Changes in proliferation and apoptosis of human choriocarcinoma JAr and prostate cancer LNCaP cells induced by polysaccharide peptide (PSP) of Yun Zhi

Abstract

The effects of polysaccharide peptide (PSP) of Yun Zhi on proliferation and apoptosis of human choriocarcinoma JAr cells and prostate cancer LNCaP cells were investigated. Human JAr cells and LNCaP cells were respectively incubated for 24 h and 48 h in serum-free medium without and with PSP. PSP induced a decrease of thymidine incorporation into Jar and LNCaP cells in a concentration-dependent manner. Significant (p ! 0.01) decreases in thymidine incorporation into JAr cells and LNCaP cells were observed when the cells had been incubated with 0.32, 0.64, 1.28 or 2.56 mg/ml of PSP. Maximal inhibition of JAr cell proliferation to 13.8% of vehicle-treated control was recorded when PSP concentration was 2.56 mg/ml, whereas, the same concentration of PSP induced maximal inhibition of LNCaP cell proliferation to 49.1% of control. For apoptosis studies, Jar and LNCaP cells were incubated for 48 h in serum-free medium without and with PSP. After 48 h incubation, histone-complexed DNA fragments (mono- and oligonucleosomes) in the cytoplasm of apoptotic JAr cells and LNCaP cells were quantitated using the immunoassay kit, Cell Death Detection ELISA Plus (Roche Molecular Biochemicals). While high concentrations of PSP (1.28 and 2.56 mg/ml) induced significant (p ! 0.05) increase in JAr cell apoptosis, both low (0.32 and 0.64 mg/ml) and high (1.28 and 2.56 mg/ml) concen-trations of PSP were found to induce significant (p < 0.01) increase in LNCaP cell apoptosis. Our data support both anti-proliferative and apoptosis-inducing actions of PSP on human choriocarcinoma and prostate cancer cells in vitro. This work was supported by the TCM Research Fund of the Faculty of Medicine, The University of Hong Kong.