Apoptosis of colon cancer CT-26 cells induced polysaccharide from Cyclocarya paliurus and its phosphorylated derivative via intrinsic mitochondrial passway

In this study, the antitumor properties and the possible molecular mechanisms of Cyclocarya paliurus polysaccharide (CP) and its phosphorylated derivative (P-CP) on CT-26 mouse colon carcinoma cells were investigated. Results found that CP had high inhibition ratio against CT-26 cells. The flow cytometry results found that CP treatment could cause the intracellular acidification, arrest the cell cycle in the S phase and increase reactive oxygen species generation. Additionally, CP treatment triggered mitochondrial membrane potential depolarization and Ca2+ overloading, and broke down the balance of antioxidant system, Na+/K+-ATPase and Ca2+-ATPase. Further analysis found CP induced cell apoptosis through improving the activities of caspase-3 and caspase-9, and increasing the level of cytochrome C. Furthermore, the comparative study of antitumor effect on CT-26 cells displayed that the phosphorylation enhanced antitumor activities of polysaccharides. These results suggest CP is a potential natural therapeutic agent for colon cancer and phosphorylation represents an effective method of enhancing the antitumor activity of CP.