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Reduced expression of FASN through SREBP-1 down-regulation is responsible for hypoxic cell death in HepG2 cells

Authors

  • Seung-Youn Jung,

    1. Department of Molecular Biology, Pusan National University, Busan 609-735, Korea
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  • Hye-Kyung Jeon,

    1. Department of Molecular Biology, Pusan National University, Busan 609-735, Korea
    Current affiliation:
    1. Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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  • Jae-Sun Choi,

    1. Department of Molecular Biology, Pusan National University, Busan 609-735, Korea
    Current affiliation:
    1. Department of Biomedical Science and Department of Anatomy and Neurobiology, School of Medicine, Kyung Hee University, Seoul 130-701, Korea
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  • Yung-Jin Kim

    Corresponding author
    1. Department of Molecular Biology, Pusan National University, Busan 609-735, Korea
    • Department of Molecular Biology, Pusan National University, Busan 609-735, Korea.
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Abstract

Cells under hypoxic stress either activate an adaptive response or undergo cell death. Although some mechanisms have been reported, the exact mechanism behind hypoxic cell death remains unclear. Recently, increased expression of fatty acid synthase (FASN) has been observed in various human cancers. In highly proliferating cells, tumor-associated FASN is considered necessary for both membrane lipids production and post-translational protein modification, but the exact mechanisms are not fully understood. Further, FASN overexpression is associated with aggressive and malignant cancer diseases and FASN inhibition induces apoptosis in cancer cells. For this reason, FASN is emerging as a key target for the potential diagnosis and treatment of various cancers. Here, we observed decreased FASN expression under hypoxic cell death conditions in HepG2 cells. Thus, we examined the effect of decreased FASN expression on hypoxia-induced cell death in HepG2 cells and also investigated the mechanism responsible for reduction of FASN expression under hypoxic cell death conditions. As a result, reduction of FASN expression resulted in hypoxic cell death via malonyl-CoA accumulation. In addition, SREBP-1 restored FASN reduction and hypoxia-induced apoptosis. Taken together, we suggest that hypoxic cell death is promoted by the reduced expression of FASN through SREBP-1 down-regulation. J. Cell. Biochem. 113: 3730–3739, 2012. © 2012 Wiley Periodicals, Inc.

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