Nigericin Suppresses the Wnt/β-catenin Signaling in Pancreatic Cancer Through Targeting Pre-miR-374b-PRKCA/HBP1 Axis.

Our previous studies identified the differentially expressed coding and noncoding RNAs during the nigericin-mediated damage by the high-throughput RNA sequencing. However, these reports provided insights into nigericin only through the bioinformatics methods. The anticancer mechanisms of nigericin in pancreatic cancer (PC) have still not been elucidated. In this study, PC cells were exposed to increasing concentrations of nigericin at different time periods, and the corresponding 50% inhibiting concentration (IC50) values were calculated. Then the effects on the biological functions of PC cells were evaluated. Subsequent experiments, including the high-throughput RNA sequencing, qRT-PCR, western blot, TOP/FOP-Flash reporter, Co-Immunoprecipitation (Co-IP) and luciferase reporter assays were employed to reveal the mechanisms of nigericin. In addition, the inhibitory effects of nigericin on PC cells were accessed in the subcutaneous tumor and peritoneal disseminated models. The data showed that nigericin was extremely sensitive to PC cells, and influenced the abilities of cell proliferation, colony formation, apoptosis, migration and invasion. The results in vitro implied that nigericin suppressed the Wnt/β-catenin signaling by upregulating PRKCA and HBP1 mRNA expressions. Si-PRKCA, si-HBP1 or silencing these two molecules simultaneously could attenuate the inactivation of Wnt/β-catenin signaling induced by nigericin. Furthermore, the dual strands of pre-miR-374b were proved to down-regulate the expressions of PRKCA and HBP1 coordinately through their mature products miR-374b-5p and -3p. Overexpression of pre-miR-374b might partly antagonize the suppressing effects of nigericin in PC cells. Suppressing the Wnt/β-catenin signaling pathway by targeting pre-miR-374b-PRKCA/HBP1 axis might represent a novel mechanism of nigericin in PC. Nigericin remained a candidate of preclinical application for PC.