| Ganoderma lucidum Polysaccharides, (GLP), are a fraction of polysaccharidesisolated from the fruiting body of Ganoderma lucidum (Leyss ex Fr. Karst.), whichare water-soluble. Numerous studies have demonstrated that Ganoderma lucidumpolysaccharides have immmunomodulatory and anti-tumor effects and the majorityof reports implied that Ganoderma lucidum polysaccharides have no directinhibitory or killing effects on tumor cells, whereas the polysaccharides showmarked anti-tumor effect in vivo. In this regard, it is generally believed that theanti-tumor effect of Ganoderma lucidum polysaccharides is mediated throughenhancement of the immune function. A lot of researchers have studied themechanism of anti-tumor action of Ganoderma lucidum polysaccharides fromimmunological perspective and made remarkable progress, but the exact mechanismis still unclear. It is, therefore, necessary for the mechanism to be studied further.Objective:1.To investigate the immunological mechanism of the anti-tumor effect ofGanoderma lucidum polysaccharides (GLP) by analyzing the relationship betweenthe weight of tumor and the amount of immunocytes.2.To investigate the effect of Ganoderma lucidum polysaccharides (GLP) on nucleotides and cell cycle distribution of the tumor cells in S-180 ascitictumor-beating mice and explore the possible mechanism of the antiturnor effect ofGLP.Methods:1.Forty mice bearing sarcoma 180 (S-180) were randomized into 3 GLP-treatedgroups and one control group. The mice in GLP-treated groups were subjected to i.g.administration of GLP daily at doses of 400, 200 and 100 mg/kg body weight for 9consecutive days, respectively. The control group mice were given normal saline inthe same way. After completion of the treatment, blood samples were collected fromthe mice for the counting of leukocytes and lymphocytes using a blood cell analyzer.Flow cytometry was performed to detect the percentages of the T cell subpopulations.The mice were then sacrificed. The implant tumors were isolated and weighed beforeprepared into paraffin sections for HE staining and microscopic examination.Quantitative stereologic morphometry was employed to measure the volume density(percentage) of the immune cells in the tumor.2. Mice beating S-180 ascitic tumor were subjected to intragastric administration ofGLP (100, 200, and 400 mg/kg), normal saline or subcutaneous injection ofcyclophosphamide (CTX) at 25 mg/kg, respectively. The treatment was given oncedaily for 9 consecutive days, and then the ascitic tumor cells were harvested fordetermination of the RNA and DNA content and their ratio as well as the cell cyclealterations. Laser scanning confocal microscopy and acridine orange staining wasperformed to evaluate the DNA and RNA fluorescence intensity, and flow cytometrywith propidium iodide (PI) staining was utilized for cell cycle analysis of the tumorcells. Results:1. GLP treatment resulted in the tumor inhibition rates of 37.85%, 45.67%, and17.98% corresponding to the doses of 400, 200, and 100 mg/kg, respectively,showing the best effect at the dose of 200 mg/kg (p＜0.01). The GLP-treated mice allhad greater total counts of leukocytes and lymphocytes than the control mice, and200 mg/kg GLP caused the most obvious increment in the number of the immunecells (p＜0.01). Compared with the control group, the 3 GLP-treated groups all hadsignificantly higher CD4~+/CD8~+ ratio and percentage of lymphocytes in the tumor,which were both the highest in 200mg/kg group (p＜0.01). Correlation analysisindicated positive correlations between each of the immunological indices and thetumor inhibition rate.2.Compared with normal saline group, the tumor cells in the 3 GLP groups allshowed reduced RNA and DNA contents, and this reduction was statisticallysignificant in 200 mg/kg GLP group (P=0.000). Significantly reduced RAN/DNAratio was noted in all the 3 GLP groups (P=0.003, 0.000, 0.008 corresponding to 400,200, and 100 mg/kg groups), suggesting that ganoderma polysaccharides moreeffectively reduced RNA content than DNA content. CTX also resulted in reducedRNA and DNA contents but not the RNA/DNA ratio. At the doses of 400, 200, and100 mg/kg, GLP increased the percentage of G0/G1 phase cells (P=0.003, 0.000,and 0.000) whereas CTX showed the contrary effect (P=0.000). GLP produced noobvious effect on S phage cells but CTX significantly reduced their percentage(P=0.000). GLP at the 3 doses all decreased the percentage of G2/M phase tumorcells (P=0.014, 0.049, 0.016) and CTX again took contrary effect (P=0.000).Conclusion:1. GLP exerts its anti-tumor effect possibly through promoting the proliferation anddifferentiation of immune cells and as a result increasing the immune cffector cellsin the tumor-bearing mice. 2. With different effect on DNA and RNA contents and cell cycle from CTX, GLPinhibit DNA and RNA synthesis in the tumor cells by mobilizing the host immunefunction to interfere with the normal cell cycles, which might be one of themechanisms for the antitumor effect of GLP. |
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