Regulation of PKCdelta Apoptotic Activity in Prostate Cancer Cells by Tyrosine Phosphorylation
Annual rept. 1 Jul 2007-30 Jun 2009
PENNSYLVANIA UNIV PHILADELPHIA
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The androgen-dependent prostate cancer cell LNCaP undergoes apoptosis in response to PMA treatment, a process primarily mediated by one of the PKC isoforms PKCdelta. Tyrosine phosphorylation, as a unique property and regulatory mechanism of PKCdelta, has been studied over years but never in prostate cancer cells. In this report we identified PKCdelta became Tyr phsophorylated at site Ty311 in response to PMA stimulation. But mutation of Tyr 311 affect neither PKCdelta translocation, nor the apoptotic effect of PMA. By using adenovirus infection approach, we found that the other five sites, Tyr52, Tyr64, Tyr155, Tyr187 and Tyr565 are not relevant to the apoptosis of LNCaP cells. We eventually developed methods to analyze the signaling events controlled by Tyr phosphorylation. Etoposide, an anti-cancer agent whose effect is dependent on PKCdelta, does not induce Tyr phosphorylation of PKCdelta in LNCaP cells, indicating different drug effects might rely on different mechanisms. In summary, in this study we found the Tyr sites we examined so far are irrelevant to the apoptotic effect of PMA in LNCaP cells. However, more study will be needed to make a final conclusion on the role of PKCdelta Tyr phosphorylation in the apoptosis induced by PMA.
- Medicine and Medical Research