Genotoxicity of 4-hydroxy-2-nonenal in human colon tumor cells is associated with cellular levels of glutathione and the modulation of glutathione S-transferase A4 expression by butyrate
Genotoxicity of 4-hydroxy-2-nonenal in human colon tumor cells is associated with cellular levels of glutathione and the modulation of glutathione S-transferase A4 expression by butyrate
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DOI：
10.1093/toxsci/kfi171
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发表时间：
2005-07-01
影响因子：
3.8
通讯作者：
Pool-Zobel, BL
中科院分区：
文献类型：
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作者：
Knoll, N;Ruhe, C;Pool-Zobel, BL
细胞内产生的 4-羟基-2-壬烯醛 (HNE) 是内源性脂质过氧化的产物，是致癌的遗传毒性危险因素。我们之前的研究表明，人类 HT29 结肠细胞在接受丁酸盐（一种与饮食相关的肠道发酵产物）治疗后，对 HNE 损伤产生了抵抗力。这种抗性归因于某些谷胱甘肽 S-转移酶（hGSTP1-1、hGSTM2-2 和 hGSTA1-1）以及三肽谷胱甘肽 (GSH) 合成酶的诱导。在本研究中，我们在 HT29 细胞中研究了对 HNE 具有高底物特异性的 hGSTA4-4 是否也可以被丁酸盐诱导，因此可能有助于之前观察到的化疗耐药性。此外，我们还研究了 L-丁硫氨酸-S,R-亚砜亚胺 (BSO) 细胞内 GSH 的消耗是否会增强 HT29 细胞对 HNE 损伤的化学敏感性。将 HT29 细胞与丁酸盐 (2-4 mM) 一起孵育，处理后 8-24 小时内，稳态 hGSTA4 mRNA 显着上调 1.8 至 3 倍。此外，4 mM 丁酸盐往往会增加 hGSTA4-4 蛋白浓度。与 100 μM BSO 一起孵育可使细胞 GSH 水平降低 77%，而细胞活力没有显着变化。与此相关的是，通过彗星测定测量，HNE 诱导的 DNA 损伤水平高出 2 倍。总的来说，这项研究的结果和我们之前的工作表明，HNE 的遗传毒性高度依赖于细胞 GSH 状态和那些有助于 HNE 结合的 GST，包括 hGSTA4-4。由于 HNE 会导致结肠癌发生，因此丁酸盐对 GSH/GST 系统的有利调节可能有助于化学预防和降低风险。
The cellular production of 4-hydroxy-2-nonenal (HNE), a product of endogenous lipid peroxidation, constitutes a genotoxic risk factor for carcinogenesis. Our previous studies have shown that human HT29 colon cells developed resistance toward HNE injury after treatment with butyrate, a diet-associated gut fermentation product. This resistance was attributed to the induction of certain glutathione S-transferases (hGSTP1-1, hGSTM2-2, and hGSTA1-1) and also for the tripeptide glutathione (GSH) synthesizing enzymes. In the present study, we have investigated in HT29 cells whether hGSTA4-4, which has a high substrate specificity for HNE, was also inducible by butyrate and, thus, could contribute to the previously observed chemoresistance. In addition, we investigated if cellular depletion of GSH by L-buthionine-S,R-sulfoximine (BSO) enhances chemosensitivity to HNE injury in HT29 cells. Incubation of HT29 cells with butyrate (2-4 mM) significantly elicited a 1.8 to 3-fold upregulation of steady state hGSTA4 mRNA over 8-24 h after treatment. Moreover, 4 mM butyrate tended to increase hGSTA4-4 protein concentrations. Incubation with 100 mu M BSO decreased cellular GSH levels by 77% without significant changes in cell viability. Associated with this was a 2-fold higher level of HNE-induced DNA damage as measured by the comet assay. Collectively, the results of this study and our previous work indicate that the genotoxicity of HNE is highly dependent on cellular GSH status and those GSTs that contribute toward HNE conjugation, including hGSTA4-4. Since HNE contributes to colon carcinogenesis, the favorable modulation of the GSH/GST system by butyrate may contribute to chemoprevention and reduction of the risks.