Brassica juncea polysaccharides induce apoptosis of colorectal cancer cells via mitochondrial- and caspasedependent apoptosis pathways

Purpose: To determine the effect of polysaccharides from Gleditsia on apoptosis of colorectal cancer cells, and the mechanism involved.Methods: Polysaccharides were extracted from Lycium barbarum, and their concentration was more than 85 %. Then, DLD-1 cells were cultured in medium with the polysaccharides at concentrations of 75 and 150 μg/mL. Cell proliferation was determined with MTT (3-(4,5)-dimethylthiahiazo (-z-y1)-3,5- diphenytetrazoliumromide) assay and colony formation assay, while apoptosis was determined with flow cytometry. Changes in MMP were measured flow cytometrically. The protein levels of PARP, Bcl-2, Bax, and caspases 3 and 9 were determined with Western blot assay.Results: Cell viability decreased time-dependently. Compared with control without polysaccharide exposure, cell viability, colony forming cells, % apoptosis, red: green fluorescence ratio, and bcl-2 expression were significantly and concentration-dependently decreased, while the expression levels of PARP, Bax, caspase-3 and caspase-8 were significantly increased (p < 0.05).Conclusion: These results indicate that the polysaccharides suppressed apoptosis of colorectal cancer cells by inhibiting the mitochondrial and caspase-dependent apoptosis pathways. Gleditsia polysaccharide may be used as an adjuvant therapy for colorectal cancer.