Neuwirt Hannes, Puhr Martin, Cavarretta Ilaria T, Mitterberger Michael, Hobisch Alfred, Culig Zoran
Department of Urology, Innsbruck Medical University, Anichtrasse 35, A-6020 Innsbruck, Austria.
Endocr Relat Cancer. 2007 Dec;14(4):1007-19. doi: 10.1677/ERC-07-0172.
Suppressors of cytokine signalling (SOCS) are induced by interleukins (ILs) and various peptide hormones and may prevent sustained activation of signalling pathways. We have previously shown that SOCS-3 antagonizes regulation of cellular events by cAMP and is expressed in human prostate cancer. To investigate possible effects of androgen on SOCS-3 protein expression, two prostate cancer cell lines (PC3-AR and LAPC4) were treated with different concentrations of R1881. Western blot analyses revealed induction of SOCS-3 protein expression in both cell lines by androgen, an effect which can be blocked by the anti-androgen bicalutamide. To further characterize the effects of R1881 on the SOCS-3 gene, promoter-reporter assay and real-time PCR were performed. We found no influence of androgen on promoter activity or SOCS-3 mRNA levels, thus suggesting a post-transcriptional effect of androgen. Concordant with our previous findings, we show a significant increase of SOCS-3 protein after androgen treatment in cells in which transcription was blocked, but not in those with impaired translation. In order to understand implications of SOCS-3 regulation by androgen, we used SOCS-3-negative LNCaP-IL-6 cells and stably transfected them with a tetracycline-responsive SOCS-3 Tet-On plasmid. We report that androgenic effects on cell proliferation and prostate-specific antigen secretion are significantly diminished following up-regulation of SOCS-3. In conclusion, androgen up-regulates SOCS-3 protein via post-transcriptional effects. SOCS-3 inhibits androgen-stimulated proliferation by influencing cell cycle regulation. Taken together with previous findings showing androgen receptor activation by IL-6, our results imply that androgen and cytokine signalling pathways interact at multiple levels in prostate cancer.
细胞因子信号转导抑制因子（SOCS）由白细胞介素（ILs）和各种肽类激素诱导产生，可能会阻止信号通路的持续激活。我们之前已经表明，SOCS-3可拮抗cAMP对细胞事件的调节作用，且在人类前列腺癌中表达。为了研究雄激素对SOCS-3蛋白表达的可能影响，用不同浓度的R1881处理两种前列腺癌细胞系（PC3-AR和LAPC4）。蛋白质免疫印迹分析显示，雄激素可诱导这两种细胞系中SOCS-3蛋白表达，抗雄激素药物比卡鲁胺可阻断这一效应。为了进一步表征R1881对SOCS-3基因的影响，进行了启动子报告基因检测和实时定量PCR。我们发现雄激素对启动子活性或SOCS-3 mRNA水平没有影响，因此提示雄激素存在转录后效应。与我们之前的研究结果一致，我们发现，在转录被阻断的细胞中，雄激素处理后SOCS-3蛋白显著增加，但在翻译受损的细胞中则没有增加。为了了解雄激素对SOCS-3调节的意义，我们使用了SOCS-3阴性的LNCaP-IL-6细胞，并将其用四环素反应性SOCS-3 Tet-On质粒进行稳定转染。我们报告称，SOCS-3上调后，雄激素对细胞增殖和前列腺特异性抗原分泌的影响显著减弱。总之，雄激素通过转录后效应上调SOCS-3蛋白。SOCS-3通过影响细胞周期调节来抑制雄激素刺激的增殖。结合之前显示IL-6激活雄激素受体的研究结果，我们的结果表明，雄激素和细胞因子信号通路在前列腺癌中存在多层次相互作用。
