Dishevelled 1, a pivotal positive regulator of the Wnt signalling pathway, mediates 5-fluorouracil resistance in HepG2 cells

Acquired resistance to 5-fluorouracil (5-FU) frequently occurs in patients with hepatocellular carcinoma (HCC), the underlying molecular mechanisms of which are poorly understood. The aim of this study was to identify candidate genes and associated signalling pathways that may play a role in developing drug resistance following repeated 5-FU treatments. In this work, we established 5-FU-resistant cells (HepG2/5-FU) using stepwise increasing concentrations of 5-FU in parental HepG2 cells. Using transcriptome sequencing, we found that the expressions of the Wnt signalling genes, including negative regulators (DKK1, DKK3, ZNRF3, RNF43 and APC2) and positive regulators (FZD10 and DVL1), were significantly downregulated and upregulated in HepG2/5-FU cells, respectively, resulting in increased Wnt signalling. Dishevelled-1 (DVL1) is an essential Wnt signalling pathway component that stabilizes β-catenin and mediates the Wnt pathway. Silencing DVL1 using siDVL1 or other small molecular inhibitors in HepG2/5-FU cells could restore 5-FU responsiveness via reduced cell proliferation and migration, and increased apoptosis. Moreover, DVL1 was found to be upregulated in BEL-7402/5-FU cells when compared to the parental BEL-7402 cells. Collectively, our results provide the first clue towards understanding the contribution of DVL1-mediated acquired resistance to 5-FU in HepG2/5-FU cells, suggesting a promising therapeutic strategy for liver cancer resistant to 5-FU.