The ABC of BTC: structural properties and biological roles of betacellulin. Semin Cell Dev Biol 2014; 28:42-8. [PMID: 24440602 DOI: 10.1016/j.semcdb.2014.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 01/08/2014] [Indexed: 12/17/2022]
Abstract
Betacellulin was initially detected as a growth-promoting factor in the conditioned medium of a mouse pancreatic β-cell tumor cell line. Sequencing of the purified protein and of the cloned cDNA supported the assumption that betacellulin is a new ligand of the epidermal growth factor receptor (EGFR), which was later confirmed experimentally. As a typical EGFR ligand, betacellulin is expressed by a variety of cell types and tissues, and the soluble growth factor is proteolytically cleaved from a larger membrane-anchored precursor. Importantly, BTC can - in addition to the EGFR - bind and activate all possible heterodimeric combinations of the related ERBB receptors including the highly oncogenic ERBB2/3 dimer, as well as homodimers of ERBB4. While a large number of studies attest a role for betacellulin in the differentiation of pancreatic β-cells, the last decade witnessed the association of betacellulin with a large number of additional biological processes, ranging from reproduction to the control of neural stem cells.
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Hartjen P, Höchst B, Heim D, von der Kammer H, Lucke J, Reinholz M, Baier A, Smeets R, Wege H, Borowski P, Schulze Zur Wiesch J. The NTPase/helicase domain of hepatitis C virus nonstructural protein 3 inhibits protein kinase C independently of its NTPase activity. Cell Mol Biol Lett 2013; 18:447-58. [PMID: 23893289 PMCID: PMC6275940 DOI: 10.2478/s11658-013-0099-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 07/17/2013] [Indexed: 11/20/2022] Open
Abstract
Helicase motif VI is a short arginine-rich motif within the NTPase/helicase domain of the non-structural protein 3 (NS3) of the hepatitis C virus (HCV). We previously demonstrated that it reduces the catalytic activity and intracellular shuttling of protein kinase C (PKC). Thus, NS3-mediated PKC inhibition may be involved in HCV-associated hepatocellular carcinoma (HCC). In this study, we expand on our earlier results, which were obtained in experiments with short fragments of NS3, to show for the first time that the catalytically active, longer C-terminal NTPase/helicase of NS3 acts as a potent PKC inhibitor in vitro. PKC inhibition assays with the NTPase-inactive mutant NS3h-D1316A revealed a mixed type kinetic inhibition pattern. A broad range of 11 PKC isotypes was tested and all of the PKC isotypes were inhibited with IC₅₀-values in the low micromolar range. These findings were confirmed for the wild-type NTPase/helicase domain in a non-radiometric PKC inhibition assay with ATP regeneration to rule out any effect of ATP hydrolysis caused by its NTPase activity. PKCα was inhibited with a micromolar IC₅₀ in this assay, which compares well with our result for NS3h-D1316A (IC₅₀ = 0.7 μM). In summary, these results confirm that catalytically active NS3 NTPase/helicase can act in an analogous manner to shorter NS3 fragments as a pseudosubstrate inhibitor of PKC.
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Affiliation(s)
- Philip Hartjen
- Department of Virology, Bernhard-Nocht-Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany.
