Down-regulation of miR-27a might inhibit proliferation and drug resistance of gastric cancer cells

The role of miR-27a in gastric cancer cells was detected using MTT assay, soft agar assay, flow cytometry assay, nude mice assay, real-time PCR, western blot and reporter gene assay, etc.Down-regulation of miR-27a could inhibit porliferation of gastric cancer cells in vitro and in vivo. Down-regulation of miR-27a could also confer sensitivity of drugs on gastric cancer cells, and might increase accumulation and decrease releasing amount of adriamycin in gastric cancer cells. Down-regulation of miR-27a could significantly decrease the expression of P-glycoprotein and the transcriptional activity of cyclin D1, and up-regulate the expression of p21.MiR-27a might play important roles in porliferation and drug resistance of gastric cancer. MiR-27a might be considered as a useful target for cancer therapy.Gastric cancer was one of the major causes of mortality in the world, especially in Asian countries. So far, the pathogenic mechanism underlying gastric carcinogenesis was not fully elucidated.MicroRNAs (miRNAs) were a class of 22-nucleotide noncoding RNAs, which might function as regulators of gene expression [1]. More and more evidences showed that miRNAs might play important roles in various biological processes, including cell proliferation, apoptosis, tumorigenesis and MDR of cancer [2]. So far, the functions of gastric cancer related miRNAs were not clear. MiR-27a might mediate drug resistance of esophageal cancer cells through regulation of MDR1 and apoptosis [3]. However, the role of miR-27a in gastric cancer was not reported yet. To our knowledge, here we have firstly investigated the role of miR-27a in proliferation and multidrug resistance of gastric cancer cells.Human gastric cancer cell line, MKN45, was routinely maintained in DMEM medium (GIBCO, Carlsbad, CA, USA) supplemented with 10% fetal bovine serum at 37°C in humidified air containing 5% carbon dioxide air atmosphere.Cells were plated in plates and cultured for 16 h, and then transfected with the anta