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Devinney MJ, Mitchell GS. Spinal activation of protein kinase C elicits phrenic motor facilitation. Respir Physiol Neurobiol 2017; 256:36-42. [PMID: 29081358 DOI: 10.1016/j.resp.2017.10.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Revised: 10/16/2017] [Accepted: 10/18/2017] [Indexed: 12/14/2022]
Abstract
The protein kinase C family regulates many cellular functions, including multiple forms of neuroplasticity. The novel PKCθ and atypical PKCζ isoforms have been implicated in distinct forms of spinal, respiratory motor plasticity, including phrenic motor facilitation (pMF) following acute intermittent hypoxia or inactivity, respectively. Although these PKC isoforms are critical in regulating spinal motor plasticity, other isoforms may be important for phrenic motor plasticity. We tested the impact of conventional/novel PKC activator, phorbol 12-myristate 13-acetate (PMA) on pMF. Rats given cervical intrathecal injections of PMA exhibited pMF, which was abolished by pretreatment of broad-spectrum PKC inhibitors bisindolymalemide 1 (BIS) or NPC-15437 (NPC). Because PMA fails to activate atypical PKC isoforms, and NPC does not block PKCθ, this finding demonstrates that classical/novel PKC isoforms besides PKCθ are sufficient to elicit pMF. These results advance our understanding of mechanisms producing respiratory motor plasticity, and may inspire new treatments for disorders that compromise breathing, such as ALS, spinal injury and obstructive sleep apnea.
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Affiliation(s)
- Michael J Devinney
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, 53706, United States
| | - Gordon S Mitchell
- Center for Respiratory Research and Rehabilitation, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, United States.
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2
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hnRNPK inhibits GSK3β Ser9 phosphorylation, thereby stabilizing c-FLIP and contributes to TRAIL resistance in H1299 lung adenocarcinoma cells. Sci Rep 2016; 6:22999. [PMID: 26972480 PMCID: PMC4789638 DOI: 10.1038/srep22999] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/26/2016] [Indexed: 11/08/2022] Open
Abstract
c-FLIP (cellular FLICE-inhibitory protein) is the pivotal regulator of TRAIL resistance in cancer cells, It is a short-lived protein degraded through the ubiquitin/proteasome pathway. The discovery of factors and mechanisms regulating its protein stability is important for the comprehension of TRAIL resistance by tumor cells. In this study, we show that, when H1299 lung adenocarcinoma cells are treated with TRAIL, hnRNPK is translocated from nucleus to cytoplasm where it interacts and co-localizes with GSK3β. We find that hnRNPK is able to inhibit the Ser9 phosphorylation of GSK3β by PKC. This has the effect of activating GSK3β and thereby stabilizing c-FLIP protein which contributes to the resistance to TRAIL in H1299 cells. Our immunohistochemical analysis using tissue microarray provides the clinical evidence of this finding by establishing a negative correlation between the level of hnRNPK expression and the Ser9 phosphorylation of GSK3β in both lung adenocarcinoma tissues and normal tissues. Moreover, in all cancer tissues examined, hnRNPK was found in the cytoplasm whereas it is exclusively nuclear in the normal tissues. Our study sheds new insights on the molecular mechanisms governing the resistance to TRAIL in tumor cells, and provides new clues for the combinatorial chemotherapeutic interventions with TRAIL.
