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Sukocheva OA, Neganova ME, Aleksandrova Y, Burcher JT, Chugunova E, Fan R, Tse E, Sethi G, Bishayee A, Liu J. Signaling controversy and future therapeutical perspectives of targeting sphingolipid network in cancer immune editing and resistance to tumor necrosis factor-α immunotherapy. Cell Commun Signal 2024; 22:251. [PMID: 38698424 PMCID: PMC11064425 DOI: 10.1186/s12964-024-01626-6] [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: 08/21/2023] [Accepted: 04/21/2024] [Indexed: 05/05/2024] Open
Abstract
Anticancer immune surveillance and immunotherapies trigger activation of cytotoxic cytokine signaling, including tumor necrosis factor-α (TNF-α) and TNF-related apoptosis-inducing ligand (TRAIL) pathways. The pro-inflammatory cytokine TNF-α may be secreted by stromal cells, tumor-associated macrophages, and by cancer cells, indicating a prominent role in the tumor microenvironment (TME). However, tumors manage to adapt, escape immune surveillance, and ultimately develop resistance to the cytotoxic effects of TNF-α. The mechanisms by which cancer cells evade host immunity is a central topic of current cancer research. Resistance to TNF-α is mediated by diverse molecular mechanisms, such as mutation or downregulation of TNF/TRAIL receptors, as well as activation of anti-apoptotic enzymes and transcription factors. TNF-α signaling is also mediated by sphingosine kinases (SphK1 and SphK2), which are responsible for synthesis of the growth-stimulating phospholipid, sphingosine-1-phosphate (S1P). Multiple studies have demonstrated the crucial role of S1P and its transmembrane receptors (S1PR) in both the regulation of inflammatory responses and progression of cancer. Considering that the SphK/S1P/S1PR axis mediates cancer resistance, this sphingolipid signaling pathway is of mechanistic significance when considering immunotherapy-resistant malignancies. However, the exact mechanism by which sphingolipids contribute to the evasion of immune surveillance and abrogation of TNF-α-induced apoptosis remains largely unclear. This study reviews mechanisms of TNF-α-resistance in cancer cells, with emphasis on the pro-survival and immunomodulatory effects of sphingolipids. Inhibition of SphK/S1P-linked pro-survival branch may facilitate reactivation of the pro-apoptotic TNF superfamily effects, although the role of SphK/S1P inhibitors in the regulation of the TME and lymphocyte trafficking should be thoroughly assessed in future studies.
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Affiliation(s)
- Olga A Sukocheva
- Department of Hepatology, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia.
| | - Margarita E Neganova
- Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432, Russian Federation
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center, Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420088, Russian Federation
| | - Yulia Aleksandrova
- Institute of Physiologically Active Compounds at Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432, Russian Federation
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center, Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420088, Russian Federation
| | - Jack T Burcher
- College of Osteopathic Medicine, Lake Erie College of Osteopathic Medicine, Bradenton, FL, 34211, USA
| | - Elena Chugunova
- Arbuzov Institute of Organic and Physical Chemistry, Federal Research Center, Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420088, Russian Federation
| | - Ruitai Fan
- Department of Radiation Oncology, Cancer Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Edmund Tse
- Department of Hepatology, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - Gautam Sethi
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117600, Singapore
| | - Anupam Bishayee
- College of Osteopathic Medicine, Lake Erie College of Osteopathic Medicine, Bradenton, FL, 34211, USA.
| | - Junqi Liu
- Department of Radiation Oncology, Cancer Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
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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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Li B, Ding Z, Calbay O, Li Y, Li T, Jin L, Huang S. FAP is critical for ovarian cancer cell survival by sustaining NF-κB activation through recruitment of PRKDC in lipid rafts. Cancer Gene Ther 2023; 30:608-621. [PMID: 36494579 PMCID: PMC10498436 DOI: 10.1038/s41417-022-00575-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 11/18/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022]
Abstract
Fibroblast activation protein (FAP) is tumor-specific and plays an important role in tumorigenecity. However, agents against its enzymatic activity or extracellular presence were unsuccessful in the clinic for undefined reasons. Here we show that FAP expression is higher in advanced ovarian cancer and is only detected in invasive ovarian cancer cells. Silencing FAP induces apoptosis and FAP's enzymatic activity is dispensable for cell survival. To elucidate the cause of apoptosis, we find that NF-κB activity is diminished when FAP is depleted and BIRC5 (survivin) acts downstream of FAP-NF-κB axis to promote cell survival. To uncover the link between FAP and NF-κB activation, we reveal that PRKDC (DNA-PK, DNA-dependent protein kinase) forms complex with FAP and is required for NF-κB activation and cell survival. Remarkably, FAP-PRKDC interaction occurs only in lipid rafts, and depleting FAP prevents lipid raft localization of PRKDC. Given the known ability of PRKDC to direct NF-κB activation, these results suggest that FAP recruits PRKDC in lipid rafts for NF-κB activation. FAP's non-enzymatic role and functioning from lipid rafts for cell survival also offer an explanation on the failure of past FAP-targeted therapies. Finally, we demonstrate that EpCAM aptamer-delivered FAP siRNA impeded intraperitoneal xenograft development of ovary tumors.
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Affiliation(s)
- Bin Li
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
| | - Zuo Ding
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
| | - Ozlem Calbay
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
| | - Yue Li
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
| | - Tao Li
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
| | - Lingtao Jin
- Deparment of Molecular Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78245, USA
| | - Shuang Huang
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, Gainesville, FL, 32611, USA.
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Erichsen L, Adjaye J. Crosstalk between age accumulated DNA-damage and the SIRT1-AKT-GSK3ß axis in urine derived renal progenitor cells. Aging (Albany NY) 2022; 14:8179-8204. [PMID: 36170022 PMCID: PMC9648809 DOI: 10.18632/aging.204300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 09/08/2022] [Indexed: 12/02/2022]
Abstract
The aging process is manifested by a multitude of inter-linked biological processes. These processes contribute to genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, de-regulated nutrient-sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. The mammalian ortholog of the yeast silent information regulator (Sir2) SIRT1 is a NAD+-dependent class III histone deacetylase and has been recognized to be involved in many of the forementioned processes. Furthermore, the physiological activity of several Sirtuin family members has been connected to the regulation of life span of lower organisms (Caenorhabditis elegans and Drosophila melanogaster) as well as mammals. In the present study, we provide evidence that SIX2-positive urine derived renal progenitor cells-UdRPCs isolated directly from human urine show typical hallmarks of aging. This includes the subsequent transcriptional downregulation of SIRT1 and its downstream targets AKT and GSK3ß with increased donor age. This transcriptional downregulation is accompanied by an increase in DNA damage and transcriptional levels of several cell cycle inhibitors such as P16. We provide evidence that the renal progenitor transcription factor SIX2 binds to the coding sequence of SIRT1. Furthermore, we show that the SIRT1 promoter region is methylation sensitive and becomes methylated during aging, dividing them into SIRT1-high and -low expressing UdRPCs. Our results highlight the importance of SIRT1 in DNA damage repair recognition in UdRPCs and the control of differentiation by regulating the activation of GSK3β through AKT.
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Affiliation(s)
- Lars Erichsen
- Institute for Stem Cell Research and Regenerative Medicine, Medical Faculty, Heinrich-Heine- University Düsseldorf, Düsseldorf 40225, Germany
| | - James Adjaye
- Institute for Stem Cell Research and Regenerative Medicine, Medical Faculty, Heinrich-Heine- University Düsseldorf, Düsseldorf 40225, Germany
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Liu M, Li Y, Zhang C, Zhang Q. Role of aurora kinase B in regulating resistance to paclitaxel in breast cancer cells. Hum Cell 2022; 35:678-693. [PMID: 35088239 PMCID: PMC8866333 DOI: 10.1007/s13577-022-00675-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 01/16/2022] [Indexed: 12/24/2022]
Abstract
Aurora kinase B (AURKB) is a type of functional kinase with primary functions of participating in cell mitosis, which has been identified to be involved in the occurrence and development of malignant tumors strongly. However, it still remains a controversial with respect to the relationship between the phosphorylation level of AURKB and its function. In our initial research, there was no significant difference in the relative content of AURKB protein between drug-resistant breast cancer cells and wild-type cells; however, its phosphorylation level in drug-resistant cells was significantly higher than that in wild-type cells. Subsequent cell and animal experiments both confirmed the positive correlation between AURKB phosphorylation and drug resistance. Furthermore, PRKCE in the upstream was identified to regulate the phosphorylation of AURKB, which promoted the change of spatial localization of AURKB from nucleus to cytoplasm. Accordingly, phosphorylated AURKB reduced the negative regulation of downstream RAB27B transcription physically, and interacted with RAB27B in cytoplasm to maintain its protein stability. Eventually, it promoted exosome secretion of drug-resistant cells and drug efflux. Using shRNA to knockdown AURKB expression, using hesperadin to inhibit AURKB activity, mutating the AURKB phosphorylation site, or using siRNA as well as BIM to inhibit the activity of the upstream AURKB phosphorylation regulatory protein PRKCE, all of which directly or indirectly reduce AURKB phosphorylation, are effective in reversing PTX resistance in cells. Collectively, this study provides experimental evidence for PRKCE/AURKB/RAB27B axis in regulating the resistance to paclitaxel (PTX) in breast cancer cells, offering a potential intervention target for reversing drug resistance.
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Affiliation(s)
- Min Liu
- Department of Oncology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, No. 23 Art museum Back street, Dongcheng District, Beijing, 100010, China
| | - Yinan Li
- Department of Oncology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, No. 23 Art museum Back street, Dongcheng District, Beijing, 100010, China.,Department of Oncology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, 100010, China.,Graduate School of Beijing University of Chinese Medicine, North Third Ring East Road 15, Chaoyang District, Beijing, 100029, China
| | - Cui Zhang
- Department of Oncology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, No. 23 Art museum Back street, Dongcheng District, Beijing, 100010, China
| | - Qing Zhang
- Department of Oncology, Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, No. 23 Art museum Back street, Dongcheng District, Beijing, 100010, China.
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Zeng H, Wang L, Zhang J, Pan T, Yu Y, Lu J, Zhou P, Yang H, Li P. Activated PKB/GSK-3 β synergizes with PKC- δ signaling in attenuating myocardial ischemia/reperfusion injury via potentiation of NRF2 activity: Therapeutic efficacy of dihydrotanshinone-I. Acta Pharm Sin B 2021; 11:71-88. [PMID: 33532181 PMCID: PMC7838031 DOI: 10.1016/j.apsb.2020.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 08/30/2020] [Accepted: 08/31/2020] [Indexed: 12/16/2022] Open
Abstract
Disrupted redox status primarily contributes to myocardial ischemia/reperfusion injury (MIRI). NRF2, the endogenous antioxidant regulator, might provide therapeutic benefits. Dihydrotanshinone-I (DT) is an active component in Salvia miltiorrhiza with NRF2 induction potency. This study seeks to validate functional links between NRF2 and cardioprotection of DT and to investigate the molecular mechanism particularly emphasizing on NRF2 cytoplasmic/nuclear translocation. DT potently induced NRF2 nuclear accumulation, ameliorating post-reperfusion injuries via redox alterations. Abrogated cardioprotection in NRF2-deficient mice and cardiomyocytes strongly supports NRF2-dependent cardioprotection of DT. Mechanistically, DT phosphorylated NRF2 at Ser40, rendering its nuclear-import by dissociating from KEAP1 and inhibiting degradation. Importantly, we identified PKC-δ-(Thr505) phosphorylation as primary upstream event triggering NRF2-(Ser40) phosphorylation. Knockdown of PKC-δ dramatically retained NRF2 in cytoplasm, convincing its pivotal role in mediating NRF2 nuclear-import. NRF2 activity was further enhanced by activated PKB/GSK-3β signaling via nuclear-export signal blockage independent of PKC-δ activation. By demonstrating independent modulation of PKC-δ and PKB/GSK-3β/Fyn signaling, we highlight the ability of DT to exploit both nuclear import and export regulation of NRF2 in treating reperfusion injury harboring redox homeostasis alterations. Coactivation of PKC and PKB phenocopied cardioprotection of DT in vitro and in vivo, further supporting the potential applicability of this rationale.
