1
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Taguchi Y, Nakaya T, Aizawa K, Noguchi Y, Maiya N, Iwamoto C, Ohba K, Sugawara M, Murata M, Nagai R, Kano F. Peptide mimetic NC114 induces growth arrest by preventing PKCδ activation and FOXM1 nuclear translocation in colorectal cancer cells. FEBS Open Bio 2024; 14:695-720. [PMID: 38425293 PMCID: PMC10988720 DOI: 10.1002/2211-5463.13784] [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: 01/28/2024] [Revised: 01/28/2024] [Accepted: 02/21/2024] [Indexed: 03/02/2024] Open
Abstract
The peptide mimetic, NC114, is a promising anticancer compound that specifically kills colorectal cancer cells without affecting normal colon epithelial cells. In our previous study, we observed that NC114 inhibited the Wnt/β-catenin pathway, with significant downregulation of both Ser 675-phosphorylated β-catenin and its target genes, cyclin D1 and survivin. However, the molecular mechanism responsible for its cytotoxic effect has not yet been fully characterized. In the present study, we demonstrated that NC114 prevented cell cycle progression from S to G2/M phase by downregulating cell cycle-related gene expression, and also induced growth arrest in SW480 and HCT-116 colorectal cancer cells. A novel covariation network analysis combined with transcriptome analysis revealed a series of signaling cascades affected by NC114 treatment, and identified protein kinase C-δ (PKCδ) and forkhead box protein M1 (FOXM1) as important regulatory factors for NC114-induced growth arrest. NC114 treatment inhibits the activation of PKCδ and its kinase activity, which suppresses MEK/ERK signaling. Attenuated MEK/ERK signaling then results in a reduction in FOXM1 phosphorylation and subsequent nuclear translocation of FOXM1 and β-catenin. Consequently, formation of a T-cell factor-4 (TCF4)/β-catenin transcription complex in the nucleus is inhibited and transcription of its target genes, such as cell cycle-related genes, is downregulated. The efficacy of NC114 on tumor growth was confirmed in a xenograft model. Collectively, elucidation of the mechanism by which NC114 induces growth arrest in colorectal cancer cells should provide a novel therapeutic strategy for colorectal cancer treatment.
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Affiliation(s)
- Yuki Taguchi
- Cell Biology Center, Institute of Innovative ResearchTokyo Institute of TechnologyYokohamaKanagawaJapan
- Multimodal Cell Analysis Collaborative Research ClusterTokyo Institute of TechnologyYokohamaKanagawaJapan
| | - Takeo Nakaya
- Department of PathologyJichi Medical UniversityShimotsukeTochigiJapan
| | - Kenichi Aizawa
- Department of Clinical PharmacologyJichi Medical UniversityShimotsukeTochigiJapan
| | - Yoshiyuki Noguchi
- Cell Biology Center, Institute of Innovative ResearchTokyo Institute of TechnologyYokohamaKanagawaJapan
- International Research Center for NeurointelligenceThe University of TokyoBunkyo‐kuTokyoJapan
| | - Nobuhiko Maiya
- Stem Cell Business Department, Healthcare Business UnitNIKON CorporationYokohamaKanagawaJapan
| | - Chisako Iwamoto
- Marketing Department, Healthcare Business UnitNIKON CorporationMinato‐kuTokyoJapan
| | - Kenichi Ohba
- Engineering Solution Business DivisionNikon System Inc.YokohamaKanagawaJapan
| | - Minoru Sugawara
- Cancer Precision Medicine CenterJapanese Foundation for Cancer ResearchKoto‐kuTokyoJapan
| | - Masayuki Murata
- Cell Biology Center, Institute of Innovative ResearchTokyo Institute of TechnologyYokohamaKanagawaJapan
- Multimodal Cell Analysis Collaborative Research ClusterTokyo Institute of TechnologyYokohamaKanagawaJapan
- International Research Center for NeurointelligenceThe University of TokyoBunkyo‐kuTokyoJapan
| | - Ryozo Nagai
- Jichi Medical UniversityShimotsukeTochigiJapan
| | - Fumi Kano
- Cell Biology Center, Institute of Innovative ResearchTokyo Institute of TechnologyYokohamaKanagawaJapan
- Multimodal Cell Analysis Collaborative Research ClusterTokyo Institute of TechnologyYokohamaKanagawaJapan
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2
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Differential roles and regulation of the protein kinases PAK4, PAK5 and PAK6 in melanoma cells. Biochem J 2022; 479:1709-1725. [PMID: 35969127 PMCID: PMC9444074 DOI: 10.1042/bcj20220184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/30/2022] [Accepted: 08/12/2022] [Indexed: 11/26/2022]
Abstract
The protein kinases PAK4, PAK5 and PAK6 comprise a family of ohnologues. In multiple cancers including melanomas PAK5 most frequently carries non-synonymous mutations; PAK6 and PAK4 have fewer; and PAK4 is often amplified. To help interpret these genomic data, initially we compared the cellular regulation of the sister kinases and their roles in melanoma cells. In common with many ohnologue protein kinases, PAK4, PAK5 and PAK6 each have two 14-3-3-binding phosphosites of which phosphoSer99 is conserved. PAK4 localises to the leading edge of cells in response to phorbol ester-stimulated binding of 14-3-3 to phosphoSer99 and phosphoSer181, which are phosphorylated by two different PKCs or PKDs. These phosphorylations of PAK4 are essential for its phorbol ester-stimulated phosphorylation of downstream substrates. In contrast, 14-3-3 interacts with PAK5 in response to phorbol ester-stimulated phosphorylation of Ser99 and epidermal growth factor-stimulated phosphorylation of Ser288; whereas PAK6 docks onto 14-3-3 and is prevented from localising to cell–cell junctions when Ser133 is phosphorylated in response to cAMP-elevating agents via PKA and insulin-like growth factor 1 via PKB/Akt. Silencing of PAK4 impairs viability, migration and invasive behaviour of melanoma cells carrying BRAFV600E or NRASQ61K mutations. These defects are rescued by ectopic expression of PAK4, more so by a 14-3-3-binding deficient PAK4, and barely by PAK5 or PAK6. Together these genomic, biochemical and cellular data suggest that the oncogenic properties of PAK4 are regulated by PKC–PKD signalling in melanoma, while PAK5 and PAK6 are dispensable in this cancer.
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3
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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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4
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Valencia FP, Marino AF, Noutsos C, Poon K. Concentration-dependent change in hypothalamic neuronal transcriptome by the dietary fatty acids: oleic and palmitic acids. J Nutr Biochem 2022; 106:109033. [DOI: 10.1016/j.jnutbio.2022.109033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 12/20/2021] [Accepted: 03/18/2022] [Indexed: 11/30/2022]
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5
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Speidel JT, Affandi T, Jones DNM, Ferrara SE, Reyland ME. Functional proteomic analysis reveals roles for PKCδ in regulation of cell survival and cell death: Implications for cancer pathogenesis and therapy. Adv Biol Regul 2020; 78:100757. [PMID: 33045516 PMCID: PMC8294469 DOI: 10.1016/j.jbior.2020.100757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/18/2022]
Abstract
Protein Kinase C-δ (PKCδ), regulates a broad group of biological functions and disease processes, including well-defined roles in immune function, cell survival and apoptosis. PKCδ primarily regulates apoptosis in normal tissues and non-transformed cells, and genetic disruption of the PRKCD gene in mice is protective in many diseases and tissue damage models. However pro-survival/pro-proliferative functions have also been described in some transformed cells and in mouse models of cancer. Recent evidence suggests that the contribution of PKCδ to specific cancers may depend in part on the oncogenic context of the tumor, consistent with its paradoxical role in cell survival and cell death. Here we will discuss what is currently known about biological functions of PKCδ and potential paradigms for PKCδ function in cancer. To further understand mechanisms of regulation by PKCδ, and to gain insight into the plasticity of PKCδ signaling, we have used functional proteomics to identify pathways that are dependent on PKCδ. Understanding how these distinct functions of PKCδ are regulated will be critical for the logical design of therapeutics to target this pathway.
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Affiliation(s)
- Jordan T Speidel
- Department of Craniofacial Biology, School of Dental Medicine, USA
| | - Trisiani Affandi
- Department of Craniofacial Biology, School of Dental Medicine, USA
| | | | - Sarah E Ferrara
- University of Colorado Comprehensive Cancer Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Mary E Reyland
- Department of Craniofacial Biology, School of Dental Medicine, USA.
