Anti-parasitic Drug Ivermectin Exhibits Potent Anticancer Activity Against Gemcitabine-resistant Cholangiocarcinoma In Vitro

Background/aim: The antiparasitic drug, ivermectin (IVM), exerts anticancer activities in diverse cancer types. However, its anticancer activity against cholangiocarcinoma (CCA), especially the drug-resistant phenotype, has not yet been explored. Materials and Methods: IVM was tested for its anticancer activity against gemcitabine-sensitive (KKU214) and gemcitabine-resistant (KKU214(GemR)) CCA cell lines in vitro using the sulforhodamine B and clonogenic assays as well as cell-cycle analysis. Results: IVM treatment inhibited cell proliferation and colony formation of both KKU214 and KKU214(GemR) in a dose- and time-dependent manner. KKU214(GemR) cells were more sensitive than KKU214 to IVM treatment. IVM treatment caused S-phase cell-cycle arrest and also cell death as indicated by an increase of sub-G(0)/G(1) population in KKU214(GemR) cells treated with IVM for 48 h. Conclusion: IVM exerts anti-CCA activities and gemcitabine-resistant KKU214(GemR) cells are more sensitive to IVM treatment. Thus, IVM might be useful as an alternative treatment for CCA, especially in patients who do not respond to gemcitabine.