KMID : 0606920140220030184
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Biomolecules & Therapeutics 2014 Volume.22 No. 3 p.184 ~ p.192
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¥â-lapachone-Induced Apoptosis of Human Gastric Carcinoma AGS Cells Is Caspase-Dependent and Regulated by the PI3K/Akt Pathway
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Yu Hai-Yang
Kim Sung-Ok Jin Cheng Yun Kim Gi-Young Kim Wun-Jae Yoo Young-Hyun Choi Yung-Hyun
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Abstract
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¥â-lapachone is a naturally occurring quinone that selectively induces apoptotic cell death in a variety of human cancer cells in vitro and in vivo; however, its mechanism of action needs to be further elaborated. In this study, we investigated the effects of ¥â-lapachone on the induction of apoptosis in human gastric carcinoma AGS cells. ¥â-lapachone significantly inhibited cellular proliferation, and some typical apoptotic characteristics such as chromatin condensation and an increase in the population of sub-G1 hypodiploid cells were observed in ¥â-lapachone-treated AGS cells. Treatment with ¥â-lapachone caused mitochondrial transmembrane potential dissipation, stimulated the mitochondria-mediated intrinsic apoptotic pathway, as indicated by caspase-9 activation, cytochrome c release, Bcl-2 downregulation and Bax upregulation, as well as death receptor-mediated extrinsic apoptotic pathway, as indicated by activation of caspase-8 and truncation of Bid. This process was accompanied by activation of caspase-3 and concomitant with cleavage of poly(ADP-ribose) polymerase. The general caspase inhibitor, z-VAD-fmk, significantly abolished ¥â-lapachone-induced cell death and inhibited growth. Further analysis demonstrated that the induction of apoptosis by ¥â-lapachone was accompanied by inactivation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. The PI3K inhibitor LY29004 significantly increased ¥â-lapachone-induced apoptosis and growth inhibition. Taken together, these findings indicate that the apoptotic activity of ¥â-lapachone is probably regulated by a caspase-dependent cascade through activation of both intrinsic and extrinsic signaling pathways, and that inhibition of the PI3K/Akt signaling may contribute to ¥â-lapachone-mediated AGS cell growth inhibition and apoptosis induction.
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KEYWORD
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¥â-lapachone, Apoptosis, Caspase, PI3K/Akt
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