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6
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Mechanisms of the Regulation and Dysregulation of Glucagon Secretion. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:3089139. [PMID: 32774668 PMCID: PMC7396046 DOI: 10.1155/2020/3089139] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 07/11/2020] [Indexed: 02/06/2023]
Abstract
Glucagon, a hormone secreted by pancreatic alpha cells, contributes to the maintenance of normal blood glucose concentration by inducing hepatic glucose production in response to declining blood glucose. However, glucagon hypersecretion contributes to the pathogenesis of type 2 diabetes. Moreover, diabetes is associated with relative glucagon undersecretion at low blood glucose and oversecretion at normal and high blood glucose. The mechanisms of such alpha cell dysfunctions are not well understood. This article reviews the genesis of alpha cell dysfunctions during the pathogenesis of type 2 diabetes and after the onset of type 1 and type 2 diabetes. It unravels a signaling pathway that contributes to glucose- or hydrogen peroxide-induced glucagon secretion, whose overstimulation contributes to glucagon dysregulation, partly through oxidative stress and reduced ATP synthesis. The signaling pathway involves phosphatidylinositol-3-kinase, protein kinase B, protein kinase C delta, non-receptor tyrosine kinase Src, and phospholipase C gamma-1. This knowledge will be useful in the design of new antidiabetic agents or regimens.
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7
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Pleiotropic Roles of Calmodulin in the Regulation of KRas and Rac1 GTPases: Functional Diversity in Health and Disease. Int J Mol Sci 2020; 21:ijms21103680. [PMID: 32456244 PMCID: PMC7279331 DOI: 10.3390/ijms21103680] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/18/2020] [Accepted: 05/21/2020] [Indexed: 12/21/2022] Open
Abstract
Calmodulin is a ubiquitous signalling protein that controls many biological processes due to its capacity to interact and/or regulate a large number of cellular proteins and pathways, mostly in a Ca2+-dependent manner. This complex interactome of calmodulin can have pleiotropic molecular consequences, which over the years has made it often difficult to clearly define the contribution of calmodulin in the signal output of specific pathways and overall biological response. Most relevant for this review, the ability of calmodulin to influence the spatiotemporal signalling of several small GTPases, in particular KRas and Rac1, can modulate fundamental biological outcomes such as proliferation and migration. First, direct interaction of calmodulin with these GTPases can alter their subcellular localization and activation state, induce post-translational modifications as well as their ability to interact with effectors. Second, through interaction with a set of calmodulin binding proteins (CaMBPs), calmodulin can control the capacity of several guanine nucleotide exchange factors (GEFs) to promote the switch of inactive KRas and Rac1 to an active conformation. Moreover, Rac1 is also an effector of KRas and both proteins are interconnected as highlighted by the requirement for Rac1 activation in KRas-driven tumourigenesis. In this review, we attempt to summarize the multiple layers how calmodulin can regulate KRas and Rac1 GTPases in a variety of cellular events, with biological consequences and potential for therapeutic opportunities in disease settings, such as cancer.
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8
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Faller DV. Response to "Selective PKCδ Inhibitor B106 Elicits Uveal Melanoma Growth Inhibitory Effects Independent of Activated PKC Isoforms". ACS Chem Biol 2019; 14:131. [PMID: 30525445 DOI: 10.1021/acschembio.8b00959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Douglas V. Faller
- Boston University, Cancer Center 80 East Concord St, Boston, Massachusetts 02118, United States
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9
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Stevenson M, Lines KE, Thakker RV. Molecular Genetic Studies of Pancreatic Neuroendocrine Tumors: New Therapeutic Approaches. Endocrinol Metab Clin North Am 2018; 47:525-548. [PMID: 30098714 PMCID: PMC7614857 DOI: 10.1016/j.ecl.2018.04.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pancreatic neuroendocrine tumors (PNETs) arise sporadically or as part of familial syndromes. Genetic studies of hereditary syndromes and whole exome sequencing analysis of sporadic NETs have revealed the roles of some genes involved in PNET tumorigenesis. The multiple endocrine neoplasia type 1 (MEN1) gene is most commonly mutated. Its encoded protein, menin, has roles in transcriptional regulation, genome stability, DNA repair, protein degradation, cell motility and adhesion, microRNA biogenesis, cell division, cell cycle control, and epigenetic regulation. Therapies targeting epigenetic regulation and MEN1 gene replacement have been reported to be effective in preclinical models.
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Affiliation(s)
- Mark Stevenson
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7LJ, UK
| | - Kate E Lines
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7LJ, UK
| | - Rajesh V Thakker
- Radcliffe Department of Medicine, Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), University of Oxford, Churchill Hospital, Headington, Oxford OX3 7LJ, UK.
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10
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Ganapathy S, Peng B, Shen L, Yu T, Lafontant J, Li P, Xiong R, Makriyannis A, Chen C. Suppression of PKC causes oncogenic stress for triggering apoptosis in cancer cells. Oncotarget 2018; 8:30992-31002. [PMID: 28415683 PMCID: PMC5458183 DOI: 10.18632/oncotarget.16047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/28/2017] [Indexed: 12/22/2022] Open
Abstract
Gain of functional mutations in ras occurs in more than 30% of human malignancies and in particular 90% of pancreatic cancer. Mutant ras, via activating multiple effector pathways, not only promote cell growth or survival, but also apoptosis, depending upon cell types or circumstances. In order to further study the mechanisms of apoptosis induced by oncogenic ras, we employed the ras loop mutant genes and demonstrated that Akt functioned downstream of Ras in human pancreatic cancer or HPNE cells ectopically expressing mutated K-ras for the induction of apoptosis after the concurrent suppression of PKC α and β. In this apoptotic process, the redox machinery was aberrantly switched on in the pancreatic cancer cells as well as prostate cancer DU145 cells. p73 was phosphorylated and translocated to the nucleus, accompanied with UPR activation and induction of apoptosis. The in vitro results were corroborated by the in vivo data. Thus, our study indicated that PKC α and β appeared coping with oncogenic Ras or mutated Akt to maintain the balance of the homeostasis in cancer cells. Once these PKC isoforms were suppressed, the redox state in the cancer cells was disrupted, which elicited persistent oncogenic stress and subsequent apoptotic crisis.
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Affiliation(s)
| | - Bo Peng
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Ling Shen
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Tianqi Yu
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Jean Lafontant
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Ping Li
- The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg, Sweden
| | - Rui Xiong
- The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg, Sweden
| | | | - Changyan Chen
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
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11
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Mohl BP, Emmott E, Roy P. Phosphoproteomic Analysis Reveals the Importance of Kinase Regulation During Orbivirus Infection. Mol Cell Proteomics 2017; 16:1990-2005. [PMID: 28851738 PMCID: PMC5672004 DOI: 10.1074/mcp.m117.067355] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/08/2017] [Indexed: 01/03/2023] Open
Abstract
Bluetongue virus (BTV) causes infections in wild and domesticated ruminants with high morbidity and mortality and is responsible for significant economic losses in both developing and developed countries. BTV serves as a model for the study of other members of the Orbivirus genus. Previously, the importance of casein kinase 2 for BTV replication was demonstrated. To identify intracellular signaling pathways and novel host-cell kinases involved during BTV infection, the phosphoproteome of BTV infected cells was analyzed. Over 1000 phosphosites were identified using mass spectrometry, which were then used to determine the corresponding kinases involved during BTV infection. This analysis yielded protein kinase A (PKA) as a novel kinase activated during BTV infection. Subsequently, the importance of PKA for BTV infection was validated using a PKA inhibitor and activator. Our data confirmed that PKA was essential for efficient viral growth. Further, we showed that PKA is also required for infection of equid cells by African horse sickness virus, another member of the Orbivirus genus. Thus, despite their preference in specific host species, orbiviruses may utilize the same host signaling pathways during their replication.
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Affiliation(s)
- Bjorn-Patrick Mohl
- From the ‡Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Edward Emmott
- §University of Cambridge, Division of Virology, Department of Pathology, Lab block level 5, Box 237, Addenbrookes Hospital, Cambridge, UK
| | - Polly Roy
- From the ‡Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK;
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12
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Co-dependency of PKCδ and K-Ras: inverse association with cytotoxic drug sensitivity in KRAS mutant lung cancer. Oncogene 2017; 36:4370-4378. [PMID: 28368426 PMCID: PMC5532068 DOI: 10.1038/onc.2017.27] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 12/15/2016] [Accepted: 01/11/2017] [Indexed: 12/29/2022]
Abstract
Recent studies suggest that the presence of a KRAS mutation may be insufficient for defining a clinically homogenous molecular group, as many KRAS mutant tumors lose reliance on K-Ras for survival. Identifying pathways that support K-Ras dependency may define clinically relevant KRAS sub-groups and lead to the identification of new drug targets. We have analyzed a panel of 17 KRAS mutant lung cancer cell lines classified as K-Ras dependent or independent, for co-dependency on PKCδ. We show that functional dependency on K-Ras and PKCδ co-segregate, and that dependency correlates with a more epithelial-like phenotype. Furthermore, we show that the pro-apoptotic and pro-tumorigenic functions of PKCδ also segregate based on K-Ras dependency, as K-Ras independent cells are more sensitive to topoisomerase inhibitors, and depletion of PKCδ in this sub-group suppresses apoptosis through increased activation of ERK. In contrast, K-Ras dependent lung cancer cells are largely insensitive to topoisomerase inhibitors, and depletion of PKCδ can increase apoptosis and decrease activation of ERK in this sub-group. We have previously shown that nuclear translocation of PKCδ is necessary and sufficient for pro-apoptotic signaling. Our current studies show that K-Ras dependent cells are refractive to PKCδ driven apoptosis. Analysis of this sub-group showed increased PKCδ expression and an increase in the nuclear:cytoplasmic ratio of PKCδ. In addition, targeting PKCδ to the nucleus induces apoptosis in K-Ras independent, but not K-Ras dependent NSCLC cells. Our studies provide tools for identification of the subset of patients with KRAS mutant tumors most amenable to targeting of the K-Ras pathway, and identify PKCδ as a potential target in this tumor population. These sub-groups are likely to be of clinical relevance, as high PKCδ expression correlates with increased overall survival and a more epithelial tumor phenotype in patients with KRAS mutant lung adenocarcinomas.
