Rap2 regulates androgen sensitivity in human prostate cancer cells
Rap2 regulates androgen sensitivity in human prostate cancer cells
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DOI：
10.1002/pros.20644
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发表时间：
2007-10-01
期刊：
影响因子：
2.8
通讯作者：
Theodorescu, Dan
中科院分区：
文献类型：
--
作者：
Bigler, Dora;Gioeli, Daniel;Theodorescu, Dan
背景前列腺癌进展为致死性雄激素非依赖性疾病与MAP激酶激活相关，这与Ras信号通路的慢性刺激一致。我们以前已经表明，Ras激活足以诱导前列腺癌细胞的雄激素非依赖性生长。MAP激酶调节的一种机制是通过其他Ras家族成员Rap基因旁系同源物Rap 1a/B和Rap 2a/B调节Ras信号传导。在这里，我们问，如果Rap蛋白发挥作用，在确定雄激素敏感性的人前列腺癌细胞，无论是单独或在激活Ras的背景下。为了评估Rap蛋白在雄激素反应性中的作用，我们使用Rap过表达与或不与突变Ras共转染和Rap siRNA敲低来评估雄激素依赖性前列腺特异性抗原（PSA）启动子报告基因表达和雄激素依赖性LNCaP和独立C4-2人前列腺癌细胞中的细胞生长。Rap 1在LNCaP和C4-2细胞之间相等地表达，因此我们集中于在C4-2中最低表达的Rap 2。Rap 2a以剂量依赖性方式影响LNCaP和C4-2细胞中雄激素依赖性PSA报告基因的表达。低水平的Rap 2a增强PSA报告基因表达，而较高浓度则抑制表达。我们发现Rap 2a拮抗前列腺癌细胞中活性RasV 12基因赋予的PSA报告基因表达增强。siRNA敲低数据表明Rap 2在LNCaP中对雄激素刺激的生长的影响大于C4-2细胞。我们发现Rap 2参与雄激素介导的人类前列腺癌细胞的转录和生长反应。
BACKGROUND. Progression of prostate cancer to a fatal androgen-independent disease is associated with activation of MAP kinase, consistent with chronic stimulation of the Ras-signaling pathway. We have previously shown that Ras activation is sufficient to induce androgen-independent growth of prostate cancer cells. One mechanism of MAP kinase regulation is modulation of Ras signaling by other Ras family members, the Rap gene paralogs Rap1a/b and Rap2a/b. Here we ask if Rap proteins play a role in determining androgen sensitivity of human prostate cancer cells either alone or in the context of an activated Ras.METHODS. To evaluate the role of Rap proteins in androgen responsiveness we use Rap overexpression with or without mutated Ras co-transfection and Rap siRNA knockdown to evaluate androgen-dependent prostate-specific antigen (PSA) promoter reporter expression and cell growth in androgen-dependent LNCaP and independent C4-2 human prostate cancer cells.RESULTS. Rap1 is equally expressed between LNCaP and C4-2 cells and thus we focused on Rap2 which is minimally expressed in C4-2. Rap2a affects androgen-dependent PSA reporter expression in a dose-dependent manner in LNCaP and C4-2 cells. Low levels of Rap2a enhance PSA reporter expression, whereas higher concentrations inhibit expression. We show that Rap2a antagonizes the enhanced PSA reporter expression conferred by an active RasV12 gene in prostate cancer cells. siRNA knockdown data indicate that Rap2 has a greater effect on androgen-stimulated growth in LNCaP than in C4-2 cells.CONCLUSIONS. We show that Rap2 is involved in androgen-mediated transcriptional and growth responses of human prostate cancer cells.