Goeptar A R, Groot E J, Scheerens H, Commandeur J N, Vermeulen N P
Division of Molecular Toxicology, Leiden/Amsterdam Center for Drug Research, Vrije Universiteit, Amsterdam, The Netherlands.
Cancer Res. 1994 May 1;54(9):2411-8.
The role of cytochrome P450 (P450) in the cytotoxicity of mitomycin C (MMC) and Adriamycin (ADR) was investigated in freshly isolated hepatocytes from phenobarbital-induced rats. The loss of cell viability [measured as lactate dehydrogenase (LDH) leakage] upon MMC exposure was accompanied by a rapid and extensive intracellular glutathione (GSH) depletion and followed by minor lipid peroxidation (LPO). Coincubation of the hepatocytes with the P450 inhibitors, metyrapone and SK&F 525-A, strongly protected against MMC-induced LDH leakage, GSH depletion, and LPO. Inasmuch as the depletion of intracellular GSH by MMC, which is considered as a critical event in the development of MMC cytotoxicity, was not accompanied by a stoichiometric oxidation to oxidized GSH (GSSG), the formation of a MMC-GSH conjugate after one-electron reductive bioactivation of MMC by P450 was anticipated. In contrast to MMC, ADR was only cytotoxic to the hepatocytes upon prior depletion of intracellular GSH with diethylmaleate. Addition of metyrapone and SK&F 525-A completely protected the hepatocytes against ADR-induced LDH leakage and LPO. Moreover, the ADR-induced LDH leakage and LPO were strongly inhibited by dimethyl sulfoxide and ethanol, indicating that hydroxyl radicals were involved in the cytotoxicity of ADR. In conclusion, the present investigations indicate that P450 plays a major role in the cytotoxicity of both MMC and ADR in freshly isolated hepatocytes from phenobarbital-induced rats. The present findings lead to a better understanding of the mechanism of the cytotoxic actions of both MMC and ADR.
在从苯巴比妥诱导的大鼠新鲜分离的肝细胞中，研究了细胞色素P450（P450）在丝裂霉素C（MMC）和阿霉素（ADR）细胞毒性中的作用。MMC暴露后细胞活力的丧失（以乳酸脱氢酶（LDH）泄漏衡量）伴随着细胞内谷胱甘肽（GSH）迅速而广泛的消耗，随后是轻微的脂质过氧化（LPO）。肝细胞与P450抑制剂美替拉酮和SK&F 525 - A共同孵育，可强烈保护细胞免受MMC诱导的LDH泄漏、GSH消耗和LPO。由于MMC引起的细胞内GSH消耗（这被认为是MMC细胞毒性发展中的关键事件）并未伴随着化学计量的氧化生成氧化型谷胱甘肽（GSSG），因此预期P450对MMC进行单电子还原生物活化后会形成MMC - GSH共轭物。与MMC相反，ADR仅在先用马来酸二乙酯耗尽细胞内GSH后才对肝细胞具有细胞毒性。添加美替拉酮和SK&F 525 - A可完全保护肝细胞免受ADR诱导的LDH泄漏和LPO。此外，ADR诱导的LDH泄漏和LPO受到二甲基亚砜和乙醇的强烈抑制，表明羟基自由基参与了ADR的细胞毒性。总之，本研究表明P450在从苯巴比妥诱导的大鼠新鲜分离的肝细胞中对MMC和ADR的细胞毒性中起主要作用。本研究结果有助于更好地理解MMC和ADR细胞毒性作用的机制。