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13
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Ganapathy S, Li P, Lafontant J, Xiong R, Yu T, Zhang G, Chen C. Chromium IV exposure, via Src/Ras signaling, promotes cell transformation. Mol Carcinog 2017; 56:1808-1815. [PMID: 28218450 DOI: 10.1002/mc.22639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 02/13/2017] [Accepted: 02/16/2017] [Indexed: 01/01/2023]
Abstract
Hexavalent chromium [Cr(VI)] is a well-known environment carcinogen. The exposure of Cr(VI) through contaminated soil, air particles, and drinking water is a strong concern for the public health worldwide. While many studies have been done, it remains unclear which intracellular molecules transduce Cr(VI)-mediated carcinogenic signaling in cells to promote cancer. In this study, we demonstrated that upon Cr(VI) treatment, the intracellular receptor src was activated, which further upregulated Ras activity, leading to the augmentation of ROS and onset of ER stress in human lung epithelial BEAS-2B or keratinocytes. These cells were formed colonies in soft agar cultures following the persistent Cr(VI) treatment. Furthermore, anti-apoptotic factor Bcl-2 was upregulated and activated in the colonies. Thus, our study suggests that Cr(VI), though activating the src and Ras signaling axis, perturbs redox state and invokes ER stress for the establishment of carcinogenic actions in the cells. In this process, Bcl-2 appears playing an important role. By uncovering these intracellular targets, our study may help developing novel strategies for better environmental protection, especially in areas contaminated or polluted by Cr(VI) as well as for effective cancer treatments.
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Affiliation(s)
- Suthakar Ganapathy
- Center for Drug Development, Northeastern University, Boston, Massachusetts
| | - Ping Li
- The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China.,The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg, Sweden
| | - Jean Lafontant
- Center for Drug Development, Northeastern University, Boston, Massachusetts
| | - Rui Xiong
- The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg, Sweden
| | - Tianqi Yu
- Center for Drug Development, Northeastern University, Boston, Massachusetts
| | - Guojun Zhang
- The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Changyan Chen
- Center for Drug Development, Northeastern University, Boston, Massachusetts
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14
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Ganapathy S, Fagman JB, Shen L, Yu T, Zhou X, Dai W, Makriyannis A, Chen C. Ral A, via activating the mitotic checkpoint, sensitizes cells lacking a functional Nf1 to apoptosis in the absence of protein kinase C. Oncotarget 2016; 7:84326-84337. [PMID: 27741517 PMCID: PMC5356664 DOI: 10.18632/oncotarget.12607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/04/2016] [Indexed: 01/08/2023] Open
Abstract
Nf1 mutations or deletions are suggested to underlie the tumor predisposition of NF1 (neurofibromatosis type 1) and few treatments are available for treating NF1 patients with advanced malignant tumors. Aberrant activation of Ras in Nf1-deficient conditions is responsible for the promotion of tumorigenesis in NF1. PKC is proven to be an important factor in supporting the viability of Nf1-defected cells, but the molecular mechanisms are not fully understood. In this study, we demonstrate that the inhibition of protein kinase C (PKC) by 1-O-Hexadecyl-2-O-methyl-rac-glycerol (HMG, a PKC inhibitor) preferentially sensitizes Nf1-defected cells to apoptosis, via triggering a persistent mitotic arrest. In this process, Ral A is activated. Subsequently, Chk1 is phosphorylated and translocated to the nucleus. Silencing Ral A significantly blocks Chk1 nuclear translocation and releases HMG-treated Nf1-deficient cells from mitotic arrest, resulting in the reduction of the magnitude of apoptosis. Thus, our study reveals that PKC is able to maintain the homeostasis or viability of Nf1-defected cells and may serve as a potential target for developing new therapeutic strategies.
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Affiliation(s)
| | - Johan B Fagman
- The Institute of Clinic Sciences, Sahlgrenska Academy, Gothenburg, SE
| | - Ling Shen
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Tianqi Yu
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
| | - Xiaodong Zhou
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
- The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Wei Dai
- Department of Environmental Medicine, New York University, Tuxedo, NY, USA
| | | | - Changyan Chen
- Center for Drug Discovery, Northeastern University, Boston, MA, USA
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15
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Zhang D, Pan J, Xiang X, Liu Y, Dong G, Livingston MJ, Chen JK, Yin XM, Dong Z. Protein Kinase C δ Suppresses Autophagy to Induce Kidney Cell Apoptosis in Cisplatin Nephrotoxicity. J Am Soc Nephrol 2016; 28:1131-1144. [PMID: 27799485 DOI: 10.1681/asn.2016030337] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 08/31/2016] [Indexed: 01/08/2023] Open
Abstract
Nephrotoxicity is a major adverse effect in cisplatin chemotherapy, and renoprotective approaches are unavailable. Recent work unveiled a critical role of protein kinase Cδ (PKCδ) in cisplatin nephrotoxicity and further demonstrated that inhibition of PKCδ not only protects kidneys but enhances the chemotherapeutic effect of cisplatin in tumors; however, the underlying mechanisms remain elusive. Here, we show that cisplatin induced rapid activation of autophagy in cultured kidney tubular cells and in the kidneys of injected mice. Cisplatin also induced the phosphorylation of mammalian target of rapamycin (mTOR), p70S6 kinase downstream of mTOR, and serine/threonine-protein kinase ULK1, a component of the autophagy initiating complex. In vitro, pharmacologic inhibition of mTOR, directly or through inhibition of AKT, enhanced autophagy after cisplatin treatment. Notably, in both cells and kidneys, blockade of PKCδ suppressed the cisplatin-induced phosphorylation of AKT, mTOR, p70S6 kinase, and ULK1 resulting in upregulation of autophagy. Furthermore, constitutively active and inactive forms of PKCδ respectively enhanced and suppressed cisplatin-induced apoptosis in cultured cells. In mechanistic studies, we showed coimmunoprecipitation of PKCδ and AKT from lysates of cisplatin-treated cells and direct phosphorylation of AKT at serine-473 by PKCδin vitro Finally, administration of the PKCδ inhibitor rottlerin with cisplatin protected against cisplatin nephrotoxicity in wild-type mice, but not in renal autophagy-deficient mice. Together, these results reveal a pathway consisting of PKCδ, AKT, mTOR, and ULK1 that inhibits autophagy in cisplatin nephrotoxicity. PKCδ mediates cisplatin nephrotoxicity at least in part by suppressing autophagy, and accordingly, PKCδ inhibition protects kidneys by upregulating autophagy.
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Affiliation(s)
- Dongshan Zhang
- Departments of *Emergency Medicine and .,Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and
| | - Jian Pan
- Departments of *Emergency Medicine and
| | | | - Yu Liu
- Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and.,Nephrology, Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Guie Dong
- Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and
| | - Man J Livingston
- Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and
| | - Xiao-Ming Yin
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood Veterans Affairs Medical Center, Augusta, Georgia; and .,Nephrology, Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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16
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Reyland ME, Jones DNM. Multifunctional roles of PKCδ: Opportunities for targeted therapy in human disease. Pharmacol Ther 2016; 165:1-13. [PMID: 27179744 DOI: 10.1016/j.pharmthera.2016.05.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The serine-threonine protein kinase, protein kinase C-δ (PKCδ), is emerging as a bi-functional regulator of cell death and proliferation. Studies in PKCδ-/- mice have confirmed a pro-apoptotic role for this kinase in response to DNA damage and a tumor promoter role in some oncogenic contexts. In non-transformed cells, inhibition of PKCδ suppresses the release of cytochrome c and caspase activation, indicating a function upstream of apoptotic pathways. Data from PKCδ-/- mice demonstrate a role for PKCδ in the execution of DNA damage-induced and physiologic apoptosis. This has led to the important finding that inhibitors of PKCδ can be used therapeutically to reduce irradiation and chemotherapy-induced toxicity. By contrast, PKCδ is a tumor promoter in mouse models of mammary gland and lung cancer, and increased PKCδ expression is a negative prognostic indicator in Her2+ and other subtypes of human breast cancer. Understanding how these distinct functions of PKCδ are regulated is critical for the design of therapeutics to target this pathway. This review will discuss what is currently known about biological roles of PKCδ and prospects for targeting PKCδ in human disease.
