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The cancer mortality has been the first of the people death for years. The most important topic is how to prevent and cure the cancer disease. Most mushroom polysaccharides, for many years, had been demonstrated that they possess the anti-cancer activities. Pleutotus tuber-regium is a well known as a traditional medicinal and edible mushroom. The mixtures of polysaccharides isolated from sclerotia of Pleutotus tuber-regium show anti-tumor properties. However, there was little known about the biological activities of extracellular polysaccharides of Pleutotus tuber-regium. In this study, I demonstrate that the apoptosis induced by extracellular polysaccharides isolated from Pleutotus tuber-regium(PTREPS) on SW620 human colon cancer cell line and the IC50 is 711μg/mL. Furthermore, there is no any cytotoxic effect on HaCaT cell (human normal keratinocyte) and CL-48(human embryonic liver cell) cell. By the ways of observing cell morphological change、flow cytometry analysis and DNA fragmentation assay lead to evidence that cell death by exposure to PTREPS is through apoptosis, not necrosis. Mechanistically, PTREPS are found to induce apoptosis on SW620 cell by activation of caspase-8、caspase-9 and its downstream caspase-3. In addition, the PTRESP treatment as well as increase the activation of p38 and decrease the activation of ERK. The results indicate the PTRESP-induced apoptosis may related to the activation of caspase pathway and regulation MAPKs pathway.
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