Roles of Specific Isoforms of Protein Kinase C in the Transcriptional Control of Cyclin D1 and Related Genes

Soh, Jae-Won; Weinstein, I. Bernard

doi:10.1074/jbc.m302016200

Cited by 180 publications

(174 citation statements)

References 38 publications

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“…In agreement with our prior studies showing PCK-d slowed G1 progression, there is increasing evidence that PKC regulates the cell cycle through multiple pathways (Arita et al, 1998;Toyoda et al, 1998;Besson and Yong, 2000;Graham et al, 2000;Zhu et al, 2000;Shanmugam et al, 2001;Wakino et al, 2001; Acevedo- Duncan et al, 2002;Kikkawa et al, 2002;La Porta et al, 2002;Lee et al, 2002;Lin et al, 2002;Brodie and Blumberg, 2003;Soh and Weinstein, 2003;Avazeri et al, 2004;Clark et al, 2004;Gavrielides et al, 2004;Leontieva and Black, 2004;Atten et al, 2005). In nontransformed rat intestinal epithelial crypt cells, PKC signaling mediates cell cycle exit through rapid downregulation of G1 cyclins and increased expression of Cip/Kip cyclin-dependent kinase inhibitors (Frey et al, 1997(Frey et al, , 2000Clark et al, 2004).…”

Section: Introductionsupporting

confidence: 73%

Protein kinase C delta inhibits Caco-2 cell proliferation by selective changes in cell cycle and cell death regulators

et al. 2006

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PKC-d is a serine/threonine kinase that mediates diverse signal transduction pathways. We previously demonstrated that overexpression of PKC-d slowed the G1 progression of Caco-2 colon cancer cells, accelerated apoptosis, and induced cellular differentiation. In this study, we further characterized the PKC-d dependent signaling pathways involved in these tumor suppressor actions in Caco-2 cells overexpressing PKC-d using a Zn 2 þ inducible expression vector. Consistent with a G1 arrest, increased expression of PKC-d caused rapid and significant downregulation of cyclin D1 and cyclin E proteins (50% decreases, Po0.05), while mRNA levels remained unchanged. The PKC agonist, phorbol 12-myristate 13-acetate (TPA, 100 nM, 4 h), induced two-fold higher protein and mRNA levels of p21 Waf1, a cyclin-dependent kinase (cdk) inhibitor in PKC-d transfectants compared with empty vector (EV) transfected cells, whereas the PKC-d specific inhibitor rottlerin (3 lM) or knockdown of this isoenzyme with specific siRNA oligonucleotides blocked p21Waf1 expression. Concomitantly, compared to EV control cells, PKC-d upregulation decreased cyclin D1 and cyclin E proteins co-immunoprecipitating with cdk6 and cdk2, respectively. In addition, overexpression of PKC-d increased binding of cdk inhibitor p27Kip1 to cdk4. These alterations in cyclin-cdks and their inhibitors are predicted to decrease G1 cyclin kinase activity. As an independent confirmation of the direct role PKC-d plays in cell growth and cell cycle regulation, we knocked down PKC-d using specific siRNA oligonucleotides. PKC-d specific siRNA oligonucleotides, but not irrelevant control oligonucleotides, inhibited PKCd protein by more than 80% in Caco-2 cells. Moreover, PKC-d knockdown enhanced cell proliferation (B1.4-2-fold, Po0.05) and concomitantly increased cyclin D1 and cyclin E expression (B1.7-fold, Po0.05). This was a specific effect, as nontargeted PKC-f was not changed by PKC-d siRNA oligonucleotides. Consistent with accelerated apoptosis in PKC-d transfectants, compared to EV cells, PKC-d upregulation increased proapoptotic regulator Bax two-fold at mRNA and protein levels, while antiapoptotic Bcl-2 protein was decreased by 50% at a post-transcriptional level. PKC-d specific siRNA oligonucleotides inhibited Bax protein expression by more than 50%, indicating that PKC-d regulates apoptosis through Bax. Taken together, these results elucidate two critical mechanisms regulated by PKC-d that inhibit cell cycle progression and enhance apoptosis in colon cancer cells. We postulate these antiproliferative pathways mediate an important tumor suppressor function for PKC-d in colonic carcinogenesis.