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Affiliation(s)
- Mary E Reyland
- Department of Craniofacial Biology, School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - David N M Jones
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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17
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Chen JH, Tsai CH, Lin HY, Huang CF, Leung YM, Lai SW, Tsai CF, Chang PC, Lu DY, Lin C. Interlukin-18 Is a Pivot Regulatory Factor on Matrix Metalloproteinase-13 Expression and Brain Astrocytic Migration. Mol Neurobiol 2015; 53:6218-6227. [PMID: 26558633 DOI: 10.1007/s12035-015-9529-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/05/2015] [Indexed: 01/28/2023]
Abstract
The expression of matrix metalloproteinase-13 (MMP-13) has been shown to be elevated in some pathophysiological conditions and is involved in the degradation of extracellular matrix in astrocytes. In current study, the function of MMP-13 was further investigated. The conditioned medium (CM) collected from activated microglia increased interleukin (IL)-18 production and enhanced MMP-13 expression in astrocytes. Furthermore, treatment with recombinant IL-18 increased MMP-13 protein and mRNA levels in astrocytes. Recombinant IL-18 stimulation also increased the enzymatic activity of MMP-13 and the migratory activity of astrocytes, while administration of MMP-13 or pan-MMP inhibitors antagonized IL-18-induced migratory activity of astrocytes. In addition, administration of recombinant IL-18 to astrocytes led to the phosphorylation of JNK, Akt, or PKCδ, and treatment of astrocytes with JNK, PI3 kinase/Akt, or PKCδ inhibitors significantly decreased the IL-18-induced migratory activity. Taken together, the results suggest that IL-18-induced MMP-13 expression in astrocytes is regulated by JNK, PI3 kinase/Akt, and PKCδ signaling pathways. These findings also indicate that IL-18 is an important regulator leading to MMP-13 expression and cell migration in astrocytes.
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Affiliation(s)
- Jia-Hong Chen
- Department of General Surgery, Taichung Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Taichung, Taiwan.,School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Chon-Haw Tsai
- Department of Neurology, China Medical University Hospital, Taichung, Taiwan.,Graduate Institute of Neural and Cognitive Sciences, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
| | - Hsiao-Yun Lin
- Graduate Institute of Neural and Cognitive Sciences, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
| | - Chien-Fang Huang
- Graduate Institute of Neural and Cognitive Sciences, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
| | - Yuk-Man Leung
- Graduate Institute of Neural and Cognitive Sciences, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
| | - Sheng-Wei Lai
- Graduate Institute of Basic Medical Science, College of Medicine, China Medical University, Taichung, Taiwan
| | - Cheng-Fang Tsai
- Department of Biotechnology, Asia University, Taichung, Taiwan
| | - Pei-Chun Chang
- Department of Bioinformatics, Asia University, Taichung, Taiwan
| | - Dah-Yuu Lu
- Graduate Institute of Neural and Cognitive Sciences, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan. .,Department of Photonics and Communication Engineering, Asia University, Taichung, Taiwan.
| | - Chingju Lin
- Department of Physiology, School of Medicine, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan.
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18
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Takashima A, English B, Chen Z, Cao J, Cui R, Williams RM, Faller DV. Protein kinase Cδ is a therapeutic target in malignant melanoma with NRAS mutation. ACS Chem Biol 2014; 9:1003-14. [PMID: 24506253 DOI: 10.1021/cb400837t] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
NRAS is the second most frequently mutated gene in melanoma. Previous reports have demonstrated the sensitivity of cancer cell lines carrying KRAS mutations to apoptosis initiated by inhibition of protein kinase Cδ (PKCδ). Here, we report that PKCδ inhibition is cytotoxic in melanomas with primary NRAS mutations. Novel small-molecule inhibitors of PKCδ were designed as chimeric hybrids of two naturally occurring PKCδ inhibitors, staurosporine and rottlerin. The specific hypothesis interrogated and validated is that combining two domains of two naturally occurring PKCδ inhibitors into a chimeric or hybrid structure retains biochemical and biological activity and improves PKCδ isozyme selectivity. We have devised a potentially general synthetic protocol to make these chimeric species using Molander trifluorborate coupling chemistry. Inhibition of PKCδ, by siRNA or small molecule inhibitors, suppressed the growth of multiple melanoma cell lines carrying NRAS mutations, mediated via caspase-dependent apoptosis. Following PKCδ inhibition, the stress-responsive JNK pathway was activated, leading to the activation of H2AX. Consistent with recent reports on the apoptotic role of phospho-H2AX, knockdown of H2AX prior to PKCδ inhibition mitigated the induction of caspase-dependent apoptosis. Furthermore, PKCδ inhibition effectively induced cytotoxicity in BRAF mutant melanoma cell lines that had evolved resistance to a BRAF inhibitor, suggesting the potential clinical application of targeting PKCδ in patients who have relapsed following treatment with BRAF inhibitors. Taken together, the present work demonstrates that inhibition of PKCδ by novel small molecule inhibitors causes caspase-dependent apoptosis mediated via the JNK-H2AX pathway in melanomas with NRAS mutations or BRAF inhibitor resistance.
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Affiliation(s)
| | - Brandon English
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | | | | | | | - Robert M. Williams
- Department
of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
- University of Colorado Cancer Center, Aurora, Colorado 80045, United States
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19
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Irie K, Yanagita RC. Synthesis and Biological Activities of Simplified Analogs of the Natural PKC Ligands, Bryostatin-1 and Aplysiatoxin. CHEM REC 2014; 14:251-67. [DOI: 10.1002/tcr.201300036] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Kazuhiro Irie
- Division of Food Science and Biotechnology; Graduate School of Agriculture; Kyoto University; Kyoto 606-8502 Japan
| | - Ryo C. Yanagita
- Department of Applied Biological Science; Faculty of Agriculture, Kagawa University; Kagawa 761-0795 Japan
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20
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Chen Z, Forman LW, Williams RM, Faller DV. Protein kinase C-δ inactivation inhibits the proliferation and survival of cancer stem cells in culture and in vivo. BMC Cancer 2014; 14:90. [PMID: 24528676 PMCID: PMC3927586 DOI: 10.1186/1471-2407-14-90] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 02/06/2014] [Indexed: 12/18/2022] Open
Abstract
Background A subpopulation of tumor cells with distinct stem-like properties (cancer stem-like cells, CSCs) may be responsible for tumor initiation, invasive growth, and possibly dissemination to distant organ sites. CSCs exhibit a spectrum of biological, biochemical, and molecular features that are consistent with a stem-like phenotype, including growth as non-adherent spheres (clonogenic potential), ability to form a new tumor in xenograft assays, unlimited self-renewal, and the capacity for multipotency and lineage-specific differentiation. PKCδ is a novel class serine/threonine kinase of the PKC family, and functions in a number of cellular activities including cell proliferation, survival or apoptosis. PKCδ has previously been validated as a synthetic lethal target in cancer cells of multiple types with aberrant activation of Ras signaling, using both genetic (shRNA and dominant-negative PKCδ mutants) and small molecule inhibitors. In contrast, PKCδ is not required for the proliferation or survival of normal cells, suggesting the potential tumor-specificity of a PKCδ-targeted approach. Methods shRNA knockdown was used validate PKCδ as a target in primary cancer stem cell lines and stem-like cells derived from human tumor cell lines, including breast, pancreatic, prostate and melanoma tumor cells. Novel and potent small molecule PKCδ inhibitors were employed in assays monitoring apoptosis, proliferation and clonogenic capacity of these cancer stem-like populations. Significant differences among data sets were determined using two-tailed Student’s t tests or ANOVA. Results We demonstrate that CSC-like populations derived from multiple types of human primary tumors, from human cancer cell lines, and from transformed human cells, require PKCδ activity and are susceptible to agents which deplete PKCδ protein or activity. Inhibition of PKCδ by specific genetic strategies (shRNA) or by novel small molecule inhibitors is growth inhibitory and cytotoxic to multiple types of human CSCs in culture. PKCδ inhibition efficiently prevents tumor sphere outgrowth from tumor cell cultures, with exposure times as short as six hours. Small-molecule PKCδ inhibitors also inhibit human CSC growth in vivo in a mouse xenograft model. Conclusions These findings suggest that the novel PKC isozyme PKCδ may represent a new molecular target for cancer stem cell populations.
