Department of Pathology, Union Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China.
PLoS One. 2013;8(1):e55719. doi: 10.1371/journal.pone.0055719. Epub 2013 Jan 31.
Recent evidence shows that altered microRNA-9 (miR-9) expression is implicated in the progression of gastric cancer. However, the exact roles and underlying mechanisms of miR-9 in the proliferation, invasion and metastasis of gastric cancer still remain unknown. In this study, miR-9 was found to be down-regulated and inversely correlated with the expression of cyclin D1 and v-ets erythroblastosis virus E26 oncogene homolog 1 (Ets1) in gastric cancer tissues and cell lines. Bioinformatics analysis revealed the putative miR-9 binding sites in the 3'-untranslated regions (3'-UTR) of cyclin D1 and Ets1 mRNA. Ectopic expression or knockdown of miR-9 resulted in responsively altered expression of cyclin D1, Ets1 and their downstream targets phosphorylated retinoblastoma and matrix metalloproteinase 9 in cultured gastric cancer cell lines SGC-7901 and AGS. In the luciferase reporter system, miR-9 directly targeted the 3'-UTR of cyclin D1 and Ets1, and these effects were abolished by mutating the miR-9 binding sites. Over-expression of miR-9 suppressed the proliferation, invasion, and metastasis of SGC-7901 and AGS cells in vitro and in vivo. Restoration of miR-9-mediated down-regulation of cyclin D1 and Ets1 by transient transfection, rescued the cancer cells from decrease in proliferation, migration and invasion. Furthermore, anti-miR-9 inhibitor promoted the proliferation, migration and invasion of gastric cancer cells, while knocking down of cyclin D1 or Ets1 partially phenocopied the effects of miR-9 over-expression. These data indicate that miR-9 suppresses the expression of cyclin D1 and Ets1 via the binding sites in their 3'-UTR, thus inhibiting the proliferation, invasion and metastasis of gastric cancer.
最近的证据表明，miR-9 的表达改变与胃癌的进展有关。然而，miR-9 在胃癌增殖、侵袭和转移中的确切作用和潜在机制仍不清楚。在这项研究中，发现在胃癌组织和细胞系中 miR-9 表达下调，与 cyclin D1 和 v-ets 红细胞增多病毒 E26 癌基因同源物 1（Ets1）的表达呈负相关。生物信息学分析显示，miR-9 在 cyclin D1 和 Ets1 mRNA 的 3'-非翻译区（3'-UTR）中存在潜在的结合位点。外源性表达或敲低 miR-9 导致培养的胃癌细胞系 SGC-7901 和 AGS 中 cyclin D1、Ets1 及其下游靶标磷酸化视网膜母细胞瘤和基质金属蛋白酶 9 的表达发生相应改变。在荧光素酶报告系统中，miR-9 直接靶向 cyclin D1 和 Ets1 的 3'-UTR，并且这些作用通过突变 miR-9 结合位点而被消除。miR-9 的过表达抑制了 SGC-7901 和 AGS 细胞在体外和体内的增殖、侵袭和转移。瞬时转染恢复 miR-9 介导的 cyclin D1 和 Ets1 下调，使癌细胞从增殖、迁移和侵袭减少中恢复。此外，抗 miR-9 抑制剂促进了胃癌细胞的增殖、迁移和侵袭，而敲低 cyclin D1 或 Ets1 部分模拟了 miR-9 过表达的作用。这些数据表明，miR-9 通过其 3'-UTR 中的结合位点抑制 cyclin D1 和 Ets1 的表达，从而抑制胃癌的增殖、侵袭和转移。
