Wen Dacheng, Li Songhe, Ji Fujian, Cao Hong, Jiang Weidong, Zhu Jiaming, Fang Xuedong
Department of General Surgery, The Second Hospital of Jilin University, No.218, Zi Qiang Str, Nan Guan District, Changchun, 130041, Jilin Province, China.
Tumour Biol. 2013 Apr;34(2):793-803. doi: 10.1007/s13277-012-0609-7. Epub 2013 Jan 9.
MicroRNAs (miRNAs) are a class of small noncoding RNAs that negatively regulate protein expression by binding protein-coding mRNAs and repressing translation. Accumulating evidence suggests that miRNAs are involved in cancer development and progression, acting as either tumor suppressors or oncogenes. Intriguingly, it has been shown that miR-133b was significantly downregulated in several types of cancers. However, its role and relevance in gastric cancer are still largely unknown. We showed that miR-133b was downregulated in human gastric cancer tissues and cell lines compared with nontumor counterparts by quantitative RT-PCR analysis. Overexpression of miR-133b could inhibit cell proliferation and colony formation of the gastric cancer cell lines MKN-45 and SGC-7901. Bioinformatics analysis indicated two putative miR-133b binding sites in the 3'-untranslated region of fibroblast growth factor receptor 1 (FGFR1) mRNA. In dual-luciferase reporter assay, miR-133b reduced the luciferase activity of Luc-FGFR1-wt, and mutation of miR-133b binding sites abolished the inhibitory effect of miR-133b. In this study, we found that miR-133b reduced the protein but not the mRNA levels of endogenous FGFR1. Furthermore, FGFR1 expression was upregulated in gastric cancer tissues and inversely correlated with miR-133b expression. Finally, knockdown of FGFR1 inhibited the growth of MKN-45 cells in a dose-dependent manner and overexpression of FGFR1 promoted the growth of GES-1 cells. These results indicate that miR-133b targets FGFR1 and inhibits gastric cancer cell growth, suggesting that it may serve as a tumor suppressive target in gastric cancer therapy.
微小RNA（miRNA）是一类小的非编码RNA，通过与蛋白质编码mRNA结合并抑制翻译来负调控蛋白质表达。越来越多的证据表明，miRNA参与癌症的发生和发展，可作为肿瘤抑制因子或癌基因发挥作用。有趣的是，已有研究表明miR-133b在几种类型的癌症中显著下调。然而，其在胃癌中的作用和相关性仍 largely未知。我们通过定量RT-PCR分析表明，与非肿瘤对应物相比，miR-133b在人胃癌组织和细胞系中下调。miR-133b的过表达可抑制胃癌细胞系MKN-45和SGC-7901的细胞增殖和集落形成。生物信息学分析表明，在成纤维细胞生长因子受体1（FGFR1）mRNA的3'-非翻译区有两个假定的miR-133b结合位点。在双荧光素酶报告基因测定中，miR-133b降低了Luc-FGFR1-wt的荧光素酶活性，miR-133b结合位点的突变消除了miR-133b的抑制作用。在本研究中，我们发现miR-133b降低了内源性FGFR1的蛋白质水平，但不影响其mRNA水平。此外，FGFR1在胃癌组织中表达上调，且与miR-133b表达呈负相关。最后，敲低FGFR1以剂量依赖的方式抑制MKN-45细胞的生长，而FGFR1的过表达促进GES-1细胞的生长。这些结果表明，miR-133b靶向FGFR1并抑制胃癌细胞生长，提示其可能作为胃癌治疗中的肿瘤抑制靶点。
