目的 探究下调XRCC6对人结直肠癌细胞凋亡、侵袭的影响及其与ATM/CHK1/p53信号通路的相关性。方法 将人结 直肠癌细胞SW620分为对照组、si⁃NC组和si⁃XRCC6组。MTT法检测各组细胞活力；流式细胞法检测各组细胞凋亡水平；细胞划 痕实验检测各组细胞迁移能力；Transwell检测各组细胞侵袭能力；定量聚合酶链反应（qPCR）检测ATM、CHK2、p53的转录水平； 免疫印迹（Western blot）检测ATM、CHK2、p53的蛋白表达和磷酸化（p⁃ATM、p⁃CHK2、p⁃p53）水平。结果 MTT实验结果表明，与 对照组和si⁃NC组相比，si⁃XRCC6组细胞活力显著降低（P<0.05）；流式细胞实验结果表明，与对照组和si⁃NC组相比，si⁃XRCC6组 细胞存活比例降低（P<0.01），早期凋亡比例增加（P<0.01），晚期凋亡细胞比例显著增加（P<0.01），si⁃NC组和si⁃XRCC6组差异无 统计学意义（P>0.05）；细胞划痕及Transwell实验结果表明，与对照组和si⁃NC组相比，si⁃XRCC6组细胞迁移能力降低（P<0.01）， 侵袭能力降低（P<0.01）。qPCR及Western blot结果表明，与对照组和si⁃NC组相比，si⁃XRCC6组细胞ATM、CHK2、p53的转录和 蛋白表达水平有上升的趋势，其磷酸化蛋白p⁃ATM、p⁃CHK2、p⁃p53表达水平也具有上升的趋势。结论 下调XRCC6可以抑制人 结直肠癌细胞活性，诱导细胞早期凋亡，其机制可能与ATM、CHK2、p53信号通路的调控及其磷酸化水平的调控相关。

Objective To explore the effect of down⁃regulation of XRCC6 on apoptosis and invasion of colorectal cancer cells and the changes of ATM/CHK2/p53 signaling pathway. Methods Human colorectal cancer SW620 cells were divided into three groups: control group, si⁃NC group and si⁃XRCC6 group. MTT assay was used to detect cell viability. Flow cytometry was used to detect cell apoptosis. Cell scratch test was used to detect cell migration. Transwell was used to detect cell invasion. qPCR was used to detect ATM, CHK2 and p53 mRNA expression. Western blot was used to detect ATM, CHK2, p53 protein expression and the phosphorylation level of p⁃ATM, p⁃CHK2 and p⁃p53. Results MTT results showed that the cell viability of si⁃XRCC6 group was significantly lower than that of control group and si⁃NC group (P<0.05). Flow cytometry results showed that the survival rate of si⁃XRCC6 group was lower than that of control group and si⁃NC group (P<0.01), the early apoptosis rate was increased (P<0.01), the proportion of late apoptotic cells increased significantly (P<0.01), and there was no significant difference between si⁃NC group and si⁃XRCC6 group (P>0.05).Compared with the control group and si⁃NC group, the migration ability and invasion ability of si⁃XRCC6 group decreased (P<0.01). qPCR and Western blot results showed that the mRNA and protein expression levels of ATM, CHK2 and p53 in si⁃XRCC6 cells increased, and the phosphorylation level of p⁃ATM, p⁃CHK2 and p⁃p53 also increased. Conclusion Down regulation of XRCC6 can inhibit the activity of human colorectal cancer cells and induce early apoptosis, which may be related to the regulation of ATM, CHK2 and p53 signaling pathways and their phosphorylation levels.