Modified apple polysaccharides could induce apoptosis in colorectal cancer cells

Multiple studies have pointed out that dietary components could inhibit cancer progression and metastasis, and it has been proven that many ingredients of apple have benefits for cancer prevention. We, therefore, extracted modified apple polysaccharides (MAP) from apple and hypothesized that MAP have a cancer-preventive effect as do other ingredients of apple. Three human colorectal cancer cell lines: SW-1116, HT-29, and Caco-2 were exposed to different concentrations of MAP (0% to 0.1%). Inhibition of cell proliferation was measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. DNA fragmentation was visualized by agarose-gel electrophoresis. The amount of apoptotic cells was assessed by flow cytometry, and protein level of caspase 3, 8, 9, Bax, and Bcl-2 was evaluated by Western blot. At the concentrations of 0.01% to 0.1%, MAP showed growth-inhibiting and apoptosis-inducing effects on cancer cells. It increased the expression of caspase 3, 8, 9, and Bax, while decreased of Bcl-2, which denoted that MAP may induce apoptosis through both the mitochondrial-mediated and death receptor-mediated apoptotic ways. These data indicate that MAP has the potential for clinical prevention and treatment for colon cancer.