Lin Lei, Tu Hong-Bin, Wu Liang, Liu Ming, Jiang Ge-Ning
Cell Physiol Biochem. 2016;38(6):2152-62. doi: 10.1159/000445571. Epub 2016 May 17.
BACKGROUND/AIMS: SMAD7 is a key inhibitor of transforming growth factor β (TGFβ) receptor signaling, which regulates the alteration of cancer cell invasiveness through epithelial-mesenchymal cell conversion. Carboplatin is a commonly used drug in the chemotherapy for non-small cell lung cancer (NSCLC). Nevertheless, the molecular mechanisms underlying its suppressive effects on the NSCLC cell invasion are not completely understood. In the current study, we addressed this question by analyzing the effects of Carboplatin on microRNA-regulated SMAD7.
We used Carboplatin to treat NSCLC cell lines. We performed bioinformatics analyses on the binding of microRNA-21 (miR-21) to the 3'-UTR of SMAD7 mRNA, and verified the biological effects of this binding using promoter luciferase reporter assay. The effects of Carboplatin or miR-21-modification on NSCLC cell invasion were evaluated in either a transwell cell invasion assay, or a scratch wound healing assay.
We found that Carboplatin inhibited the NSCLC cell invasion, in either a transwell cell invasion assay, or a scratch wound healing assay. Moreover, Carboplatin increased the levels of SMAD7 protein, but not mRNA, in NSCLC cells, suggesting presence of post-transcriptional control of SMAD7 by Carboplatin. Furthermore, expression of miR-21 was found to be inhibited by Carboplatin, and bioinformatics analyses showed that miR-21 targeted the 3'-UTR of SMAD7 mRNA to inhibit its translation, which was confirmed by luciferase reporter assay.
Carboplatin may upregulate SMAD7 through suppression of miR-21 to inhibit TGFβ receptor signaling mediated NSCLC cell invasion.
背景/目的：SMAD7是转化生长因子β（TGFβ）受体信号传导的关键抑制剂，其通过上皮-间充质细胞转化调节癌细胞侵袭性的改变。卡铂是用于非小细胞肺癌（NSCLC）化疗的常用药物。然而，其对NSCLC细胞侵袭抑制作用的分子机制尚未完全明确。在本研究中，我们通过分析卡铂对微小RNA调控的SMAD7的影响来解决这个问题。
我们使用卡铂处理NSCLC细胞系。我们对微小RNA-21（miR-21）与SMAD7 mRNA的3'-非翻译区（3'-UTR）的结合进行了生物信息学分析，并使用启动子荧光素酶报告基因检测验证了这种结合的生物学效应。在Transwell细胞侵袭试验或划痕伤口愈合试验中评估卡铂或miR-21修饰对NSCLC细胞侵袭的影响。
我们发现，在Transwell细胞侵袭试验或划痕伤口愈合试验中，卡铂均可抑制NSCLC细胞侵袭。此外，卡铂增加了NSCLC细胞中SMAD7蛋白的水平，但未增加其mRNA水平，提示卡铂对SMAD7存在转录后调控。此外，发现卡铂可抑制miR-21的表达，生物信息学分析表明miR-21靶向SMAD7 mRNA的3'-UTR以抑制其翻译，荧光素酶报告基因检测证实了这一点。
卡铂可能通过抑制miR-21上调SMAD7，从而抑制TGFβ受体信号传导介导的NSCLC细胞侵袭。
