A polysaccharide from the leaves of Aralia elata induces apoptosis in U-2 OS cells via mitochondrial-dependent pathway

In the present study, we isolated and characterized one purified polysaccharide (AEP-1) from the leaves of Aralia elata, and investigated its effect on human osteosarcoma (OS) U-2 OS cell line and analyzed its mechanism. MTT assays showed that AEP-1 markedly inhibited the growth of U-2 OS cells in a dose- and time-dependent fashion, suggesting a cytotoxic effect. The AEP-1 also dose-dependently induced DNA fragmentation and caused apoptotic death in U-2 OS cells. The event of apoptosis was accompanied by increased ratio of Bax/Bcl-2, depolarization of mitochondrial membrane potential (Δym) and the release of cytochrome c from mitochondria into the cytoplasm. Moreover, AEP-1 treatment triggered the activation of caspase-9 and caspase-3, as well as the cleavage of poly (ADP-ribose) polymerase (PAPR) in U-2 OS cells. All these results suggests that the induction of apoptosis by AEP-1 in U-2 OS cells occurs through the mitochondria-dependent pathway and AEP-1 may be useful in treating OS and improving cancer chemotherapy.