Overexpression of protein kinase C β1 in the SW480 colon cancer cell line growth suppression

Goldstein, Debra; Cacace, Angela; Weinstein, I. Bernard

doi:10.1093/carcin/16.5.1121

Cited by 38 publications

(18 citation statements)

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“…We focused on the h isoforms of PKC because of their ubiquitous expression in various cell types and the previous evidence that they might play important roles in other types of cancer (12,(33)(34)(35)(36). We used the drug LY379196 that specifically inhibits the activities of PKCh1 and h2 to address this question.…”

Section: Discussionmentioning

confidence: 99%

Protein Kinase C β Enhances Growth and Expression of Cyclin D1 in Human Breast Cancer Cells

Weinstein

2006

Cancer Research

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Although alterations in the expressions of protein kinase C (PKC) have been implicated in breast carcinogenesis, the roles of specific isoforms in this process remain elusive. In the present study, we examined the specific roles of PKCB1 and B2 in growth control in human breast cancer cell lines. The PKCB-specific inhibitor LY379196 significantly inhibited growth of the breast cancer cell lines MCF-7, MDA-MB-231, and BT474, but not the normal mammary epithelial cell line MCF-10F. Treatment of MCF-7 cells with LY379196 caused an increase in the fraction of cells in the G 1 phase of the cell cycle. To explore the roles of PKCB1 and B2, we used cDNA expression vectors that encode wild-type and constitutively activated or dominant negative mutants of these two proteins. When compared with vector controls, derivatives of MCF-7 cells that stably overexpress wild-type PKCB1 or PKCB2 displayed a slight increase in growth rate; derivatives that stably express the constitutively active mutants of PKCB1 or PKCB2 displayed a marked increase in growth rate; and derivatives that stably express a dominant negative mutant of PKCB1 or B2 displayed inhibition of growth. The derivatives of MCF-7 cells that stably express the constitutively activated mutants of PKCB1 or B2 were more resistant to growth inhibition by LY379196 than the vector control MCF-7 cells. Immunoblot analysis indicated that MCF-7 cells that stably overexpress wild-type or constitutively activated mutants of PKCB1 or B2 had higher cellular levels of cyclin D1 than vector control cells, whereas cells that express a dominant negative mutant had decreased levels of cyclin D1. The derivatives that stably express the constitutively activated mutants of PKCB1 or B2 also displayed increased cyclin D1 promoter activity in transient transfection luciferase reporter assays, and this induction of activity requires activator protein 1. Constitutively activated PKCB1 and B2 also enhanced the transcription of c-fos in transient transfection luciferase reporter assays. Thus, PKCB1 and B2 may play important positive roles in the growth of at least a subset of human breast cancers. Therefore, inhibitors of these isoforms may be useful in breast cancer chemoprevention or therapy. (Cancer Res 2006; 66(23): 11399-408)

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Section: Discussionmentioning

confidence: 99%

Protein Kinase C β Enhances Growth and Expression of Cyclin D1 in Human Breast Cancer Cells

Weinstein

2006

Cancer Research

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“…This subclone was then used to develop derivatives that conditionally overexpress PKCa. Since our laboratory had previously studied in detail PKCb1 (Choi et al, 1990;Goldstein et al, 1995;Housey et al, 1988;Hsiao et al, 1989) it was also of interest to develop derivatives that conditionally over-express this closely related isoform of PKC to see if it would have e ects similar to those of PKCa. Pools and individual clones of cells that inducibly overexpress either PKCa (HC11-PKCa) or PKCb 1 (HC11-PKCb 1 ) and vector control cells (HC11-UHD) were obtained from the tTA3 cell line and further analysed.…”

Section: E Ects Of Tpa On Growth and Expression Of Endogenous Isoformmentioning

confidence: 99%

The α isoform of protein kinase C mediates phorbol ester-induced growth inhibition and p21cip1 induction in HC11 mammary epithelial cells

et al. 1999

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“…Studies have demonstrated that PKC-d promotes cell death in many noncolonic cell lines, including keratinocytes (Denning et al, 1998), neutrophils (Pongracz et al, 1999), cerebral granule cells (Villalba, 1998), HL-60 and prostate cancer cells (Savickiene et al, 1999;Yin et al, 2005), but not in breast cancer cells (McCracken et al, 2003;Nabha et al, 2005). In studies in colonic cells, PKC signaling pathways are also involved in cell cycle and cell death regulation (Goldstein et al, 1995;Qiao et al, 1996;Sauma et al, 1996;Abraham et al, 1998;Perletti et al, 1998Perletti et al, , 1999Andre et al, 1999;Assert et al, 1999;Weller et al, 1999;Umar et al, 2000;Cerda et al, 2001;Lin et al, 2002;McMillan et al, 2003;Di Mari et al, 2005;Meyer et al, 2005). Several studies, including our own investigations, have demonstrated a tumor suppressor role for PKC-d in colon cancer cells, including cell cycle arrest and enhanced apoptosis (Weller et al, 1999;Cerda et al, 2001;Lin et al, 2002;McMillan et al, 2003;Perletti et al, 2004Perletti et al, , 2005.…”

Section: Introductionmentioning

confidence: 99%

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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Overexpression of protein kinase C β1 in the SW480 colon cancer cell line growth suppression

Cited by 38 publications

References 0 publications

Protein Kinase C β Enhances Growth and Expression of Cyclin D1 in Human Breast Cancer Cells

Protein Kinase C β Enhances Growth and Expression of Cyclin D1 in Human Breast Cancer Cells

The α isoform of protein kinase C mediates phorbol ester-induced growth inhibition and p21cip1 induction in HC11 mammary epithelial cells

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

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