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Affiliation(s)
| | | | | | | | | | | | | | - Hua Yang
- Corresponding authors. Tel./fax: +86 25 83271379.
| | - Ping Li
- Corresponding authors. Tel./fax: +86 25 83271379.
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Regulation of Autophagy by Protein Kinase C-ε in Breast Cancer Cells. Int J Mol Sci 2020; 21:ijms21124247. [PMID: 32549199 PMCID: PMC7352677 DOI: 10.3390/ijms21124247] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 11/24/2022] Open
Abstract
Protein kinase C-ε (PKCε), an anti-apoptotic protein, plays critical roles in breast cancer development and progression. Although autophagy is an important survival mechanism, it is not known if PKCε regulates autophagy in breast cancer cells. We have shown that silencing of PKCε by siRNA inhibited basal and starvation-induced autophagy in T47D breast cancer cells as determined by the decrease in LC3-II, increase in p62, and decrease in autophagy puncta both in the presence and absence of bafilomycin A1. The mechanistic target of rapamycin (mTOR) associates with Raptor or Rictor to form complex-1 (mTORC1) or complex-2 (mTORC2), respectively. Knockdown of PKCε attenuated an increase in autophagy caused by the depletion of Raptor and Rictor. Overexpression of PKCε in MCF-7 cells caused activation of mTORC1 and an increase in LC3-I, LC3-II, and p62. The mTORC1 inhibitor rapamycin abolished the increase in LC3-I and p62. Knockdown of mTOR and Rictor or starvation enhanced autophagy in PKCε overexpressing cells. While overexpression of PKCε in MCF-7 cells inhibited apoptosis, it induced autophagy in response to tumor necrosis factor-α. However, inhibition of autophagy by Atg5 knockdown restored apoptosis in PKCε-overexpressing cells. Thus, PKCε promotes breast cancer cell survival not only by inhibiting apoptosis but also by inducing autophagy.
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Szymonowicz K, Oeck S, Malewicz NM, Jendrossek V. New Insights into Protein Kinase B/Akt Signaling: Role of Localized Akt Activation and Compartment-Specific Target Proteins for the Cellular Radiation Response. Cancers (Basel) 2018; 10:cancers10030078. [PMID: 29562639 PMCID: PMC5876653 DOI: 10.3390/cancers10030078] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/15/2018] [Accepted: 03/16/2018] [Indexed: 12/19/2022] Open
Abstract
Genetic alterations driving aberrant activation of the survival kinase Protein Kinase B (Akt) are observed with high frequency during malignant transformation and cancer progression. Oncogenic gene mutations coding for the upstream regulators or Akt, e.g., growth factor receptors, RAS and phosphatidylinositol-3-kinase (PI3K), or for one of the three Akt isoforms as well as loss of the tumor suppressor Phosphatase and Tensin Homolog on Chromosome Ten (PTEN) lead to constitutive activation of Akt. By activating Akt, these genetic alterations not only promote growth, proliferation and malignant behavior of cancer cells by phosphorylation of various downstream signaling molecules and signaling nodes but can also contribute to chemo- and radioresistance in many types of tumors. Here we review current knowledge on the mechanisms dictating Akt’s activation and target selection including the involvement of miRNAs and with focus on compartmentalization of the signaling network. Moreover, we discuss recent advances in the cross-talk with DNA damage response highlighting nuclear Akt target proteins with potential involvement in the regulation of DNA double strand break repair.
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Affiliation(s)
- Klaudia Szymonowicz
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen Medical School, 45122 Essen, Germany.
| | - Sebastian Oeck
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen Medical School, 45122 Essen, Germany.
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Nathalie M Malewicz
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Verena Jendrossek
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen Medical School, 45122 Essen, Germany.
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Chung JH. The role of DNA-PK in aging and energy metabolism. FEBS J 2018; 285:1959-1972. [PMID: 29453899 DOI: 10.1111/febs.14410] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/15/2018] [Accepted: 02/12/2018] [Indexed: 12/17/2022]
Abstract
DNA-dependent protein kinase (DNA-PK) is a very large holoenzyme comprised of the p470 kDa DNA-PK catalytic subunit (DNA-PKcs ) and the Ku heterodimer consisting of the p86 (Ku 80) and p70 (Ku 70) subunits. It is best known for its nonhomologous end joining (NHEJ) activity, which repairs double-strand DNA (dsDNA) breaks (DSBs). As expected, the absence of DNA-PK activity results in sensitivity to ionizing radiation, which generates DSBs and defect in lymphocyte development, which requires NHEJ of the V(D)J region in the immunoglobulin and T-cell receptor loci. DNA-PK also has been reported to have functions seemingly unrelated to NHEJ. For example, DNA-PK responds to insulin signaling to facilitate the conversion of carbohydrates to fatty acids in the liver. More recent evidence indicates that DNA-PK activity increases with age in skeletal muscle, promoting mitochondrial loss and weight gain. These discoveries suggest that our understanding of DNA-PK is far from complete. As many excellent reviews have already been written about the role of DNA-PK in NHEJ, here we will review the non-NHEJ role of DNA-PK with a focus on its role in aging and energy metabolism.
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Affiliation(s)
- Jay H Chung
- Laboratory of Obesity and Aging Research, Genetics and Developmental Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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10
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Isakov N. Protein kinase C (PKC) isoforms in cancer, tumor promotion and tumor suppression. Semin Cancer Biol 2017; 48:36-52. [PMID: 28571764 DOI: 10.1016/j.semcancer.2017.04.012] [Citation(s) in RCA: 160] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/22/2017] [Accepted: 04/25/2017] [Indexed: 12/27/2022]
Abstract
The AGC family of serine/threonine kinases (PKA, PKG, PKC) includes more than 60 members that are critical regulators of numerous cellular functions, including cell cycle and differentiation, morphogenesis, and cell survival and death. Mutation and/or dysregulation of AGC kinases can lead to malignant cell transformation and contribute to the pathogenesis of many human diseases. Members of one subgroup of AGC kinases, the protein kinase C (PKC), have been singled out as critical players in carcinogenesis, following their identification as the intracellular receptors of phorbol esters, which exhibit tumor-promoting activities. This observation attracted the attention of researchers worldwide and led to intense investigations on the role of PKC in cell transformation and the potential use of PKC as therapeutic drug targets in cancer diseases. Studies demonstrated that many cancers had altered expression and/or mutation of specific PKC genes. However, the causal relationships between the changes in PKC gene expression and/or mutation and the direct cause of cancer remain elusive. Independent studies in normal cells demonstrated that activation of PKC is essential for the induction of cell activation and proliferation, differentiation, motility, and survival. Based on these observations and the general assumption that PKC isoforms play a positive role in cell transformation and/or cancer progression, many PKC inhibitors have entered clinical trials but the numerous attempts to target PKC in cancer has so far yielded only very limited success. More recent studies demonstrated that PKC function as tumor suppressors, and suggested that future clinical efforts should focus on restoring, rather than inhibiting, PKC activity. The present manuscript provides some historical perspectives on the tumor promoting function of PKC, reviewing some of the observations linking PKC to cancer progression, and discusses the role of PKC in the pathogenesis of cancer diseases and its potential usage as a therapeutic target.
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Affiliation(s)
- Noah Isakov
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences and the Cancer Research Center, Ben Gurion University of the Negev, P.O.B. 653, Beer Sheva 84105, Israel.
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Ghandadi M, Mohammadi A, Behravan J, Abnous K, Haj-Ali N, Gharaee ME, Mosaffa F. Inhibition of Akt phosphorylation attenuates resistance to TNF-α cytotoxic effects in MCF-7 cells, but not in their doxorubicin resistant derivatives. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2017; 19:1363-1367. [PMID: 28096970 PMCID: PMC5220243 DOI: 10.22038/ijbms.2016.7924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Objective(s): Acquisition of TNF-α resistance plays role in the onset and growth of malignant tumors. Previous studies have demonstrated that MCF-7 cell line and its doxorubicin resistant variant MCF-7/Adr are resistant against the cytotoxic effects of TNF-α. In this study, we investigated the role of Akt activation in resistance of MCF-7 and MCF-7/Adr against TNF-α cytotoxicity. Materials and Methods: The role of Akt activation in TNF-α cytotoxicity was investigated by MTT cell viability assay following treatment of the cells with the chemical inhibitor of Akt activation with or without TNF-α treatment. Phosphorylation of Akt at Ser473 before and after 72 hr TNF-α treatment was also determined by western blot. Results: TNF-α treatment led to enhancement of Akt Ser473 phosphorylation. Treatment of MCF-7 cells with TNF-α along with Akt-inhibitor agent, tricribine, attenuated Akt Ser473 phosphorylation and sensitized these cells to the cytotoxic effects of TNF-α in a dose and time dependent manner while tricribine treatment did not cause any significant cytotoxicity in MCF-7/Adr cells alone or in combination with TNF-α. Conclusion: These results demonstrate that Akt phosphorylation plays pivotal role in the resistance of MCF-7 cells against TNF-α-induced cytotoxicity while it might play no significant role in the resistance of MCF-7/Adr cells against TNF-α.
