Effect of protein-bound polysaccharide (PSK) combined with paclitaxel (PTX) and carboplatin (CBDCA) in lung cancer cell lines Free

1903

Background and Objectives: PSK (Krestin®) is a protein-bound polysaccharide extracted from the cultured mycelium of Basidiomycetes. Combined use of PSK and chemotherapy has been shown to prolong the survival and response period in patients with gastric cancer, colorectal cancer and small cell lung cancer. In the present study, we studied the effect of a combination of PSK and standard chemotherapeutic agents (PTX and CBDCA) in lung cancer cell lines (NCI-H69 and NCI-H441). Methods: Cell proliferation was examined using the 3H-thymidine uptake method. The cell cycle analysis was performed by propidium iodide staining approach and flow cytometry. Results: No significant change was observed with PSK alone (25 to 100 μg/mL) whereas a dose-dependent growth inhibition was observed with PTX (0.1 to 1 nM) or CBDCA (1 to 10 μM) alone, and further augmentation of dose-dependent growth inhibition was observed when PSK was added in combination. At PTX concentrations of 1 nM and below, there were no changes in the proportion of cells in sub-G1 and G2/M phase in the absence of PSK, but the sub-G1 phase cells tended to increase in the presence of PSK. Conclusions: These results suggest that PSK augments the growth inhibitory effect of anti-cancer agents in lung cancer cells, and the mechanism partially involves induction of apoptosis. The detailed mechanisms are being investigated.