MiR-195 reverses 5-FU resistance through targeting HMGA1 in gastric cancer cells.

OBJECTIVE: To investigate the role of micro ribonucleic acid (miR)-195 in acquired resistance to 5-fluorouracil (5-FU) in gastric cancer and its potential mechanism. MATERIALS AND METHODS: The drug resistance of AGS/5-FU and SGC-7901/5-FU cells compared with their parental cells was verified via methyl thiazolyl tetrazolium (MTT) assay, and the expression levels of miR-195 and high-mobility group protein A1 (HMGA1) in AGS/5-FU and SGC-7901/5-FU cells were detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) and Western blotting. MiR-195 mimic and miR-195 inhibitor were transfected into AGS/5-FU and AGS cells, respectively, the changes in HMGA1 expression were detected via qRT-PCR and Western blotting, and the sensitivity of cells to 5-FU after transfection was detected via MTT assay. After the wild-type and mutant-type luciferase reporter plasmids of HMGA1 were co-transfected with miR-195 mimic or miR-195 NC into cells, the luciferase activity was analyzed using the dual-luciferase reporter system. Finally, the rescue experiment was performed to confirm whether the changes in HMGA1 expression promote the formation of drug resistance in gastric cancer. RESULTS: Both AGS/5-FU and SGC-7901/5-FU cells were significantly resistant to 5-FU compared with their parental cells, and miR-195 was down-regulated in AGS/5-FU and SGC-7901/5-FU cells, while HMGA1 was up-regulated in AGS and SGC-7901 cells. The transfection with miR-195 mimic could suppress the expression level of HMGA1 in AGS/5-FU cells, while the transfection with miR-195 inhibitor could up-regulate the expression level of HMGA1 in AGS cells. Moreover, miR-195 could bind to HMGA1 3'-untranslated region (3'UTR) in a targeted way, thereby inhibiting its expression. It was confirmed via a rescue experiment that the changes in HMGA1 expression promoted the formation of drug resistance in gastric cancer. CONCLUSIONS: The down-regulation of miR-195 induces the resistance to 5-FU in gastric cancer through promoting the expression of HMGA1.