Fujii T, García-Bermejo M L, Bernabó J L, Caamaño J, Ohba M, Kuroki T, Li L, Yuspa S H, Kazanietz M G
Center for Experimental Therapeutics and Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
J Biol Chem. 2000 Mar 17;275(11):7574-82. doi: 10.1074/jbc.275.11.7574.
Phorbol esters, the activators of protein kinase C (PKC), induce apoptosis in androgen-sensitive LNCaP prostate cancer cells. The role of individual PKC isozymes as mediators of this effect has not been thoroughly examined to date. To study the involvement of the novel isozyme PKCdelta, we used a replication-deficient adenovirus (PKCdeltaAdV), which allowed for a tightly controlled expression of PKCdelta in LNCaP cells. A significant reduction in cell number was observed after infection of LNCaP cells with PKCdeltaAdV. Overexpression of PKCdelta markedly enhanced the apoptotic effect of phorbol 12-myristate 13-acetate in LNCaP cells. PKCdelta-mediated apoptosis was substantially reduced by the pan-caspase inhibitor z-VAD and by Bcl-2 overexpression. Importantly, and contrary to other cell types, PKCdelta-mediated apoptosis does not involve its proteolytic cleavage by caspase-3, suggesting that allosteric activation of PKCdelta is sufficient to trigger apoptosis in LNCaP cells. In addition, phorbol ester-induced apoptosis was blocked by a kinase-deficient mutant of PKCdelta, supporting the concept that PKCdelta plays an important role in the regulation of apoptotic cell death in LNCaP prostate cancer cells.
佛波酯是蛋白激酶C（PKC）的激活剂，可诱导雄激素敏感的LNCaP前列腺癌细胞凋亡。迄今为止，尚未对单个PKC同工酶作为这种效应的介导者的作用进行全面研究。为了研究新型同工酶PKCδ的参与情况，我们使用了一种复制缺陷型腺病毒（PKCδAdV），它可以在LNCaP细胞中严格控制PKCδ的表达。用PKCδAdV感染LNCaP细胞后，观察到细胞数量显著减少。PKCδ的过表达显著增强了佛波醇12-肉豆蔻酸酯13-乙酸酯对LNCaP细胞的凋亡作用。泛半胱天冬酶抑制剂z-VAD和Bcl-2的过表达显著降低了PKCδ介导的凋亡。重要的是，与其他细胞类型相反，PKCδ介导的凋亡不涉及caspase-3对其的蛋白水解切割，这表明PKCδ的变构激活足以触发LNCaP细胞的凋亡。此外，佛波酯诱导的凋亡被PKCδ的激酶缺陷型突变体阻断，这支持了PKCδ在LNCaP前列腺癌细胞凋亡调控中起重要作用的观点。