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Section: Introductionsupporting

confidence: 73%

Protein kinase C delta inhibits Caco-2 cell proliferation by selective changes in cell cycle and cell death regulators

et al. 2006

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“…In HUVEC cells phorbol esters potentiate growth factor mitogenic activity when added in early G 1 phase, but they inhibit DNA synthesis when added in late G 1 phase (6). In NIH 3T3 cells, PKC␣ and PKC⑀ enhance cell cycle progression and proliferation by stimulating cyclin D1 transcription (7). On the other hand, PKC inhibits cdk2 activity in human keratinocytes, and overexpression of either PKC or PKC␦, but not PKC␣, leads to G 1 arrest and differentiation (8,9).…”

mentioning

confidence: 99%

S-Phase-specific Activation of PKCα Induces Senescence in Non-small Cell Lung Cancer Cells

Oliva

Caino

Senderowicz

et al. 2008

Journal of Biological Chemistry

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Protein kinase C (PKC) has been widely implicated in positive and negative control of cell proliferation. We have recently shown that treatment of non-small cell lung cancer (NSCLC) cells with phorbol 12-myristate 13-acetate (PMA) during G 1 phase inhibits the progression into S phase, an effect mediated by PKC␦-induced up-regulation of the cell cycle inhibitor p21 Cip1 . However, PMA treatment in asynchronously growing NSCLC cells leads to accumulation of cells in G 2 /M. Studies in post-G 1 phases revealed that PMA induced an irreversible G 2 /M cell cycle arrest in NSCLC cells and conferred morphological and biochemical features of senescence, including elevated SA-␤-Gal activity and reduced telomerase activity. Remarkably, this effect was phase-specific, as it occurred only when PKC was activated in S, but not in G 1 , phase. Mechanistic analysis revealed a crucial role for the classical PKC␣ isozyme as mediator of the G 2 /M arrest and senescence, as well as for inducing p21 Cip1 an obligatory event for conferring the senescence phenotype. In addition to the unappreciated role of PKC isozymes, and specifically PKC␣, in senescence, our data introduce the paradigm that discrete PKCs trigger distinctive responses when activated in different phases of the cell cycle via a common mechanism that involves p21 Cip1 up-regulation.Activation of protein kinase C (PKC) 4 with phorbol esters and related natural compounds causes an array of effects on differentiation, mitogenesis, survival, apoptosis, and transformation. The diverse effects of phorbol esters both in normal and cancerous cells is due to the existence of numerous intracellular effectors, of which PKC isozymes have been the most widely characterized. The PKC family comprises 3 subfamilies that include 10 structurally related phospholipid-dependent serine/threonine kinases (1, 2). Members of the classical cPKC (␣, ␤I, ␤II, and ␥) and the novel nPKC (␦, ⑀, , and ) subfamilies are activated by phorbol esters and their cellular analogue, the second messenger diacylglycerol, which leads to redistribution (translocation) of the enzymes from cytosol to intracellular membrane compartments, where they phosphorylate specific substrates. The marked heterogeneity in the signaling events and cell type-specific responses triggered by phorbol esters could be explained by the distinctive pattern of expression and intracellular localization of PKC isozymes and their substrates, which ultimately results in selective pathway activation.One of the paradigms that best exemplifies the functional versatility of PKC isozymes is the regulation of the cell cycle machinery. It became evident in the last years that PKCs can impact on the cell cycle both in positive and negative manners with a strict degree of cell type and isozyme specificity. PKC isozymes have been shown to regulate the progression of cells from G 1 to S phase as well as with the transition from G 2 to M phase (3) via transcriptional, translational, and post-translational mechanisms. PKCs control the activity of cyc...