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Affiliation(s)
- Morteza Ghandadi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Atieh Mohammadi
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Javad Behravan
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran; Biotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Khalil Abnous
- Pharmaceutical Research Center, Department of Medicinal Chemistry, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Negin Haj-Ali
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Melika Ehtesham Gharaee
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Fatemeh Mosaffa
- Department of Pharmaceutical Biotechnology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran; Biotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
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Tenconi PE, Giusto NM, Salvador GA, Mateos MV. Phospholipase D1 modulates protein kinase C-epsilon in retinal pigment epithelium cells during inflammatory response. Int J Biochem Cell Biol 2016; 81:67-75. [DOI: 10.1016/j.biocel.2016.10.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 10/11/2016] [Accepted: 10/19/2016] [Indexed: 12/13/2022]
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13
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Long chain n-3 polyunsaturated fatty acids increase the efficacy of docetaxel in mammary cancer cells by downregulating Akt and PKCε/δ-induced ERK pathways. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:380-90. [DOI: 10.1016/j.bbalip.2016.01.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Revised: 01/15/2016] [Accepted: 01/22/2016] [Indexed: 12/21/2022]
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Cross Talk Mechanism among EMT, ROS, and Histone Acetylation in Phorbol Ester-Treated Human Breast Cancer MCF-7 Cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:1284372. [PMID: 27127545 PMCID: PMC4830742 DOI: 10.1155/2016/1284372] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 03/17/2016] [Accepted: 03/20/2016] [Indexed: 01/12/2023]
Abstract
Epithelial-mesenchymal transition (EMT) plays a pivotal role in the progression of cancer, and some transcription factors including Slug and Snail are known to be involved in EMT processes. It has been well established that the excess production of reactive oxygen species (ROS) and epigenetics such as DNA methylation and histone modifications participate in carcinogenesis; however, the cross talk mechanism among EMT, ROS, and epigenetics remains unclear. In the present study, we demonstrated that the treatment of human breast cancer MCF-7 cells with phorbol ester (TPA), a protein kinase C activator, significantly induced cell proliferation and migration, and these were accompanied by the significant induction of Slug expression. Moreover, the TPA-elicited induction of Slug expression was regulated by histone H3 acetylation and NADPH oxidase (NOX) 2-derived ROS signaling, indicating that ROS and histone acetylation are involved in TPA-elicited EMT processes. We herein determined the cross talk mechanism among EMT, ROS, and histone acetylation, and our results provide an insight into the progression of cancer metastasis.
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15
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Man SM, Karki R, Kanneganti TD. AIM2 inflammasome in infection, cancer, and autoimmunity: Role in DNA sensing, inflammation, and innate immunity. Eur J Immunol 2015; 46:269-80. [PMID: 26626159 DOI: 10.1002/eji.201545839] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/13/2015] [Accepted: 11/26/2015] [Indexed: 12/15/2022]
Abstract
Recognition of DNA by the cell is an important immunological signature that marks the initiation of an innate immune response. AIM2 is a cytoplasmic sensor that recognizes dsDNA of microbial or host origin. Upon binding to DNA, AIM2 assembles a multiprotein complex called the inflammasome, which drives pyroptosis and proteolytic cleavage of the proinflammatory cytokines pro-IL-1β and pro-IL-18. Release of microbial DNA into the cytoplasm during infection by Francisella, Listeria, Mycobacterium, mouse cytomegalovirus, vaccinia virus, Aspergillus, and Plasmodium species leads to activation of the AIM2 inflammasome. In contrast, inappropriate recognition of cytoplasmic self-DNA by AIM2 contributes to the development of psoriasis, dermatitis, arthritis, and other autoimmune and inflammatory diseases. Inflammasome-independent functions of AIM2 have also been described, including the regulation of the intestinal stem cell proliferation and the gut microbiota ecology in the control of colorectal cancer. In this review we provide an overview of the latest research on AIM2 inflammasome and its role in infection, cancer, and autoimmunity.
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Affiliation(s)
- Si Ming Man
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Rajendra Karki
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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16
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Caruso M, Zhang X, Ma D, Yang Z, Qi Y, Yi Z. Novel Endogenous, Insulin-Stimulated Akt2 Protein Interaction Partners in L6 Myoblasts. PLoS One 2015; 10:e0140255. [PMID: 26465754 PMCID: PMC4605787 DOI: 10.1371/journal.pone.0140255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 09/23/2015] [Indexed: 12/28/2022] Open
Abstract
Insulin resistance and Type 2 diabetes are marked by an aberrant response in the insulin signaling network. The phosphoinositide-dependent serine/threonine kinase, Akt2, plays a key role in insulin signaling and glucose uptake, most notably within skeletal muscle. Protein-protein interaction regulates the functional consequence of Akt2 and in turn, Akt2's role in glucose uptake. However, only few insulin-responsive Akt2 interaction partners have been identified in skeletal muscle cells. In the present work, rat L6 myoblasts, a widely used insulin sensitive skeletal muscle cell line, were used to examine endogenous, insulin-stimulated Akt2 protein interaction partners. Akt2 co-immunoprecipitation was coupled with 1D-SDS-PAGE and fractions were analyzed by HPLC-ESI-MS/MS to reveal Akt2 protein-protein interactions. The pull-down assay displayed specificity for the Akt2 isoform; Akt1 and Akt3 unique peptides were not detected. A total of 49 were detected with a significantly increased (47) or decreased (2) association with Akt2 following insulin administration (n = 4; p<0.05). Multiple pathways were identified for the novel Akt2 interaction partners, such as the EIF2 and ubiquitination pathways. These data suggest that multiple new endogenous proteins may associate with Akt2 under basal as well as insulin-stimulated conditions, providing further insight into the insulin signaling network. Data are available via ProteomeXchange with identifier PXD002557.
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Affiliation(s)
- Michael Caruso
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Danjun Ma
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Zhao Yang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Yue Qi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI, United States of America
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17
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Wilson JE, Petrucelli AS, Chen L, Koblansky AA, Truax AD, Oyama Y, Rogers AB, Brickey WJ, Wang Y, Schneider M, Mühlbauer M, Chou WC, Barker BR, Jobin C, Allbritton NL, Ramsden DA, Davis BK, Ting JPY. Inflammasome-independent role of AIM2 in suppressing colon tumorigenesis via DNA-PK and Akt. Nat Med 2015; 21:906-13. [PMID: 26107252 DOI: 10.1038/nm.3908] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 06/18/2015] [Indexed: 12/11/2022]
Abstract
The inflammasome activates caspase-1 and the release of interleukin-1β (IL-1β) and IL-18, and several inflammasomes protect against intestinal inflammation and colitis-associated colon cancer (CAC) in animal models. The absent in melanoma 2 (AIM2) inflammasome is activated by double-stranded DNA, and AIM2 expression is reduced in several types of cancer, but the mechanism by which AIM2 restricts tumor growth remains unclear. We found that Aim2-deficient mice had greater tumor load than Asc-deficient mice in the azoxymethane/dextran sodium sulfate (AOM/DSS) model of colorectal cancer. Tumor burden was also higher in Aim2(-/-)/Apc(Min/+) than in APC(Min/+) mice. The effects of AIM2 on CAC were independent of inflammasome activation and IL-1β and were primarily mediated by a non-bone marrow source of AIM2. In resting cells, AIM2 physically interacted with and limited activation of DNA-dependent protein kinase (DNA-PK), a PI3K-related family member that promotes Akt phosphorylation, whereas loss of AIM2 promoted DNA-PK-mediated Akt activation. AIM2 reduced Akt activation and tumor burden in colorectal cancer models, while an Akt inhibitor reduced tumor load in Aim2(-/-) mice. These findings suggest that Akt inhibitors could be used to treat AIM2-deficient human cancers.
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Affiliation(s)
- Justin E Wilson
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Alex S Petrucelli
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Liang Chen
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - A Alicia Koblansky
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Agnieszka D Truax
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Yoshitaka Oyama
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Arlin B Rogers
- Department of Biomedical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, USA
| | - W June Brickey
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Yuli Wang
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Monika Schneider
- The American Association of Immunologists, Bethesda, Maryland, USA
| | - Marcus Mühlbauer
- 1] Department of Medicine, Division of Gastroenterology, University of Florida College of Medicine, Gainesville, Florida, USA. [2] Department of Infectious Diseases &Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Wei-Chun Chou
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Brianne R Barker
- Department of Biology, Drew University, Madison, New Jersey, USA
| | - Christian Jobin
- 1] Department of Medicine, Division of Gastroenterology, University of Florida College of Medicine, Gainesville, Florida, USA. [2] Department of Infectious Diseases &Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Nancy L Allbritton
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Dale A Ramsden
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Beckley K Davis
- Department of Biology, Franklin &Marshall College, Lancaster, Pennsylvania, USA
| | - Jenny P Y Ting
- 1] Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, USA. [2] Department of Genetics, University of North Carolina, Chapel Hill, North Carolina, USA. [3] Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
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18
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Zhao W, Wang P, Ma J, Liu YH, Li Z, Li ZQ, Wang ZH, Chen LY, Xue YX. MiR-34a regulates blood-tumor barrier function by targeting protein kinase Cε. Mol Biol Cell 2015; 26:1786-96. [PMID: 25788289 PMCID: PMC4436826 DOI: 10.1091/mbc.e14-10-1474] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 03/12/2015] [Indexed: 11/21/2022] Open
Abstract
It is shown for the first time that overexpression of miR-34a increases blood–tumor barrier permeability by targeting PKCε, which is activated by p-PKCε and directly regulates the expression of tight junction–related proteins. MicroRNA-34a (miR-34a) functions to regulate protein expression at the posttranscriptional level by binding the 3′ UTR of target genes and regulates functions of vascular endothelial cells. However, the role of miR-34a in regulating blood–tumor barrier (BTB) permeability remains unknown. In this study, we show that miR-34a overexpression leads to significantly increased permeability of BTB, whereas miR-34a silencing reduces the permeability of the BTB. In addition, miR-34a overexpression significantly down-regulates the expression and distribution of tight junction–related proteins in glioma endothelial cells (GECs), paralleled by protein kinase Cε (PKCε) reduction. Moreover, luciferase reporter gene analysis shows that PKCε is the target gene of miR-34a. We also show that cotransfection of miR-34a and PKCε inversely coregulates BTB permeability and protein expression levels of tight junction–related proteins. Pretreatment of ψεRACK, a PKCε-specific activator, decreases BTB permeability in miR-34a–overexpressed GECs and up-regulates expression levels of tight junction proteins. In contrast, pretreatment of εV1-2, a specific PKCε inhibitor, gives opposite results. Collectively, our findings indicate that miR-34a regulates BTB function by targeting PKCε; after phosphorylation, PKCε is activated and contributes to regulation of the expression of tight junction–related proteins, ultimately altering BTB permeability.
