Cholangiocarcinoma (CCA) often exhibits poor responses to chemotherapy due to mechanisms of chemoresistance (MOCs). The Wnt/β-catenin pathway, hyperactivated in CCA and crucial for cell proliferation, migration, and angiogenesis, may contribute to CCA chemoresistance. This study investigates the role of Wnt/β-catenin in CCA multidrug resistance phenotype and explores the therapeutic potential of combining chemotherapy with Wnt/β-catenin inhibitors.

In vitro assays using CCA cell lines treated with Wnt/β-catenin inhibitors (C59, XAV939, PRI724) evaluated the expression of Wnt target genes and MOC genes through TLDA, single RT-qPCR, and WB. β-catenin silencing was achieved using sh-RNA transduction. Cell viability (MTT test) was assessed after treatment with inhibitors, alone or combined with cisplatin, gemcitabine, or 5-FU. Rats bearing chemically induced CCA were treated with PRI724 alone or with 5-FU to assess in vivo antitumor effects.

β-catenin silencing and treatment with C59, XAV939, or PRI724 inhibited the activity of the Wnt/β-catenin pathway in CCA cells, as demonstrated by the down-regulation of target genes. This led to altered expression of several genes included in the resistome. In vitro assays showed that combined treatment with PRI724 and antitumor drugs induced an additive effect by reducing cell proliferation. Similarly, in vivo assays revealed that the treatment with the combination of PRI724 and 5-FU showed a significant reduction in tumor size compared to animals receiving the vehicle.

Inhibiting the Wnt/β-catenin pathway chemosensitizes CCA cells by modulating MOC gene expression. The combination of Wnt/β-catenin inhibitors with chemotherapy may enhance the therapeutic outcomes for CCA patients.