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Gao X, Xu F, Zhang HT, Chen M, Huang W, Zhang Q, Zeng Q, Liu L. PKCα-GSK3β-NF-κB signaling pathway and the possible involvement of TRIM21 in TRAIL-induced apoptosis. Biochem Cell Biol 2016; 94:256-64. [PMID: 27219672 DOI: 10.1139/bcb-2016-0009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Tumor necrosis factor related apoptosis-inducing ligand (TRAIL) is a highly promising therapeutic agent for cancer treatment, owing to its ability to selectively target tumor cells for cell death while having little effect on most normal cells. However, recent research has found that many cancers, including non-small cell lung cancer (NSCLC), display resistance to TRAIL. Therefore, it is important to elucidate the molecular mechanisms governing the resistance of tumor cells to TRAIL treatment. In this study, we show that GSK3β antagonized TRAIL-induced apoptosis in H1299 NSCLC cells, and determined that the PKCα isozyme is an upstream regulator of GSK3β that phosphorylates and inactivates GSK3β, thereby sensitizing cancer cells to TRAIL-induced apoptosis. Furthermore, we demonstrated that the anti-apoptotic effect of GSK3β is mediated by the NF-κB pathway, whereas the tripartite motif 21 (TRIM21) was able to inhibit the activation of NF-κB by GSK3β, and leads to the promotion of cell apoptosis. Taken together, our study further delineated the underpinning mechanism of resistance to TRAIL-induced apoptosis in H1299 cells, and provided new clues for sensitizing NSCLC cells to TRAIL therapy.
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Affiliation(s)
- Xuejuan Gao
- a Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Fengmei Xu
- a Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Huan-Tian Zhang
- b Institute of Orthopedic Diseases and Department of Orthopedics, the First Affiliated Hospital, Jinan University, Guangzhou 510630, China
| | - Miaojuan Chen
- c Department of Interventional Radiology and Vascular Anomalies, Guangzhou Women and Children's Medical Center, Guangzhou 510623, China
| | - Wensi Huang
- a Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Qihao Zhang
- d Institute of Biomedicine, and National Engineering Research Center of Genetic Medicine; Guangdong Provincial Key Laboratory of Bioengineering Medicine, Jinan University, Guangzhou 510632, China
| | - Qingzhong Zeng
- a Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
| | - Langxia Liu
- a Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Institute of Life and Health Engineering, Jinan University, Guangzhou 510632, China
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Obis T, Hurtado E, Nadal L, Tomàs M, Priego M, Simon A, Garcia N, Santafe MM, Lanuza MA, Tomàs J. The novel protein kinase C epsilon isoform modulates acetylcholine release in the rat neuromuscular junction. Mol Brain 2015; 8:80. [PMID: 26625935 PMCID: PMC4665914 DOI: 10.1186/s13041-015-0171-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/25/2015] [Indexed: 01/20/2023] Open
Abstract
Background Various protein kinase C (PKC) isoforms contribute to the phosphorylating activity that modulates neurotransmitter release. In previous studies we showed that nPKCε is confined in the presynaptic site of the neuromuscular junction and its presynaptic function is activity-dependent. Furthermore, nPKCε regulates phorbol ester-induced acetylcholine release potentiation, which further indicates that nPKCε is involved in neurotransmission. The present study is designed to examine the nPKCε involvement in transmitter release at the neuromuscular junction. Results We use the specific nPKCε translocation inhibitor peptide εV1-2 and electrophysiological experiments to investigate the involvement of this isoform in acetylcholine release. We observed that nPKCε membrane translocation is key to the synaptic potentiation of NMJ, being involved in several conditions that upregulate PKC isoforms coupling to acetylcholine (ACh) release (incubation with high Ca2+, stimulation with phorbol esters and protein kinase A, stimulation with adenosine 3′,5′-cyclic monophosphorothioate, 8-Bromo-, Rp-isomer, sodium salt -Sp-8-BrcAMP-). In all these conditions, preincubation with the nPKCε translocation inhibitor peptide (εV1-2) impairs PKC coupling to acetylcholine release potentiation. In addition, the inhibition of nPKCε translocation and therefore its activity impedes that presynaptic muscarinic autoreceptors and adenosine autoreceptors modulate transmitter secretion. Conclusions Together, these results point to the importance of nPKCε isoform in the control of acetylcholine release in the neuromuscular junction.
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Affiliation(s)
- Teresa Obis
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Erica Hurtado
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Laura Nadal
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Marta Tomàs
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Mercedes Priego
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Anna Simon
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Neus Garcia
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Manel M Santafe
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain
| | - Maria A Lanuza
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain.
| | - Josep Tomàs
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201, Reus, Spain.
