title: p21(Waf1/Cip1) and p53 are downstream effectors of protein kinase C delta in tumor suppression and differentiation in human colon cancer cells.
abstract: We have previously demonstrated that the delta isoform of protein kinase C (PKCdelta) is importantly involved in cell growth inhibition and tumor suppression in colon cancer cells. To investigate further the activity and mechanism of action of PKCdelta, we have retrovirally transduced a PKCdelta cDNA in HCT116 human colon cancer cells. PKCdelta-overexpressing cells (HCT116/PKCdelta) were growth-inhibited, showed marked morphologic changes and underwent multinucleation and phenotypic changes characteristic of mitotic catastrophe. Compared to controls, HCT116/PKCdelta cells showed a highly attenuated tumorigenic profile and poor anchorage-independent growth. In addition, transfected cells established junction-coordinated intercellular communications, expressed cell surface microvilli and overexpressed the colon differentiation marker alkaline phosphatase. HCT116/PKCdelta cells also produced the 89 kDa, carboxy-terminal catalytic domain of PARP. In HCT116/PKCdelta cells, p21(Waf1/Cip1) and p53 were transiently upregulated for 48 hr after PKCdelta transduction. In a p21 null subline of HCT116 cells (HCT116/p21null), overexpression of PKCdelta did not affect tumorigenicity or differentiation, indicating that p21 is essential for the antitumorigenic activity of PKCdelta. Similarly, overexpression of PKCdelta caused no significant phenotypic changes in HCT116/E6 cells, an HCT116 subline in which the p53 protein is downregulated by the human papillomavirus E6 gene product. We conclude that overexpression of PKCdelta in human colon cancer cells induces multiple antineoplastic effects that depend on the activities of p21(Waf1/Cip1) and p53.
authors.affiliation: Department of Structural and Functional Biology, University of Insubria, Varese/Busto Arsizio, Italy. gianpaolo.perletti@uninsubria.it
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Perletti
authors.forename: Emanuela
authors.initials: E
authors.lastname: Marras
authors.forename: Davide
authors.initials: D
authors.lastname: Dondi
authors.forename: Daniela
authors.initials: D
authors.lastname: Osti
authors.forename: Terenzio
authors.initials: T
authors.lastname: Congiu
authors.forename: Roberto
authors.initials: R
authors.lastname: Ferrarese
authors.forename: Magda
authors.initials: M
authors.lastname: de Eguileor
authors.forename: Armen H
authors.initials: AH
authors.lastname: Tashjian
mesh_terms: D015153:Blotting, Western; D002454:Cell Differentiation; D003110:Colonic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta