Mir-200A Inhibits The Proliferative And Invasive Ability Of Human Gastric Cancer Cell Line SGC7901in Vitro By Targeting CTNNB1

MicroRNAs (miRNAs) are single-stranded noncoding RNAs of21to23nucleotides that repress translation or induce cleavage of target mRNAs that are partially complementary to the3’or5’untranslated regions (UTRs). MiRNAs have recently been implicated in the regulation of tumorigenesis, differentiation, proliferation and survival through the regulation of major cellular pathways, especially in epithelial tumors. The relationship between microRNAs and the Wnt/β-catenin pathway in epithelial tumors has become a central point of interest.Constitutive activation of the Wnt/β-catenin signal pathway promotes uncontrolled cell growth and survival, and can consequently drive cancer formation. Dysregulated Wnt/β-catenin signaling is a common feature of many malignant tumors of epithelial tissue origin. In epithelial tumors, mutations in components of the β-catenin, destruction complex (such as APC, AXIN and GSK3β) or in the β-catenin gene were shown to contribute to the cytosolic accumulation of p-catenin and the activation of the Wnt/β-catenin pathway.Our previous review on the Wnt/β-catenin pathway described multiple genes involved in its regulation, with special focus on the function of miRNAs. Several miRNAs have been found to be regulators, either as oncogenes or tumor suppressor genes that regulate the activity of the Wnt/β-catenin pathway. MiR-200a was reported to down-regulate β-catenin-mediated transcription; however, little is known about the mechanism involved in this activity.In the current study, we investigated whether up-or down-regulation of miR-200a expression was accompanied by changes in the activity of the Wnt/β-catenin signal pathway in gastric adenocarcinoma SGC7901cells. We employed TOP/FOP flash luciferase assays to identify the effect of miR-200a on the Wnt/p-catenin pathway and we confirmed our observations using fluorescence microscopy. To determine target genes of miR-200a, a3’untranslated region (3’UTR) luciferase assay was performed. Cell viability, invasion and wound healing assays were carried out for functional analysis after miRNA transfection. We further investigated the role of miR-200a in EMT by Western blot analysis. These results suggest that miR-200a can influence the biological characteristics of SGC7901cells by regulating the down-stream targets of Wnt/β-catenin signaling. Furthermore, we confirmed that CTNNB1is a direct target of miR-200a. Also, we determined that miR-200a is an inhibitor of EMT in SGC7901cells.