Stewart Jubilee R, O'Brian Catherine A
Department of Cancer Biology, U.T.M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Invest New Drugs. 2004 Apr;22(2):107-17. doi: 10.1023/B:DRUG.0000011787.75522.ec.
The development of androgen-independent prostate cancer (AI PrCa) involves constitutive Erk1/2 activation sustained by the epidermal growth factor/transforming growth factor-alpha/EGF receptor (EGF/TGFalpha/EGFR) axis and other trophic signaling mechanisms in neoplastic human prostate epithelial cells in vivo. In this report, we show that growth-inhibitory concentrations of the dietary phytochemical resveratrol suppress EGFR-dependent Erk1/2 activation pathways stimulated by EGF and phorbol ester (12- O -tetradecanoyl phorbol 13-acetate, TPA) in human AI PrCa PC-3 cells in vitro. Because protein kinase C (PKC) is the major cellular receptor for phorbol esters and taking into consideration that resveratrol is PKC-inhibitory, we investigated resveratrol effects on cellular PKC isozymes associated with the suppression of TPA-induced Erk1/2 activation. The PKC isozyme composition of PC-3 cells was defined by Western analysis of the cell lysate with a comprehensive set of isozyme-selective PKC Ab's. PC-3 cells expressed PKCalpha, epsilon, zeta, iota, and PKD (PKCmicro), as did another human AI PrCa cell line of distinct genetic origin, DU145. The effects of resveratrol on TPA-induced PKC isozyme activation were defined by monitoring PKC isozyme translocation and autophosphorylation. Under conditions where resveratrol suppressed TPA-induced Erk1/2 activation, the phytochemical produced isozyme-selective interference with TPA-induced translocation of cytosolic PKCalpha to the membrane/cytoskeleton and selectively diminished the amount of autophosphorylated PKCalpha in the membrane/cytoskeleton of the TPA-treated cells. These results demonstrate that resveratrol abrogation of a PKC-mediated Erk1/2 activation response in PC-3 cells correlates with isozyme-selective PKCalpha inhibition. The results provide evidence that resveratrol may have value as an adjuvant cancer therapeutic in advanced prostate cancer.
雄激素非依赖性前列腺癌（AI PrCa）的发展涉及由表皮生长因子/转化生长因子-α/表皮生长因子受体（EGF/TGFα/EGFR）轴以及体内肿瘤性人前列腺上皮细胞中的其他营养信号传导机制维持的组成型Erk1/2激活。在本报告中，我们表明，膳食植物化学物质白藜芦醇的生长抑制浓度在体外抑制了人AI PrCa PC-3细胞中由EGF和佛波酯（12 - O -十四酰佛波醇13 - 乙酸酯，TPA）刺激的EGFR依赖性Erk1/2激活途径。由于蛋白激酶C（PKC）是佛波酯的主要细胞受体，并且考虑到白藜芦醇具有PKC抑制作用，我们研究了白藜芦醇对与TPA诱导的Erk1/2激活抑制相关的细胞PKC同工酶的影响。通过用一套全面的同工酶选择性PKC抗体对细胞裂解物进行蛋白质印迹分析来确定PC-3细胞的PKC同工酶组成。PC-3细胞表达PKCalpha、epsilon、zeta、iota和PKD（PKCmicro），另一种具有不同遗传起源的人AI PrCa细胞系DU145也表达这些同工酶。通过监测PKC同工酶易位和自磷酸化来确定白藜芦醇对TPA诱导的PKC同工酶激活的影响。在白藜芦醇抑制TPA诱导的Erk1/半激活的条件下，这种植物化学物质对TPA诱导的胞质PKCalpha向膜/细胞骨架易位产生同工酶选择性干扰，并选择性地减少了TPA处理细胞的膜/细胞骨架中自磷酸化PKCalpha的量。这些结果表明白藜芦醇对PC-3细胞中PKC介导的Erk1/2激活反应的消除与同工酶选择性PKCalpha抑制相关。这些结果提供了证据，表明白藜芦醇作为晚期前列腺癌的辅助癌症治疗药物可能具有价值。
