Detoxification of 1-chloro-2,4-dinitrobenzene in MCF7 breast cancer cells expressing glutathione S-transferase P1-1 and or multidrug resistance protein 1
Detoxification of 1-chloro-2,4-dinitrobenzene in MCF7 breast cancer cells expressing glutathione S-transferase P1-1 and or multidrug resistance protein 1
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DOI：
10.1006/taap.1999.8672
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发表时间：
1999-06-01
影响因子：
3.8
通讯作者：
Morrow, CS
中科院分区：
文献类型：
--
作者：
Diah, SK;Smitherman, PK;Morrow, CS
我们研究了谷胱甘肽S-转移酶（GST）P1-1和谷胱甘肽S-结合物（GS-X）转运蛋白，多药耐药蛋白1（MRP 1），单独或组合，在1-氯-2，4-二硝基苯（CDNB）的解毒作用。开发了单独或组合表达GST P1-1和MRP 1的MCF 7乳腺癌细胞的衍生物。在细胞中测量脱乙酰化，作为CDNB的谷胱甘肽缀合物S-（2，4-二硝基苯基）-谷胱甘肽（DNP-SG）的形成、DNP-SG的流出以及最终保护免受CDNB细胞毒性。在不存在GST P1-1的情况下，MRP 1表达赋予对CDNB的三至四倍抗性，这与DNP-SG流出的最大速率增加>10倍有关。在表达MRP 1的MCF 7细胞中，DNP-SG的外排是ATP依赖性的，并表现出95 μ M的DNP-SG表观Km。然而，单独的MRP 1表达对DNP-SG形成没有影响。当细胞暴露于10 μ M CDNB时，GST P1-1和MRP 1的联合表达增加了DNP-SG形成的速率。此外，GST P1 -1和MRP 1的联合表达适度地增强了MRP 1介导的对CDNB的抗性，但仅在短期（10分钟）暴露于CDNB期间，其中IC 50值在8-10 μ M范围内。相比之下，GST P1-1的表达在MRP 1的情况下稍微敏化细胞的毒性CDNB（10分钟的曝光），尽管增加的DNP-SG的形成率。在单独表达GST P1-1的细胞中对CDNB的致敏与DNP-SG的细胞内积累增加相关，表明DNP-SG可能有助于CDNB毒性。DNP-SG的潜在毒性也通过以下发现而得到提示：通过先前的谷胱甘肽耗尽抑制DNP-SG形成赋予了对MRP 1缺乏的MCF 7细胞中的CDNB细胞毒性的抗性。总之，我们的研究结果表明，谷胱甘肽结合和MRP 1介导的结合物外排可以一起工作，赋予耐CDNB。数据表明，MRP 1介导的缀合物流出是CDNB的细胞保护所必需的，因为其缀合物（DNP-SG），当以高细胞内水平存在时，也可能对细胞有毒。(C)北京：科学出版社.
We examined the roles of glutathione S-transferase (GST) P1-1 and the glutathione S-conjugate (GS-X) transporter, multidrug resistance protein 1 (MRP1), singly or in combination, in the detoxification of 1-chloro-2,4-dinitrobenzene (CDNB). Derivatives of MCF7 breast carcinoma cells expressing GST P1-1 and MRP1 alone or in combination were developed. Detoxification was measured in cells as formation of the glutathione conjugate of CDNB, S-(2,4-dinitrophenyl)-glutathione (DNP-SG), efflux of DNP-SG, and ultimately protection from CDNB cytotoxicity. MRP1 expression in the absence of GST P1-1 confers a three- to fourfold resistance to CDNB, which is associated with a >10-fold increase in the maximum rate of DNP-SG efflux. DNP-SG efflux in MRP1-expressing MCF7 cells was ATP-dependent and exhibited an apparent K-m for DNP-SG of 95 mu M. MRP1 expression alone, however, had no effect on DNP-SG formation. Combined expression of GST P1-1 and MRP1 increased the rates of DNP-SG formation when cells were exposed to 10 mu M CDNB, Moreover, combined expression of GSTP1-1 with MRP1 moderately augmented MRP1-mediated resistance to CDNB but only during short term (10 min) exposures to CDNB where IC50 values were in the 8-10 mu M range. In contrast, expression of GST P1-1 in the absence of MRP1 slightly sensitized cells to the toxicity of CDNB (10 min exposures), despite increasing rates of DNP-SG formation. The sensitization to CDNB in cells expressing GST P1-1 alone was associated with increased intracellular accumulation of DNP-SG, indicating that DNP-SG may contribute to CDNB toxicity. The potential toxicity of DNP-SG is also suggested by the finding that inhibition of DNP-SG formation by prior glutathione depletion confers resistance to CDNB cytotoxicity in MRP1-poor MCF7 cells. Altogether, our results demonstrate that glutathione conjugation and MRP1-mediated conjugate efflux can operate together to confer resistance to CDNB. The data indicate that MRP1-mediated conjugate efflux is required for cytoprotection from CDNB because its conjugate (DNP-SG), when present at high intracellular levels, may also be toxic to cells. (C) 1999 Academic Press.