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Protein kinase C zeta regulates human pancreatic cancer cell transformed growth and invasion through a STAT3-dependent mechanism. PLoS One 2013; 8:e72061. [PMID: 24015205 PMCID: PMC3756013 DOI: 10.1371/journal.pone.0072061] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 07/05/2013] [Indexed: 12/25/2022] Open
Abstract
Pancreatic cancer is a very aggressive disease with few therapeutic options. In this study, we investigate the role of protein kinase C zeta (PKCζ) in pancreatic cancer cells. PKCζ has been shown to act as either a tumor suppressor or tumor promoter depending upon the cellular context. We find that PKCζ expression is either maintained or elevated in primary human pancreatic tumors, but is never lost, consistent with PKCζ playing a promotive role in the pancreatic cancer phenotype. Genetic inhibition of PKCζ reduced adherent growth, cell survival and anchorage-independent growth of human pancreatic cancer cells in vitro. Furthermore, PKCζ inhibition reduced orthotopic tumor size in vivo by inhibiting tumor cell proliferation and increasing tumor necrosis. In addition, PKCζ inhibition reduced tumor metastases in vivo, and caused a corresponding reduction in pancreatic cancer cell invasion in vitro. Signal transducer and activator of transcription 3 (STAT3) is often constitutively active in pancreatic cancer, and plays an important role in pancreatic cancer cell survival and metastasis. Interestingly, inhibition of PKCζ significantly reduced constitutive STAT3 activation in pancreatic cancer cells in vitro and in vivo. Pharmacologic inhibition of STAT3 mimicked the phenotype of PKCζ inhibition, and expression of a constitutively active STAT3 construct rescued the transformed phenotype in PKCζ-deficient cells. We conclude that PKCζ is required for pancreatic cancer cell transformed growth and invasion in vitro and tumorigenesis in vivo, and that STAT3 is an important downstream mediator of the pro-carcinogenic effects of PKCζ in pancreatic cancer cells.
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Protein kinase Cα suppresses Kras-mediated lung tumor formation through activation of a p38 MAPK-TGFβ signaling axis. Oncogene 2013; 33:2134-44. [PMID: 23604119 DOI: 10.1038/onc.2013.147] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 03/08/2013] [Accepted: 03/11/2013] [Indexed: 12/29/2022]
Abstract
Protein kinase C alpha (PKCα) can activate both pro- and anti-tumorigenic signaling depending upon cellular context. Here, we investigated the role of PKCα in lung tumorigenesis in vivo. Gene expression data sets revealed that primary human non-small lung cancers (NSCLC) express significantly decreased PKCα levels, indicating that loss of PKCα expression is a recurrent event in NSCLC. We evaluated the functional relevance of PKCα loss during lung tumorigenesis in three murine lung adenocarcinoma models (LSL-Kras, LA2-Kras and urethane exposure). Genetic deletion of PKCα resulted in a significant increase in lung tumor number, size, burden and grade, bypass of oncogene-induced senescence, progression from adenoma to carcinoma and a significant decrease in survival in vivo. The tumor promoting effect of PKCα loss was reflected in enhanced Kras-mediated expansion of bronchio-alveolar stem cells (BASCs), putative tumor-initiating cells, both in vitro and in vivo. LSL-Kras/Prkca(-/-) mice exhibited a decrease in phospho-p38 MAPK in BASCs in vitro and in tumors in vivo, and treatment of LSL-Kras BASCs with a p38 inhibitor resulted in increased colony size indistinguishable from that observed in LSL-Kras/Prkca(-/-) BASCs. In addition, LSL-Kras/Prkca(-/-) BASCs exhibited a modest but reproducible increase in TGFβ1 mRNA, and addition of exogenous TGFβ1 to LSL-Kras BASCs results in enhanced growth similar to untreated BASCs from LSL-Kras/Prkca(-/-) mice. Conversely, a TGFβR1 inhibitor reversed the effects of PKCα loss in LSL-Kras/Prkca(-/-) BASCs. Finally, we identified the inhibitors of DNA binding (Id) Id1-3 and the Wilm's Tumor 1 as potential downstream targets of PKCα-dependent tumor suppressor activity in vitro and in vivo. We conclude that PKCα suppresses tumor initiation and progression, at least in part, through a PKCα-p38MAPK-TGFβ signaling axis that regulates tumor cell proliferation and Kras-induced senescence. Our results provide the first direct evidence that PKCα exhibits tumor suppressor activity in the lung in vivo.