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Affiliation(s)
- Wei Zhao
- Department of Neurobiology, China Medical University, Shenyang 110122, China Department of Physiology, College of Basic Medicine, China Medical University, Shenyang 110122, China
| | - Ping Wang
- Department of Neurobiology, China Medical University, Shenyang 110122, China Department of Physiology, College of Basic Medicine, China Medical University, Shenyang 110122, China
| | - Jun Ma
- Department of Neurobiology, China Medical University, Shenyang 110122, China Department of Physiology, College of Basic Medicine, China Medical University, Shenyang 110122, China
| | - Yun-Hui Liu
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Zhen Li
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Zhi-Qing Li
- Department of Neurobiology, China Medical University, Shenyang 110122, China Department of Physiology, College of Basic Medicine, China Medical University, Shenyang 110122, China
| | - Zhen-Hua Wang
- Institute of Pathology and Pathophysiology, China Medical University, Shenyang 110122, China
| | - Liang-Yu Chen
- Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang 110004, China
| | - Yi-Xue Xue
- Department of Neurobiology, China Medical University, Shenyang 110122, China Department of Physiology, College of Basic Medicine, China Medical University, Shenyang 110122, China
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19
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Ellis L, Ku SY, Ramakrishnan S, Lasorsa E, Azabdaftari G, Godoy A, Pili R. Combinatorial antitumor effect of HDAC and the PI3K-Akt-mTOR pathway inhibition in a Pten defecient model of prostate cancer. Oncotarget 2014; 4:2225-36. [PMID: 24163230 PMCID: PMC3926822 DOI: 10.18632/oncotarget.1314] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Increased expression of histone deacetylases (HDACs) and activation of the PI3K-Akt-mTORC1 pathway are common aberrations in prostate cancer (PCa). For this reason, inhibition of such targets is an exciting avenue for the development of novel therapeutic strategies to treat patients with advanced PCa. Previous reports demonstrated that HDAC inhibitors (HDACi) increases DNA damage and induce greater apoptosis in PCa cell lines that express androgen receptor (AR). In this study we utilized the AR negative PCa cell line and observed that re-expression of AR (PC3-AR) results in greater levels of apoptosis when treated with the pan-DACi, panobinostat (PAN). PAN mediated apoptosis in PC3 and PC3-AR cells was associated with increased levels of double strand DNA breaks, indicated by p-ɣH2AX. Further, PAN treatment in PC3-AR cells resulted in moderate attenuation of the ATM-Akt-ERK DNA damage response pathway. For this reason, we combined PAN with the dual PI3K-mTOR inhibitor, BEZ235. Combination of PAN with BEZ235 resulted in significant attenuation of the DNA damage repair protein ATM and significantly increased anti-tumor activity compared to each single treatment. Overall, superior anti-tumor activity with combination of PAN with BEZ235 was independent of AR status. These findings suggest that this therapeutic strategy should be further developed in clinical trials.
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Affiliation(s)
- Leigh Ellis
- Genitourinary Program, Roswell Park Cancer Institute, Buffalo NY
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20
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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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21
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Reed SA, Raja JS, Hoffman ML, Zinn SA, Govoni KE. Poor maternal nutrition inhibits muscle development in ovine offspring. J Anim Sci Biotechnol 2014; 5:43. [PMID: 25247074 PMCID: PMC4170199 DOI: 10.1186/2049-1891-5-43] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/01/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Maternal over and restricted nutrition has negative consequences on the muscle of offspring by reducing muscle fiber number and altering regulators of muscle growth. To determine if over and restricted maternal nutrition affected muscle growth and gene and protein expression in offspring, 36 pregnant ewes were fed 60%, 100% or 140% of National Research Council requirements from d 31 ± 1.3 of gestation until parturition. Lambs from control-fed (CON), restricted-fed (RES) or over-fed (OVER) ewes were necropsied within 1 d of birth (n = 18) or maintained on a control diet for 3 mo (n = 15). Semitendinosus muscle was collected for immunohistochemistry, and protein and gene expression analysis. RESULTS Compared with CON, muscle fiber cross-sectional area (CSA) increased in RES (58%) and OVER (47%) lambs at 1 d of age (P < 0.01); however at 3 mo, CSA decreased 15% and 17% compared with CON, respectively (P < 0.01). Compared with CON, muscle lipid content was increased in OVER (212.4%) and RES (92.5%) at d 1 (P < 0.0001). Muscle lipid content was increased 36.1% in OVER and decreased 23.6% in RES compared with CON at 3 mo (P < 0.0001). At d 1, myostatin mRNA abundance in whole muscle tended to be greater in OVER (P = 0.07) than CON. Follistatin mRNA abundance increased in OVER (P = 0.04) and tended to increase in RES (P = 0.06) compared with CON at d 1. However, there was no difference in myostatin or follistatin protein expression (P > 0.3). Phosphorylated Akt (ser473) was increased in RES at 3 mo compared with CON (P = 0.006). CONCLUSIONS In conclusion, maternal over and restricted nutrient intake alters muscle lipid content and growth of offspring, possibly through altered gene and protein expression.
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Affiliation(s)
- Sarah A Reed
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Joseline S Raja
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Maria L Hoffman
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Steven A Zinn
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
| | - Kristen E Govoni
- Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA
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22
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Hamilton D, Rugg C, Davis N, Kvezereli M, Tafti BA, Busque S, Fontaine M. A Preconditioning Regimen with a PKCε Activator Improves Islet Graft Function in a Mouse Transplant Model. Cell Transplant 2014; 23:913-9. [DOI: 10.3727/096368913x665567] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Transplantation of islets isolated from deceased donor pancreata is an attractive method of β-cell replacement therapy for patients with type 1 diabetes (T1D). However, the loss of islet cell viability and function during the peritransplant period is a limiting factor to long-term islet engraftment. Activation of the isoenzyme PKCe may improve islet survival and function. The current study assesses the effects of PKCe activation on islet graft function in a syngeneic streptozotocin-induced diabetic mouse model. Islets were isolated from wild-type BALB/c mice preconditioned with either a PKCe activator (ψεRACK) or a TAT carrier control peptide. Islets were further treated with the same agents during isolation, purification, and incubation prior to transplantation. Two hundred seventy-five islet equivalents were transplanted under the kidney capsule of streptozotocin-induced diabetic BALB/c mice. Islet function was assessed by measurement of blood glucose levels every 3 days for 42 days after transplant and through an intraperitoneal glucose tolerance test (IPGTT). The time for return to euglycemia in mice transplanted with islets treated with ψεRACK was improved at 14 ± 6 days versus 21 ± 6 days with TAT-treated islets. The IPGTT showed a 50% reduction in the area under the curve associated with an improved insulin response in mice transplanted with ψεRACK-treated islets compared to TAT-treated islets. A preconditioning regimen using PKCe agonist before pancreatic recovery and during islet isolation improves islet graft function and resistance to high glucose stress after transplantation.
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Affiliation(s)
- Diana Hamilton
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Caitlin Rugg
- Department of Pathology, Stanford University, Stanford, CA, USA
| | - Nicolynn Davis
- Department of Pathology, Stanford University, Stanford, CA, USA
| | | | | | - Stephan Busque
- Department of Surgery, Stanford University, Stanford, CA, USA
| | - Magali Fontaine
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
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23
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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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24
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Jain K, Basu A. The Multifunctional Protein Kinase C-ε in Cancer Development and Progression. Cancers (Basel) 2014; 6:860-78. [PMID: 24727247 PMCID: PMC4074807 DOI: 10.3390/cancers6020860] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 12/31/2022] Open
Abstract
The protein kinase C (PKC) family proteins are important signal transducers and have long been the focus of cancer research. PKCɛ, a member of this family, is overexpressed in most solid tumors and plays critical roles in different processes that lead to cancer development. Studies using cell lines and animal models demonstrated the transforming potential of PKCɛ. While earlier research established the survival functions of PKCɛ, recent studies revealed its role in cell migration, invasion and cancer metastasis. PKCɛ has also been implicated in epithelial to mesenchymal transition (EMT), which may be the underlying mechanism by which it contributes to cell motility. In addition, PKCɛ affects cell-extracellular matrix (ECM) interactions by direct regulation of the cytoskeletal elements. Recent studies have also linked PKCɛ signaling to cancer stem cell functioning. This review focuses on the role of PKCɛ in different processes that lead to cancer development and progression. We also discussed current literatures on the pursuit of PKCɛ as a target for cancer therapy.
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Affiliation(s)
- Kirti Jain
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, and Focused on Resources for her Health Education and Research, Fort Worth, TX 76107, USA.
| | - Alakananda Basu
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, and Focused on Resources for her Health Education and Research, Fort Worth, TX 76107, USA.
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25
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Jain K, Basu A. Protein Kinase C-ε Promotes EMT in Breast Cancer. BREAST CANCER-BASIC AND CLINICAL RESEARCH 2014; 8:61-7. [PMID: 24701121 PMCID: PMC3972078 DOI: 10.4137/bcbcr.s13640] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/15/2013] [Accepted: 12/16/2013] [Indexed: 01/17/2023]
Abstract
Protein kinase C (PKC), a family of serine/threonine kinases, plays critical roles in signal transduction and cell regulation. PKCε, a member of the novel PKC family, is known to be a transforming oncogene and a tumor biomarker for aggressive breast cancers. In this study, we examined the involvement of PKCε in epithelial to mesenchymal transition (EMT), the process that leads the way to metastasis. Overexpression of PKCε was sufficient to induce a mesenchymal phenotype in non-tumorigenic mammary epithelial MCF-10 A cells. This was accompanied by a decrease in the epithelial markers, such as E-cadherin, zonula occludens (ZO)-1, and claudin-1, and an increase in mesenchymal marker vimentin. Transforming growth factor β (TGFβ) induced Snail expression and mesenchymal morphology in MCF-10 A cells, and these effects were partially reversed by the PKCε knockdown. PKCε also mediated cell migration and anoikis resistance, which are hallmarks of EMT. Thus, our study demonstrates that PKCε is an important mediator of EMT in breast cancer.
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Affiliation(s)
- Kirti Jain
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, Fort Worth, TX, USA. ; Focused on Resources for her Health Education and Research, Fort Worth, TX, USA
| | - Alakananda Basu
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, Fort Worth, TX, USA. ; Focused on Resources for her Health Education and Research, Fort Worth, TX, USA
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Zhuang J, Tu X, Cao K, Guo S, Mao X, Pan J, Huang B, Chen X, Gao Y, Qiu S. The expression and role of tyrosine kinase ETK/BMX in renal cell carcinoma. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2014; 33:25. [PMID: 24606948 PMCID: PMC3984736 DOI: 10.1186/1756-9966-33-25] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/28/2014] [Indexed: 11/29/2022]
Abstract
Background Expression of the non-receptor tyrosine kinase ETK/BMX has been reported in several solid tumors, but the underlying molecular mechanisms and its clinical significance in renal cell carcinoma (RCC) remain to be elucidated. Methods ETK expression in 90 human RCC and 30 human normal renal tissue samples was examined by immunohistochemistry and compared with several clinicopathologic parameters. To further demonstrate the biological function of ETK in RCC, Western blot was used to test the expression level of ETK protein in RCC cell lines. Subsequent to the downregulation of ETK by small interfering RNA, the effects of ETK on RCC cell growth, apoptosis, migration and invasion were assessed by methyl thiazol tetrazolium assay, flow cytometry and transwell assay. And the varying expression of VEGF, STAT3 and phosphorylated STAT3 (p-STAT3) in RCC were evaluated by Western blot. Results Immunohistochemistry analysis showed that ETK expression was highly increased in RCC and was positively correlated with clinical stage, grade and metastasis. Simultaneously, the overall survival time in patients with higher ETK expression was obviously shorter than that in patients with lower ETK expression. ETK was also detected in RCC cell lines. Moreover, the down-regulating ETK significantly inhibited RCC cell growth, migration, invasion and promoted apoptosis. The expression of VEGF and p-STAT3 were also decreased. Conclusions Our study suggests that the overexpression of ETK is associated with the malignancy and disease progression of RCC. Since ETK is also involved in RCC cell biological function and VEGF-ETK-STAT3 loop, ETK may be used as a potential therapeutic target for RCC.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Shaopeng Qiu
- Department of Urology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.
