Ganoderma atrum polysaccharide modulates TNF-α secretion and mRNA expression in macrophages of S-180 tumor-bearing mice

Previous researches focused on the chemical structure of Ganoderma atrum polysaccharide (PSG-1), and found it has antitumor and immunoregulatory activities. However, the mechanisms behind these biological activities remain unclear. The purpose of this study was to investigate the possible signaling pathways involved in the PSG-1 activated macrophage of S180 tumor-bearing mice. In vitro, PSG-1 probably stimulated macrophages resulting in an increase in phosphorylation of NF-kappa B, Akt and MAPK family proteins, which are indicative of activations of NF-kappa B pathway activation. Furthermore, the levels of TNF-alpha protein and TNF-alpha mRNA expression were significantly suppressed when macrophages were pretreated with various inhibitors, including NF-kappa B inhibitors, I kappa B inhibitors, MAPK inhibitors and PI3K/Akt inhibitors. These findings indicated the possible involvement of NF-kappa B signaling pathway in PSG-1-induced TNF-alpha secretion and mRNA expression, and provided new insights into the therapeutic potential of modulating NF-kappa B by PSG-1. (C) 2015 Elsevier Ltd. All rights reserved.