[Proteomics analysis of Astragalus polysaccharide on TLR4-activated lung cancer cell-derived exosomes]

Astragalus polysaccharide(APS), one of the main active components of Astragali Radix, plays an anti-tumor effect by regulating the inflammatory microenvironment of tumors. Exosomes are small extracellular vesicles with a diameter ranging from 50 to 200 nm and carry several biological components from parental cells such as nucleic acids and proteins. When combined with recipient cells, they play an important role in intercellular communication and immune response. In this study, exosomes released from H460 cells at the inflammatory state or with APS addition activated by Toll-like receptor 4(TLR4) were extracted by ultracentrifugation and characterized by Western blot, transmission electron microscopy, and nanoparticle tracking analysis. The exosomal proteins derived from H460 cells in the three groups were further analyzed by label-free proteomics, and 897, 800, and 911 proteins were identified in the three groups(Con, LPS, and APS groups), 88% of which belonged to the ExoCarta exosome protein database. Difference statistical analysis showed that the expression of 111 proteins was changed in the LPS group and the APS group(P<0.05). The biological information analysis of the differential proteins was carried out. The molecular functions, biological processes, and signaling pathways related to the differential proteins mainly involved viral processes, protein binding, and bacterial invasion of proteasome and epithelial cells. Key differential proteins mainly included plasminogen activator inhibitor-1, laminin α5, laminin α1, and CD44, indicating that tumor cells underwent systemic changes in different states and were reflected in exosomes in the inflammatory microenvironment. The analysis results also suggested that APS might affect the inflammatory microenvironment through the TLR4/MyD88/NF-κB signaling pathway or the regulation of the extracellular matrix. This study is conducive to a better understanding of the mechanism of tumor development in the inflammatory state and the exploration of the anti-inflammatory effect of APS at the exosome level.