Abstract
A homogenous polysaccharide (APP), with a molecular weight of 120 kDa, was isolated from the dried aerial parts of Agrimonia pilosa. Gas chromatography (GC) and GC-MS analysis revealed that APP has a backbone of 1,3-linked Glcp and 1,3, 6-linked Glcp, and branched with 1-linked Glcp terminal along the main chain in a relative ratio of 2:1:1. We investigated the response of human osteosarcoma U-2 OS cells to APP treatment. MTT result showed that APP significantly inhibited cell viability in a concentration dependent manner via induction of apoptotic death in U-2 OS cells, as determined by annexin V/propidium iodide (PI) staining. Western blot analysis also indicated that APP CRA increased in Bax/Bcl-2 ratios by up-regulating Bax expression and triggered the release of cytochrome c from mitochondria into the cytoplasm. Moreover, APP supplement induced the activation of caspase-3, and -9, but not caspase-8 in U-2 OS cells. Likewise, APP administration significantly suppressed tumor growth in BALB/C nude mice bearing U-2 OS xenograft tumors. All these results indicate that APP-induced apoptosis is associated with the activation of a caspase-3-mediated mitochondrial pathway.