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“…All these studies have investigated the apoptotic actions of plitidepsin, and the results cannot be directly extrapolated to cytostatic actions. However, it is interesting to speculate a possible involvement of this pathway because protein kinase C-y represses transcription from the cyclin D1 promoter (52). Although initially p21Cip1 was considered a straightforward tumor suppressor, it has subsequently been established that it promotes the association and stability of cyclin D1-cdk4 complexes (53).…”

Section: Discussionmentioning

confidence: 99%

Plitidepsin Has a Cytostatic Effect in Human Undifferentiated (Anaplastic) Thyroid Carcinoma

Bravo¹,

García-Rendueles²,

Prado

et al. 2005

Clinical Cancer Research

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Undifferentiated (anaplastic) thyroid carcinoma is a highly aggressive human cancer with very poor prognosis. Although there have been a few studies of candidate treatments, the fact that it is an infrequent tumor makes it very difficult to design clinical trials. A strong association has been observed between undifferentiated thyroid carcinoma and TP53 mutations in numerous molecular genetic and expression studies. Plitidepsin (Aplidin, PharmaMar, Madrid, Spain) is a novel anticancer compound obtained from a sea tunicate.This compound has been reported to induce apoptosis independently of TP53 status.We investigated the actions of plitidepsin in human thyroid cancer cells. In initial experiments using primary cultured cells from a differentiated (papillary) carcinoma, we found that100 nmol/L plitidepsin induced apoptosis, whereas lower doses were cytostatic. Because our aim was to study the effects of plitidepsin at clinically relevant concentrations, subsequent experiments were done with a dosage regimen reflecting plasma concentrations observed in previously reported clinical trials: 100 nmol/L for 4 hours, followed by 10 nmol/L for 20 hours (4 100 /20 10 plitidepsin). This plitidepsin dosage regimen blocked the proliferation of a primary undifferentiated/anaplastic thyroid carcinoma culture obtained in our laboratory and of a commercial cell line (8305C) obtained from an undifferentiated thyroid carcinoma; however, it did not induce apoptosis.The proportion of cells in the G 1 phase of the cell cycle was greatly increased and the proportionin the S/G 2 -M phases greatly reduced, suggesting that plitidepsin blocks G 1 -to-S transition. Levels of the cyclin D1/cyclin-dependent kinase 4/p21 complex proteins were decreased and, in line with this, the levels of unphosphorylated Rb1increased.The decrease in cell cycle proteins correlated with hypoacetylation of histone H3. Finally, we did experiments to assess how rapidly tumor cells return to their initial pretreatment proliferative behavior after 4 100 /20 10 plitidepsin treatment. Cells from undifferentiated tumors needed more than 3 days to recover logarithmic growth, and after 7 days, cell number was still significantly lower than in control cultures. 4 100 /20 10 plitidepsininhibited the growthin soft agar.Together, our data show that plitidepsin is able to block in vitro cell cycle progression at concentrations similar to serum concentrations observed in vivo, and that this effect is persistent for several days after plitidepsin removal.Whether plitidepsin will prove to be clinically useful in the treatment of undifferentiated thyroid cancers remains to be established. However, our results raise the possibility that plitidepsin might be effective alone or in combination with radiotherapy and/or other drug treatments.Undifferentiated (anaplastic) thyroid carcinoma is a highly aggressive malignant neoplasm typified by rapidly progressive local disease (ref. 1 and references therein). Almost all patients with undifferentiated thyroid carcinoma present...

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Roles of Specific Isoforms of Protein Kinase C in the Transcriptional Control of Cyclin D1 and Related Genes

Cited by 180 publications

References 38 publications

Protein kinase C delta inhibits Caco-2 cell proliferation by selective changes in cell cycle and cell death regulators

Protein kinase C delta inhibits Caco-2 cell proliferation by selective changes in cell cycle and cell death regulators

S-Phase-specific Activation of PKCα Induces Senescence in Non-small Cell Lung Cancer Cells

Plitidepsin Has a Cytostatic Effect in Human Undifferentiated (Anaplastic) Thyroid Carcinoma

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