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do Carmo A, Balça-Silva J, Matias D, Lopes MC. PKC signaling in glioblastoma. Cancer Biol Ther 2013; 14:287-94. [PMID: 23358475 PMCID: PMC3667867 DOI: 10.4161/cbt.23615] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 01/14/2013] [Accepted: 01/15/2013] [Indexed: 01/11/2023] Open
Abstract
Glioblastoma Multiforme (GBM) is the most aggressive brain tumor characterized by intratumoral heterogeneity at cytopathological, genomic and transcriptional levels. Despite the efforts to develop new therapeutic strategies the median survival of GBM patients is 12-14 months. Results from large-scale gene expression profile studies confirmed that the genetic alterations in GBM affect pathways controlling cell cycle progression, cellular proliferation and survival and invasion ability, which may explain the difficulty to treat GBM patients. One of the signaling pathways that contribute to the aggressive behavior of glioma cells is the protein kinase C (PKC) pathway. PKC is a family of serine/threonine-specific protein kinases organized into three groups according the activating domains. Due to the variability of actions controlled by PKC isoforms, its contribution to the development of GBM is poorly understood. This review intends to highlight the contribution of PKC isoforms to proliferation, survival and invasive ability of glioma cells.
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Affiliation(s)
- Anália do Carmo
- Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
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Lum MA, Pundt KE, Paluch BE, Black AR, Black JD. Agonist-induced down-regulation of endogenous protein kinase c α through an endolysosomal mechanism. J Biol Chem 2013; 288:13093-109. [PMID: 23508961 DOI: 10.1074/jbc.m112.437061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Protein kinase C (PKC) isozymes undergo down-regulation upon sustained stimulation. Previous studies have pointed to the existence of both proteasome-dependent and -independent pathways of PKCα processing. Here we demonstrate that these down-regulation pathways are engaged in different subcellular compartments; proteasomal degradation occurs mainly at the plasma membrane, whereas non-proteasomal processing occurs in the perinuclear region. Using cholesterol depletion, pharmacological inhibitors, RNA interference, and dominant-negative mutants, we define the mechanisms involved in perinuclear accumulation of PKCα and identify the non-proteasomal mechanism mediating its degradation. We show that intracellular accumulation of PKCα involves at least two clathrin-independent, cholesterol/lipid raft-mediated pathways that do not require ubiquitination of the protein; one is dynamin-dependent and likely involves caveolae, whereas the other is dynamin- and small GTPase-independent. Internalized PKCα traffics through endosomes and is delivered to the lysosome for degradation. Supportive evidence includes (a) detection of the enzyme in EEA1-positive early endosomes, Rab7-positive late endosomes/multivesicular bodies, and LAMP1-positive lysosomes and (b) inhibition of its down-regulation by lysosome-disrupting agents and leupeptin. Only limited dephosphorylation of PKCα occurs during trafficking, with fully mature enzyme being the main target for lysosomal degradation. These studies define a novel and widespread mechanism of desensitization of PKCα signaling that involves endocytic trafficking and lysosome-mediated degradation of the mature, fully phosphorylated protein.
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Affiliation(s)
- Michelle A Lum
- The Eppley Institute, University of Nebraska Medical Center, Omaha, Nebraska 68198-5950, USA
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Lin SC, Chen WY, Lin KY, Chen SH, Chang CC, Lin SE, Fang CL. Clinicopathological correlation and prognostic significance of protein kinase cα overexpression in human gastric carcinoma. PLoS One 2013; 8:e56675. [PMID: 23468872 PMCID: PMC3582558 DOI: 10.1371/journal.pone.0056675] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 01/16/2013] [Indexed: 01/24/2023] Open
Abstract
OBJECTIVES This study investigated the PKCα protein expression in gastric carcinoma, and correlated it with clinicopathological parameters. The prognostic significance of PKCα protein expression in gastric carcinoma was analyzed. METHODS Quantitative real-time PCR test was applied to compare the PKCα mRNA expression in tumorous and nontumorous tissues of gastric carcinoma in ten randomly selected cases. Then PKCα protein expression was evaluated in 215 cases of gastric carcinoma using immunohistochemical method. The immunoreactivity was scored semiquantitatively as: 0 = absent; 1 = weak; 2 = moderate; and 3 = strong. All cases were further classified into two groups, namely PKCα overexpression group with score 2 or 3, and non-overexpression group with score 0 or 1. The PKCα protein expression was correlated with clinicopathological parameters. Survival analysis was performed to determine the prognostic significance of PKCα protein expression in patients with gastric carcinoma. RESULTS PKCα mRNA expression was upregulated in all ten cases of gastric carcinoma via quantitative real-time PCR test. In immunohistochemical study, eighty-eight out of 215 cases (41%) of gastric carcinoma revealed PKCα protein overexpression, which was statistically correlated with age (P = 0.0073), histologic type (P<0.0001), tumor differentiation (P = 0.0110), depth of invasion (P = 0.0003), angiolymphatic invasion (P = 0.0373), pathologic stage (P = 0.0047), and distant metastasis (P = 0.0048). We found no significant difference in overall and disease free survival rates between PKCα overexpression and non-overexpression groups (P = 0.0680 and 0.0587). However, PKCα protein overexpression emerged as a significant independent prognostic factor in multivariate Cox regression analysis (hazard ratio 0.632, P = 0.0415). CONCLUSIONS PKCα protein is upregulated in gastric carcinoma. PKCα protein expression is statistically correlated with age, histologic type, tumor differentiation, depth of invasion, angiolymphatic invasion, pathologic stage, and distant metastasis. The PKCα protein overexpression in patients with gastric carcinoma is a significant independent prognostic factor in multivariate Cox regression analysis.
