Wright Michael E, Tsai Ming-Jer, Aebersold Ruedi
Institute for Systems Biology, Seattle, Washington 98103, USA.
Mol Endocrinol. 2003 Sep;17(9):1726-37. doi: 10.1210/me.2003-0031. Epub 2003 May 29.
Androgen-ablation therapy is an effective method for treating prostate cancer. However, prostate tumors that survive long-term androgen-ablation therapy are classified as androgen-independent as they proliferate in the absence of androgens, and they tend to be enriched for neuroendocrine (NE) cells. Androgen withdrawal causes androgen-dependent prostate cancer cells to adopt a pronounced NE phenotype, suggesting that androgen receptor (AR) represses an intrinsic NE transdifferentiation process in prostate cancer cells. In this report we show that short interfering RNA-induced AR silencing induced a NE phenotype that manifested itself in the growth of dendritic-like processes in both the androgen-dependent LNCaP and androgen-independent LNCaP-AI human prostate cancer cells. Western blot analysis revealed that neuronal-specific enolase, a marker of the neuronal lineage, was increased by AR knockdown in LNCaP cells. The expression levels of the neuronal-specific cytoskeletal proteins beta-tubulin III, nestin, and glial acidic fibrillary protein were also characterized in AR knockdown cells. Most interestingly, AR silencing induced beta-tubulin III expression in LNCaP cells, while AR knockdown increased glial acidic fibrillary protein levels in both LNCaP and LNCaP-AI cells. Lastly, AR silencing reduced the proliferative capacity of LNCaP and LNCaP-AI cells. Our data demonstrate that AR actively represses an intrinsic NE transdifferentiation process in androgen-responsive prostate cancer cells and suggest a potential link between AR inactivation and the increased frequency of NE cells in androgen-independent tumors.
雄激素剥夺疗法是治疗前列腺癌的一种有效方法。然而，长期接受雄激素剥夺疗法后仍存活的前列腺肿瘤被归类为雄激素非依赖性肿瘤，因为它们在没有雄激素的情况下仍能增殖，并且往往富含神经内分泌（NE）细胞。雄激素撤退会使雄激素依赖性前列腺癌细胞呈现出明显的NE表型，这表明雄激素受体（AR）抑制了前列腺癌细胞内源性的NE转分化过程。在本报告中，我们发现短发夹RNA诱导的AR沉默会诱导NE表型，这在雄激素依赖性LNCaP和雄激素非依赖性LNCaP-AI人前列腺癌细胞中表现为树突状样突起的生长。蛋白质印迹分析显示，神经元谱系标志物神经元特异性烯醇化酶在LNCaP细胞中因AR敲低而增加。在AR敲低的细胞中也对神经元特异性细胞骨架蛋白β-微管蛋白III、巢蛋白和胶质纤维酸性蛋白的表达水平进行了表征。最有趣的是，AR沉默在LNCaP细胞中诱导β-微管蛋白III表达，而AR敲低在LNCaP和LNCaP-AI细胞中均增加了胶质纤维酸性蛋白水平。最后，AR沉默降低了LNCaP和LNCaP-AI细胞的增殖能力。我们的数据表明，AR在雄激素反应性前列腺癌细胞中积极抑制内源性NE转分化过程，并提示AR失活与雄激素非依赖性肿瘤中NE细胞频率增加之间可能存在联系。
