化疗已被证明在治疗癌症方面广泛有效。化疗剂通常包括DNA损伤剂和非DNA损伤剂。评估基因毒性效应在化疗药物开发过程中具有重要意义，因为DNA损伤剂的攻击DNA的能力是关系到治疗效果的主要问题，同时还应评估基因毒性以确保化疗药物的安全性，尤其是非DNA损伤剂。然而，目前体外遗传毒性测定的适用性受到遗传毒性结果具有相对较高的假阳性率这一事实的阻碍。 γ-H2AX 已被证明是一种反映 DNA 损伤反应和修复的双功能生物标志物。此前，我们开发了一种基于使用质谱法定量 γ-H2AX 的体外遗传毒性测定方法。在这里，我们采用该方法定量评估 34 种经典化疗药物对 HepG2 细胞的基因毒性作用。结果表明，细胞 γ-H2AX 的评估可以成为筛选和区分不同类别化疗药物作用类型的有效方法。此外，利用我们开发的在线工具估计的DNA修复动力学曲线的两个关键指标，即k（γ-H2AX下降速度）和t50（γ-H2AX下降到最大值一半所需的时间）来进一步评估9种代表性化疗药物，显示其与治疗指数或致癌水平密切相关。本研究表明，γ-H2AX 的质谱定量可能是初步评估化疗药物基因毒性作用的合适工具。版权所有 © 2024 Qu、Chen、Xu、Shi、Zhao、Wang、Li、Ma、Xu、Ye 和 Xie 。

Chemotherapy has already proven widely effective in treating cancer. Chemotherapeutic agents usually include DNA damaging agents and non-DNA damaging agents. Assessing genotoxic effect is significant during chemotherapy drug development, since the ability to attack DNA is the major concern for DNA damaging agents which relates to the therapeutic effect, meanwhile genotoxicity should also be evaluated for chemotherapy agents' safety especially for non-DNA damaging agents. However, currently applicability of in vitro genotoxicity assays is hampered by the fact that genotoxicity results have comparatively high false positive rates. γ-H2AX has been shown to be a bifunctional biomarker reflecting both DNA damage response and repair. Previously, we developed an in vitro genotoxicity assay based on γ-H2AX quantification using mass spectrometry. Here, we employed the assay to quantitatively assess the genotoxic effects of 34 classic chemotherapy agents in HepG2 cells. Results demonstrated that the evaluation of cellular γ-H2AX could be an effective approach to screen and distinguish types of action of different classes of chemotherapy agents. In addition, two crucial indexes of DNA repair kinetic curve, i.e., k (speed of γ-H2AX descending) and t50 (time required for γ-H2AX to drop to half of the maximum value) estimated by our developed online tools were employed to further evaluate nine representative chemotherapy agents, which showed a close association with therapeutic index or carcinogenic level. The present study demonstrated that mass spectrometric quantification of γ-H2AX may be an appropriate tool to preliminarily evaluate genotoxic effects of chemotherapy agents.Copyright © 2024 Qu, Chen, Xu, Shi, Zhao, Wang, Li, Ma, Xu, Ye and Xie.