Xie Yan, Wolff Dennis W, Lin Ming-Fong, Tu Yaping
Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178, USA.
Mol Pharmacol. 2007 Jul;72(1):73-85. doi: 10.1124/mol.107.033894. Epub 2007 Apr 12.
Acquisition of androgen independence by prostate cancer is the key problem of prostate cancer progression. Vasoactive intestinal peptide (VIP), a neuropeptide, may act as a survival factor for prostate cancer cells under androgen deprivation. However, the molecular mechanisms by which VIP promotes the androgen-independent growth of androgen-sensitive prostate cancer cells have not been addressed. We therefore investigated the biological effect and signal pathway of VIP in LNCaP cells, a prostate cancer cell line that requires androgens for growth. We showed that low nanomolar concentrations of VIP, acting through G(s)-protein-coupled VIP receptors, can induce LNCaP cell growth in the absence of androgen. Blockade of androgen-receptor (AR) in these cells by AR antagonist bicalutamide or by anti-AR small interfering RNA, inhibited the proliferative effect of VIP. In addition, VIP stimulated androgen-independent activation of AR with an EC(50) of 3.0 +/- 0.8 nM. We then investigated VIP-stimulated signaling events that may interact with the AR pathway in prostate cancer cells. VIP regulation of AR activation, mediated by VIP receptors, was protein kinase A (PKA)-dependent, and extracellular signal-regulated kinase 1/2 (ERK1/2) activation contributes to VIP-mediated AR activation. Furthermore, PKA-dependent Rap1 activation is required for both ERK1/2 activation and androgen-independent AR activation in LNCaP cells upon VIP stimulation. Finally, we showed that VIP-induced AR activation was also present in prostate cancer CWR22Rv1 and PC3 cells transfected with the wild-type AR. Altogether, we demonstrate that VIP acting through its G(s)-protein-coupled receptors can cause androgen-independent transactivation of AR through a PKA/Rap1/ERK1/2 pathway, thus promoting androgen-independent proliferation of androgen-sensitive prostate cancer cells.
前列腺癌获得雄激素非依赖性是前列腺癌进展的关键问题。血管活性肠肽（VIP）作为一种神经肽，在雄激素剥夺条件下可能作为前列腺癌细胞的存活因子。然而，VIP促进雄激素敏感性前列腺癌细胞雄激素非依赖性生长的分子机制尚未得到阐明。因此，我们研究了VIP在LNCaP细胞（一种依赖雄激素生长的前列腺癌细胞系）中的生物学效应和信号通路。我们发现，低纳摩尔浓度的VIP通过G(s)蛋白偶联的VIP受体发挥作用，可在无雄激素的情况下诱导LNCaP细胞生长。用雄激素受体（AR）拮抗剂比卡鲁胺或抗AR小干扰RNA阻断这些细胞中的AR，可抑制VIP的增殖作用。此外，VIP以3.0±0.8 nM的EC(50)刺激AR的雄激素非依赖性激活。然后，我们研究了VIP刺激的可能与前列腺癌细胞中AR通路相互作用的信号事件。由VIP受体介导的VIP对AR激活的调节是蛋白激酶A（PKA）依赖性的，细胞外信号调节激酶1/2（ERK1/2）的激活有助于VIP介导的AR激活。此外，PKA依赖性的Rap1激活是VIP刺激后LNCaP细胞中ERK1/2激活和雄激素非依赖性AR激活所必需的。最后，我们发现VIP诱导的AR激活也存在于转染野生型AR的前列腺癌CWR22Rv1和PC3细胞中。总之，我们证明，VIP通过其G(s)蛋白偶联受体发挥作用，可通过PKA/Rap1/ERK1/2途径导致AR的雄激素非依赖性反式激活，从而促进雄激素敏感性前列腺癌细胞的雄激素非依赖性增殖。