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Tu Y, Ji C, Yang B, Yang Z, Gu H, Lu CC, Wang R, Su ZL, Chen B, Sun WL, Xia JP, Bi ZG, He L. DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-SIN1 association mediates ultraviolet B (UVB)-induced Akt Ser-473 phosphorylation and skin cell survival. Mol Cancer 2013; 12:172. [PMID: 24365180 PMCID: PMC3922905 DOI: 10.1186/1476-4598-12-172] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 12/10/2013] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The exposure of skin keratinocytes to Ultraviolet (UV) irradiation leads to Akt phosphorylation at Ser-473, which is important for the carcinogenic effects of excessive sun exposure. The present study investigated the underlying mechanism of Akt Ser-473 phosphorylation by UVB radiation. RESULTS We found that DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and mammalian target of rapamycin (mTOR) complex 2 (mTORC2) were both required for UVB-induced Akt Ser-473 phosphorylation in keratinocytes. Inhibition of DNA-PKcs activity via its inhibitor NU7026, a dominant-negative kinase-dead mutation, RNA interference (RNAi) or gene depletion led to the attenuation of UVB-induced Akt Ser-473 phosphorylation. Meanwhile, siRNA silencing or gene depletion of SIN1, a key component of mTORC2, abolished Akt Ser-473 phosphorylation by UVB. Significantly, we discovered that DNA-PKcs was associated with SIN1 in cytosol upon UVB radiation, and this complexation appeared required for Akt Ser-473 phosphorylation. Meanwhile, this DNA-PKcs-SIN1 complexation by UVB was dependent on epidermal growth factor receptor (EGFR) activation, and was disrupted by an EGFR inhibitor (AG1478) or by EGFR depletion. UVB-induced complexation between DNA-PKcs and mTORC2 components was also abolished by NU7026 and DNA-PKcs mutation. Finally, we found that both DNA-PKcs and SIN1 were associated with apoptosis resistance of UVB radiation, and inhibition of them by NU7026 or genetic depletion significantly enhanced UVB-induced cell death and apoptosis. CONCLUSION Taken together, these results strongly suggest that DNA-PKcs-mTORC2 association is required for UVB-induced Akt Ser-473 phosphorylation and cell survival, and might be important for tumor cell transformation.
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Affiliation(s)
| | - Chao Ji
- Department of Dermatology, The First Affiliated Hospital of Kunming Medical University, Yunnan Provincial Institute of Dermatology, Kunming 650032, Yunnan, China.
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Zhang X, Li D, Li M, Ye M, Ding L, Cai H, Fu D, Lv Z. MicroRNA-146a targets PRKCE to modulate papillary thyroid tumor development. Int J Cancer 2013; 134:257-67. [PMID: 23457043 DOI: 10.1002/ijc.28141] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 02/14/2013] [Indexed: 12/21/2022]
Abstract
MicroRNAs are single-stranded noncoding RNAs composed of approximately 22 nucleotides that suppress gene expression by selectively binding via base-pairing to the complementary 3'-untranslated region (3'-UTR) of messenger RNA transcripts. Protein kinase C epsilon (PKCε) is an important modulating member of the transducing Ras/Raf-1 signal pathway; a computational search revealed miR-146a putatively binds to the 3'-UTR of the PRKCE gene, and thus decreasing PKCε expression. Moreover, PKCε inhibits mitochondrial apoptosis and is associated with the Bcl family. However, it has been previously reported that miR-146a expression in papillary thyroid carcinoma (PTC) is slightly elevated. Thus, we hypothesized that because miR-146a expression depends on nuclear factor kappaB (NF-κB) activation and NF-κB expression is elevated in PTC, miR-146a is potentially upregulated in PTC via negative feedback of NF-κB, and thus suppressing PKCε expression. In our study, we investigated whether overexpression of miR-146a, a tumor-suppressing-miR, in PTC cells decreases cell survival and induces apoptosis. Luciferase reporter assay analysis confirmed the direct binding of miR-146a and PRKCE 3'-UTR. Specific overexpression of exogenous miR-146a significantly decreased PKCε levels in PTC cell line NPA-187 and increased apoptosis. Additionally, using stably expressing miR-146a thyroid carcinoma cells to establish subcutaneous tumors, the tumor growth exhibited significant inhibition. Our study confirmed the tumor-suppressing role of miR-146a in thyroid carcinoma cells and contributes to the knowledge regarding modulation of Ras/Raf-1 signal transduction and apoptosis via PKCε targeted by miR-146a in PTC; moreover, our findings confirmed that miR-146a is involved in the feedback system of the classical NF-κB signal pathway in PTC.
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Affiliation(s)
- Xiaoping Zhang
- Department of Nuclear Medicine, Shanghai 10th People's Hospital, School of Medicine, Tongji University, Shanghai, People's Republic of China
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Li Y, Wang X, Yue P, Tao H, Ramalingam SS, Owonikoko TK, Deng X, Wang Y, Fu H, Khuri FR, Sun SY. Protein phosphatase 2A and DNA-dependent protein kinase are involved in mediating rapamycin-induced Akt phosphorylation. J Biol Chem 2013; 288:13215-24. [PMID: 23536185 DOI: 10.1074/jbc.m113.463679] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The mechanisms underlying rapamycin-induced Akt phosphorylation have not been fully elucidated. RESULTS Inhibition of PP2A or DNA-PK attenuates or abrogates rapamycin-induced Akt phosphorylation and co-inhibition of mTOR and DNA-PK enhances anticancer activity. CONCLUSION PP2A-dependent and DNA-PK-mediated mechanism is involved in rapamycin-induced Akt phosphorylation. SIGNIFICANCE A previously unknown mechanism underlying rapamycin-induced Akt phosphorylation and a novel strategy to enhance mTOR-targeted cancer therapy may be suggested. Inhibition of mammalian target of rapamycin complex 1 (mTORC1), for example with rapamycin, increases Akt phosphorylation while inhibiting mTORC1 signaling. However, the underlying mechanisms have not been fully elucidated. The current study has uncovered a previously unknown mechanism underlying rapamycin-induced Akt phosphorylation involving protein phosphatase 2A (PP2A)-dependent DNA protein kinase (DNA-PK) activation. In several cancer cell lines, inhibition of PP2A with okadaic acid, fostriecin, small T antigen, or PP2A knockdown abrogated rapamycin-induced Akt phosphorylation, and rapamycin increased PP2A activity. Chemical inhibition of DNA-PK, knockdown or deficiency of DNA-PK catalytic subunit (DNA-PKcs), or knock-out of the DNA-PK component Ku86 inhibited rapamycin-induced Akt phosphorylation. Exposure of cancer cells to rapamycin increased DNA-PK activity, and gene silencing-mediated PP2A inhibition attenuated rapamycin-induced DNA-PK activity. Collectively these results suggest that rapamycin induces PP2A-dependent and DNA-PK-mediated Akt phosphorylation. Accordingly, simultaneous inhibition of mTOR and DNA-PK did not stimulate Akt activity and synergistically inhibited the growth of cancer cells both in vitro and in vivo. Thus, our findings also suggest a novel strategy to enhance mTOR-targeted cancer therapy by co-targeting DNA-PK.
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Affiliation(s)
- Yikun Li
- Departments of Hematology and Medical Oncology, Emory University School of Medicine and Winship Cancer Institute, Atlanta, Georgia 30322, USA
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Pal D, Outram SP, Basu A. Novel regulation of protein kinase C-η. Biochem Biophys Res Commun 2012; 425:836-41. [PMID: 22892130 DOI: 10.1016/j.bbrc.2012.07.163] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 07/30/2012] [Indexed: 10/28/2022]
Abstract
Protein kinase C (PKC) is the receptor for tumor promoting phorbol esters, which are potent activators of conventional and novel PKCs, but persistent treatment with phorbol esters leads to downregulation of these PKCs. However, PKCη, a novel PKC isozyme, resists downregulation by tumor-promoting phorbol esters, but little is known about how PKCη level is regulated. Phosphorylation and dephosphorylation play an important role in regulating activity and stability of PKCs. In the present study, we have investigated the molecular mechanism of PKCη regulation. Several PKC activators, including phorbol 12,13-dibutyrate, 12-O-tetradecanoylphorbol-13-acetate and indolactam V caused upregulation of PKCη, whereas the general PKC inhibitor Gö 6983, but not the conventional PKC inhibitor Gö 6976 led to the downregulation of PKCη. Upregulation of PKCη was associated with an increase in phosphorylation of PKCη. Silencing of phosphoinositide-dependent kinase-1, which phosphorylates PKCη at the activation loop, failed to prevent PKC activator-induced upregulation of PKCη. Knockdown of PKCε but not PKCα inhibited PKC activator-induced upregulation of PKCη. Thus, our results suggest that the regulation of PKCη is unique and PKCε is required for the PKC activator-induced upregulation of PKCη.
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Affiliation(s)
- Deepanwita Pal
- Department of Molecular Biology & Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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Awadelkarim KD, Callens C, Rossé C, Susini A, Vacher S, Rouleau E, Lidereau R, Bièche I. Quantification of PKC family genes in sporadic breast cancer by qRT-PCR: evidence that PKCι/λ overexpression is an independent prognostic factor. Int J Cancer 2012; 131:2852-62. [PMID: 22511072 DOI: 10.1002/ijc.27600] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 04/05/2012] [Indexed: 11/11/2022]
Abstract
Drugs targeting protein kinase C (PKC) show promising therapeutic activity. However, little is known about the expression patterns of the 11 PKC genes in human tumors, and the clinical significance of most PKC genes is unknown. We used qRT-PCR assays to quantify mRNA levels of the 11 PKC genes in 458 breast tumors from patients with known clinical/pathological status and long-term outcome. The proportion of tumors in which the expression of the different genes was altered varied widely, from 9.6% for PKN2 to 40.2% for PKCι/λ. In breast tumors, overexpression was the main alteration observed for PKCι/λ (33.4%), PKCδ (29.5%) and PKCζ (9.6%), whereas underexpression was the main alteration observed for PKCα (27.3%), PKCε (11.6%), PKCη (8.7%) and PKN2 (8.1%). Both overexpression and underexpression were observed for PKCβ (underexpression 15.5%, overexpression 13.8%), PKCθ (underexpression 14.8%, overexpression 10.0%) and PKN1 (underexpression 6.6%, overexpression 7.4%). Several links were found between different PKC genes; and also between the expression patterns of PKC genes and several classical pathological and clinical parameters. PKCι/λ alone was found to have prognostic significance (p = 0.043), whereas PKCα showed a trend towards an influence on relapse-free survival (p = 0.052). PKCι/λ retained its prognostic significance in Cox multivariate regression analysis (p = 0.031). These results reveal very complex expression patterns of PKC genes in breast tumors, and suggest that their expression should be considered together when evaluating anti-tumoral drugs. PKCι/λ seems to be the most promising therapeutic target in breast cancer.
