MicroRNA‐21 induces 5‐fluorouracil resistance in human pancreatic cancer cells by regulating PTEN and PDCD4

Pancreatic cancer patients are often resistant to chemotherapy treatment, which results in poor prognosis. The objective of this study was to delineate the mechanism by which miR‐21 induces drug resistance to 5‐fluorouracil (5‐FU) in human pancreatic cancer cells (PATU8988 and PANC‐1). We report that PATU8988 cells resistant to 5‐FU express high levels of miR‐21 in comparison to sensitive primary PATU8988 cells. Suppression of miR‐21 expression in 5‐Fu‐resistant PATU8988 cells can alleviate its 5‐FU resistance. Meanwhile, lentiviral vector‐mediated overexpression of miR‐21 not only conferred resistance to 5‐FU but also promoted proliferation, migration, and invasion of PATU8988 and PANC‐1 cells. The proresistance effects of miR‐21 were attributed to the attenuated expression of tumor suppressor genes, including PTEN and PDCD4. Overexpression of PTEN and PDCD4 antagonized miR‐21‐induced resistance to 5‐FU and migration activity. Our work demonstrates that miR‐21 can confer drug resistance to 5‐FU in pancreatic cancer cells by regulating the expression of tumor suppressor genes, as the target genes of miR‐21, PTEN and PDCD4 can rescue 5‐FU sensitivity and the phenotypic characteristics disrupted by miR‐21.