Dipsacus asperoides polysaccharide induces apoptosis in osteosarcoma cells by modulating the PI3K/Akt pathway

An alkaline extractable and water-soluble polysaccharide (ADAPW), with an average molecular weight of 16 kDa, was purified from the alkaline extraction of the roots of Dipsacus asperoides. Monosaccharide component analysis indicated that ADAPW was composed of glucose, rhamnose, arabinose and mannose in a molar ratio of 8.54:1.83:1.04:0.42. This study aimed to investigate the effect of ADAPW on the viability of human osteosarcoma cell line HOS cells, and explore the possible mechanisms. The results revealed that ADAPW inhibited the proliferation of HOS cells in a dose-dependent manner by inducing apoptosis. Furthermore, treatment with ADAPW caused a loss of mitochondrial membrane potential and accumulation of reactive oxygen species (ROS). In addition, Western blot analysis demonstrated that ADAPW down-regulated the protein expressions of PI3K and phosphorylated Akt (pAkt) in HOS cells. Taken together, induction of apoptosis on HOS cells by ADAPW was mainly associated with ROS production, mitochondrial dysfunction, and inhibition of PI3K/Akt signaling pathway. So this finding suggests that ADAPW may be potentially effective in cancer prevention against human osteosarcoma. (C) 2013 Elsevier Ltd. All rights reserved.