6-Shogaol improves sorafenib efficacy in colorectal cancer cells by modulating its cellular accumulation and metabolism

Carcinoma of the colon and rectum, also known as colorectal cancer, ranks as the third most frequently diagnosed malignancy globally. Sorafenib exhibits broad-spectrum antitumor activity against Raf, VEGF, and PDGF pathways in hepatocellular, thyroid, and renal cancers, but faces resistance in colorectal malignancies. 6-Shogaol, a prominent natural compound found in Zingiberaceae, exhibits antioxidant, anti-inflammatory, anticancer, and antiemetic properties. We investigated the influence of 6-shogaol on sorafenib’s cytotoxic profile against colorectal cancer cell lines (HT-29, HCT-116, CaCo-2, and LS174T) through its effects on cellular accumulation and metabolism. Cytotoxicity was assessed using the sulpharodamine B assay, caspase-3 and c-PARP cleavage, cell cycle distribution analysis, and P-gp efflux activity. 6-Shogoal showed considerable cytotoxicity with decreased IC₅₀ in colorectal cancer cell lines. Combining sorafenib and 6-shogaol increased c-PARP and pro-caspase-3 concentrations in HCT-116 cells compared to sorafenib alone. In combination, pro-caspase-3 concentrations were decreased in CaCo-2 cells compared to alone. Sorafenib combinations with 6-shogaol showed a significant drop in cell cycle distribution from 16.96±1.10 % to 9.16±1.85 %, respectively. At 100 µM, sorafenib and 6-shogaol showed potent and significant activity with intra-cellular rhodamine concentration on P-gp efflux activity in CRC cell lines. In conclusion, 6-shogaol substantially improved the cytotoxic profile of sorafenib by affecting its cellular uptake and metabolism. Future research should focus on dosage optimization and formulation and evaluate the efficacy and safety of the combination in animal models with colorectal cancer.