Chen Ni, Chen Xueqin, Huang Rui, Zeng Hao, Gong Jing, Meng Wentong, Lu Yiping, Zhao Fang, Wang Lin, Zhou Qiao
Laboratory of Pathology, Departments of Pathology and Urology, and Laboratory of Stem Cell Research, State Key Laboratory of Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu, China 610041.
J Biol Chem. 2009 Apr 10;284(15):10004-12. doi: 10.1074/jbc.M805997200. Epub 2009 Feb 10.
The transcription factor hypoxia-inducible factor-1alpha (HIF-1alpha) plays pivotal roles in physiology and pathophysiology. Constitutive or hypoxia-induced HIF-1alpha overexpression is observed in many types of cancers including prostate adenocarcinoma, in which it is associated with resistance to apoptosis and therapeutic agents. BCL-xL, a hypoxia-responsive, anti-apoptotic protein of the Bcl-2 family, is also overexpressed in prostate carcinoma and many other cancers. Despite this connection, whether BCL-xL expression is directly regulated by HIF-1alpha is not known. We used prostate cancer PC-3 cell with constitutive high HIF-1alpha level as a model to address this important question. We first generated prostate cancer PC-3 cells in which HIF-1alpha was stably knocked-down (HIF-KD) by using small interference RNA. BCL-xL was dramatically decreased in HIF-KD PC-3 cells, in parallel with sensitization to apoptosis with caspase-3 activation as well as decreased cell proliferation. We then demonstrated that HIF-1alpha directly regulated BCL-xL transcription by binding to a hypoxia-responsive element in the BCL-xL promoter (-865 to -847) by reporter gene assay, chromatin immunoprecipitation, and electrophoretic mobility shift and supershift assays. HIF-1alpha-dependent BCL-xL overexpression may be an important mechanism by which HIF-1alpha protects prostate cancer cells from apoptosis and leads to treatment resistance.
转录因子缺氧诱导因子-1α（HIF-1α）在生理和病理生理过程中发挥着关键作用。在包括前列腺腺癌在内的多种癌症中均观察到组成型或缺氧诱导的HIF-1α过表达，在前列腺腺癌中，它与细胞对凋亡和治疗药物的抗性相关。BCL-xL是Bcl-2家族的一种缺氧反应性抗凋亡蛋白，在前列腺癌和许多其他癌症中也过表达。尽管存在这种关联，但BCL-xL的表达是否直接受HIF-1α调控尚不清楚。我们使用组成型高HIF-1α水平的前列腺癌PC-3细胞作为模型来解决这个重要问题。我们首先通过使用小干扰RNA构建了HIF-1α稳定敲低（HIF-KD）的前列腺癌PC-3细胞。在HIF-KD PC-3细胞中，BCL-xL显著降低，同时伴随着对凋亡的敏感性增加、caspase-3激活以及细胞增殖减少。然后，我们通过报告基因检测、染色质免疫沉淀以及电泳迁移率变动和超迁移检测证明，HIF-1α通过与BCL-xL启动子（-865至-847）中的缺氧反应元件结合直接调控BCL-xL转录。HIF-1α依赖的BCL-xL过表达可能是HIF-1α保护前列腺癌细胞免于凋亡并导致治疗抗性的重要机制。
