Date of Award
Master of Science
Pharmacology and Toxicology
Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemo-and radio-therapy in Asia. Many clinical triais using PSP have been done in China. The most promising pharmacological activities of PSP are their immunomodulatory and anti-cancer effects. In this study, water soluble PSP extract (crude PSP) was prepared from a commercially available source. This crude PSP was shown to be an immunostimulant on the basis of its upregulation of nitric oxide, and prostaglandin E2 production in RAW264.7 cells. The anticancer effects included induction of apoptosis of B16 cells and inhibition of angiogenesis as determined by its reduction of matrigel-based tubulization of EA hy 926 cells. It also suppressed the mouse liver metastases induced by injection of melanoma cells via the portal vein. However, the active components of PSP are not known. Fractionation of crude PSP by Sephadex G-75 chromatography has yielded two major fractions: high molecular weight fraction (HMF, 16% by weight) and small molecular weight fraction (SMF, 50% by weight). Immunostimulatory activity of these fractions was examined in the stimulation of RAW264.7 cells. SMF was found to be 10 times more effective than crude PSP in the up-regulation of NO (EC50 values of 9.71 μg∕mL versus 158.8 μg∕mL), PGE2 as well as interferon-β (IFN-β). However, SMF was less active than crude PSP on iii induction of melanoma cells apoptosis. On the other hand, HMF was found to be primarily responsible for the anti-angiogenic effect of crude PSP. In vivo study in mice showed that SMF treatment (14 days) was more effective than crude PSP as an inhibitor of liver metastasis induced by injection of melanoma cells. SMF also upregulated immune response in vivo and ex vivo (macrophage function, proliferation of lymphocyte and elevation of serum IFN-β level); and these immunostimulatory effects may contribute to the anti-metastasis effect of SMF. Our data suggested that SMF was more potent than crude PSP on immunostimulation as well as inhibition of tumor liver metastases. The application of these products may be important in treatment of some tumors and cancer metastases.
Lu, Xuerong, "Characterization of Immunostimulation and Anti-cancer Activity of Poiysaccharide Peptide (PSP) with Special Reference to a Small Molecular Weight Fraction (SMF)" (2008). Digitized Theses. 4301.