中文摘要：

结直肠癌目前是世界第三大肿瘤,手术治疗后约50％的患者会复发和转移,目前美国国立综合癌症网络（NCCN）肿瘤学临床实践指南推荐常规接受适型外照射治疗.由于放疗将显著增加不良反应,如何最大程度减小辐射剂量,提高辐射敏感性至关重要.近年来人们不仅发现了microRNAs参与了结直肠癌的发病和演进,而且越来越多的证据表明,microRNAs在结直肠癌的辐射敏感性中发挥了重要的作用.辐射引起的DNA损伤反应包括ATM的激活,组蛋白修饰和染色质重塑,细胞周期停滞,损伤修复和凋亡等系列过程,microRNAs可以通过作用于任何一个环节调节DNA损伤修复过程,从而调控肿瘤的辐射敏感性.本综述重点阐述microRNAs影响DNA损伤修复的作用机制,并展望了microRNAs通过影响肿瘤辐射敏感性在临床上的应用.

英文摘要：

Colorectal cancer is currently the third most common cancer worldwide,and there are still half of the patients undergoing recurrence and metastasis after surgical treatment,so it is necessary for colorectal cancer patients to receive radiation therapy routinely.Due to the side effects brought by radiotherapy,it is of great importance to solve how to minimize the radiation dose in radiation therapy and improve radiation sensitivity.In recent years,people discovered that microRNAs can not only be involved in the origins of colorectal cancer and progress,but also play a increasingly important role in cancer radiosensitivity.MicroRNAs can regulate tumor radiosensitivity by influencing tumor microenvironment and function on target genes.DNA damage response caused by radiation includes the activation of ATM,histone modification and chromatin remodeling,cell cycle arrest,damage repair and apoptosis.microRNAs can regulate tumor radiosensitivity through above processes.This review focuses on the mechanism of microRNAs in affecting DNA damage repair and prospects the future of microRNAs in influencing the sensitivity of cancer radiotherapy in clinical application.