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Affiliation(s)
- Shee-Chan Lin
- Division of Gastroenterology, Department of Internal Medicine, Mackay Memorial Hospital, Taipei, Taiwan
| | - Wei-Yu Chen
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Kai-Yuan Lin
- Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan
- Department of Biotechnology, Chia Nan University of Pharmacy and Science, Tainan, Taiwan
| | - Sheng-Hsuan Chen
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Gastroenterology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chun-Chao Chang
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Gastroenterology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Sey-En Lin
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Department of Pathology, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chia-Lang Fang
- Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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Black AR, Black JD. Protein kinase C signaling and cell cycle regulation. Front Immunol 2013; 3:423. [PMID: 23335926 PMCID: PMC3547298 DOI: 10.3389/fimmu.2012.00423] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 12/21/2012] [Indexed: 12/20/2022] Open
Abstract
A link between T cell proliferation and the protein kinase C (PKC) family of serine/threonine kinases has been recognized for about 30 years. However, despite the wealth of information on PKC-mediated control of, T cell activation, understanding of the effects of PKCs on the cell cycle machinery in this cell type remains limited. Studies in other systems have revealed important cell cycle-specific effects of PKC signaling that can either positively or negatively impact proliferation. The outcome of PKC activation is highly context-dependent, with the precise cell cycle target(s) and overall effects determined by the specific isozyme involved, the timing of PKC activation, the cell type, and the signaling environment. Although PKCs can regulate all stages of the cell cycle, they appear to predominantly affect G0/G1 and G2. PKCs can modulate multiple cell cycle regulatory molecules, including cyclins, cyclin-dependent kinases (cdks), cdk inhibitors and cdc25 phosphatases; however, evidence points to Cip/Kip cdk inhibitors and D-type cyclins as key mediators of PKC-regulated cell cycle-specific effects. Several PKC isozymes can target Cip/Kip proteins to control G0/G1 → S and/or G2 → M transit, while effects on D-type cyclins regulate entry into and progression through G1. Analysis of PKC signaling in T cells has largely focused on its roles in T cell activation; thus, observed cell cycle effects are mainly positive. A prominent role is emerging for PKCθ, with non-redundant functions of other isozymes also described. Additional evidence points to PKCδ as a negative regulator of the cell cycle in these cells. As in other cell types, context-dependent effects of individual isozymes have been noted in T cells, and Cip/Kip cdk inhibitors and D-type cyclins appear to be major PKC targets. Future studies are anticipated to take advantage of the similarities between these various systems to enhance understanding of PKC-mediated cell cycle regulation in T cells.
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Affiliation(s)
- Adrian R Black
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center Omaha, NE, USA
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50
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Involvement of PKCα activation in TF/VIIa/PAR2-induced proliferation, migration, and survival of colon cancer cell SW620. Tumour Biol 2012; 34:837-46. [DOI: 10.1007/s13277-012-0614-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/28/2012] [Indexed: 02/08/2023] Open
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