Abstract: Objective: To explore the effect of Ganoderma lucidum polysacchrides (GLP) combined with fluorouracil treatment on the proliferation and apoptosis of human colon carcinoma HCT-116 cells in vitro. Methods: The inhibitory effects of both drugs on the proliferation of HCT-116 cells were measured by using MTT assay. The combinatorial index method was used to analyze their synergistic inhibitory effect. Observations of morphological changes were carried out with Hoechst33258 fluorescence staining. The impact of GLP on cell cycle and apoptosis rate of HCT-116 cells was evaluated by flow cytometry (FCM). Results: GLP and 5-FU treatment alone suppressed the proliferation of HCT-116 cells. GLP treatment (＞659 μg/mL) in combination with 5-FU (＞1.6 μg/mL) revealed an obvious synergistic effect on the proliferation of HCT-116 cells (CI＜1) which exhibited a significant difference when compared with 5-FU treatment alone (P＜0.01) in a time-dependent manner. After treatments for 48 h, the cells showed typical apoptosis characteristics. The apoptotic HCT-116 cells were 36.14% after GLP (5 mg/mL) combined with 5-FU (50μg/mL) treatment for 24 h, which was higher than that obtained from 5-FU treatment alone (26.07%). The apoptotic HCT-116 cells induced by 1.25 mg/mL GLP combined with 12.5μg/mL 5-FU, 2.5 mg/mL GLP combined with 25μg/mL 5-FU, and 5 mg/mL GLP combined with 50μg/mL 5-FU for 48 h were 20.95%, 32.87% and 30.01%, respectively, showing an increase compared with 5-FU (50 μg/mL) treatment alone (14.51%). The arrested cell cycle in combinatorial treatment group was observed at S phase. Conclusion: GLP at higher concentration combined with 5-FU can synergistically suppress the proliferation of human colon cancer HCT-116 cells, and enhanced apoptosis and cell cycle arrest in HCT-116 cells.

Key words: Ganoderma lucidum polysacchrides, colon carcinoma, fluorouracil, apoptosis, cell cycle