Anticancer Activities of Peanut (Arachis hypogaea L.) Testa Extract in Combination With Cisplatin and 5-Fluorouracil Against Cholangiocarcinoma Cells In Vitro and in Mouse Xenograft Models

Cholangiocarcinoma (CCA) is a very aggressive cancer and CCA treatments with cisplatin and 5-fluorouracil (5-FU) often cause side effects and drug resistance. This study aimed to investigate the combined effects of Valencia KK4-type peanut’s (Arachis hypogaea L.) skin ethanolic extract (KK4-PSE) and cisplatin or 5-FU on CCA cells in vitro and in nude mouse xenografts. Antiproliferative activity was evaluated using MTT assay. The in vitro drug interaction was studied by the Chou–Talalay method. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. The levels of proteins involved in apoptosis were evaluated by western blot analysis. Mouse xenograft models were used to evaluate the anticancer activity of KK4-PSE in animals (in vivo). KK4-PSE inhibited the proliferation of CCA cell line (IC₅₀ = 37.22 ± 4.31, 26.27 ± 0.78, and 17.72 ± 0.50 μg/mL at 24 h, 48 h, and 72 h exposures, respectively) more effectively than that of the noncancer H69 cholangiocyte cell line (IC₅₀ = 193.35 ± 6.55, 75.35 ± 1.00, and 57.41 ± 0.96 μg/mL at 24 h, 48 h, and 72 h exposures, respectively). In KKU-M213B cells, KK4-PSE treatments in combination with cisplatin caused cell cycle arrest at G2/M, whereas combined KK4-PSE and 5-FU caused a significant increase of Sub G1 population for 24 h exposure. Furthermore, a significant increase in the percentage of apoptotic cells was also observed in combination treatments. The combination treatments of KK4-PSE with cisplatin and 5-FU caused downregulation of pERK1/2 and Bcl2 and caused a decrease in the Bcl2/Bax ratio, resulting in enhanced apoptosis. In addition, KK4-PSE treatments in combination with 5-FU suppressed tumor growth in BALB/cAJcl-Nu/Nu xenograft models more effectively than the combinations with cisplatin. Taken together, KK4-PSE may be an effective synergistic agent with 5-FU and cisplatin for CCA chemotherapy, warranting further clinical examination.