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2′-Epi-2′-O-acetylthevetin B induces apoptosis partly via Ca2+-mediated mitochondrial pathway in human hepatocellular carcinoma HepG2 cells

Authors

  • Bo Feng,

    1. Department of Biochemistry and Molecular Biology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, People's Republic of China
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  • Cai-Guo Huang,

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, People's Republic of China
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  • Ruo-Hua Chen,

    1. Changhai Hospital, Shanghai 200433, People's Republic of China
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  • Yue-Wei Guo,

    1. State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, People's Republic of China
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  • Bing-Hua Jiao

    Corresponding author
    1. Department of Biochemistry and Molecular Biology, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, People's Republic of China
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Abstract

2′-Epi-2′-O-acetylthevetin B (GHSC-74), a cardiac glycoside, can be isolated from the seeds of Cerbera manghas L. We demonstrated that GHSC-74 reduced the viability of HepG2 cells in a time- and dose-dependent manner, and efficiently induced apoptosis without significantly decreasing the viability of Chang human liver cells and Swiss albino 3T3 fibroblasts, as indicated by annexin-V/PI binding assay and Hoechst 33342 staining. In addition, stimulation of HepG2 cells with GHSC-74 induced a series of intracellular events: (1) loss of mitochondrial membrane potential; (2) sustained elevation of cytosolic [Ca2+]; and (3) downregulation of Bcl-2. BAPTA-AM, a cytosolic Ca2+ chelator, partly suppressed cell death and prevented mitochondrial membrane potential from losing in GHSC-74-treated HepG2 cells. In contrast, EGTA, an extracellular Ca2+ chelator, exhibited a weaker effect as compared to that of BAPTA-AM. Taken together, the Ca2+-mediated mitochondrial pathway was found to be involved in GHSC-74-induced HepG2 cell apoptosis.

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