MiR-215Modulates Gastric Cancer Cell Proliferation By Targeting RB1

From a worldwide perspective, gastric carcinoma is the fourth most common malignant cancer and the second leading cause of cancer-related deaths.Despite multiple efforts have been made to explore the mechanism of gastric cancer development and progression, stomach cancer is still a main clinical burden nowadays. Accumulated evidence indicates that noncoding RNAs have been involved in mass of biological processes, and alteration in its expression plays an important role in tumorigenesis and cancer progression. While noncoding RNAs have been reported frequently deregulated in gastric cancer, the function and mechanism of these RNAs have not been well explored in gastric cancer.Recent years, microRNAs (miRNAs) as a new class of short, endogenous, conserved, non-coding RNA have entered the sight of researchers to explore new targets for cancer therapy. MiRNAs were well demonstrated to play pivotal roles in kinds of biological processes, such as cell proliferation, apoptosis, migration, angiogenesis and epithelial to mesenchymal transition (EMT),by nucleotide complement with the mRNA of its target genes.We have analyzed the miRNA prolife in gastric cancer, and found a series of miRNAs deregulated in tumor samples compared with normal mucosa. Quantitative real-time PCR analysis proved that miR-192, miR-335and miR-215were up-regulated in gastric tumor samples,while miR-148a and miR-768-5p were down-regulated in gastric cancer compared with their adjacent nonneoplastic gastric mucosa. Because miR-215is the most up-regulated miRNA gastric cancers, we focus our efforts on the function study of miR-215in gastric cancer cells.Ectopic expression the precursor of miR-215can promotes cell proliferation in gastric cancer cell lines AGS and MKN28.Down-regulation of miR-215by anti-miR-215obviously inhibits gastric cancer cell proliferation in NCI-N87and AGS cell lines with inducing G0/G1-phase cell cycle arrest. Immunoblotting analysis and Luciferase Reporter Assay demonstrate that RBI is one of the targets regulated by miR-215and RBI is involved in the regulation of proliferation induced by miR-215.On the other hand, Genomic PCR showed that the gene of miR-215is frequently amplified in human gastric cancer samples and cell lines. Correlation analysis demonstrated that miR-215expression level is positively related to its gene copy number. These findings elucidate the mechanism that miR-215which is activated by genomic amplification regulates cell proliferation by targeting RBI in gastric cancer, indicating that miR-215is a new potential candidate diagnostic biomarker and therapy target in gastric carcinoma.