FAS/FAS-L-mediated apoptosis and autophagy of SPC-A-1 cells induced by water-soluble polysaccharide from Polygala tenuifolia

In this study, a water-soluble polysaccharide was extracted from Polygonum tenuifolia to inhibit the proliferation of SPC-A-1 cells by the FAS/FAS-L-mediated pathway and autophagy. The molecular weight, composition, and structure of the Polygala tenuifolia polysaccharide (PTP) was detected by HPLC, HPAEC-PAD, NMR and FT-IR. The purified polysaccharide was composed of Ara, Gal, and Glc (molar ratio: 2.6:1.8:1.0) with α- and β-configurations. Morphological changes were observed with microscopes, and the cell apoptosis-related markers detected by flow cytometry indicated that apoptosis and autophagy occurred in the SPC-A-1 cells. Western blot analysis showed that the expression of proteins was related to apoptosis and autophagy. The death receptor pathway demonstrated the up-regulated expression of FAS, ligand FAS-L, and FADD, which led to a cascade reaction of the caspase family that induced cell apoptosis. The up-regulation of LC 3B-II and the down-regulation of P62 indicated the occurrence of autophagy. In summary, these results showed that PTP can induce FAS/FAS-L-mediated apoptosis and autophagy in SPC-A-1 cells, and provide a strong theoretical basis for tumor prevention and clinical application of PTP in the future.