| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系暨研究所 === 96 === Protein deamidation regulates a cellular response was first demonstrated in a study of Bcl-xL deamidation induced by DNA damaging agents. Deamidation of the Bcl-xL protein inhibits its antiapoptotic ability and leads to apoptosis, and this event is dependent on Rb inactivation. We then showed that Bcl-xL deamidation also contributes to E1A-mediated cisplatin sensitization by inactivation of Rb in an ovarian cancer cell line. However, in a recent study, stimulation of Bcl-xL deamidation was evidenced by increased pH inside the thymocytes due to the up-regulation of an NHE-1, a Na+/H+ exchange 1 gene.
In this study, we observe when pretreated the cells (Hep3B, HeLa) with the anti-oxidant drug, N-acetylcystein (NAC), Bcl-xL deamidation induced by cisplatin could be abrogated. This inhibition correlated with increasing viability of the cells. We also show that reactive oxygen species (ROS) induced by cisplatin decreased in NAC pretreated cells. In contrast, increased ROS by reduction of glutathione (GSH) level using buthionine-sulfoxime (BSO) was detected that resulted in increased Bcl-xL deamidation by cisplatin. We also observed that NHE-1 levels were decreased in cells treated with either cisplatin or DMA, an NHE-1 inhibitor, or shRNA against NHE-1. The reduction of NHE-1 correlated with enhanced Bcl-xL deamidation and cell death.
In summary, our data suggests that both ROS and NHE-1 are involved in cisplatin-induced Bcl-xL deamidation in cancer cells.
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