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Abstract
Acute intermittent hypoxia (AIH) induces a form of spinal motor plasticity known as phrenic long-term facilitation (pLTF); pLTF is a prolonged increase in phrenic motor output after AIH has ended. In anesthetized rats, we demonstrate that pLTF requires activity of the novel PKC isoform, PKCθ, and that the relevant PKCθ is within phrenic motor neurons. Whereas spinal PKCθ inhibitors block pLTF, inhibitors targeting other PKC isoforms do not. PKCθ is highly expressed in phrenic motor neurons, and PKCθ knockdown with intrapleural siRNAs abolishes pLTF. Intrapleural siRNAs targeting PKCζ, an atypical PKC isoform expressed in phrenic motor neurons that underlies a distinct form of phrenic motor plasticity, does not affect pLTF. Thus, PKCθ plays a critical role in spinal AIH-induced respiratory motor plasticity, and the relevant PKCθ is localized within phrenic motor neurons. Intrapleural siRNA delivery has considerable potential as a therapeutic tool to selectively manipulate plasticity in vital respiratory motor neurons.
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Abera MB, Kazanietz MG. Protein kinase Cα mediates erlotinib resistance in lung cancer cells. Mol Pharmacol 2015; 87:832-41. [PMID: 25724832 DOI: 10.1124/mol.115.097725] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Overexpression and mutational activation of the epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of non-small cell lung cancer (NSCLC). EGFR tyrosine-kinase inhibitors (TKIs) are given as a primary therapy for advanced patients with EGFR-activating mutations; however, the majority of these tumors relapse and patients eventually develop resistance to TKIs. To address a potential role of protein kinase C (PKC) isozymes in the resistance to TKIs, we used the isogenic NSCLC H1650 cell line and its erlotinib-resistant derivative H1650-M3, a cell line that displays a mesenchymal-like morphology driven by transforming growth factor-β signaling. We found that H1650-M3 cells display remarkable PKCα upregulation and PKCδ downregulation. Notably, silencing PKCα from H1650-M3 cells using RNA interference caused a significant reduction in the expression of epithelial-to-mesenchymal transition (EMT) markers vimentin, Zeb2, Snail, and Twist. Moreover, pharmacological inhibition or PKCα RNA interference depletion and PKCδ restoring sensitized H1650-M3 cells to erlotinib. Whereas ectopic overexpression of PKCα in parental H1650 cells was not sufficient to alter the expression of EMT genes or to confer resistance to erlotinib, it caused downregulation of PKCδ expression, suggesting a unidirectional crosstalk. Finally, mechanistic studies revealed that PKCα upregulation in H1650-M3 cells is driven by transforming growth factor-β. Our results identified important roles for specific PKC isozymes in erlotinib resistance and EMT in lung cancer cells, and highlight PKCα as a potential target for lung cancer treatment.
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Affiliation(s)
- Mahlet B Abera
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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7
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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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8
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Mencalha AL, Corrêa S, Abdelhay E. Role of calcium-dependent protein kinases in chronic myeloid leukemia: combined effects of PKC and BCR-ABL signaling on cellular alterations during leukemia development. Onco Targets Ther 2014; 7:1247-54. [PMID: 25045273 PMCID: PMC4099416 DOI: 10.2147/ott.s64303] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Calcium-dependent protein kinases (PKCs) function in a myriad of cellular processes, including cell-cycle regulation, proliferation, hematopoietic stem cell differentiation, apoptosis, and malignant transformation. PKC inhibitors, when targeted to these pathways, have demonstrated efficacy against several types of solid tumors as well as leukemia. Chronic myeloid leukemia (CML) represents 20% of all adult leukemia. The aberrant Philadelphia chromosome has been reported as the main cause of CML development in hematopoietic stem cells, due to the formation of the BCR-ABL oncogene. PKCs and BCR-ABL coordinate several signaling pathways that are crucial to cellular malignant transformation. Experimental and clinical evidence suggests that pharmacological approaches using PKC inhibitors may be effective in the treatment of CML. This mini review summarizes articles from the National Center for Biotechnology Information website that have shown evidence of the involvement of PKC in CML.
