Molecular mechanism of Antrodia cinnamomea sulfated polysaccharide on the suppression of lung cancer cell growth and migration via induction of transforming growth factor β receptor degradation

Abstract

A sulfated polysaccharide of edible mushroom Antrodia cinnamomea (SPS) has been identified as a novel immunomodulatory agent. We examined the anti-cancer effects of SPS by conducting a series of in vitro studies. We found that SPS inhibits the growth of A549 and LLC1 lung cancer cells via the induction of cell cycle arrest and activation of caspase 3 and PARP. By contrast, we found that a non-sulfated polysaccharide of A. cinnamomea (NSPS) does not inhibit lung cancer cell viability. Moreover, NSPS does not induce changes in cell cycle distribution or activate apoptosis-related molecules in both A549 and LLC1 cells. High expression of transforming growth factor β (TGFβ) and TGFβ receptors (TGFRs) is correlated with lung tumorigenesis. SPS suppresses TGFβ-induced intracellular signaling events, including phosphorylation of Smad2/3, FAK, Akt, and cell migration. By contrast, non-sulfated polysaccharide (NSPS) does not exhibit the similar biological functions in both A549 and LLC1 cells. Mechanistically, we demonstrated SPS effectively reduces TGFR protein levels via induction of proteasome-dependent degradation pathway. Our study is the first to identify the pivotal role of SPS in the induction of TGFR degradation and activation of Caspase 3 and PARP, which leads to suppress viability and migration of lung cancer cells.