Qin Yan, Li Longhai, Wang Fang, Zhou Xinyi, Liu Yankui, Yin Yuan, Qi Xiaowei
Department of Pathology, the Affiliated Hospital of Jiangnan University, Wuxi 4th People's Hospital, Wuxi, China.
Wuxi Oncology Institute, the Affiliated Hospital of Jiangnan University, Wuxi 4th People's Hospital, Wuxi, China.
Cell Physiol Biochem. 2018;48(4):1628-1637. doi: 10.1159/000492284. Epub 2018 Aug 2.
BACKGROUND/AIMS: Aberrant expression of microRNAs (miRNAs) is found to be responsible for tumorigenesis, cancer development and chemoresistance. Although oxaliplatin is an effective chemotherapeutic drug for treatment of colorectal cancer (CRC), CRC cells can develop some mechanisms to evade oxaliplatin-induced cell death. It is urgent to explore the novel strategies to increase the chemosensitivity of CRC cells.
QRT-PCR analysis was performed to detect the expression of miR-135b in CRC patients' serum and CRC cell lines. MTT assays were used to evaluate the effect of anti-miR-135b on oxaliplatin-induced cell death in CRC cell lines. Western blot, flow cytometry and luciferase reporter assays were performed to evaluate the potential mechanism and pathway of anti-miR-135b-promoted apoptosis in oxaliplatin-treated CRC cells.
Significant upregulation of miR-135b was observed in CRC cell lines and CRC patients' serum. Knockdown of miR-135b was found to sensitize colorectal cancer cells to oxaliplatin-induced cytotoxicity. Mechanically, knockdown of miR-135b increased the expression level of FOXO1 in CRC. As the downstream, the increased FOXO1 induced by anti-miR-135b promoted the expression of Bim and Noxa. Since Bim and Noxa act as key pro-apoptotic proteins in mitochondrial apoptosis, anti-miR-135b was able to enhance the oxaliplatin-induced apoptosis dependent on the anti-miR-135b/FOXO1 axis.
Anti-miR-135b enhanced the anti-tumor effect of oxaliplatin on CRC. Combination with miR-135b antisense nucleotides may represent a novel strategy to sensitize CRC to oxaliplatin-based treatment.
背景/目的：微小RNA（miRNA）的异常表达被发现与肿瘤发生、癌症发展及化疗耐药有关。尽管奥沙利铂是治疗结直肠癌（CRC）的一种有效化疗药物，但CRC细胞可产生一些机制来逃避奥沙利铂诱导的细胞死亡。探索提高CRC细胞化疗敏感性的新策略迫在眉睫。
采用定量逆转录聚合酶链反应（QRT-PCR）分析检测CRC患者血清及CRC细胞系中miR-135b的表达。采用MTT法评估抗miR-135b对CRC细胞系中奥沙利铂诱导细胞死亡的影响。进行蛋白质免疫印迹法、流式细胞术和荧光素酶报告基因检测，以评估抗miR-135b促进奥沙利铂处理的CRC细胞凋亡的潜在机制和途径。
在CRC细胞系和CRC患者血清中观察到miR-135b显著上调。发现敲低miR-135b可使结肠癌细胞对奥沙利铂诱导的细胞毒性敏感。机制上，敲低miR-135b可增加CRC中FOXO1的表达水平。作为下游分子，抗miR-135b诱导的FOXO1增加促进了Bim和Noxa的表达。由于Bim和Noxa是线粒体凋亡中的关键促凋亡蛋白，抗miR-135b能够依赖抗miR-135b/FOXO1轴增强奥沙利铂诱导的凋亡。
抗miR-135b增强了奥沙利铂对CRC的抗肿瘤作用。与miR-135b反义核苷酸联合使用可能代表一种使CRC对基于奥沙利铂的治疗敏感的新策略。