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Ma J, Ding Y, Fang X, Wang R, Sun Z. Protein kinase C-θ inhibits inducible regulatory T cell differentiation via an AKT-Foxo1/3a-dependent pathway. THE JOURNAL OF IMMUNOLOGY 2012; 188:5337-47. [PMID: 22539794 DOI: 10.4049/jimmunol.1102979] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Protein kinase C (PKC)-θ has been shown to be a critical TCR signaling molecule that promotes the activation and differentiation of naive T cells into inflammatory effector T cells. In this study, we demonstrate that PKC-θ-mediated signals inhibit inducible regulatory T cell (iTreg) differentiation via an AKT-Foxo1/3A pathway. TGF-β-induced iTreg differentiation was enhanced in PKC-θ(-/-) T cells or wild-type cells treated with a specific PKC-θ inhibitor, but was inhibited by the PKC-θ activator PMA, or by CD28 crosslinking, which enhances PKC-θ activation. PKC-θ(-/-) T cells had reduced activity of the AKT kinase, and the expression of a constitutively active form of AKT in PKC-θ(-/-) T cells restored the ability to inhibit iTreg differentiation. Furthermore, knockdown or overexpression of the AKT downstream targets Foxo1 and Foxo3a was found to inhibit or promote iTreg differentiation in PKC-θ(-/-) T cells accordingly, indicating that the AKT-Foxo1/3A pathway is responsible for the inhibition of iTreg differentiation of iTregs downstream of PKC-θ. We conclude that PKC-θ is able to control T cell-mediated immune responses by shifting the balance between the differentiation of effector T cells and inhibitory Tregs.
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Affiliation(s)
- Jian Ma
- Division of Immunology, Beckman Research Institute of City of Hope, Duarte, CA 91010, USA
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33
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Akt: a double-edged sword in cell proliferation and genome stability. JOURNAL OF ONCOLOGY 2012; 2012:951724. [PMID: 22481935 PMCID: PMC3317191 DOI: 10.1155/2012/951724] [Citation(s) in RCA: 173] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 12/29/2011] [Indexed: 01/31/2023]
Abstract
The Akt family of serine/threonine protein kinases are key regulators of multiple aspects of cell behaviour, including proliferation, survival, metabolism, and tumorigenesis. Growth-factor-activated Akt signalling promotes progression through normal, unperturbed cell cycles by acting on diverse downstream factors involved in controlling the G1/S and G2/M transitions. Remarkably, several recent studies have also implicated Akt in modulating DNA damage responses and genome stability. High Akt activity can suppress ATR/Chk1 signalling and homologous recombination repair (HRR) via direct phosphorylation of Chk1 or TopBP1 or, indirectly, by inhibiting recruitment of double-strand break (DSB) resection factors, such as RPA, Brca1, and Rad51, to sites of damage. Loss of checkpoint and/or HRR proficiency is therefore a potential cause of genomic instability in tumor cells with high Akt. Conversely, Akt is activated by DNA double-strand breaks (DSBs) in a DNA-PK- or ATM/ATR-dependent manner and in some circumstances can contribute to radioresistance by stimulating DNA repair by nonhomologous end joining (NHEJ). Akt therefore modifies both the response to and repair of genotoxic damage in complex ways that are likely to have important consequences for the therapy of tumors with deregulation of the PI3K-Akt-PTEN pathway.
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Shankar E, Vykhovanets EV, Vykhovanets OV, MacLennan GT, Singh R, Bhaskaran N, Shukla S, Gupta S. High-fat diet activates pro-inflammatory response in the prostate through association of Stat-3 and NF-κB. Prostate 2012; 72:233-43. [PMID: 21604287 PMCID: PMC3161175 DOI: 10.1002/pros.21425] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 04/28/2011] [Indexed: 01/05/2023]
Abstract
BACKGROUND Signal transducer and activator of transcription (Stat)-3 and nuclear factor-kappa B (NF-κB) are important signaling pathways constitutively activated during inflammation. We previously reported that high-fat diet (HFD) intake induces oxidative stress in the prostate through elevated expression of NADPH oxidase subunits causing NF-κB activation. We sought to determine whether Stat-3 is involved in the activation of NF-κB in the prostate as a result of HFD feeding, leading to inflammation. METHODS C57BL/6 mice were either fed with regular diet (RD) or HFD for 4 and 8 weeks. Plasma cytokine levels were determined by multiplex analysis. Western blotting was performed to determine the expression of NF-κB, Stat-3, Akt, PDK1, PKCε, and their phosphorylated forms along with pathologic evaluation of the prostate. Immunoprecipitation and electrophoretic mobility shift assay (EMSA) were conducted to study the association between Stat-3 and NF-κB. RESULTS C57BL/6 mice fed with HFD showed a significant increase in the plasma levels of IL-1ß, IL-6, IL-17, and TNFα after 4 and 8 weeks of feeding, compared with RD controls. HFD feeding elevated the intraprostatic expression of IL-6 and caused activation of PKCε and Akt, the upstream kinase regulating Stat-3 and NF-κB. Nuclear extracts from the prostates of mice fed with HFD exhibited constitutively activated levels of Stat-3 and NF-κB/p65. Increased association between the activated forms of Stat-3 and NF-κB/p65 was observed in the nucleus as a result of HFD feeding, a finding that was accompanied by morphologic evidence of increased intraprostatic inflammation. CONCLUSIONS Our findings suggest that HFD activates Stat-3 and NF-κB/p65 in the prostate, and their interaction is associated with increased inflammation in the prostate.
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Affiliation(s)
- Eswar Shankar
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Eugene V Vykhovanets
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Olena V Vykhovanets
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Gregory T MacLennan
- Department of Pathology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Rajesh Singh
- Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, Georgia 30310
| | - Natarajan Bhaskaran
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Sanjeev Shukla
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
| | - Sanjay Gupta
- Department of Urology, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
- Department of Nutrition, Case Western Reserve University & The Urology Institute, University Hospitals Case Medical Center, Cleveland, Ohio 44106
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Shahaf G, Rotem-Dai N, Koifman G, Raveh-Amit H, Frost SA, Livneh E. PKCη is a negative regulator of AKT inhibiting the IGF-I induced proliferation. Exp Cell Res 2012; 318:789-99. [PMID: 22305966 DOI: 10.1016/j.yexcr.2012.01.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 10/14/2022]
Abstract
The PI3K-AKT pathway is frequently activated in human cancers, including breast cancer, and its activation appears to be critical for tumor maintenance. Some malignant cells are dependent on activated AKT for their survival; tumors exhibiting elevated AKT activity show sensitivity to its inhibition, providing an Achilles heel for their treatment. Here we show that the PKCη isoform is a negative regulator of the AKT signaling pathway. The IGF-I induced phosphorylation on Ser473 of AKT was inhibited by the PKCη-induced expression in MCF-7 breast adenocarcinoma cancer cells. This was further confirmed in shRNA PKCη-knocked-down MCF-7 cells, demonstrating elevated phosphorylation on AKT Ser473. While PKCη exhibited negative regulation on AKT phosphorylation it did not alter the IGF-I induced ERK phosphorylation. However, it enhanced ERK phosphorylation when stimulated by PDGF. Moreover, its effects on IGF-I/AKT and PDGF/ERK pathways were in correlation with cell proliferation. We further show that both PKCη and IGF-I confer protection against UV-induced apoptosis and cell death having additive effects. Although the protective effect of IGF-I involved activation of AKT, it was not affected by PKCη expression, suggesting that PKCη acts through a different route to increase cell survival. Hence, our studies show that PKCη provides negative control on AKT pathway leading to reduced cell proliferation, and further suggest that its presence/absence in breast cancer cells will affect cell death, which could be of therapeutic value.
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Affiliation(s)
- Galit Shahaf
- The Shraga Segal department of Microbiology and Immunology, Faculty of Health Science and the Cancer Research Center, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
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Huang B, Cao K, Li X, Guo S, Mao X, Wang Z, Zhuang J, Pan J, Mo C, Chen J, Qiu S. The expression and role of protein kinase C (PKC) epsilon in clear cell renal cell carcinoma. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2011; 30:88. [PMID: 21955404 PMCID: PMC3193168 DOI: 10.1186/1756-9966-30-88] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 09/28/2011] [Indexed: 11/23/2022]
Abstract
Protein kinase C epsilon (PKCε), an oncogene overexpressed in several human cancers, is involved in cell proliferation, migration, invasion, and survival. However, its roles in clear cell renal cell carcinoma (RCC) are unclear. This study aimed to investigate the functions of PKCε in RCC, especially in clear cell RCC, to determine the possibility of using it as a therapeutic target. By immunohistochemistry, we found that the expression of PKCε was up-regulated in RCCs and was associated with tumor Fuhrman grade and T stage in clear cell RCCs. Clone formation, wound healing, and Borden assays showed that down-regulating PKCε by RNA interference resulted in inhibition of the growth, migration, and invasion of clear cell RCC cell line 769P and, more importantly, sensitized cells to chemotherapeutic drugs as indicated by enhanced activity of caspase-3 in PKCε siRNA-transfected cells. These results indicate that the overexpression of PKCε is associated with an aggressive phenotype of clear cell RCC and may be a potential therapeutic target for this disease.
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Affiliation(s)
- Bin Huang
- Department of Urology, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China
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Proteins kinase Cɛ is required for non-small cell lung carcinoma growth and regulates the expression of apoptotic genes. Oncogene 2011; 31:2593-600. [PMID: 21996750 DOI: 10.1038/onc.2011.428] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Protein kinase C (PKC)ɛ, a member of the novel PKC family, has key roles in mitogenesis and survival in normal and cancer cells. PKCɛ is frequently overexpressed in epithelial cancers, particularly in lung cancer. Using a short-hairpin RNA approach, here we established that PKCɛ is required for non-small cell lung carcinoma (NSCLC) growth in vitro as well as tumor growth when inoculated into athymic mice. Moreover, sustained delivery of a PKCɛ-selective inhibitor peptide, ɛV1-2, reduced xenograft growth in mice. Both RNA interference depletion and pharmacological inhibition of PKCɛ caused a marked elevation in the number of apoptotic cells in NSCLC tumors. PKCɛ-depleted NSCLC cells show elevated expression of pro-apoptotic proteins of the Bcl-2 family, caspase recruitment domain-containing proteins and tumor necrosis factor ligands/receptor superfamily members. Moreover, a Gene Set Enrichment Analysis revealed that a vast majority of the genes changed in PKCɛ-depleted cells were also deregulated in human NSCLC. Our results strongly suggest that PKCɛ is required for NSCLC cell survival and maintenance of NSCLC tumor growth. Therefore, PKCɛ may represent an attractive therapeutic target for NSCLC.
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Bononi A, Agnoletto C, De Marchi E, Marchi S, Patergnani S, Bonora M, Giorgi C, Missiroli S, Poletti F, Rimessi A, Pinton P. Protein kinases and phosphatases in the control of cell fate. Enzyme Res 2011; 2011:329098. [PMID: 21904669 PMCID: PMC3166778 DOI: 10.4061/2011/329098] [Citation(s) in RCA: 203] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/06/2011] [Accepted: 06/08/2011] [Indexed: 12/19/2022] Open
Abstract
Protein phosphorylation controls many aspects of cell fate and is often deregulated in pathological conditions. Several recent findings have provided an intriguing insight into the spatial regulation of protein phosphorylation across different subcellular compartments and how this can be finely orchestrated by specific kinases and phosphatases. In this review, the focus will be placed on (i) the phosphoinositide 3-kinase (PI3K) pathway, specifically on the kinases Akt and mTOR and on the phosphatases PP2a and PTEN, and on (ii) the PKC family of serine/threonine kinases. We will look at general aspects of cell physiology controlled by these kinases and phosphatases, highlighting the signalling pathways that drive cell division, proliferation, and apoptosis.
