Study on the anti-tumor effects of miR-31 combined with 5-Fu in vitro and in vivo

ZHANG Wei; TAN Yongsheng; MA Heping

doi:10.3969/j.issn.1002-7386.2016.22.009

Abstract：Objective To explore the effects of miR-31 on the sensitivity of 5-fluorouracil (5-Fu) in gastric cancer cells in vitro,and to investigate the effects of miR-31 combined with 5-Fu on mice in vivo.Methods The expression levels of miR-31 in peripheral blood mononuclear cell ( PMBC) and the cancer tissues of patients with gastric cancer and with clinical resistance and the expression levels of miR-31 in PMBC and gastric tissues of patients without gastric cancer were detected by Real-time PCR,moreover, which in wild type MFC cells and MFC cells with chemoresistance to 5-Fu ( MFC-R cells) were also detected by Real-time PCR in vitro.Meanwhile the proportion of Treg cells ( CD3+CD4+CD2+5 FOXP3+T cells) in gastric cancer tissues of patients with gastric cancer and in peripheral blood of patients without gastric cancer were detected by flow cytometry,moreover, the correlation between miR-31and FOXP3 was analyzed.The effects of miR-31on proliferation of MFC cells were detected by MTS,moreover, the effects of miR-31 combined with 5-Fu on tumor growth of mice in vivo were detected by MTS.Besides the effects of CD8+T cells on MFC were detected by LDH releasing assay.Results The expression levels of miR-31 in cancer tissues and PMBC of patients with gastric cancer as well as clinical resistance were significantly lower than those of patients without gastric cancer ( P <0.05), however, the proportion of CD3+CD4+CD2+5FOXP3+T cells in peripheral blood of patients with gastric cancer was significantly higher than that of patients without gastric cancer ( P <0.05), furthermore, there was an negative correlation between them ( P <0.05).However in MFC cells with chemoresistance to 5-Fu,the expression levels of miR-31were decreased.After miR-31was transfected into MFC cells, the high-expression of miR-31increased the sensitivity to 5-Fu ( P <0.05) .The experimental results in mice in vivo showed that miR-31combined with 5-Fu could obviously inhibit the growth of MFC cells in mice in vivo,moreover, miR-31 could decrease tumor infiltration of mice with tumor and could decrease the proportion of Treg cells in peripheral blood of mice and enhance CTL function of CD8+T cells ( P <0.05).Conclusion miR-31can inhibit the growth of gastric cancer MFC cells by increasing the sensitivity of cancer cells to chemotherapeutic drugs directly and by inhibiting the function of Treg cells.