The combination of ulinastatin and 5-fluorouracil synergistically inhibits hepatocellular carcinoma growth

OBJECTIVE: Chemoresistance is a major problem during hepatocellular carcinoma (HCC) treatment; thus, finding novel chemosensitizers and elucidating the underlying mechanisms that contribute to chemoresistance in HCC is critical. METHODS: Cell viability assays were used to detect the combined effects of ulinastatin (UTI) and 5-fluorouracil (5-FU) on the proliferation of HCC cells. RT-qPCR, western blot, sphere formation, and aldehyde dehydrogenase 1 (ALDH1) activity assays were used to examine UTI-mediated effects on HCC cell stemness and related mechanisms. RESULTS: We constructed 5-FU-resistant HCC cell lines and found that their stemness was higher than parental cells, as evidenced by increased sphere-formation ability, ALDH1 activity, and expression of stemness regulatory genes. While UTI had no effect on the viability of HCC cells, it significantly reduced the stemness of 5-FU-resistant HCC cells, which was determined by decreased sphere-formation capacity, ALDH1 activity, and expression of stemness-related genes. Furthermore, UTI attenuated 5-FU resistance in 5-FU-resistant HCC cells and enhanced the 5-FU sensitivity of parental cells. Mechanistic studies revealed that UTI suppressed the Wnt/β-catenin pathway, which was responsible for the activity of UTI on the stemness of HCC cells. CONCLUSIONS: UTI enhanced the 5-FU sensitivity of HCC cells by attenuating their stemness via inhibiting Wnt/β-catenin signaling.