MiR-494-5p expression has been suggested to be associated with colorectal cancer (CRC) and its metastases in our previous studies. However, functional investigations on the molecule-mediating actions of this miR in CRC are lacking. In silico analysis in the present study revealed a putative binding sequence within the 3′UTR of JAK1. Overexpression of miR-494-5p in cultured CRC significantly reduced the luciferase activity of a reporter plasmid containing the wild-type JAK1-3′UTR, which was abolished by seed sequence mutation. Furthermore, the overexpression of miR-494-5p in CRC cell lines led to a significant reduction in JAK1 expression, proliferation, in vitro migration, and invasion. These effects were abolished by co-transfection with a specific double-stranded RNA that inhibits endogenous miR-494-5p. Moreover, IL-4-induced migration, invasion, and phosphorylation of JAK1, STAT6, and AKT proteins were reduced after an overexpression of this miR, suggesting that this miR affects one of the most essential pathways in CRC. A Kaplan–Meier plotter analysis revealed that patients with high JAK1 expression show reduced survival. Together, these data suggest that miR-494-5p physically inhibits the expression of JAK1 at the translational level as well as in migration and invasion, supporting the hypothesis of miR-494-5p as an early tumor suppressor and inhibitor of early steps of metastasis in CRC.
我们既往研究表明，miR-494-5p的表达与结直肠癌及其转移存在关联，但该miRNA在结直肠癌中分子介导作用的功能研究尚属空白。本研究通过生物信息学分析发现JAK1基因3′UTR区域存在潜在结合位点。在培养的结直肠癌细胞中过表达miR-494-5p能显著降低含野生型JAK1-3′UTR报告质粒的荧光素酶活性，该效应可被种子序列突变所消除。进一步实验显示，在结直肠癌细胞系中过表达miR-494-5p能显著抑制JAK1表达、细胞增殖、体外迁移及侵袭能力，这些效应可通过共转染特异性双链RNA抑制内源性miR-494-5p而逆转。此外，过表达该miRNA可降低IL-4诱导的细胞迁移、侵袭及JAK1、STAT6和AKT蛋白磷酸化水平，提示其影响结直肠癌关键信号通路。Kaplan-Meier生存分析表明JAK1高表达患者生存期缩短。综上，本研究证实miR-494-5p能在翻译水平直接抑制JAK1表达，并抑制细胞迁移和侵袭，支持miR-494-5p作为结直肠癌早期抑癌因子及转移初始阶段抑制因子的假说。
JAK1 Is a Novel Target of Tumor- and Invasion-Suppressive microRNA 494-5p in Colorectal Cancer
肿瘤(癌症)患者之家