Abstract
MicroRNAs (miRNAs) are a group of small non‑coding RNA molecules, which serve an important function in the development of multidrug resistance in cancer through the post‑transcriptional regulation of gene expression and RNA silencing. In the present study, the functional effects of miR‑197 were analyzed in chemo‑resistant gastric cancer cells. Low expression levels of miR‑197 were observed in the fluorouracil (5‑FU)‑resistant gastric cell line SGC7901/5‑FU when compared with those in the parental gastric cell line SGC7901. Overexpression of miR‑197 in SGC7901/5‑FU cells was identified to partially restore 5‑FU sensitivity. miRNA target prediction algorithms suggested that mitogen‑activated protein kinase 1 (MAPK1) is a candidate target gene for miR‑197. A luciferase reporter assay confirmed that miR‑197 led to silencing of the MAPK1 gene by recognizing and then specifically binding to the predicted site of the MAPK1 mRNA 3'‑untranslated region. When miR‑197 was overexpressed in SGC7901 cells, the protein levels of MAPK1 were downregulated. Furthermore, MAPK1 knockdown significantly increased the growth inhibition rate of the SGC7901/5‑FU cells compared with those in the control group. These results indicated that miR‑197 may influence the sensitivity of 5‑FU treatment in a gastric cancer cell line by targeting MAPK1.