Chen Haiqun, Dai Gang, Cai Yiting, Gong Qinhao, Wu Wei, Gao Min, Fei Zhewei
1Department of General Surgery, The ChongMing Branch of XinHua Hospital, The Affiliated Hospital of Shanghai Jiao Tong University, Shanghai, 200240 China.
2Department of General Surgery, XinHua Hospital, The Affiliated Hospital of Shanghai Jiao Tong University, No. 1665, Kong Jiang Road, Shanghai, 200240 China.
Cancer Cell Int. 2018 Jul 9;18:97. doi: 10.1186/s12935-018-0573-4. eCollection 2018.
MicroRNAs (miRNAs) are small non-coding RNAs which play important roles in the carcinogenesis of gastric cancer (GC). Expression profiling of miRNAs in paired gastric cancer and adjacent normal gastric tissues has demonstrated that miR-4455 is down-regulated in gastric cancer tissues, but its functional role in the carcinogenesis of GC had not previously been investigated.
The purpose of this study was to investigate the functional and biological mechanisms of miR-4455 in the progression of GC, in vitro.
Expression of miR-4455 was compared in human GC tissue samples and paired adjacent normal tissue samples. The in vitro effects of miR-4455 expression in MGC-803 cells on their proliferation, invasion, and migration were assessed by MTT assays and 5-bromo-2'-deoxyuridine staining, matrigel-invasion analysis and wound healing assays. Bioinformatics analysis (using PicTar, target scan and miRBase target) was used to identify potential targets for miR-4455, and the luciferase reporter assay, qRT-PCR and Western-blotting analyses were used to confirm VASP as the target of miR-4455. In addition, the effects of downregulation of VASP on the activation of PI3K/AKT signaling pathway were measured using Western-blot analysis.
The expression of miR-4455 was markedly down-regulated in gastric cancer tissues vs. adjacent normal tissues, and miR-4455 expression inhibited the proliferation, invasion and migration of MGC-803 GC cells in vitro. Luciferase reporter assays revealed that miR-4455 inhibited VASP expression by targeting the 3'-UTR sequence of VASP. Furthermore, silencing of VASP markedly inhibited the activation of the PI3K/AKT signaling pathway.
Our results suggest that miR-4455 functions as a tumor suppressor in gastric cancer, by targeting VASP leading to activation of the PI3K/AKT signaling pathway and the inhibition of VASP mediated proliferation, migration and invasion of gastric cancer cells.
微小RNA（miRNA）是一类小的非编码RNA，在胃癌（GC）的致癌过程中发挥重要作用。配对的胃癌组织和相邻正常胃组织中miRNA的表达谱显示，miR-4455在胃癌组织中表达下调，但其在胃癌致癌过程中的功能作用此前尚未得到研究。
本研究旨在体外研究miR-4455在胃癌进展中的功能及生物学机制。
比较人胃癌组织样本和配对的相邻正常组织样本中miR-4455的表达。通过MTT法和5-溴-2'-脱氧尿苷染色、基质胶侵袭分析和伤口愈合试验评估miR-4455在MGC-803细胞中表达对其增殖、侵袭和迁移的体外影响。利用生物信息学分析（使用PicTar、TargetScan和miRBase Target）鉴定miR-4455的潜在靶点，并通过荧光素酶报告基因试验、qRT-PCR和蛋白质免疫印迹分析确认血管扩张刺激磷蛋白（VASP）为miR-4455的靶点。此外，使用蛋白质免疫印迹分析检测VASP下调对PI3K/AKT信号通路激活的影响。
与相邻正常组织相比，miR-4455在胃癌组织中的表达明显下调，且miR-4455表达在体外抑制MGC-803胃癌细胞的增殖、侵袭和迁移。荧光素酶报告基因试验显示，miR-4455通过靶向VASP的3'-UTR序列抑制VASP表达。此外，VASP沉默显著抑制PI3K/AKT信号通路的激活。
我们的结果表明，miR-4455在胃癌中作为肿瘤抑制因子发挥作用，通过靶向VASP导致PI3K/AKT信号通路激活，并抑制VASP介导的胃癌细胞增殖、迁移和侵袭。
