International Master Program of Translational Medicine, National United University, Miaoli, Taiwan Research Center for Precision Environmental Medicine, Kaohsiung Medical University, CS Building, 100 Shih-Chuan First Road, Kaohsiung 807, Taiwan.
Research Center for Precision Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan Department of Family Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, CS Building, 100 Shih-Chuan First Road, Kaohsiung 807, Taiwan.
Chem Res Toxicol. 2022 Oct 17;35(10):1863-1880. doi: 10.1021/acs.chemrestox.2c00153. Epub 2022 Jul 25.
Smoking is a major risk factor for bladder cancer (BC), with up to 50% of BC cases being attributed to smoking. There are 70 known carcinogens in tobacco smoke; however, the principal chemicals responsible for BC remain uncertain. The aromatic amines 4-aminobiphenyl (4-ABP) and 2-naphthylamine (2-NA) are implicated in BC pathogenesis of smokers on the basis of the elevated BC risk in factory workers exposed to these chemicals. However, 4-ABP and 2-NA only occur at several nanograms per cigarette and may be insufficient to induce BC. In contrast, other genotoxicants, including acrolein, occur at 1000-fold or higher levels in tobacco smoke. There is limited data on the toxicological effects of tobacco smoke in human bladder cells. We have assessed the cytotoxicity, oxidative stress, and DNA damage of tobacco smoke condensate (TSC) in human RT4 bladder cells. TSC was fractionated by liquid-liquid extraction into an acid-neutral fraction (NF), containing polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, phenols, and aldehydes, and a basic fraction (BF) containing aromatic amines, heterocyclic aromatic amines, and -nitroso compounds. The TSC and NF induced a time- and concentration-dependent cytotoxicity associated with oxidative stress, lipid peroxide formation, glutathione (GSH) depletion, and apurinic/apyrimidinic (AP) site formation, while the BF showed weak effects. LC/MS-based metabolomic approaches showed that TSC and NF altered GSH biosynthesis pathways and induced more than 40 GSH conjugates. GSH conjugates of several hydroquinones were among the most abundant conjugates. RT4 cell treatment with synthetic hydroquinones and cresol mixtures at levels present in tobacco smoke accounted for most of the TSC-induced cytotoxicity and the AP sites formed. GSH conjugates of acrolein, methyl vinyl ketone, and crotonaldehyde levels also increased owing to TSC-induced oxidative stress. Thus, TSC is a potent toxicant and DNA-damaging agent, inducing deleterious effects in human bladder cells at concentrations of <1% of a cigarette in cell culture media.
吸烟是膀胱癌（BC）的主要危险因素，高达 50%的 BC 病例归因于吸烟。烟草烟雾中含有 70 种已知的致癌物质；然而，导致 BC 的主要化学物质仍不确定。芳香胺 4-氨基联苯（4-ABP）和 2-萘胺（2-NA）在基于暴露于这些化学物质的工厂工人中 BC 风险升高的情况下，被认为与吸烟者的 BC 发病机制有关。然而，4-ABP 和 2-NA 仅在每支香烟中出现几个纳克，可能不足以诱导 BC。相比之下，烟草烟雾中的其他遗传毒性物质，包括丙烯醛，其含量高出 1000 倍或更高。关于烟草烟雾对人膀胱细胞的毒理学影响的数据有限。我们评估了烟草烟雾冷凝物（TSC）在人 RT4 膀胱细胞中的细胞毒性、氧化应激和 DNA 损伤。TSC 通过液-液萃取分离为酸性-中性部分（NF），包含多环芳烃（PAHs）、硝基-PAHs、酚和醛，以及碱性部分（BF），包含芳香胺、杂环芳香胺和 -亚硝胺。TSC 和 NF 诱导与氧化应激、脂质过氧化物形成、谷胱甘肽（GSH）耗竭和无嘌呤/无嘧啶（AP）部位形成相关的时间和浓度依赖性细胞毒性，而 BF 则表现出较弱的作用。基于 LC/MS 的代谢组学方法表明，TSC 和 NF 改变了 GSH 生物合成途径，并诱导了 40 多种 GSH 缀合物。几种对苯二酚的 GSH 缀合物是最丰富的缀合物之一。在细胞培养物中，RT4 细胞用存在于烟草烟雾中的水平的合成对苯二酚和甲酚混合物处理，占 TSC 诱导的细胞毒性和形成的 AP 部位的大部分。由于 TSC 诱导的氧化应激，丙烯醛、甲基乙烯基酮和巴豆醛的 GSH 缀合物水平也增加。因此，TSC 是一种有效的毒物和 DNA 损伤剂，在细胞培养物培养基中浓度低于香烟的 1%时，就会在人膀胱细胞中引起有害影响。
