Pleurotus nebrodensis polysaccharide induces apoptosis in human non-small cell lung cancer A549 cells

Polysaccharides derived from edible fungi inhibit the proliferation of tumor cells. In this study, we investigated the effects of a polysaccharide (PN50G) from Pleurotus nebrodensis on A549 cell proliferation and apoptosis. MTT assay showed that PN50G induced apoptosis in the A549 cells in a dose-dependent. However, PN50G did not affect the proliferation viability of human fetal lung fibroblast cells MRC-5. Scanning electro microscopy (SEM) results indicate that PN50G induced a typical apoptotic morphological feature in A549. DNA accumulation and fragmentation were determined by acridine orange/ethidium bromide (AO/EB) staining. Flow cytometric analysis demonstrated that PN50G caused A549 cell apoptosis via cell arrest at the S phase. PN50G also extended the comet tail length in single-cell gel electrophoresis and disrupted the mitochondrial membrane potential as determined by Rdamine-123 staining. Further analysis by qRT-PCR showed that the expression of caspase-3 and caspase-9 mRNA increased. These findings suggest that PN50G can inhibit A549 cell proliferation and induce apoptosis mainly by activating the intrinsic mitochondrial pathway.