Chemoresistance remains a main clinical obstacle in the treatment of gastric cancer (GC). microRNAs have been revealed to participate in the regulation of drug resistance in a variety of cancers. However, little is known about the function and detailed molecular mechanism of miR-101 in GC chemoresistance.

The expressions of miR-101 and Annexin A2 (ANXA2) in GC tissues and cells were detected by qRT-PCR and western blot. The effects of miR-101 overexpression on P-glycoprotein (P-gp) at mRNA and protein levels, cell viability, and apoptosis in drug-resistant GC cells were examined by qRT-PCR, western blot, MTT and flow cytometry analysis, respectively. Luciferase reporter assay, RNA immunoprecipitation (RIP) and qRT-PCR were applied to confirm whether miR-101 could target ANXA2 and regulate its expression. Rescue experiment was performed to verify the mechanism by which miR-101 involved in chemoresistance.

miR-101 was downregulated in GC tissues and drug-resistant GC cells. A negative correlation between miR-101 and ANXA2 expression was observed in GC tissues. Forced expression of miR-101 significantly reduced P-gp expression at mRNA and protein levels in drug-resistant GC cells. Overexpression of miR-101 enhanced sensitivity to cisplatin (DDP) or vincristine (VCR) via viability inhibition and apoptosis promotion. ANXA2 was identified as a direct target of miR-101 and miR-101 negatively regulated ANXA2 expression. Moreover, ectopic expression of ANXA2 reversed the effect of miR-101 on P-gp expression, cell viability and apoptosis.

miR-101 alleviated chemoresistance of gastric cancer cells by targeting ANXA2. Therefore, targeting miR-101 may be a potential therapeutic approach for drug-resistant GC.