Nature Cell Biology
7, 909 - 915 (2005)
Published online: 21 August 2005; | doi:10.1038/ncb1291
Clusterin inhibits apoptosis by interacting with activated BaxHonglai Zhang1, Jin Koo Kim1, Chris A. Edwards2, Zhaohui Xu3, Russell Taichman4
& Cun-Yu Wang11
Laboratory of Molecular Signaling and Apoptosis, Department of Biological and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI
48109-1078, USA. 2
Microscopy and Image-Analysis Core, Department of Cell and Developmental Biology, School of Dentistry, University of Michigan, Ann Arbor, MI
48109-1078, USA. 3
Life Science Institute, School of Dentistry, University of Michigan, Ann Arbor, MI
48109-1078, USA. 4
Department of Periodontics, Prevention and Geriatrics, School of Dentistry, University of Michigan, Ann Arbor, MI
48109-1078, USA.
Correspondence should be addressed to Cun-Yu Wang cunywang@umich.edu Clusterin is an enigmatic glycoprotein that is overexpressed in several human cancers such as prostate and breast cancers, and squamous cell carcinoma1,
2. Because the suppression of clusterin expression renders human cancer cells sensitive to chemotherapeutic drug-mediated apoptosis, it is currently an antisense target in clinical trials for prostate cancer. However, the molecular mechanisms by which clusterin inhibits apoptosis in human cancer cells are unknown. Here we report that intracellular clusterin inhibits apoptosis by interfering with Bax activation in mitochondria. Intriguingly, in contrast to other inhibitors of Bax, clusterin specifically interacts with conformation-altered Bax in response to chemotherapeutic drugs. This interaction impedes Bax oligomerization, which leads to the release of cytochrome c from mitochondria and caspase activation. Moreover, we also find that clusterin inhibits oncogenic c-Myc-mediated apoptosis by interacting with conformation-altered Bax. Clusterin promotes c-Myc-mediated transformation in vitro and tumour progression in vivo. Taken together, our results suggest that the elevated level of clusterin in human cancers may promote oncogenic transformation and tumour progression by interfering with Bax pro-apoptotic activities.
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