Benzene is a human carcinogen that requires metabolic activation. We previously observed that benzene and its hydroxylated metabolites induce micronuclei in mammalian cells expressing human CYP2E1. This study was initially aimed to study another endpoint, the induction of gene mutations by those compounds in the same cell models. A V79‐derived cell line expressing human CYP2E1 and sulfotransferase (SULT) 1A1 (V79‐hCYP2E1‐hSULT1A1) pretreated with ethanol (a CYP2E1 stabilizer) was used in the hprt gene mutagenicity assay. Phenol, hydroquinone, catechol, and 1,2,4‐trihydroxybenzene all induced gene mutations, while they were inactive, or only weakly positive (hydroquinone), in parental V79‐Mz cells. Unexpectedly, benzene was non‐mutagenic in both cell lines, but it became positive in V79‐hCYP2E1‐hSULT1A1 cells using regimes of short exposure/long recovery without ethanol pretreatment, for both gene mutations and micronuclei formation. In silico molecular simulation showed binding energies and positions favorable for each compound to be oxidized by human CYP2E1, benzene demonstrating the highest affinity. By tunnel analysis, ethanol binding did not limit benzene to pass tunnel S, which was specifically active for benzene. However, its end product, acetic acid, decreased the occurrence of tunnel S from 5.4 to 2.2% and extended the length of its bottleneck from 5.5 to 9.0 Å. With residual ethanol molecules still being present in CYP2E1 for a period of time after benzene exposure, the acetic acid formed could limit the entrance of benzene, thus inhibit its metabolic activation. In summary, ethanol may interfere with the activation of benzene to mutagenic metabolites, at least in cultured cells.

中文翻译：

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人CYP2E1依赖性的V79衍生细胞中苯及其羟基化代谢产物的致突变性：通过乙醇预处理抑制和增强。

苯是一种人类致癌物质，需要代谢激活。我们先前观察到苯及其羟基化代谢产物在表达人CYP2E1的哺乳动物细胞中诱导微核。这项研究最初旨在研究另一个终点，即那些化合物在相同细胞模型中诱导的基因突变。在hprt中使用了V79衍生的细胞系，该细胞系表达了人CYP2E1和磺基转移酶（SULT）1A1（V79-hCYP2E1-hSULT1A1），并用乙醇（CYP2E1稳定剂）预处理基因诱变分析。苯酚，对苯二酚，邻苯二酚和1,2,4-三羟基苯均在亲代V79-Mz细胞中诱导了基因突变，但它们是无活性的，或仅是弱阳性（对苯二酚）。出乎意料的是，苯在两种细胞系中均无致突变性，但在短时暴露/长期回收且无乙醇预处理的情况下，V79-hCYP2E1-hSULT1A1细胞中的苯甲酸在基因突变和微核形成中均呈阳性。在计算机模拟中，分子对人的CYP2E1氧化的结合能和位置有利于每种化合物的氧化，苯显示出最高的亲和力。通过隧道分析，乙醇结合不会限制苯通过隧道S，该隧道S对苯具有特别的活性。但是，其最终产物乙酸将隧道S的发生率从5.4减少到2。2％并将瓶颈长度从5.5扩展到9.0Å。在苯暴露后的一段时间内，残留的乙醇分子仍存在于CYP2E1中，形成的乙酸可能会限制苯的进入，从而抑制其代谢活化。总之，至少在培养的细胞中，乙醇可能会干扰苯向诱变代谢产物的活化。