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Affiliation(s)
- André L Mencalha
- Biophysics and Biometry Department, Roberto Alcântara Gomes Biology Institute, Rio de Janeiro's State University (UERJ), Rio de Janeiro, Brazil
| | - Stephany Corrêa
- Bone Marrow Transplantation Unit (CEMO), National Cancer Institute (INCA), Rio de Janeiro, Brazil
| | - Eliana Abdelhay
- Bone Marrow Transplantation Unit (CEMO), National Cancer Institute (INCA), Rio de Janeiro, Brazil
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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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10
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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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11
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Sarveswaran S, Ghosh J. OXER1, a G protein-coupled oxoeicosatetraenoid receptor, mediates the survival-promoting effects of arachidonate 5-lipoxygenase in prostate cancer cells. Cancer Lett 2013; 336:185-95. [PMID: 23643940 DOI: 10.1016/j.canlet.2013.04.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/14/2013] [Accepted: 04/26/2013] [Indexed: 12/30/2022]
Abstract
Inhibition of 5-Lox induces apoptosis in prostate cancer cells by inactivating PKCε which is prevented by 5-oxoETE, and activators of PKCε prevent 5-Lox inhibition-induced apoptosis, suggesting that 5-Lox metabolites exert survival signaling via PKCε. However, mechanisms by which 5-Lox metabolites activate PKCε are not understood yet. We found that prostate cancer cells express high levels of OXER1, a G protein-coupled 5-oxoETE receptor, which delivers signal by generating diacyl-glycerol through phospholipase C-beta. Interestingly, we found that U73122, an inhibitor of PLC-beta, interrupts the apoptosis-preventing effect of 5-oxoETE, and exogenous diacyl-glycerol effectively prevents 5-Lox inhibition-induced apoptosis, suggesting that 5-oxoETE signals via OXER1 to promote prostate cancer cell survival.
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12
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Protein kinase C epsilon and genetic networks in osteosarcoma metastasis. Cancers (Basel) 2013; 5:372-403. [PMID: 24216982 PMCID: PMC3730329 DOI: 10.3390/cancers5020372] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Revised: 03/22/2013] [Accepted: 03/26/2013] [Indexed: 12/20/2022] Open
Abstract
Osteosarcoma (OS) is the most common primary malignant tumor of the bone, and pulmonary metastasis is the most frequent cause of OS mortality. The aim of this study was to discover and characterize genetic networks differentially expressed in metastatic OS. Expression profiling of OS tumors, and subsequent supervised network analysis, was performed to discover genetic networks differentially activated or organized in metastatic OS compared to localized OS. Broad trends among the profiles of metastatic tumors include aberrant activity of intracellular organization and translation networks, as well as disorganization of metabolic networks. The differentially activated PRKCε-RASGRP3-GNB2 network, which interacts with the disorganized DLG2 hub, was also found to be differentially expressed among OS cell lines with differing metastatic capacity in xenograft models. PRKCε transcript was more abundant in some metastatic OS tumors; however the difference was not significant overall. In functional studies, PRKCε was not found to be involved in migration of M132 OS cells, but its protein expression was induced in M112 OS cells following IGF-1 stimulation.
