The surface morphology of Platycodon grandiflorus polysaccharide and its anti-apoptotic effect by targeting autophagy.

BACKGROUND

Fumonisin B1 is categorised as possible carcinogenic to humans which commonly contaminate maize and maize-based products worldwide, FB1, like other environmental pollutants, may activate apoptosis, autophagy, the inflammatory response and oxidative stress. Platycodon grandiflorus polysaccharide (PGPS) is prepared from a traditional herbal medicine in Asia with tremendous pharmacological activities. However, whether PGPS could relieve FB1-induced apoptosis has not been elucidated. The study aimed to evaluate the surface morphology of PGPS and its protective effect on fumonisin B1-induced apoptosis.

METHODS

The surface morphology of PGPS was evaluated by SEM and AFM. Expressions of proteins involved in autophagy and apoptosis were detected by western blot analysis. Western blot, transient transfection, JC-1 and Annexin V-FITC/PI staining, CCK8, Live-cell imaging and autophagy inhibitor were used to observe the effect and explore the mechanism of PGPS on FB1-induced apoptosis of 3D4/21 cells.

RESULTS

PGPS had triple helix conformation, and had the characteristics of compact, polyporous and agglomerated morphology. PGPS promoted the expression of LC3-II and Beclin1, reduced the expression of p62, and significantly activated autophagy. PGPS inhibited the Akt/mTOR signaling pathway at 24 h. Besides, PGPS increased the expression of Bcl-2 and decreased the expression of Cleaved Caspase-3. PGPS-mediated autophagy was inhibited by 3-MA, accompanied by the upregulation of Caspase-3 and Cleaved Caspase-3, suggesting that enhanced autophagy inhibited apoptosis.

CONCLUSION

PGPS can activate autophagy, which in turn protects FB1-induced apoptosis. Targeting autophagy may provide a new way to improve the health of humans or animals in FB1 contaminated areas.