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KMID : 0578320140370020178
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Molecules and Cells
2014 Volume.37 No. 2 p.178 ~ p.186
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Hypoxia Inducible Factor-1α Directly Regulates Nuclear Clusterin Transcription by Interacting with Hypoxia Response Elements in the Clusterin Promoter
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Park Jeong-Sook
Shin Eun-Kyung
Lee Sun-Hee
Lee Sun-Hee
Kim Yoon-Sook
Lee Dong-Hoon
Roh Gu-Seob
Kim Hyun-Joon
Kang Sang-Soo
Cho Gyeong-Jae
Jeong Bo-Young
Kim Hwa-Jin
Choi Wan-Sung
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Abstract
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Differential transcription of the clusterin (CLU) gene yields two CLU isoforms, a nuclear form (nCLU) and a secretory form (sCLU), which play crucial roles in prostate tumorigenesis. Pro-apoptotic nCLU and anti-apoptotic sCLU have opposite effects and are differentially expressed in normal and cancer cells; however, their regulatory mechanisms at the transcriptional level are not yet known. Here, we examined the transcriptional regulation of nCLU in response to hypoxia. We identified three putative hypoxia response elements (HREs) in the human CLU promoter between positions ?806 and +51 bp. Using a luciferase reporter, electrophoretic gel mobility shift, and chromatin immunoprecipitation assays, we further showed that hypoxia-inducible factor-1α (HIF-1α) bound directly to these sites and activated transcription. Exposure to the hypoxiamimetic compound CoCl2, incubation under 1% O2 conditions, or overexpression of HIF-1α enhanced nCLU expression and induced apoptosis in human prostate cancer PC3M cells. However, LNCaP prostate cancer cells were resistant to hypoxia-induced cell death. Methylation-specific PCR analysis revealed that the CLU promoter in PC3M cells was not methylated; in contrast, the CLU promoter in LNCap cells was methylated. Co-treatment of LNCaP cells with CoCl2 and a demethylating agent promoted apoptotic cell death through the induction of nCLU. We conclude that nCLU expression is regulated by direct binding of HIF-1α to HRE sites and is epigenetically controlled by methylation of its promoter region.
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KEYWORD
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HIF-1α, hypoxia response element, nuclear clusterin, promoter methylation, prostate cancer
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