Synergistic anticancer effects of peanut hairy root culture crude extract in combination with gemcitabine against cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly aggressive malignancy with limited treatment options and frequent chemoresistance. Peanut hairy root culture crude extract (PCE) has previously demonstrated selective cytotoxicity toward CCA cells. Here, we investigated the combinatorial effects of PCE with standard chemotherapeutic agents on CCA cell lines. In KKU-213 A cells, PCE exhibited antagonistic and additive interactions with gemcitabine (Gem) and 5-fluorouracil (5-FU), respectively. In contrast, both combinations showed synergistic effects in KKU-100 cells, with the strongest synergy observed for PCE and Gem. Further investigation in KKU-100 cells revealed that the PCE-Gem combination significantly induced apoptosis, as evidenced by increased levels of cleaved caspase-8, caspase-3, and PARP, without affecting cell cycle progression. Notably, no cytotoxic effect was observed in normal human fibroblasts (HSF-hTERT). In a nude mouse xenograft model, co-treatment with PCE and Gem significantly inhibited tumor growth and reduced Ki-67 expression compared to monotherapies. These findings suggest that PCE enhances the anticancer efficacy of Gem in CCA and may serve as a supportive combinatorial strategy.