Huang Y L, Shen C K, Luh T Y, Yang H C, Hwang K C, Chou C K
Institute of Biochemistry, National Yang-Ming University, Taipei, Taiwan.
Eur J Biochem. 1998 May 15;254(1):38-43. doi: 10.1046/j.1432-1327.1998.2540038.x.
Transforming growth factor-beta (TGF-beta) has been shown to induce apoptosis in normal hepatocytes and hepatoma cells both in vivo and in vitro. However, the mechanism by which TGF-beta induces apoptosis is not clear. The antiapoptotic activity of antioxidants including N-acetyl-L-cysteine (Ac-Cys), ascorbic acid and a novel free radical scavenger, carboxyfullerene (C60) on TGF-beta-treated human hepatoma Hep3B cells was examined. Only the water-soluble hexacarboxylic acid derivative of C60 was found to prevent TGF-beta-induced apoptosis. Antiapoptotic activity of C60 correlated its ability to eliminate TGF-beta-generated reactive oxygen species (ROSs). However, C60 did not interfere with TGF-beta-activated PAI-1 promoter activity in the Hep3B cells. These results indicate that the signaling pathway of TGF-beta-induced apoptosis may be related to the generation of ROSs and may be uncoupled from the TGF-beta-activated gene promoter activity. Furthermore, the regioisomer of C60 with a C3 symmetry was more potent in protecting cells from apoptosis than that with a D3 symmetry, and the C3 isomer had stronger interactions with lipid bilayers than the D3 isomer. The spectroscopic analysis revealed that the C3 isomer had stronger interactions with artificial lipid bilayers than the D3 isomer. Therefore, our study indicates that C60 may interact with membrane to eliminate TGF-beta-induced ROSs and to prevent apoptosis occur in human hepatoma cells.
转化生长因子-β（TGF-β）已被证实在体内和体外均可诱导正常肝细胞和肝癌细胞凋亡。然而，TGF-β诱导凋亡的机制尚不清楚。研究了抗氧化剂包括N-乙酰-L-半胱氨酸（Ac-Cys）、抗坏血酸以及一种新型自由基清除剂羧基富勒烯（C60）对TGF-β处理的人肝癌Hep3B细胞的抗凋亡活性。仅发现C60的水溶性六羧酸衍生物可预防TGF-β诱导的凋亡。C60的抗凋亡活性与其清除TGF-β产生的活性氧（ROS）的能力相关。然而，C60并不干扰Hep3B细胞中TGF-β激活的PAI-1启动子活性。这些结果表明，TGF-β诱导凋亡的信号通路可能与ROS的产生有关，并且可能与TGF-β激活的基因启动子活性解偶联。此外，具有C3对称性的C60区域异构体在保护细胞免受凋亡方面比具有D3对称性的异构体更有效，并且C3异构体与脂质双层的相互作用比D3异构体更强。光谱分析表明，C3异构体与人工脂质双层的相互作用比D3异构体更强。因此，我们的研究表明，C60可能与膜相互作用以消除TGF-β诱导的ROS并防止人肝癌细胞发生凋亡。