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Affiliation(s)
- Angela Bononi
- Section of General Pathology, Department of Experimental and Diagnostic Medicine, Interdisciplinary Center for the Study of Inflammation (ICSI) and LTTA Center, University of Ferrara, 44100 Ferrara, Italy
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Kong X, Shen Y, Jiang N, Fei X, Mi J. Emerging roles of DNA-PK besides DNA repair. Cell Signal 2011; 23:1273-80. [PMID: 21514376 DOI: 10.1016/j.cellsig.2011.04.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2010] [Revised: 03/13/2011] [Accepted: 04/04/2011] [Indexed: 10/24/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a DNA-activated serine/threonine protein kinase, and abundantly expressed in almost all mammalian cells. The roles of DNA-PK in DNA-damage repair pathways, including non-homologous end-joining (NHEJ) repair and homologous recombinant (HR) repair, have been studied intensively. However, the high levels of DNA-PK in human cells are somewhat paradoxical in that it does not impart any increased ability to repair DNA damage. If DNA-PK essentially exceeds the demand for DNA damage repair, why do human cells universally express such high levels of this huge complex? DNA-PK has been recently reported to be involved in metabolic gene regulation in response to feeding/insulin stimulation; our studies have also suggested a role of DNA-PK in the regulation of the homeostasis of cell proliferation. These novel findings expand our horizons about the importance of DNA-PK.
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Affiliation(s)
- Xianming Kong
- Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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Abstract
The 40S ribosomal protein S6 kinase (S6K) acts downstream of mTOR, which plays important roles in cell proliferation, protein translation, and cell survival and is a target for cancer therapy. mTOR inhibitors are, however, of limited success. Although Akt is believed to act upstream of mTOR, persistent inhibition of p70 S6 kinase or S6K1 can activate Akt via a negative feedback loop. S6K exists as two homologues, S6K1 and S6K2, but little is known about the function of S6K2. In the present study, we have examined the effects of S6K2 on Akt activation and cell survival. Silencing of S6K1 caused a modest decrease, whereas knockdown of S6K2 caused a substantial increase in TNF-α and TRAIL (TNF-related apoptosis-inducing ligand)-mediated apoptosis. In contrast to S6K1, depletion of S6K2 by siRNA decreased basal and TNF-induced Akt phosphorylation. Ectopic expression of constitutively active Akt in MCF-7 cells restored cell survival in S6K2-depleted cells. We have previously shown that activation of Akt induces downregulation of Bid via p53. Knockdown of S6K2 caused an increase in p53, and downregulation of p53 by siRNA decreased Bid level. Silencing of Bid blunted the ability of S6K2 deficiency to enhance TNF-induced apoptosis. Taken together, our study shows that the two homologues of S6K have distinct effects on Akt activation and cell survival. Thus, targeting S6K2 may be an effective therapeutic strategy to treat cancers.
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Affiliation(s)
- Savitha Sridharan
- Department of Molecular Biology & Immunology, University of North Texas Health Science Center, Fort Worth, Texas, USA
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41
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Lemjabbar-Alaoui H, Sidhu SS, Mengistab A, Gallup M, Basbaum C. TACE/ADAM-17 phosphorylation by PKC-epsilon mediates premalignant changes in tobacco smoke-exposed lung cells. PLoS One 2011; 6:e17489. [PMID: 21423656 PMCID: PMC3057966 DOI: 10.1371/journal.pone.0017489] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 02/05/2011] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Tobacco smoke predisposes humans and animals to develop lung tumors, but the molecular events responsible for this are poorly understood. We recently showed that signaling mechanisms triggered by smoke in lung cells could lead to the activation of a growth factor signaling pathway, thereby promoting hyperproliferation of lung epithelial cells. Hyperproliferation is considered a premalignant change in the lung, in that increased rates of DNA synthesis are associated with an increased number of DNA copying errors, events that are exacerbated in the presence of tobacco smoke carcinogens. Despite the existence of DNA repair mechanisms, a small percentage of these errors go unrepaired and can lead to tumorigenic mutations. The results of our previous study showed that an early event following smoke exposure was the generation of oxygen radicals through the activation of NADPH oxidase. Although it was clear that these radicals transduced signals through the epidermal growth factor receptor (EGFR), and that this was mediated by TACE-dependent cleavage of amphiregulin, it remained uncertain how oxygen radicals were able to activate TACE. PRINCIPAL FINDINGS In the present study, we demonstrate for the first time that phosphorylation of TACE at serine/threonine residues by tobacco smoke induces amphiregulin release and EGFR activation. TACE phosphorylation is triggered in smoke-exposed lung cells by the ROS-induced activation of PKC through the action of SRC kinase. Furthermore, we identified PKCε as the PKC isoform involved in smoke-induced TACE activation and hyperproliferation of lung cells. CONCLUSIONS Our data elucidate new signaling paradigms by which tobacco smoke promotes TACE activation and hyperproliferation of lung cells.
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Affiliation(s)
- Hassan Lemjabbar-Alaoui
- Thoracic Oncology Laboratory, Department of Surgery, Comprehensive Cancer Center, University of California San Francisco, San Francisco, California, United States of America.
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Liccardi G, Hartley JA, Hochhauser D. EGFR nuclear translocation modulates DNA repair following cisplatin and ionizing radiation treatment. Cancer Res 2011; 71:1103-14. [PMID: 21266349 DOI: 10.1158/0008-5472.can-10-2384] [Citation(s) in RCA: 205] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Epidermal growth factor receptor (EGFR) overexpression is associated with resistance to chemotherapy and radiotherapy. It modulates DNA repair after radiation-induced damage through association with the catalytic subunit of DNA protein kinase (DNA-PKcs). We investigated the role of EGFR nuclear import and its association with DNA-PKcs on DNA repair after exposure to cisplatin or ionizing radiation (IR). The model system was based on EGFR-null murine NIH3T3 fibroblasts in which EGFR expression was restored with isoforms that were wild-type (wt), derived from human cancers (L858R, EGFRvIII), or mutated in the nuclear localization signal (NLS) sequence. In cells expressing wtEGFR or EGFRvIII, there was complete unhooking of cisplatin-induced interstrand cross-links and repair of IR-induced strand breaks. In contrast, cells expressing L858R or NLS mutations showed reduced unhooking of interstrand cross-links and repair of strand breaks. Immunoprecipitation showed wtEGFR and EGFRvIII binding to DNA-PKcs, increasing 2-fold 18 hours after cisplatin therapy. Confocal microscopy and proximity ligation assay showed that this interaction in the cytoplasm and nucleus was associated with increased DNA protein kinase complex (DNA-PK) activity. Cells expressing the EGFR L858R mutation, which has constitutive kinase activity, exhibited reduced DNA repair without nuclear localization. EGFR-NLS mutants showed impaired nuclear localization and DNA-PKcs association with reduced DNA repair and DNA-PK kinase activity. In summary, EGFR nuclear localization was required for modulation of cisplatin and IR-induced repair of DNA damage. EGFR-DNA-PKcs binding was induced by cisplatin or IR but not by EGFR nuclear translocation per se. Our findings show that EGFR subcellular distribution can modulate DNA repair kinetics, with implications for design of EGFR-targeted combinational therapies.
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Affiliation(s)
- Gianmaria Liccardi
- Cancer Research UK Drug-DNA Interactions Research Group, UCL Cancer Institute, University College London, London, United Kingdom
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Benavides F, Blando J, Perez CJ, Garg R, Conti CJ, DiGiovanni J, Kazanietz MG. Transgenic overexpression of PKCε in the mouse prostate induces preneoplastic lesions. Cell Cycle 2011; 10:268-77. [PMID: 21224724 DOI: 10.4161/cc.10.2.14469] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
It is well established that protein kinase C (PKC) isozymes play distinctive roles in mitogenic and survival signaling as well as in cancer progression. PKCε, the product of the PRKCE gene, is up-regulated in various types of cancers including prostate, lung and breast cancer. To address a potential role for PKCs in prostate cancer progression we generated three mouse transgenic lines expressing PKCα, PKCδ, or PKCε in the prostate epithelium under the control of the rat probasin (PB) promoter. Whereas PB-PKCε and PB-PKCδ mice did not show any evident phenotype, PB-PKCε mice developed prostate hyperplasia as well as prostate intraepithelial neoplasia (PIN) that displayed enhanced phospho-Akt, phospho-S6, and phospho-Stat3 levels, as well as enhanced resistance to apoptotic stimuli. PKCε overexpression was insufficient to drive neoplastic changes in the mouse prostate. Notably, overexpression of PKCε by adenoviral means in normal immortalized RWPE-1 prostate cells confers a growth advantage and hyperactivation of Erk and Akt. Our results argue for a causal link between PKCε overexpression and prostate cancer development.
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Affiliation(s)
- Fernando Benavides
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX, USA
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Meshki J, Caino MC, von Burstin VA, Griner E, Kazanietz MG. Regulation of prostate cancer cell survival by protein kinase Cepsilon involves bad phosphorylation and modulation of the TNFalpha/JNK pathway. J Biol Chem 2010; 285:26033-40. [PMID: 20566643 DOI: 10.1074/jbc.m110.128371] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Protein kinase Cepsilon (PKCepsilon), a diacyglycerol- and phorbol ester-responsive serine-threonine kinase, has been implicated in mitogenic and survival control, and it is markedly overexpressed in human tumors, including in prostate cancer. Although prostate cancer cells undergo apoptosis in response to phorbol ester stimulation via PKCdelta-mediated release of death factors, the involvement of PKCepsilon in this response is not known. PKCepsilon depletion by RNAi or expression of a dominant negative kinase-dead PKCepsilon mutant potentiated the apoptotic response of PMA and sensitized LNCaP cells to the death receptor ligand TNFalpha. On the other hand, overexpression of PKCepsilon by adenoviral means protected LNCaP cells against apoptotic stimuli. Interestingly, PKCepsilon RNAi depletion significantly enhanced the release of TNFalpha in response to PMA and greatly potentiated JNK activation by this cytokine. Further mechanistic analysis revealed that PMA fails to promote phosphorylation of Bad in Ser(112) in PKCepsilon-depleted LNCaP cells, whereas PKCepsilon overexpression greatly enhanced Bad phosphorylation. This effect was independent of Akt, ERK, or p90Rsk, well established kinases for Ser(112) in Bad. Moreover, expression of a S112A-Bad mutant potentiated PMA-induced apoptosis. Finally, we found that upon activation PKCepsilon accumulated in mitochondrial fractions in LNCaP cells and that Bad was a substrate of PKCepsilon in vitro. Our results established that PKCepsilon modulates survival in prostate cancer cells via multiple pathways.
