Effect of miRNA-1266-5p repression on the increasing cell survival and alterations of the cell cycle in AGS cell line

Background: Gastric cancer is among the most common malignancies in certain parts of the world, such as northwest Iran. miRNAs are small and single-stranded noncoding RNAs with about 19-23 nucleotides. Several studies have shown that miRNAs play important roles in gastric tumorigenesis. The aim of this study was to determine the effect of miRNA-1266-5p repression on the cell survival and alterations of the cell cycle in gastric cancer cell line of AGS (NCBI Code: C131, Gastric epithelial cell line). Methods: This experimental study was performed from April to December 2017 in Cellular-Molecular Research Center of Ardabil University of Medical Sciences, Iran. In this study, AGS cells were cultured in RPMI-1640 medium containing 10% serum and 1% antibiotic. The cells were transfected with miR-1266-5p mimic, miR-1266-5p inhibitor and HiPerFect reagent alone as negative control. The miR-1266-5p expression and transfection efficiency were analyzed by Stem-loop TaqMan qRT-PCR. The cell proliferation and cell cycle alterations were determined using MTT calorimetric assay and flow cytometry, respectively. The results were analyzed using SPSS 19.0 statistics software (SPSS Inc., Chicago, IL, USA) and presented as the means±standard deviation (SD). Results: miR-1266-5p expression was increased in AGS cells transfected with miR-1266-5p mimic compared to control cells (P=0), while miR-1266-5p expression was decreased in transfected cells with the inhibitor compared to controls (P=0). Among different time points, the most effects of miR-1266-5p mimic and inhibitor were noticed after 48 hours of transfection. The upregulated miR-1266-5p significantly decreased cell growth, in contrast, inhibitor promoted cell proliferation (P=0). In addition, miR-1266-5p upregulation induced cell cycle arrest at the transition of G1 to S phase and led to G0/G1 entry (P=0), while of miR-1266-5p led to G2/M entry (P=0.001). Conclusion: According to the results obtained from this study, miR-1266-5p can reduce cell survival and induce cell cycle arrest and act as a tumor suppressor in AGS cells. While its inhibition can increase cell survival and reduce apoptosis