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Peterson TA, Stamnes M. ARF1-regulated coatomer directs the steady-state localization of protein kinase C epsilon at the Golgi apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012. [PMID: 23195223 DOI: 10.1016/j.bbamcr.2012.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein kinase C epsilon (PKCε) contributes to multiple signaling pathways affecting human disease. The function of PKCε requires it to undergo changes in subcellular distribution in response to signaling events. While the mechanisms underlying this translocation are incompletely understood, it involves the receptor for activated C kinase protein (RACK2/β'-COP). This receptor also functions as a vesicle coat protein in the secretory pathway where it is regulated by the small GTP-binding protein ADP-ribosylation factor, ARF1. We inhibited ARF1 activation to test the requirement for RACK2/β'-COP in PKCε localization in NIH3T3 fibroblasts. We found that steady-state localization of PKCε at the Golgi complex requires ARF1-regulated RACK2/β'-COP function. By contrast, we did not observe any defects in phorbol ester-induced translocation when ARF1 was inhibited. We also found that PKCε bound to isolated membranes through two distinct mechanisms. One mechanism was dependent upon RACK2/β'-COP while a second was RACK2/β'-COP-independent and stimulated by phorbol esters. Finally, we show that RACK2/β'-COP affects the subcellular distribution of a constitutively active form of PKCε, in a manner similar to what we observed for wild-type PKCε. Together, our data support a role for RACK2/β'-COP in the steady-state localization of PKCε at the Golgi apparatus, which may be independent of its role during PKCε translocation to the cell surface.
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Affiliation(s)
- Tabitha A Peterson
- Department of Molecular Physiology & Biophysics, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
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14
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Caino MC, Lopez-Haber C, Kissil JL, Kazanietz MG. Non-small cell lung carcinoma cell motility, rac activation and metastatic dissemination are mediated by protein kinase C epsilon. PLoS One 2012; 7:e31714. [PMID: 22384062 PMCID: PMC3288050 DOI: 10.1371/journal.pone.0031714] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 01/17/2012] [Indexed: 11/18/2022] Open
Abstract
Background Protein kinase C (PKC) ε, a key signaling transducer implicated in mitogenesis, survival, and cancer progression, is overexpressed in human primary non-small cell lung cancer (NSCLC). The role of PKCε in lung cancer metastasis has not yet been established. Principal Findings Here we show that RNAi-mediated knockdown of PKCε in H358, H1299, H322, and A549 NSCLC impairs activation of the small GTPase Rac1 in response to phorbol 12-myristate 13-acetate (PMA), serum, or epidermal growth factor (EGF). PKCε depletion markedly impaired the ability of NSCLC cells to form membrane ruffles and migrate. Similar results were observed by pharmacological inhibition of PKCε with εV1-2, a specific PKCε inhibitor. PKCε was also required for invasiveness of NSCLC cells and modulated the secretion of extracellular matrix proteases and protease inhibitors. Finally, we found that PKCε-depleted NSCLC cells fail to disseminate to lungs in a mouse model of metastasis. Conclusions Our results implicate PKCε as a key mediator of Rac signaling and motility of lung cancer cells, highlighting its potential as a therapeutic target.
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Affiliation(s)
- M Cecilia Caino
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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15
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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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16
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Sarveswaran S, Thamilselvan V, Brodie C, Ghosh J. Inhibition of 5-lipoxygenase triggers apoptosis in prostate cancer cells via down-regulation of protein kinase C-epsilon. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:2108-17. [PMID: 21824498 DOI: 10.1016/j.bbamcr.2011.07.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 07/22/2011] [Accepted: 07/25/2011] [Indexed: 12/31/2022]
Abstract
Previous studies have shown that human prostate cancer cells constitutively generate 5-lipoxygenase (5-LOX) metabolites from arachidonic acid, and inhibition of 5-LOX blocks production of 5-LOX metabolites and triggers apoptosis in prostate cancer cells. This apoptosis is prevented by exogenous metabolites of 5-LOX, suggesting an essential role of 5-LOX metabolites in the survival of prostate cancer cells. However, downstream signaling mechanisms which mediate the survival-promoting effects of 5-LOX metabolites in prostate cancer cells are still unknown. Recently, we reported that MK591, a specific inhibitor of 5-LOX activity, induces apoptosis in prostate cancer cells without inhibition of Akt, or ERK, two well-characterized regulators of pro-survival mechanisms, suggesting the existence of an Akt and ERK-independent survival mechanism in prostate cancer cells regulated by 5-LOX. Here, we report that 5-LOX inhibition-induced apoptosis in prostate cancer cells occurs via rapid inactivation of protein kinase C-epsilon (PKCε), and that exogenous 5-LOX metabolites prevent both 5-LOX inhibition-induced down-regulation of PKCε and induction of apoptosis. Interestingly, pre-treatment of prostate cancer cells with diazoxide (a chemical activator of PKCε), or KAE1-1 (a cell-permeable, octa-peptide specific activator of PKCε) prevents 5-LOX inhibition-induced apoptosis, which indicates that inhibition of 5-LOX triggers apoptosis in prostate cancer cells via down-regulation of PKCε. Altogether, these findings suggest that metabolism of arachidonic acid by 5-LOX activity promotes survival of prostate cancer cells via signaling through PKCε, a pro-survival serine/threonine kinase.
