Ginger polysaccharide promotes myeloid-derived suppressor cell apoptosis by regulating lipid metabolism.

Recently, targeting myeloid-derived suppressor cells (MDSCs) which mainly play an immunosuppressive role in tumor microenvironment has become a hot spot in tumor immunotherapy. This study focuses on biological effect of ginger polysaccharide extracted from natural plants on promoting apoptosis of MDSCs by regulating lipid metabolism. An MTT assay was used to detect the inhibitory effect of ginger polysaccharide on the growth of an MDSC-like cell line (MSC-2). The apoptosis-promoting effect of ginger polysaccharide on MSC-2 cells was detected by flow cytometry. Expression levels of apoptosis proteins (caspase 9 and Bcl-2) and lipid metabolism enzymes (fatty acid synthase (FASN) and diacylglycerol acyltransferase 2) in MSC-2 cells treated with different concentrations of ginger polysaccharide were detected by western blot assay. Nile red staining was used to quantitatively detect the effect of ginger polysaccharide on lipid droplet synthesis. Ginger polysaccharide inhibited proliferation of MSC-2 cells and promoted their apoptosis by upregulating pro-apoptotic caspase 9 protein, downregulating anti-apoptotic Bcl-2 protein, inhibiting expression of FASN and diacylglycerol acyltransferase 2 (key enzymes in fatty acid synthesis and lipid droplet formation, respectively). Ginger polysaccharide promoted apoptosis of MDSCs by regulating key lipid metabolism enzymes, inhibiting fatty acid synthesis and lipid droplet accumulation, and reducing the energy supply of cells.