OBJECTIVE: We hypothesized that the combination of PIP with CXB will have a synergistic anti-proliferative effect on colon cancer cells.
METHODS: The potency of PIP and CXB alone and in combination was evaluated in HT-29 human colon adenocarcinoma cells and mechanism of growth inhibition was investigated by analyzing the players in apoptotic and Wnt/β-catenin signaling pathways.
METHODS: The effect of PIP on the oral bioavailability of CXB in mice was investigated using HPLC analysis. The study investigated the synergistic anti-proliferative effect of CXB and PIP on HT-29 cells and IEC-6 non-tumorigenic rat intestinal epithelial cells by SRB cell viability assay. Further, the cellular and molecular mechanism(s) involved in the anti-proliferative combinatorial effect was extensively explored in HT-29 cells by flow cytometry and western blotting. The in vivo efficacy of this combination was studied in CT26.WT tumor syngeneic Balb/c mice model.
RESULTS: PIP as a bioenhancer increased the oral bioavailability of CXB (129%). The IC50 of CXB and PIP were evaluated to select doses for combination treatment of HT-29 cells. The drug combinations having combination index (CI) less than 1 were screened using CompuSyn software. These combinations were significantly cytotoxic to HT-29 cells but IEC-6 were least effected. Further, the mechanism behind CXB and PIP mediated cell death was explored. The co-treatment led to reactive oxygen species generation, mitochondrial dysfunction, caspase activation and enhanced apoptosis in HT-29 cells. Additionally, the combination treatment synergistically modulated Wnt/β-catenin pathway, downregulated the stemness markers and boosted therapeutic response in CT26 syngeneic Balb/c mice.
CONCLUSIONS: The outcomes of the study suggests that combining CXB and PIP offers a novel approach for the treatment of colon cancer.