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Affiliation(s)
| | | | | | - Douglas V Faller
- Cancer Center, Boston University School of Medicine, K-712C, 72 E, Concord St,, Boston, MA 02118, USA.
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21
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Abstract
INTRODUCTION The Ras proteins (K-Ras, N-Ras, and H-Ras) are GTPases that function as molecular switches for a variety of critical cellular activities and their function is tightly and temporally regulated in normal cells. Oncogenic mutations in the RAS genes, which create constitutively-active Ras proteins, can result in uncontrolled proliferation or survival in tumor cells. AREAS COVERED The paper discusses three therapeutic approaches targeting the Ras pathway in cancer: i) Ras itself, ii) Ras downstream pathways, and iii) synthetic lethality. The most adopted approach is targeting Ras downstream signaling, and specifically the PI3K-AKT-mTOR and Raf-MEK pathways, as they are frequently major oncogenic drivers in cancers with high Ras signaling. Although direct targeting of Ras has not been successful clinically, newer approaches being investigated in preclinical studies, such as RNA interference-based and synthetic lethal approaches, promise great potential for clinical application. EXPERT OPINION The challenges of current and emerging therapeutics include the lack of "tumor specificity" and their limitation to those cancers which are "dependent" on aberrant Ras signaling for survival. While the newer approaches have the potential to overcome these limitations, they also highlight the importance of robust preclinical studies and bidirectional translational research for successful clinical development of Ras-related targeted therapies.
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Affiliation(s)
- Asami Takashima
- Boston University School of Medicine, Cancer Research Center , 72 E. Concord St. Boston MA, 02118 , USA
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22
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Chen Z, Forman LW, Miller KA, English B, Takashima A, Bohacek RA, Williams RM, Faller DV. Protein kinase Cδ inactivation inhibits cellular proliferation and decreases survival in human neuroendocrine tumors. Endocr Relat Cancer 2011; 18:759-71. [PMID: 21990324 PMCID: PMC3527126 DOI: 10.1530/erc-10-0224] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The concept of targeting cancer therapeutics toward specific mutations or abnormalities in tumor cells, which are not found in normal tissues, has the potential advantages of high selectivity for the tumor and correspondingly low secondary toxicities. Many human malignancies display activating mutations in the Ras family of signal-transducing genes or over-activity of p21(Ras)-signaling pathways. Carcinoid and other neuroendocrine tumors have been similarly demonstrated to have activation of Ras signaling directly by mutations in Ras, indirectly by loss of Ras-regulatory proteins, or via constitutive activation of upstream or downstream effector pathways of Ras, such as growth factor receptors or PI(3)-kinase and Raf/mitogen-activated protein kinases. We previously reported that aberrant activation of Ras signaling sensitizes cells to apoptosis when the activity of the PKCδ isozyme is suppressed and that PKCδ suppression is not toxic to cells with normal levels of p21(Ras) signaling. We demonstrate here that inhibition of PKCδ by a number of independent means, including genetic mechanisms (shRNA) or small-molecule inhibitors, is able to efficiently and selectively repress the growth of human neuroendocrine cell lines derived from bronchopulmonary, foregut, or hindgut tumors. PKCδ inhibition in these tumors also efficiently induced apoptosis. Exposure to small-molecule inhibitors of PKCδ over a period of 24 h is sufficient to significantly suppress cell growth and clonogenic capacity of these tumor cell lines. Neuroendocrine tumors are typically refractory to conventional therapeutic approaches. This Ras-targeted therapeutic approach, mediated through PKCδ suppression, which selectively takes advantage of the very oncogenic mutations that contribute to the malignancy of the tumor, may hold potential as a novel therapeutic modality.
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Affiliation(s)
- Zhihong Chen
- Cancer Center, 72 East Concord St., Boston University School of Medicine, Boston, MA 02118
| | - Lora W. Forman
- Cancer Center, 72 East Concord St., Boston University School of Medicine, Boston, MA 02118
| | - Kenneth A. Miller
- Department of Chemistry, Colorado State University, 115 Centre St., Fort Collins, CO
| | - Brandon English
- Department of Chemistry, Colorado State University, 115 Centre St., Fort Collins, CO
| | - Asami Takashima
- Cancer Center, 72 East Concord St., Boston University School of Medicine, Boston, MA 02118
| | | | - Robert M. Williams
- Department of Chemistry, Colorado State University, 115 Centre St., Fort Collins, CO
| | - Douglas V. Faller
- Cancer Center, 72 East Concord St., Boston University School of Medicine, Boston, MA 02118
- Departments of Medicine, Pediatrics, Biochemistry, Microbiology, Pathology and Laboratory Medicine, 72 East Concord St., Boston University School of Medicine, Boston, MA 02118
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23
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Zhu T, Chen L, Du W, Tsuji T, Chen C. Synthetic Lethality Induced by Loss of PKC δ and Mutated Ras. Genes Cancer 2011; 1:142-51. [PMID: 21031151 DOI: 10.1177/1947601909360989] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Synthetic lethal interaction between oncogenic Ha-ras and loss of PKC has been demonstrated. Recently, the authors reported that the concurrent knockdown of PKC α and β, via upregulating PKC δ, sensitizes cells with aberrant Ras signaling to apoptosis. As a continuation of the study, using shRNA, the authors demonstrate that loss of PKC δ causes a lethal reaction in NIH3T3/Hras or prostate cancer DU145 cells that overexpress JNK. In this apoptotic process, PKC α and β are upregulated and then associated with RACK1 (an adaptor for activated PKC) and JNK. Immunoblotting analysis shows that JNK is phosphorylated, accompanied with caspase 8 cleavage. The inhibition of JNK abrogates this apoptotic process triggered by PKC δ knockdown. Interestingly, without blocking PKC δ, the concurrent overexpression of wt- or CAT-PKC α and β is insufficient to induce apoptosis in the cells. Together with the authors' previous findings, the data suggest that PKC α/β and δ function oppositely to maintain a balance that supports cells expressing v-ras to survive and prevents them from being eliminated through oncogenic stress-induced apoptosis.
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Affiliation(s)
- Tongbo Zhu
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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24
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Guo J, Zhu T, Chen L, Nishioka T, Tsuji T, Xiao ZXJ, Chen CY. Differential sensitization of different prostate cancer cells to apoptosis. Genes Cancer 2011; 1:836-46. [PMID: 21132068 DOI: 10.1177/1947601910381645] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 07/02/2010] [Accepted: 07/20/2010] [Indexed: 11/17/2022] Open
Abstract
Although protein kinase C (PKC) plays an important role in sensitizing prostate cancer cells to apoptosis, and suppression of PKC is able to trigger an apoptotic crisis in cells harboring oncogenic ras, little is known about whether dyregulation of Ras effectors in prostate cancer cells, together with loss of PKC, is synthetically lethal. The current study aims at investigating whether prostate cancer cells with aberrant Ras effector signaling are sensitive to treatment with HMG (a PKC inhibitor) for the induction of apoptosis. We show that prostate cancer DU145 cells expressing a high level of JNK1 become susceptible to apoptosis after treatment with HMG, in which caspase 8 is activated and cytochrome c is released to the cytosol. In contrast, the addition of HMG sensitizes LNCaP or PC3 prostate cancer cells harboring an active Akt to apoptosis, in which ROS is upregulated to induce the UPR and GADD153 expression. The concurrent activation of JNK1 and Akt has an additive effect on apoptosis following PKC suppression. Thus, the data identify Akt and JNK1 as potential targets in prostate cancer cells for PKC inhibition-induced apoptosis.
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Affiliation(s)
- Jinjin Guo
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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25
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Tsai RK, He MS, Chen ZY, Wu WC, Wu WS. PKCδ-dependent signaling mediates ethambutol-induced toxic effects on human retinal pigment cells. Mol Vis 2011; 17:1564-76. [PMID: 21738386 PMCID: PMC3123160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 06/06/2011] [Indexed: 11/03/2022] Open
Abstract
PURPOSE Our previous report demonstrated that ethambutol (EMB) might induce cytoplasmic vacuolization and reduce the uptake of photoreceptor rod outer segments (ROS) in retinal pigment epithelium (RPE) cells, which are mediated via a protein kinase C (PKC)-dependent pathway. In the present study, we sought to identify the PKC isozyme(s) involved. METHODS EMB-induced cytoplasmic vacuolization and uptake of ROS were observed under a phase contrast microscope. Western blots were performed to observe the membrane translocation of PKC isozymes and cytoplasmic release of cathepsin D. Quantitative PCR were performed to analyze gene expression of PKCδ. Human RPE cell line RPE50 and ARPE19 cells were pretreated with specific inhibitors or transfected with shRNAs of various PKC isozymes, including PKCα, β, ε, γ, and δ, to examine whether EMB-induced toxic effects were prevented. RESULTS In RPE50 cells, gene expression of PKCδ on both mRNA and protein levels was induced by EMB within 30 min to 3 h. EMB-induced cytoplasmic vacuolization in both RPE50 and ARPE19 cells was prevented by pretreating the cells with a specific inhibitor of PKCδ, Rottlerin, or depletion of PKCδ by shRNA. EMB-triggered reduction of ROS uptake was also significantly suppressed by pretreatment with Rottlerin, or depletion of PKCδ by shRNA technology. In contrast, pretreatment of the cells with specific inhibitors of PKCα, β, ε, or γ, or depletion of PKCα or β didn't influence the aforementioned EMB-triggered toxic effects. In addition, in RPE50, EMB induced the release of lysosomal enzyme cathepsin D into cytosol within 30 min to 6 h, which was also prevented by Rottlerin. CONCLUSIONS EMB-induced vacuole formation, cytoplasmic release of cathepsin D, and reduction of phagocytosis in RPE are intimately correlated and regulated by the PKCδ signal pathway.
