| Summary: | 碩士 === 中山醫學院 === 生物化學研究所 === 89 === Glutathione S-transferase (GST), an important detoxification dimeric enzyme in mammalian cells, includes six isoforms: alpha, pi, mu, theta, zeta and sigma classes. Previous investigations showed that GST would conjugate xenobiotics with the sulfhydry group of GSH (glutathione) to increase the solubility of these xenobiotics. On the other hand, GST has anti-oxidation function, which protect lipid or nucleic acid from the attack of toxins. Therefore, GST plays an important role in the mechanism of detoxification and anti-carcinogenesis. Among the isoforms, GST mu is thought to be related to cancer susceptibility. It is also suggested that GSTM1 could serve as a predictive marker for invasive bladder cancer. After the treatment of carcinogens, the expression of GST mu would increase in the hepatocytes. In order to clarify the role of GST mu, a transient expression system of GST mu was set up to study how the overexpression of GST mu affects the hepatotoxicity and genotoxicity of carcinogen.
We used the primary cultured hepatocytes of SD rat to establish the transient transfection system of rGST mu (Yb1), and challenged the cells with Aflatoxin B1. We found that the transfected rGST mu would attenuate the damage of hepatocytes caused by Aflatoxin B1. The treatment of Aflatoxin B1 for 12hr increased the cytosolic GST activity in both GST and control vector-transfected cells in a dose-dependent manner. The GST activity in the cells transfected with rGST mu was higher than those transfected with pcDNA3. The releases of AST and LDH activity, from the Aflatoxin B1-treated cells were inhibited by the transfection of rGST mu as compared to the control.
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