Role of protein kinase C-iota in transformed non-malignant RWPE-1 cells and androgen-independent prostate carcinoma DU-145 cells

• Published in: Cell proliferation Vol. 42; no. 2; pp. 182 - 194
• Main Authors: Win, H. Y., Acevedo-Duncan, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2009
• Subjects: Apoptosis - physiology; bcl-Associated Death Protein - metabolism; bcl-X Protein - metabolism; Cell Count; Cell Cycle - physiology; Cell Line, Transformed; Cell Line, Tumor; Cell Survival - physiology; Cyclin-Dependent Kinase 2 - metabolism; Cyclin-Dependent Kinases - metabolism; Humans; Isoenzymes - metabolism; Isoenzymes - physiology; Male; Original; Phosphorylation; Poly(ADP-ribose) Polymerases - metabolism; Prostate - enzymology; Prostate - metabolism; Prostate - pathology; Prostatic Neoplasms - enzymology; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Protein Kinase C - metabolism; Protein Kinase C - physiology; RNA, Small Interfering - genetics
• ISSN: 0960-7722; 1365-2184
• DOI: 10.1111/j.1365-2184.2009.00582.x

Prostate cancer is one of the leading causes of death among men in the USA. Objective:  In this study, we investigated the role of atypical protein kinase C‐iota (PKC‐ι) in androgen‐independent prostate DU‐145 carcinoma cells compared to transformed non‐malignant prostate RWPE‐1 cells. Materials and methods:  Western blotting and immunoprecipitations demonstrated that PKC‐ι is associated with cyclin‐dependent kinase activating kinase (CAK/Cdk7) in RWPE‐1 cells, but not in DU‐145 cells. Results:  Treatment of prostate RWPE‐1 cells with PKC‐ι silencing RNA (siRNA) decreased cell viability, cell‐cycle accumulation at G2/M phase, and phosphorylation of Cdk7 and Cdk2. In addition, PKC‐ι siRNA treatment caused less phosphorylation of Bad at ser‐155, ser‐136, and greater Bad/Bcl‐xL heterodimerization, leading to apoptosis. In DU‐145 cells, PKC‐ι was anti‐apoptotic and was required for cell survival. Treatment with PKC‐ι siRNA blocked increase in cell number, and inhibited G1/S transition by accumulation of cells in G0/G1 phase. In addition to cell‐cycle arrest, both RWPE‐1 and DU‐145 cells underwent apoptosis due to mitochondrial dysfunction and apoptosis cascades, such as release of cytochrome c, activation of caspase‐7, and poly (ADP‐ribose) polymerase (PARP) cleavage. Conclusion:  Our results suggest that PKC‐ι is required for cell survival in both transformed non‐malignant prostate RWPE‐1 cells and androgen‐independent malignant prostate DU‐145 cells, whereas suppressing PKC‐ι lead to apoptosis in DU‐145 prostate cells.