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Affiliation(s)
- Rong Kung Tsai
- Department of Ophthalmology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan,Department of Ophthalmology and Visual Science, Hualien, Taiwan
| | - Ming Shan He
- Department of Ophthalmology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
| | - Zih-Yao Chen
- Department of Medical Technology, Tzu Chi University, Hualien, Taiwan
| | - Wen Chen Wu
- Department of Ophthalmology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Wen Sheng Wu
- Department of Medical Technology, Tzu Chi University, Hualien, Taiwan
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26
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Symonds JM, Ohm AM, Carter CJ, Heasley LE, Boyle TA, Franklin WA, Reyland ME. Protein kinase C δ is a downstream effector of oncogenic K-ras in lung tumors. Cancer Res 2011; 71:2087-97. [PMID: 21335545 DOI: 10.1158/0008-5472.can-10-1511] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Oncogenic activation of K-ras occurs commonly in non-small cell lung cancer (NSCLC), but strategies to therapeutically target this pathway have been challenging to develop. Information about downstream effectors of K-ras remains incomplete, and tractable targets are yet to be defined. In this study, we investigated the role of protein kinase C δ (PKCδ) in K-ras-dependent lung tumorigenesis by using a mouse carcinogen model and human NSCLC cells. The incidence of urethane-induced lung tumors was decreased by 69% in PKCδ-deficient knockout (δKO) mice compared with wild-type (δWT) mice. δKO tumors are smaller and showed reduced proliferation. DNA sequencing indicated that all δWT tumors had activating mutations in KRAS, whereas only 69% of δKO tumors did, suggesting that PKCδ acts as a tumor promoter downstream of oncogenic K-ras while acting as a tumor suppressor in other oncogenic contexts. Similar results were obtained in a panel of NSCLC cell lines with oncogenic K-ras but which differ in their dependence on K-ras for survival. RNA interference-mediated attenuation of PKCδ inhibited anchorage-independent growth, invasion, migration, and tumorigenesis in K-ras-dependent cells. These effects were associated with suppression of mitogen-activated protein kinase pathway activation. In contrast, PKCδ attenuation enhanced anchorage-independent growth, invasion, and migration in NSCLC cells that were either K-ras-independent or that had WT KRAS. Unexpectedly, our studies indicate that the function of PKCδ in tumor cells depends on a specific oncogenic context, as loss of PKCδ in NSCLC cells suppressed transformed growth only in cells dependent on oncogenic K-ras for proliferation and survival.
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Affiliation(s)
- Jennifer M Symonds
- Program in Cancer Biology, School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045, USA
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27
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K-Ras4B phosphorylation at Ser181 is inhibited by calmodulin and modulates K-Ras activity and function. Oncogene 2010; 29:5911-22. [PMID: 20802526 DOI: 10.1038/onc.2010.298] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fine tuning of Ras activity is widely known as a mechanism to induce different cellular responses. Recently, we have shown that calmodulin (CaM) binds to K-Ras and that K-Ras phosphorylation inhibits its interaction with CaM. In this study we report that CaM inhibits K-Ras phosphorylation at Ser181 by protein kinase C (PKC) in vivo, and this is a mechanism to modulate K-Ras activity and signaling. Although CaM inhibition increased the activation of endogenous K-Ras, PKC inhibition decreased its activation status. We demonstrate that K-Ras phosphorylation decreased susceptibility to p120GAP activity. Accordingly, we also observed that non-phosphorylable K-Ras mutant exhibits a less sustained activation profile and do not efficiently activate AKT at low growth factor doses compared with wild-type K-Ras. It is interesting that the physiological responses induced by K-Ras are affected by this phosphorylation; when K-Ras cannot be phosphorylated it exhibits a remarkably decreased ability to stimulate proliferation in non-saturated serum conditions. Finally, we demonstrate that phosphorylation also regulates oncogenic K-Ras functions, as focus formation capacity, mobility and apoptosis resistance upon adriamycin treatment of cells expressing oncogenic K-Ras that cannot be phosphorylated are highly compromised. Moreover, at low serum concentration proliferation and survival is practically inhibited when cells cannot phosphorylate oncogenic K-Ras. In this condition, K-Ras phosphorylation is essential to ensure a proper activation of mitogen-activated protein kinase and PI3K/AKT pathways. In summary, our findings suggest that the interplay between CaM interaction and PKC phosphorylation is essential to regulate non-oncogenic and oncogenic K-Ras activity and functionality.
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28
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Aggregation of spectrin and PKCtheta is an early hallmark of fludarabine/mitoxantrone/dexamethasone-induced apoptosis in Jurkat T and HL60 cells. Mol Cell Biochem 2010; 339:63-77. [PMID: 20058056 DOI: 10.1007/s11010-009-0370-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 12/16/2009] [Indexed: 12/20/2022]
Abstract
It has been shown that changes in spectrin distribution in early apoptosis preceded changes in membrane asymmetry and phosphatidylserine (PS) exposure. PKCtheta was associated with spectrin during these changes, suggesting a possible role of spectrin/PKCtheta aggregation in regulation of early apoptotic events. Here we dissect this hypothesis using Jurkat T and HL60 cell lines as model systems. Immunofluorescent analysis of alphaIIbetaII spectrin arrangement in Jurkat T and HL60 cell lines revealed the redistribution of spectrin and PKCtheta into a polar aggregate in early apoptosis induced by fludarabine/mitoxantrone/dexamethasone (FND). The appearance of an alphaIIbetaII spectrin fraction that was insoluble in a non-ionic detergent (1% Triton X-100) was observed concomitantly with spectrin aggregation. The changes were observed within 2 h after cell exposure to FND, and preceded PS exposure. The changes seem to be restricted to spectrin and not to other cytoskeletal proteins such as actin or vimentin. In studies of the mechanism of these changes, we found that (i) neither changes in apoptosis regulatory genes (e.g., Bcl-2 family proteins) nor changes in cytoskeleton-associated proteins were detected in gene expression profiling of HL60 cells after the first hour of FND treatment, (ii) caspase-3, -7, -8, and -10 had minor involvement in the early apoptotic rearrangement of spectrin/PKCtheta, and (iii) spectrin aggregation was shown to be partially dependent on PKCtheta activity. Our results indicate that spectrin/PKCtheta aggregate formation is related to an early stage in drug-induced apoptosis and possibly may be regulated by PKCtheta activity. These findings indicate that spectrin/PKCtheta aggregation could be considered as a hallmark of early apoptosis and presents the potential to become a useful diagnostic tool for monitoring efficiency of chemotherapy as early as 24 h after treatment.
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29
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Abstract
Emerging evidence indicates that suppression of protein kinase C (PKC) renders the susceptibility of cells expressing mutated ras to apoptosis. Although the effort has been made, the underlying molecular mechanisms are not fully understood. In this study, using small hairpin RNAs (shRNAs) or PKC inhibitor, we show that the concurrent suppression of PKC-alpha and beta induces cells ectopically expressing v-ras to undergo apoptosis. In this apoptotic process, PKC-delta is upregulated and translocated from the cytosol to the nucleus. The activated PKC-delta associates with and phosphorylates p73 to initiate apoptosis. In this apoptotic process, Akt seems to be downstream of oncogenic Ras. Moreover, overexpression of PKC-delta, without co-suppression of PKC-alpha and beta, is not apoptotic to the cells, suggesting that PKC-delta and PKC-alpha/beta function oppositely to facilitate cells harboring v-ras to survive. Thus, our study shows that PKC-alpha and beta are necessary for sustaining the homeostasis in cells containing a hyperactive Ras. The abrogation of these two isoforms switches on the p73-regulated apoptotic machinery through the activation of PKC-delta.
