Atypical protein kinase C phosphorylates IKKalphabeta in transformed non-malignant and malignant prostate cell survival.

Mechanistic pathways involving atypical protein kinase C-iota (aPKC-iota) have been targeted in various cancer cells such as lung cancer, brain and prostate due to PKCiota's antiapoptotic function, and role in cell proliferation and cell survival. In the current study, we examined the involvement of PKC-iota in the NF-kappaB pathway following treatment of prostate cells with the pro-inflammatory cytokine tumor necrosis factor alpha (TNFalpha). Results demonstrated that androgen-independent DU-145 prostate carcinoma is insensitive to TNFalpha while transformed non-tumorigenic prostate RWPE-1 cells showed a slight sensitivity to TNFalpha. However, androgen-dependent LNCaP prostate cells are more sensitive to TNFalpha treatment and undergo apoptosis. Results demonstrated that in DU-145 cells, TNFalpha-induced PKC-iota in phosphorylation of IKKalphabeta. In RWPE-1 cells, PKC-zeta phosphorylates IKKalphabeta. Degradation of IkappaBalpha was observed in all three cell lines, allowing NF-kappaB/p65 translocation to the nucleus. Although, IKKalpha is weakly activated in LNCaP cells, the upstream kinase phosphorylation of IKKalphabeta via aPKCs was not observed. Hence, aPKCs may play a role in activation of NFkappaB pathway in prostate cancer cells.