Sun Wei, Ping Wei, Tian Yitao, Zou Wenbin, Liu Jiawei, Zu Yukun
Cell Physiol Biochem. 2018;51(5):2160-2171. doi: 10.1159/000495835. Epub 2018 Dec 6.
BACKGROUND/AIMS: KRas is usually mutated in non-small cell lung cancer (NSCLC). The mutated KRas gene is a negative prognostic indicator that promotes tumor proliferation, metastasis, and drug resistance in NSCLC, and thus has become a target for cancer therapy. This study is focused on the effects of the microRNA (miR)-202/KRas axis in regulating chemosensitivity in NSCLC.
Quantitative reverse transcriptase real-time PCR analysis was performed to examine the expression of miR-202. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays were performed to evaluate the sensitivity of cisplatin against NSCLC cells. The miR-202/KRas axis was confirmed by western blot and luciferase reporter assays. Cell apoptosis was measured by flow cytometry. KRas expression, MEK1/2 and ERK1/2 phosphorylation, and activation of caspase-9 and caspase-3 were detected by western blot.
A significant decrease in miR-202 expression was observed in NSCLC cells both in vivo and in vitro. In addition, miR-202 expression was associated with drug resistance. Recovery of miR-202 expression levels was found to increase the sensitivity of both NCI-H441 and A549 NSCLC cells to cisplatin treatment. Mechanically, as the Ras/mitogen-activated protein kinase (MAPK) pathway was aberrantly activated in NCI-H441 and A549 NSCLC cells, the overexpression of miR-202 was found to inhibit the Ras/MAPK pathway by targeting the KRas gene. As a result, increased miR-202 expression expanded apoptosis signaling induced by cisplatin in NSCLC cells.
The miR-202/KRas axis controlled the chemosensitivity of NSCLC by mediating the Ras/MAPK pathway. Thus, the combination of platinum-based drugs with miR-202 may represent a novel strategy to enhance the anti-tumor effect against NSCLC.
背景/目的：KRas在非小细胞肺癌（NSCLC）中通常发生突变。突变的KRas基因是一种负性预后指标，可促进NSCLC的肿瘤增殖、转移和耐药，因此已成为癌症治疗的靶点。本研究聚焦于微小RNA（miR）-202/KRas轴在调节NSCLC化疗敏感性中的作用。
采用定量逆转录实时PCR分析检测miR-202的表达。进行MTT（3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐）试验以评估顺铂对NSCLC细胞的敏感性。通过蛋白质印迹和荧光素酶报告基因试验证实miR-202/KRas轴。采用流式细胞术检测细胞凋亡。通过蛋白质印迹检测KRas表达、MEK1/2和ERK1/2磷酸化以及caspase-9和caspase-3的激活。
在体内和体外的NSCLC细胞中均观察到miR-202表达显著降低。此外，miR-202表达与耐药相关。发现恢复miR-202表达水平可增加NCI-H441和A549 NSCLC细胞对顺铂治疗的敏感性。机制上，由于Ras/丝裂原活化蛋白激酶（MAPK）途径在NCI-H441和A549 NSCLC细胞中异常激活，发现miR-202的过表达通过靶向KRas基因抑制Ras/MAPK途径。结果，miR-202表达增加扩大了顺铂诱导的NSCLC细胞凋亡信号。
miR-202/KRas轴通过介导Ras/MAPK途径控制NSCLC的化疗敏感性。因此，铂类药物与miR-202联合应用可能代表一种增强抗NSCLC肿瘤效应的新策略。