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30
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Lønne GK, Masoumi KC, Lennartsson J, Larsson C. Protein kinase Cdelta supports survival of MDA-MB-231 breast cancer cells by suppressing the ERK1/2 pathway. J Biol Chem 2009; 284:33456-65. [PMID: 19833733 DOI: 10.1074/jbc.m109.036186] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mechanisms that mediate apoptosis resistance are attractive therapeutic targets for cancer. Protein kinase Cdelta (PKCdelta) is considered a pro-apoptotic factor in many cell types. In breast cancer, however, it has shown both pro-survival and pro-apoptotic effects. Here, we report for the first time that down-regulation of PKCdelta per se leads to apoptosis of MDA-MB-231 cells. Inhibition of MEK1/2 by either PD98059 or U0126 suppressed the induction of apoptosis of PKCdelta-depleted MDA-MB-231 cells but did not support survival of MCF-7 or MDA-MB-468 cells. Basal ERK1/2 phosphorylation was substantially higher in MDA-MB-231 cells than in the other cell lines. PKCdelta depletion led to even higher ERK1/2 phosphorylation levels and also to lower expression levels of the ERK1/2 phosphatase MKP3. Depletion of MKP3 led to apoptosis and higher levels of ERK1/2 phosphorylation, suggesting that this may be a mechanism mediating the effect of PKCdelta down-regulation. However, PKCdelta silencing also induced increased MEK1/2 phosphorylation, indicating that PKCdelta regulates ERK1/2 phosphorylation both upstream and downstream. Moreover, PKCdelta silencing led to increased levels of the E3 ubiquitin ligase Nedd4, which is a potential regulator of MKP3, because down-regulation led to increased MKP3 levels. Our results highlight PKCdelta as a potential target for therapy of breast cancers with high activity of the ERK1/2 pathway.
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Affiliation(s)
- Gry Kalstad Lønne
- Center for Molecular Pathology, Department of Laboratory Medicine, Lund University, and Malmö University Hospital, Sweden
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Guo J, Zhu T, Luo LY, Huang Y, Sunkavalli RG, Chen CY. PI3K Acts in synergy with loss of PKC to elicit apoptosis via the UPR. J Cell Biochem 2009; 107:76-85. [PMID: 19241442 DOI: 10.1002/jcb.22102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It is known that Ras mutations, together with loss of PKC, are apoptotic in various types of mammalian cells. The mechanism of how aberrant Ras transmits this apoptotic signaling remains unclear. Using three V12-Ha-ras loop mutants that preferentially bind to and activate one of Ras effectors, we tested the role of Ras downstream pathways in the induction of apoptosis in rat lung epithelia, human lung or prostate cancer cells. After PKC inhibition, the activation of PI3K/Akt renders the susceptibility of cells to apoptosis. We also demonstrate that the amount of ROS is moderately increased in the cells ectopically expressing V12C40 and dramatically elevated by suppression of PKC, which leads to apoptosis through the activation of UPR. Thus, our study suggests that after PKC abrogation, PI3K functions downstream of Ras to perturb the state of cellular redox and signals to ER stress-regulated apoptotic machinery.
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Affiliation(s)
- Jinjin Guo
- Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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Oxidized low-density lipoprotein-induced matrix metalloproteinase-9 expression via PKC-delta/p42/p44 MAPK/Elk-1 cascade in brain astrocytes. Neurotox Res 2009; 17:50-65. [PMID: 19554388 DOI: 10.1007/s12640-009-9077-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
Abstract
After ischemic injury to brain, disruption of the blood-brain barrier (BBB) raises the possibility of exposing the central nervous system (CNS) to oxidized low-density lipoprotein (oxLDL), a risk factor implicated in neurodegenerative diseases. Matrix metalloproteinases (MMPs), especially MMP-9, contribute to extracellular matrix (ECM) remodeling during the CNS diseases. However, the molecular mechanisms underlying oxLDL-induced MMP-9 expression in astrocytes remained unclear. Here, we reported that oxLDL induced MMP-9 expression via a PKC-delta/p42/p44 MAPK-dependent Elk-1 activation in rat brain astrocyte (RBA)-1 cells, revealed by gelatin zymography, RT-PCR, and Western blotting analyses. These responses were attenuated by pretreatment with pharmacological inhibitors and transfection with dominant negative mutants. Moreover, Elk-1-mediated MMP-9 gene transcription was confirmed by transfection with an Elk-1 binding site-mutated MMP-9 promoter construct (mt-Ets-MMP9), which blocked oxLDL-stimulated MMP-9 luciferase activity. Understanding the regulatory mechanisms by which oxLDL induced MMP-9 expression in astrocytes might provide a new therapeutic strategy of brain diseases.
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Lacreusette A, Barbieux I, Nguyen JM, Pandolfino MC, Dréno B, Jacques Y, Godard A, Blanchard F. Defective activations of STAT3 Ser727 and PKC isoforms lead to oncostatin M resistance in metastatic melanoma cells. J Pathol 2009; 217:665-76. [DOI: 10.1002/path.2490] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Xia S, Chen Z, Forman LW, Faller DV. PKCdelta survival signaling in cells containing an activated p21Ras protein requires PDK1. Cell Signal 2009; 21:502-8. [PMID: 19146951 PMCID: PMC2644428 DOI: 10.1016/j.cellsig.2008.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 01/02/2023]
Abstract
Protein kinase C delta (PKCdelta) modulates cell survival and apoptosis in diverse cellular systems. We recently reported that PKCdelta functions as a critical anti-apoptotic signal transducer in cells containing activated p21(Ras) and results in the activation of AKT, thereby promoting cell survival. How PKCdelta is regulated by p21(Ras), however, remains incompletely understood. In this study, we show that PKCdelta, as a transducer of anti-apoptotic signals, is activated by phosphotidylinositol 3' kinase/phosphoinositide-dependent kinase 1 (PI(3)K-PDK1) to deliver the survival signal to Akt in the environment of activated p21(Ras). PDK1 is upregulated in cells containing an activated p21Ras. Knock-down of PDK1, PKCdelta, or AKT forces cells containing activated p21(Ras) to undergo apoptosis. PDK1 regulates PKCdelta activity, and constitutive expression of PDK1 increases PKCdelta activity in different cell types. Conversely, expression of a kinase-dead (dominant-negative) PDK1 significantly suppresses PKCdelta activity. p21(Ras)-mediated survival signaling is therefore regulated by via a PI(3)K-AKT pathway, which is dependent upon both PDK1 and PKCdelta, and PDK1 activates and regulates PKCdelta to determine the fate of cells containing a mutated, activated p21(Ras).
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Affiliation(s)
- Shuhua Xia
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Zhihong Chen
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Lora W. Forman
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Douglas V. Faller
- Cancer Research Canter, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Muscella A, Urso L, Calabriso N, Vetrugno C, Rochira A, Storelli C, Marsigliante S. Anti-apoptotic effects of protein kinase C-delta and c-fos in cisplatin-treated thyroid cells. Br J Pharmacol 2009; 156:751-63. [PMID: 19254279 DOI: 10.1111/j.1476-5381.2008.00049.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND AND PURPOSE We showed previously that cisplatin inititates a signalling pathway mediated by PKC-delta/extracellular signal-regulated kinase (ERK), important for maintaining viability in PC Cl3 thyroid cells. The studies described herein examined whether c-fos was associated with cisplatin resistance and the signalling link between c-fos and PKC-delta/ERK. EXPERIMENTAL APPROACH Cells were treated with various pharmacological inhibitors of PKCs and ERK, or were depleted of c-fos, PKC-delta, PKC-epsilon and caspase-3 by small interfering RNA (siRNA), then incubated with cisplatin and cytotoxicity assessed. KEY RESULTS Cisplatin provokes the induction of c-fos and the activation of conventional PKC-beta, and novel PKC-delta and -epsilon. The cisplatin-provoked c-fos induction was decreased by Gö6976, a PKC-beta inhibitor; by siRNA for PKC-delta- but not that for PKC-epsilon or by PD98059, a mitogen-activated protein kinase/ERK kinase inhibitor. Expression of c-fos was abolished by GF109203X, an inhibitor of all PKC isoforms, or by PD98059 plus Gö6976 or by PKC-delta-siRNA plus Gö6976. When c-fos expression was blocked by siRNA, cisplatin cytotoxicity was strongly enhanced with increased caspase-3 activation. In PKC-delta-depleted cells treated with cisplatin, caspase-3 activation was increased and cell viability decreased. In these PKC-delta-depleted cells, PD98059 did not affect caspase-3 activation. CONCLUSIONS AND IMPLICATIONS In PC Cl3 cells, in the cell signalling pathways that lead to cisplatin resistance, PKC-delta controls ERK activity and, together with PKC-beta, also the induction of c-fos. Hence, the protective role of c-fos in thyroid cells has the potential to provide new opportunities for therapeutic intervention.
