microRNA-218 promotes gemcitabine sensitivity in human pancreatic cancer cells by regulating HMGB1 expression

Objective： The purpose of this study was to examine the effect of gemcitabine（GEM） on micro RNA-218（mi R-218） expression in human pancreatic cancer cells.Methods： Quantitative reverse transcription polymerase chain reaction（q RT-PCR） was performed to examine the differences in mi R-218 expression between the GEM-sensitive Bx PC-3 pancreatic cancer cells and GEM-resistant PANC-1 cells. The effect of GEM on the expression of mi R-218 in PANC-1 cells was also investigated. PANC-1 cells were transfected either with HMGB1 si RNA to knock down the expression of HMGB1 or with the recombinant HMGB1 expression vector（pc DNA3.1-HMGB1） to overexpress HMGB1. The effect of ectopic expression of HMGB1 on the apoptosis of mi R-218-transfected and GEMtreated PANC-1 cells was examined by flow cytometric analysis.Results： The mi R-218 expression level was lower in GEM-resistant PANC-1 cells compared to GEMsensitive Bx PC-3 cells（P〈0.05）. The percentage of apoptotic PANC-1 cells was significantly increased in the mi R-218 mimic ＋ GEM group compared to the mimic ctrl ＋ GEM group and the normal control group（P〈0.01）. The HMGB1 expression level was markedly decreased in PANC-1 cells transfected with HMGB1 si RNA but was significantly increased in PANC-1 cells transfected with the recombinant HMGB1 expression vector, pc DNA3.1-HMGB1（P〈0.01）. The proportion of apoptotic PANC-1 cells was significantly lower in the mi R-218 mimic ＋ GEM ＋ pc DNA3.1-HMGB1 group compared to the mi R-218 mimic ＋ GEM ＋ HMGB1 si RNA group（P〈0.01）.Conclusions： The expression level of mi R-218 was downregulated in the GEM-resistant cell line. mi R-218 promoted the sensitivity of PANC-1 cells to GEM, which was achieved mainly through regulating the expression of HMGB1 in PANC-1 cells.