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J Biol Chem. 2009 Apr 10;284(15):10004-12. doi: 10.1074/jbc.M805997200. Epub 2009 Feb 10.

BCL-xL is a target gene regulated by hypoxia-inducible factor-1{alpha}.

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  • 1Laboratory 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.

Abstract

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.

PMID:
19211554
[PubMed - indexed for MEDLINE]
PMCID:
PMC2665055
Free PMC Article
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