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Totoń E, Ignatowicz E, Skrzeczkowska K, Rybczyńska M. Protein kinase Cε as a cancer marker and target for anticancer therapy. Pharmacol Rep 2011; 63:19-29. [DOI: 10.1016/s1734-1140(11)70395-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 06/10/2010] [Indexed: 01/23/2023]
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Kloskowski T, Gurtowska N, Drewa T. Does ciprofloxacin have an obverse and a reverse? Pulm Pharmacol Ther 2010; 23:373-5. [PMID: 20211752 DOI: 10.1016/j.pupt.2010.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 02/20/2010] [Accepted: 02/28/2010] [Indexed: 11/25/2022]
Abstract
Ciprofloxacin is an antibiotic that belongs to fluoroquinoles, characterized by broad spectrum of action against pathogens, especially Gram(-) aerobic bacilli. For a long time, it has been thought that ciprofloxacin has an effect only on bacterial cells. Now it is known, that this drug can significantly affect eukaryotic cells including human cancer cells. Its bactericidal action relay on inhibition of topoisomerase II, enzyme responsible for alterations in 3D structure of DNA during replication, transcription and chromatin condensation. Thanks to that, ciprofloxacin can induce cell cycle arrest and apoptosis of cancer cells. The effectiveness of ciprofloxacin was confirmed in several in vitro studies on tumor cell lines such as: human bladder cells, leukaemic cell lines, human osteosarcoma cells, human prostate cancer cells, human colorectal carcinoma cells and human non-small cell lung cancer cell line. Ciprofloxacin is particularly effective against non-small cell lung cancer mainly due to accumulation of ciprofloxacin in lung tissue after intravenous administration and its toxicity against lung cancer lines in vitro in a concentration and time-dependent manner.
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Affiliation(s)
- Tomasz Kloskowski
- Department of Tissue Engineering, Chair of Medical Biology, Nicolaus Copernicus University, Bydgoszcz, Poland.
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TRAIL receptor targeting therapies for non-small cell lung cancer: Current status and perspectives. Drug Resist Updat 2010; 13:2-15. [DOI: 10.1016/j.drup.2009.11.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Accepted: 11/25/2009] [Indexed: 12/17/2022]
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Min Y, Shi J, Zhang Y, Liu S, Liu Y, Zheng D. Death receptor 5-recruited raft components contributes to the sensitivity of Jurkat leukemia cell lines to TRAIL-induced cell death. IUBMB Life 2009; 61:261-7. [PMID: 19242990 DOI: 10.1002/iub.166] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the present study we demonstrated Jurkat leukemia cell lines of TIB152 and TIB153 with different sensitivities to recombinant soluble TRAIL cytotoxicity. TRAIL receptor death receptor 5 (DR5) was constitutively localized in the rafts in both cell lines. FADD, caspase-8, and PI3K-p85 subunit were recruited into DR5 lipid rafts of TIB152 but not in TIB153 cells. The expression and enzyme activity of acid sphingomyelinase, which digests sphingomyeline to produce ceramide and plays an essential role in lipid raft assembling, were higher in the rafts of TIB152 than in TIB153. These data provide evidences that DR5-recruited raft components contribute to the different sensitivity of Jurkat leukemia cell lines to TRAIL-induced cell death and may throw some light on the development of better therapeutic strategies for the cancer cells resistant to TRAIL treatment.
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Affiliation(s)
- Yifan Min
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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