A Comparative Analysis of the Action Mechanisms of Cannabidiol, Cannabigerol, and Cannabinol in Human Cholangiocarcinoma Cell Lines

Background: Chemoresistance remains a major obstacle in managing cholangiocarcinoma (CCA). The cannabis plant contains several phytocannabinoids, including cannabidiol (CBD), cannabigerol (CBG), and cannabinol (CBN), which exhibit anticancer properties. However, to the best of our knowledge, their effects on CCA have not been previously investigated. This study aimed to explore the molecular mechanisms underlying the anticancer effects of CBD, CBG, and CBN in CCA cells. Methods: KKU-100 and KKU-452 cells were treated with varying concentrations of CBD, CBG, and CBN for 24 and 48 h. Cytotoxicity was assessed using the MTT assay, and half maximal inhibitory concentration (IC50) values were calculated. KKU 452 cells were further analyzed for apoptosis, mitochondrial membrane potential (MMP), and Ki67 expression using flow cytometry. Proteomics profiling was performed to compare the effect of these cannabinoids with those of gefitinib and cisplatin. Results: Monotherapy with CBD, CBG, or CBN induced dose-dependent cytotoxicity at 24 and 48 h with lower IC50 values than those of cisplatin and comparable efficacy to that of gefitinib. At low doses, CBD, CBG, and CBN induced early apoptosis, while higher doses triggered late apoptosis. MMP loss increased by 2.5-, 4.9-, and 1.7-fold, respectively, after 6 h. Ki67, highly expressed in KKU-452 cells (Ki67-positive ratio = 3.16 ± 0.16), was significantly reduced after the cannabinoid treatment, with Ki67-positive ratios of 0.38 ± 0.22, 0.38 ± 0.13, and 0.32 ± 0.23 for CBD, CBG, and CBN, respectively. Proteomics analysis identified 2781 proteins affected by CBD, CBG, CBN, cisplatin, and gefitinib. All three cannabinoids downregulated key upstream regulatory proteins (LARP1, TFEB, and BCR). Similar patterns of LARP1 and TFEB downregulation were also observed with cisplatin and gefitinib. CBN showed the closest similarity to cisplatin, followed by gefitinib, by targeting CDK4/6 and PCGEM1 proteins. CBD and CBG exhibited the greatest similarity to each other, also influencing MASTL expression. Conclusions: CBD, CBG, and CBN exhibit potential anticancer activity in CCA by suppressing proliferation, reducing Ki67 expression, and inducing apoptosis through MMP disruption. The identification of shared molecular targets, including LARP1 and TFEB, provides new mechanistic insight and supports the potential development of cannabinoid-based therapeutic strategies for cholangiocarcinoma.