Chang M A, Patel V, Gwede M, Morgado M, Tomasevich K, Fong E L, Farach-Carson M C, Delk Nikki A
Department of BioSciences, Rice University, BioScience Research Collaborative, 6500 Main, MS 601, Houston, TX, 77030.
J Cell Biochem. 2014 Dec;115(12):2188-97. doi: 10.1002/jcb.24897.
Chronic inflammation is associated with advanced prostate cancer (PCa), although the mechanisms governing inflammation-mediated PCa progression are not fully understood. PCa progresses to an androgen independent phenotype that is incurable. We previously showed that androgen independent, androgen receptor negative (AR(-) ) PCa cell lines have high p62/SQSTM1 levels required for cell survival. We also showed that factors in the HS-5 bone marrow stromal cell (BMSC) conditioned medium can upregulate p62 in AR(+) PCa cell lines, leading us to investigate AR expression under those growth conditions. In this paper, mRNA, protein, and subcellular analyses reveal that HS-5 BMSC conditioned medium represses AR mRNA, protein, and nuclear accumulation in the C4-2 PCa cell line. Using published gene expression data, we identify the inflammatory cytokine, IL-1β, as a candidate BMSC paracrine factor to regulate AR expression and find that IL-1β is sufficient to both repress AR and upregulate p62 in multiple PCa cell lines. Immunostaining demonstrates that, while the C4-2 population shows a primarily homogeneous response to factors in HS-5 BMSC conditioned medium, IL-1β elicits a strikingly heterogeneous response; suggesting that there are other regulatory factors in the conditioned medium. Finally, while we observe concomitant AR loss and p62 upregulation in IL-1β-treated C4-2 cells, silencing of AR or p62 suggests that IL-1β regulates their protein accumulation through independent pathways. Taken together, these in vitro results suggest that IL-1β can drive PCa progression in an inflammatory microenvironment through AR repression and p62 induction to promote the development and survival of androgen independent PCa.
慢性炎症与晚期前列腺癌(PCa)相关,尽管炎症介导的PCa进展机制尚未完全明确。PCa会发展为无法治愈的雄激素非依赖型表型。我们之前发现,雄激素非依赖、雄激素受体阴性(AR(-))的PCa细胞系具有细胞存活所需的高p62/SQSTM1水平。我们还发现,HS-5骨髓基质细胞(BMSC)条件培养基中的因子可上调AR(+) PCa细胞系中的p62,这促使我们研究在这些生长条件下的AR表达。本文通过mRNA、蛋白质和亚细胞分析表明,HS-5 BMSC条件培养基可抑制C4-2 PCa细胞系中的AR mRNA、蛋白质及核内积累。利用已发表的基因表达数据,我们确定炎性细胞因子IL-1β是调节AR表达的候选BMSC旁分泌因子,并发现IL-1β足以在多个PCa细胞系中抑制AR并上调p62。免疫染色显示,虽然C4-2群体对HS-5 BMSC条件培养基中的因子表现出基本一致的反应,但IL-1β引发了显著的异质性反应;这表明条件培养基中存在其他调节因子。最后,虽然我们在IL-1β处理的C4-2细胞中观察到AR缺失和p62上调同时出现,但AR或p62的沉默表明IL-1β通过独立途径调节它们的蛋白质积累。综上所述,这些体外研究结果表明,IL-1β可通过抑制AR和诱导p62在炎症微环境中驱动PCa进展,以促进雄激素非依赖型PCa的发展和存活。