Inhibitory effect of miR-140-5p on doxorubicin resistance of hepatocellular carcinoma

To investigate the role of microRNA (miR)-140-5p in doxorubicin (DOX) sensitivity in hepatocellular carcinoma, miR-140-5p and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) expression was first evaluated in hepatocellular carcinoma tissues using starBase. Next, in vitro experiments were performed. Cell line expression of miR-140-5p and PIN1 expression was detected by reverse transcription polymerase chain reaction. Cell viability and proliferation were determined by the Cell Counting Kit-8 and EdU assays. The relationship between miR-140-5p and PIN1 was evaluated by TargetScan and a luciferase reporter system. Western blotting was used to detect the expression of PIN1. It was observed that miR-140-5p was downregulated in hepatocellular carcinoma tissues and cell lines compared with normal samples in HCC or normal liver cells. Gain-of-function experiments revealed that miR-140-5p mimics were able to enhance DOX sensitivity of hepatocellular carcinoma cells. Further studies revealed that PIN1 was a target gene of miR-140-5p. Suppression of PIN1 led to higher DOX sensitivity in hepatocellular carcinoma cells. Finally, when comparing a PIN1-siRNA alone group and a PIN1-siRNA plus miR-140-5p inhibitor group, there was no significant difference in cell viability. Furthermore, miR-140-5p mimics did not reduce the sensitivity of PIN1mut plasmid to DOX in HUH7 and SNU449 cells. The present study demonstrated that miR-140-5p could enhance DOX sensitivity in hepatocellular carcinoma cells by targeting PIN1.