Abstract: Objective: To analysis the microRNA expression profile and drug resistance characteristic and explore the roles of microRNA-200c on drug resistance in gastric cancer cell line SGC7901/DDP. Methods: Drug sensitivity of SGC7901/DDP and SGC7901 cells were tested by means of MTT assay. microRNA array was used to analyze microRNA expression profile, and bioinformatics analysis was also used to predict possible targets and biological functions of differentially expressed microRNAs. Real-time fluorescent quantitative RT-PCR was used to validate the result of microRNA-200c expression change from microRNA array analysis. And the effects of microRNA-200c on drug resistance were also analyzed in SGC7901/DDP cells by means of cell transfection. Results: The IC50 of cisplatin, doxorubicin, 5-fluorouracil and paclitaxel were significantly higher in SGC7901/DDP cells than in SGC7901 cells (P<0.05). Compared with SGC7901 cells, 5 microRNAs were upregulated more than 2-fold, and 14 microRNAs were downregulated more than 2-fold in SGC7901/DDP cells. The predicted targets both in downregulated and upregulated microRNA expression group were involved in the biological processes of signal transduction, cell cycle, cell differentiation, apoptosis, proliferation and etc. microRNA-200c was confirmed down expressed in SGC7901/DDP cells by real-time fluorescent quantitative RT-PCR. And SGC7901/DDP cells transfected with microRNA-200c precursor displayed significantly decreased IC50 of cisplatin, doxorubicin, 5-fluorouracil and paclitaxel (P<0.05).Conclusion: Changes of microRNA expression profile may be related to the multidrug-resistant in SGC7901/DDP cells, and its reversed drug resistance phenotype may be correlate with the microRNA-200c expression.

Key words: microRNA, gastric cancer, drug resistance, expression profile