MiR-145Inhibits Gastric Carcinoma Stem Cells Proliferation By Targeting Nanog

More and more research have revealed that miRNAs plays an important role in theregulation of gene expression in the oncogenesis and development of malignant tumor.Different type of stomach neoplasm (Ming’s infiltrative type and expanding type) showdistinct biological behavior and clinical prognosis. There is important theoretical andpractical significance about research on regulatory mechanism of growth patterns of stomachneoplasm. Series of evidence suggest that the growth type of stomach neoplasm may beregulated by miRNAs.In this study,95cases surgically resected gastric cancer were collected,include gastriccancer tissues and corresponding normal gastric epithelium from March2012to September2013in the zhongshan hospital of Xiamen. Real-time PCR method was applied to detectmiR-145expression levels in gastric cancer and the corresponding normal epithelium,.Thepotential target gene of miR-145was predicted by online bioinformatics software. Stem cellfactor Nanog gene which showed good targeted relationship was picked up as research object.Nanog mRNA was examined by quantitative real-time PCR detection in different growthpatterns of gastric cancer. Luciferase reporter assay system was used to measure the targetedrelationship between miR-145and Nanog. Overexpression of miR-145through lentiviralvector construction, the expression changes of Nanog mRNA level was tested by quantitativereal-time PCR. In addition, gasric cell spheroid formation were apply to detect the effectionof forced expression of miR-145in gastric cancer cells MGC-803including cell proliferation.Results shows that miR-145was down-regulated in stomach neoplasm tissues, a lowerdown-regulation in infiltrative gastric cancer compare to expanding gastric cancer, togetherthe level of Nanog mRNA expressing was significantly higher in infiltrative type thanexpanding type gastric cancer. In gastric tissues, the expression level of miR-145wassignificantly higher in the、larger tumors (≥7cm)、 more number of lymphnode metastasis(N2+N3)、earlier the clinical stages (phase Ⅲ and Ⅳ)、type Ⅰa nd Ⅱof Borrmann’sclassification and expanding type of Ming’s classification comparing with smaller tumors (< 7cm)、less number of lymphnode metastasis (N0+N1)、earlier the clinical stages (phase I andⅡ)、type Ⅲ and Ⅳo f Borrmann’s classification andinflirtative type of Ming’s classification,respectively. Expression of miR-145and Nanog is negatively related in gastric cancer.miR-145is directly targeting Nanog and suppresses gastric cancer cells spheroid formation.In addition, knocking down the expression of Nanog leads to the suppression of gastriccancer cells spheroid formation and re-expressing Nanog in miR-145expressing cells reversetheir proliferation defects. Moreover, the miR-145suppresses gastric carcinoma stem cellsproliferation by targeting Nanog.