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Affiliation(s)
- Antonella Muscella
- Department of Biological and Environmental Sciences and Technologies (Di.S.Te.B.A.), Università del Salento, Lecce, Italy
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Sriraman V, Modi SR, Bodenburg Y, Denner LA, Urban RJ. Identification of ERK and JNK as signaling mediators on protein kinase C activation in cultured granulosa cells. Mol Cell Endocrinol 2008; 294:52-60. [PMID: 18694803 DOI: 10.1016/j.mce.2008.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 06/02/2008] [Accepted: 07/14/2008] [Indexed: 01/11/2023]
Abstract
PKC signaling is critical for follicular development and the induction of ovulatory genes including Pgr, Prkg2, and Cyp11a1 (SCC). We investigated PKC signaling mechanisms in the JC-410 porcine granulosa cell line stably expressing an SCC-luciferase reporter gene containing 2kb of the porcine SCC promoter. Addition of phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C, induced the promoter approximately 6-fold over the basal levels in 4h. This effect was predominantly mediated by the PKC beta and delta isoforms. PMA-mediated induction of the SCC promoter was sensitive to inhibition of ERK1/2 or JNK. Inhibition of p38 MAP kinase or Src tyrosine kinase did not alter the PMA-mediated inducibility of the promoter. SCC promoter induction in response to PMA treatment required basal EGF-receptor activity, but did not involve ectodomain shedding. Western blot analyses using phospho-specific antibodies showed that PMA treatment of JC-410 cells induced phosphorylation of MEK1/2, ERK1/2, and its downstream target p90 RSK at 15min. We also documented the rapid phosphorylation of JNK1/2 in response to PMA treatment. Phosphorylation of ERK and JNK was robust and sustained in contrast to activation of PKA and EGF-receptor signaling in these cells. Pretreatment of JC-410 granulosa cells with IGF-1 had a synergistic effect on PMA-mediated induction of the SCC promoter. We demonstrated the importance of PMA activation of ERK signaling and the synergism with IGF-1 by showing similar responses for Prkg2 expression in primary granulosa cells. In conclusion, our studies demonstrated PMA activation of ERK and JNK signaling which is relevant in the regulation of gene expression during follicular development, ovulation, and luteinization.
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Affiliation(s)
- Venkataraman Sriraman
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-1060, USA.
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Kim YH, Kim YS, Park CH, Chung IY, Yoo JM, Kim JG, Lee BJ, Kang SS, Cho GJ, Choi WS. Protein kinase C-delta mediates neuronal apoptosis in the retinas of diabetic rats via the Akt signaling pathway. Diabetes 2008; 57:2181-90. [PMID: 18443201 PMCID: PMC2494683 DOI: 10.2337/db07-1431] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Protein kinase C (PKC)-delta, an upstream regulator of the Akt survival pathway, contributes to cellular dysfunction in the pathogenesis of diabetes. Herein, we examined the role of PKC-delta in neuronal apoptosis through Akt in the retinas of diabetic rats. RESEARCH DESIGN AND METHODS We used retinas from 24- and 35-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) diabetic and Long-Evans Tokushima Otsuka (LETO) nondiabetic rats. To assess whether PKC-delta affects Akt signaling and cell death in OLETF rat retinas, we examined 1) PKC-delta activity and apoptosis; 2) protein levels of phosphatidylinositol 3-kinase (PI 3-kinase) p85, heat shock protein 90 (HSP90), and protein phosphatase 2A (PP2A); 3) Akt phosphorylation; and 4) Akt binding to HSP90 or PP2A in LETO and OLETF retinas in the presence or absence of rottlerin, a highly specific PKC-delta inhibitor, or small interfering RNAs (siRNAs) for PKC-delta and HSP90. RESULTS In OLETF retinas from 35-week-old rats, ganglion cell death, PKC-delta and PP2A activity, and Akt-PP2A binding were significantly increased and Akt phosphorylation and Akt-HSP90 binding were decreased compared with retinas from 24-week-old OLETF and LETO rats. Rottlerin and PKC-delta siRNA abrogated these effects in OLETF retinas from 35-week-old rats. HSP90 siRNA significantly increased ganglion cell death and Akt-PP2A complexes and markedly decreased HSP90-Akt binding and Akt phosphorylation in LETO retinas from 35-week-old rats compared with those from nontreated LETO rats. CONCLUSIONS PKC-delta activation contributes to neuro-retinal apoptosis in diabetic rats by inhibiting Akt-mediated signaling pathways.
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Affiliation(s)
- Young-Hee Kim
- Department of Anatomy and Neurobiology, School of Medicine, Institute of Health Science, Gyeongsang National University, Jinju, Gyeongnam, South Korea
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Lomonaco SL, Kahana S, Blass M, Brody Y, Okhrimenko H, Xiang C, Finniss S, Blumberg PM, Lee HK, Brodie C. Phosphorylation of protein kinase Cdelta on distinct tyrosine residues induces sustained activation of Erk1/2 via down-regulation of MKP-1: role in the apoptotic effect of etoposide. J Biol Chem 2008; 283:17731-9. [PMID: 18434324 DOI: 10.1074/jbc.m801727200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism underlying the important role of protein kinase Cdelta (PKCdelta) in the apoptotic effect of etoposide in glioma cells is incompletely understood. Here, we examined the role of PKCdelta in the activation of Erk1/2 by etoposide. We found that etoposide induced persistent activation of Erk1/2 and nuclear translocation of phospho-Erk1/2. MEK1 inhibitors decreased the apoptotic effect of etoposide, whereas inhibitors of p38 and JNK did not. The activation of Erk1/2 by etoposide was downstream of PKCdelta since the phosphorylation of Erk1/2 was inhibited by a PKCdelta-KD mutant and PKCdelta small interfering RNA. We recently reported that phosphorylation of PKCdelta on tyrosines 64 and 187 was essential for the apoptotic effect of etoposide. Using PKCdeltatyrosine mutants, we found that the phosphorylation of PKCdeltaon these tyrosine residues, but not on tyrosine 155, was also essential for the activation of Erk1/2 by etoposide. In contrast, nuclear translocation of PKCdelta was independent of its tyrosine phosphorylation and not necessary for the phosphorylation of Erk1/2. Etoposide induced down-regulation of kinase phosphatase-1 (MKP-1), which correlated with persistent phosphorylation of Erk1/2 and was dependent on the tyrosine phosphorylation of PKCdelta. Moreover, silencing of MKP-1 increased the phosphorylation of Erk1/2 and the apoptotic effect of etoposide. Etoposide induced polyubiquitylation and degradation of MKP-1 that was dependent on PKCdelta and on its tyrosine phosphorylation. These results indicate that distinct phosphorylation of PKCdeltaon tyrosines 64 and 187 specifically activates the Erk1/2 pathway by the down-regulation of MKP-1, resulting in the persistent phosphorylation of Erk1/2 and cell apoptosis.
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Affiliation(s)
- Stephanie L Lomonaco
- William and Karen Davidson Laboratory of Cell Signaling and Tumorigenesis, Hermelin Brain Tumor Center, Department of Neurosurgery, Henry Ford Hospital, Detroit, Michigan 48202, USA
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Koshkin V, Dai FF, Robson-Doucette CA, Chan CB, Wheeler MB. Limited Mitochondrial Permeabilization Is an Early Manifestation of Palmitate-induced Lipotoxicity in Pancreatic β-Cells. J Biol Chem 2008; 283:7936-48. [DOI: 10.1074/jbc.m705652200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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40
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Qi X, Mochly-Rosen D. The PKCdelta -Abl complex communicates ER stress to the mitochondria - an essential step in subsequent apoptosis. J Cell Sci 2008; 121:804-13. [PMID: 18285444 DOI: 10.1242/jcs.024653] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Conditions that compromise protein folding in the endoplasmic reticulum trigger the unfolded protein response (UPR), which either restores proper protein folding or results in cellular demise through apoptosis. In this study, we found that, in response to ER stress in vivo and in vitro, PKCdelta translocates to the ER where it binds to the tyrosine kinase Abl. Tyrosine phosphorylation and kinase activity of PKCdelta are required for PKCdelta binding to Abl in the ER. Moreover, we found that inhibition of PKCdelta by the PKCdelta-specific peptide inhibitor deltaV1-1 or by silencing of PKCdelta reduces ER-stress-induced JNK activation and inhibits ER-stress-mediated apoptosis. Furthermore, the inhibitor of PKCdelta kinase activity rottlerin blocks the translocation of the PKCdelta-Abl complex from the ER to the mitochondria and confers protection against apoptosis. Thus, PKCdelta communicates ER stress to the mitochondria by binding to ER-localized Abl. The PKCdelta-Abl complex then translocates to the mitochondria, communicating ER stress to this organelle, thereby, triggering apoptosis.
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Affiliation(s)
- Xin Qi
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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