Role of glutathione S-transferase P1-1 in the cellular detoxification of cisplatin.
Role of glutathione S-transferase P1-1 in the cellular detoxification of cisplatin.
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DOI：
10.1158/1535-7163.mct-08-0250
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发表时间：
2008-10
影响因子：
5.7
通讯作者：
Morrow CS
中科院分区：
文献类型：
--
作者：
Peklak-Scott C;Smitherman PK;Townsend AJ;Morrow CS
使用表达升高水平的人GST 1和/或外排转运蛋白MRP 1或2的等位基因变体的细胞来评估GST 1 -1在顺铂抗性中的作用。这些研究表明，GST P1 -1赋予MCF 7细胞对顺铂诱导的细胞毒性的低水平抗性（1.4-1.7倍）。然而，MRP 1（MCF 7细胞）或MRP 2（HepG 2细胞）的表达未能增加或增强GSTP 1 -1介导的耐药性。为了理解GSTP 1 -1变体赋予顺铂抗性的机制，检测了它们催化顺铂与谷胱甘肽缀合的相对能力。由检测的所有三种等位基因GSTP 1a（I104 A113）、GSTP 1b（V104 A113）和GSTP 1c（V104 V113）编码的酶增加了顺铂单铂谷胱甘肽衍生物的形成速率，相对催化活性为1.0（GSTP 1a-1a变体）和1.8-1.9（GSTP 1b-1b和GSTP 1c-1c变体）。虽然这些数据与GST P1 -1介导的顺铂/谷胱甘肽缀合可能赋予对顺铂的极低水平耐药性的想法一致，但两个观察结果表明，这种催化作用在保护顺铂毒性中起次要作用。首先，GSTP 1 -1介导的结合速率非常慢（250 ℃时为1.7-2.6 hr-1）。第二，尽管GSTP 1b-1b或GSTP 1c-1c对顺铂偶联的催化作用比GSTP 1a-1a增加了80- 90%，但我们观察到当在MCF 7细胞中表达时，这些替代变体赋予的相对抗性没有明显差异。我们的结论是，在其他研究中归因于GSTP 1 -1的高水平顺铂耐药不太可能是由于顺铂偶联的催化作用，而是必须由其他机制来解释，这些机制可能包括GSTP 1介导的信号通路调节。
Cells expressing elevated levels of allelic variants of human GSTP1 and/or efflux transporters, MRP 1 or 2, were used to evaluate the role of GSTP1-1 in cisplatin resistance. These studies revealed that GSTP1-1 confers low-level resistance (1.4–1.7-fold) to cisplatin-induced cytotoxicity in MCF7 cells. However, expression of MRP1 (MCF7 cells) or MRP2 (HepG2 cells) failed to augment or potentiate GSTP1-1-mediated resistance in either cell line. To understand the mechanism by which variants of GSTP1-1 confer resistance to cisplatin, their relative abilities to catalyze conjugation of cisplatin with glutathione were examined. Enzymes encoded by all three alleles tested GSTP1a (I104A113), GSTP1b (V104A113) and GSTP1c (V104V113) —increased the formation rate of the mono-platinum-glutathione derivative of cisplatin with relative catalytic activities of 1.0 (GSTP1a-1a variant) and 1.8–1.9 (GSTP1b-1b and GSTP1c-1c variants). While these data are consistent with the idea that very low-level resistance to cisplatin may be conferred by GSTP1-1-mediated cisplatin/glutathione conjugation, two observations indicate that such catalysis plays a minor role in the protection from cisplatin toxicity. First, the rates of GSTP1-1-mediated conjugation are extremely slow (1.7–2.6 hr−1 at 250C). Second, despite an 80–90 % increase in catalysis of cisplatin conjugation by GSTP1b-1b or GSTP1c-1c over GSTP1a-1a, we observed no discernable differences in relative resistances conferred by these alternative variants when expressed in MCF7 cells. We conclude that high-level cisplatin resistance attributed to GSTP1-1 in other studies is not likely due to catalysis of cisplatin conjugation but rather must be explained by other mechanisms — mechanisms which may include GSTP1-mediated modulation of signaling pathways.