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Affiliation(s)
- John Meshki
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA
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Mariotti V, Melissari E, Amar S, Conte A, Belmaker RH, Agam G, Pellegrini S. Effect of prolonged phenytoin administration on rat brain gene expression assessed by DNA microarrays. Exp Biol Med (Maywood) 2010; 235:300-10. [PMID: 20404047 DOI: 10.1258/ebm.2009.009225] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Preliminary clinical trials have recently shown that phenytoin, an antiepileptic drug, may also be beneficial for treatment of bipolar disorder. To examine molecular mechanisms of action of phenytoin as a potential mood stabilizer, DNA microarrays were used to study the effect of phenytoin on gene expression in the hippocampus and frontal cortex of Sprague-Dawley rats. While our particular interest is in bipolar disorder, this is the first DNA microarray study on the effect of phenytoin in brain tissue, in general. As compared with control rats, treated rats had 508 differentially expressed genes in the hippocampus and 62 in the frontal cortex. Phenytoin modulated the expression of genes which may affect neurotransmission, e.g. glutamate decarboxylase 1 (Gad1) and gamma-aminobutyric acid A receptor, alpha 5 (Gabra5). Phenytoin also exerted an effect on neuroprotection-related genes, namely the survival-promoting and antioxidant genes v-akt murine thymoma viral oncogene homolog 1 (Akt1), FK506 binding protein 12-rapamycin associated protein 1 (Frap1), glutathione reductase (Gsr) and glutamate cysteine ligase catalytic subunit (Gclc). The expression of genes potentially associated with mechanisms of mood regulation such as adenylate cyclase-associated protein 1 (Cap1), Glial Fibrillary Acidic Protein (Gfap) and prodynorphin (Pdyn) was also altered. Some of the above genes are regarded as targets of classical mood stabilizers and their modulation supports the clinical observation that phenytoin may have mood-stabilizing effects. The results may provide new insights regarding the mechanism of action of phenytoin and genes found differentially expressed following phenytoin administration may play a role in the pathophysiology of either bipolar disorder or epilepsy.
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Affiliation(s)
- Veronica Mariotti
- Department of Experimental Pathology, Medical Biotechnology, Infectious Diseases and Epidemiology, University of Pisa, Italy
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46
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Chua BT, Gallego-Ortega D, Ramirez de Molina A, Ullrich A, Lacal JC, Downward J. Regulation of Akt(ser473) phosphorylation by choline kinase in breast carcinoma cells. Mol Cancer 2009; 8:131. [PMID: 20042122 PMCID: PMC2806310 DOI: 10.1186/1476-4598-8-131] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 12/31/2009] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The serine/threonine kinase PKB/Akt plays essential role in various cellular processes including cell growth and proliferation, metabolism and cell survival. The importance of the Akt pathway is highlighted by the mutation of various components of the pathway such as the PTEN and PI3-kinase (P110alpha) in human cancers. In this paper, we employed an RNA interference library targeting all human kinases to screen for kinases involved in the regulation of Akt activation, in particular serine 473 phosphorylation. Here, we transfected the MDA-MB 468 breast cell line with the human kinome siRNA library and measured Akt activation using an antibody specific for phosphoserine 473 of Akt. RESULTS The screen revealed that phosphorylation of Akt(ser473) can be regulated by more than 90 kinases. Interestingly, phosphorylation of Akt(ser473), but not thr308, can be severely reduced by inhibition of Choline kinase activity via siRNA or small molecule inhibitors. We show here that the regulation of Akt phosphorylation by Choline kinase is PI3K-independent. In addition, xenograft tumors treated with Choline kinase inhibitors demonstrated a statistically significant decrease in Akt(ser473) phosphorylation. Importantly, the reduction in phosphorylation correlates with regression of these xenograft tumors in the mouse model. CONCLUSION High Choline kinase expression and activity has previously been implicated in tumor development and metastasis. The mechanism by which Choline kinase is involved in tumor formation is still not fully resolved. From our data, we proposed that Choline kinase plays a key role in regulating Akt(ser473) phosphorylation, thereby promoting cell survival and proliferation.
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Affiliation(s)
- Boon Tin Chua
- Singapore OncoGenome Project, Institute of Medical Biology, A*STAR, 8A Biomedical Grove, 06-06 Immunos, Singapore.
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Gonelli A, Milani D, Rimondi E, Voltan R, Grill V, Celeghini C. Activation of PKC-ε counteracts maturation and apoptosis of HL-60 myeloid leukemic cells in response to TNF family members. Eur J Histochem 2009; 53:e21. [PMID: 30256868 PMCID: PMC3168235 DOI: 10.4081/ejh.2009.e21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2009] [Indexed: 12/17/2022] Open
Abstract
Protein kinase C (PKC)-ε, a component of the serine/threo-nine PKC family, has been shown to influence the survival and differentiation pathways of normal hematopoietic cells. Here, we have modulated the activity of PKC-ε with specific small molecule activator or inhibitor peptides. PKC-ε inhibitor and activator peptides showed modest effects on HL-60 maturation when added alone, but PKC-ε activator peptide significantly counteracted the pro-maturative activity of tumor necrosis factor (TNF)-α towards the monocytic/macrophagic lineage, as evaluated in terms of CD14 surface expression and morphological analyses. Moreover, while PKC-ε inhibitor peptide showed a reproducible increase of TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis, PKC-ε activator peptide potently counteracted the pro-apoptotic activity of TRAIL. Taken together, the anti-maturative and anti-apoptotic activities of PKC-ε envision a potentially important proleukemic role of this PKC family member.
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Affiliation(s)
- A Gonelli
- Department of Morphology and Embryology, University of Ferrara, Ferrara
| | - D Milani
- Department of Morphology and Embryology, University of Ferrara, Ferrara
| | - E Rimondi
- Interdepartmental Center of Molecular Medicine, University of Trieste, Trieste
| | - R Voltan
- Interdepartmental Center of Molecular Medicine, University of Trieste, Trieste
| | - V Grill
- Department of Biomedicine, University of Trieste, Trieste, Italy
| | - C Celeghini
- Department of Biomedicine, University of Trieste, Trieste, Italy
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Mannell H, Hammitzsch A, Mettler R, Pohl U, Krötz F. Suppression of DNA-PKcs enhances FGF-2 dependent human endothelial cell proliferation via negative regulation of Akt. Cell Signal 2009; 22:88-96. [PMID: 19781633 DOI: 10.1016/j.cellsig.2009.09.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 09/09/2009] [Accepted: 09/14/2009] [Indexed: 10/20/2022]
Abstract
Angiogenesis initiation is crucially dependent on endothelial proliferation and can be stimulated by the fibroblast growth factor 2 (FGF-2). The DNA dependent protein kinase (DNA-PK), long known for its importance in repairing DNA double strand breaks, belongs to the phosphatidylinositol-3 kinase (PI3-K) super family and has recently been identified as one of the enzymes phosphorylating and activating Akt. Due to its similarity with PI3-K, we hypothesized that DNA-PK may have similar effects on endothelial angiogenic processes and signalling. We used primary endothelial cells (HUVEC and PAEC) and human microvascular endothelial cells (HMEC) to study the role of DNA-PK in endothelial proliferation and signalling. DNA-PKcs suppression with the compound NU7026 or with siRNA induced basal endothelial cell proliferation as well as enhanced FGF-2 dependent proliferation. This was associated with an increase in phosphorylated Akt. Tube formation was not affected by DNA-PKcs clearly showing that the role of DNA-PK in endothelial processes differs from that of PI3-K. Our findings indicate DNA-PK as an important enzyme maintaining the quiescent endothelial phenotype by actively inhibiting Akt thus restraining endothelial cell proliferation preventing excessive growth.
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Affiliation(s)
- Hanna Mannell
- Cardiology, Medical Policlinic, Ludwig-Maximilians-University, Ziemssenstrasse 1, 80336 Munich, Germany
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49
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Basu A, Sridharan S, Persaud S. Regulation of protein kinase C delta downregulation by protein kinase C epsilon and mammalian target of rapamycin complex 2. Cell Signal 2009; 21:1680-5. [PMID: 19632318 DOI: 10.1016/j.cellsig.2009.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 07/13/2009] [Indexed: 11/12/2022]
Abstract
Phosphorylation and dephosphorylation of PKCs can regulate their activity, stability and function. We have previously shown that downregulation of PKC delta by tumor promoting phorbol esters was compromised when HeLa cells acquired resistance to cisplatin (HeLa/CP). In the present study, we have used these cells to understand the mechanism of PKC delta downregulation. A brief treatment of HeLa cells with phorbol 12,13-dibutyrate (PDBu) induced phosphorylation of PKC delta at the activation loop (Thr505), turn motif (Ser643), hydrophobic motif (Ser662) and Tyr-311 sites to a greater extent in HeLa/CP cells compared to HeLa cells. Prolonged treatment with PDBu led to downregulation of PKC delta in HeLa but not in HeLa/CP cells. The PKC inhibitor Gö 6983 inhibited PDBu-induced downregulation of PKC delta, decreased Thr505 phosphorylation and increased PKC delta tyrosine phosphorylation at Tyr-311 site. However, knockdown of c-Abl, c-Src, Fyn and Lyn had little effect on PKC delta downregulation and Tyr311 phosphorylation. Pretreatment with the phosphatidylinositol 3-kinase inhibitor Ly294002 and mTOR inhibitor rapamycin restored the ability of PDBu to downregulate PKC delta in HeLa/CP cells. Knockdown of mTOR and rictor but not raptor facilitated PKC delta downregulation. Depletion of PKC epsilon also enhanced PKC delta downregulation by PDBu. These results suggest that downregulation of PKC delta is regulated by PKC epsilon and mammalian target of rapamycin complex 2 (mTORC2).
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Affiliation(s)
- Alakananda Basu
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA.
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50
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Yang ES, Wang H, Jiang G, Nowsheen S, Fu A, Hallahan DE, Xia F. Lithium-mediated protection of hippocampal cells involves enhancement of DNA-PK-dependent repair in mice. J Clin Invest 2009; 119:1124-35. [PMID: 19425167 DOI: 10.1172/jci34051] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Long-term neurological deficiencies resulting from hippocampal cytotoxicity induced by cranial irradiation (IR) present a challenge in the treatment of primary and metastatic brain cancers, especially in children. Previously, we showed that lithium protected hippocampal neurons from IR-induced apoptosis and improved neurocognitive function in treated mice. Here, we demonstrate accelerated repair of IR-induced chromosomal double-strand breaks (DSBs) in lithium-treated neurons. Lithium treatment not only increased IR-induced DNA-dependent protein kinase (DNA-PK) threonine 2609 foci, a surrogate marker for activated nonhomologous end-joining (NHEJ) repair, but also enhanced double-strand DNA end-rejoining activity in hippocampal neurons. The increased NHEJ repair coincided with reduced numbers of IR-induced gamma-H2AX foci, well-characterized in situ markers of DSBs. These findings were confirmed in vivo in irradiated mice. Consistent with a role of NHEJ repair in lithium-mediated neuroprotection, attenuation of IR-induced apoptosis of hippocampal neurons by lithium was dramatically abrogated when DNA-PK function was abolished genetically in SCID mice or inhibited biochemically by the DNA-PK inhibitor IC86621. Importantly, none of these findings were evident in glioma cancer cells. These results support our hypothesis that lithium protects hippocampal neurons by promoting the NHEJ repair-mediated DNA repair pathway and warrant future investigation of lithium-mediated neuroprotection during cranial IR, especially in the pediatric population.
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Affiliation(s)
- Eddy S Yang
- Department of Radiation Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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