Cisplatin, a widely prescribed chemotherapeutic agent for treating solid tumors, induces DNA adducts and activates cellular defense mechanisms, including DNA repair, cell cycle checkpoint control, and apoptosis. Considering the circadian rhythmicity displayed by most chemotherapeutic agents and their varying therapeutic efficacy based on treatment timing, our study aimed to investigate whether the circadian clock system influences the DNA damage responses triggered by cisplatin in synchronized cells. We examined the DNA damage responses in circadian-synchronized wild-type mouse embryonic fibroblasts (WT-MEF; clock-proficient cells), cryptochrome1 and 2 double knock-out MEF (CRY^DKO; clock-deficient cells), and mouse hepatocarcinoma Hepa1c1c7 cells. Varying the treatment time resulted in a significant difference in the rate of platinum-DNA adduct removal specifically in circadian-synchronized WT-MEF, while CRY^DKO did not exhibit such variation. Moreover, diurnal variation in other DNA damage responses, such as cell cycle checkpoint activity indicated by p53 phosphorylation status and apoptosis measured by DNA break frequency, was observed only in circadian-synchronized WT-MEF, not in CRY^DKO or mouse hepatocarcinoma Hepa1c1c7 cells. These findings highlight that the DNA damage responses triggered by cisplatin are indeed governed by circadian control exclusively in clock-proficient cells. This outcome bears potential implications for enhancing or devising chronotherapy approaches for cancer patients.

顺铂是一种广泛用于治疗实体瘤的化疗药物，可诱导 DNA 加合物并激活细胞防御机制，包括 DNA 修复、细胞周期检查点控制和细胞凋亡。考虑到大多数化疗药物所表现出的昼夜节律性以及它们根据治疗时间而变化的治疗效果，我们的研究旨在调查生物钟系统是否影响同步细胞中顺铂触发的DNA损伤反应。我们检查了昼夜节律同步的野生型小鼠胚胎成纤维细胞（WT-MEF；时钟熟练细胞）、隐花色素1和2双敲除MEF（CRY DKO；时钟缺陷细胞）和小鼠肝癌Hepa1c1c7细胞中的DNA^损伤反应。改变处理时间会导致铂-DNA 加合物去除率显着差异，特别是在昼夜节律同步的 WT-MEF 中，而 CRY ^DKO则没有表现出这种变化。此外，其他 DNA 损伤反应的昼夜变化，例如 p53 磷酸化状态指示的细胞周期检查点活性和 DNA 断裂频率测量的细胞凋亡，仅在昼夜同步 WT-MEF 中观察到，而在 CRY DKO 或小鼠肝癌 Hepa1c1c7 细胞中未观察^到。这些发现强调，顺铂引发的 DNA 损伤反应确实仅在生物钟熟练细胞中受到昼夜节律控制。这一结果对于增强或设计癌症患者的时间疗法具有潜在的意义。