| Objective Through the establishment of rat liver cancer model, the role of Stichopus japonicus acid mucopolysaccharide(SJAMP) in the development of hepatocellular carcinoma induced by diethylnitrosamine(DEN) was explored in rats and the possible immunological mechanisms was determined.Methods50wistar rats were randomly divided into five groups:normal control group(group A), model group(group B), SAJMP low dose group (17.5mg/Kg, group C), SJAMP moderate dose group (35mg/Kg, group D), SJAMP high dose group (70mg/Kg, group E) by weight. In addition to normal control group, all the rats were given orally2%o DEN saline solution to the16th week to induce hepatocelluar carcinoma, meanwhile they were intervened with different doses of SJAMP during the process of carcinogenesis. All the rats were weighed once a week during the breeding, and at the end of the16th week, all the rats were anaesthetized by using chloral hydrate, blood samples were drew from the abdominal aorta; spleen and thymus were excised under sterile conditions and weighed, spleen index and thymus index were calculated. The number of the nodules more than3mm or5mm in diameter were counted, in addition, the size of the largest nodule were compared among groups. The tumor inhibitory rate was calculated. Macrophagocytes(Mf) were purified via attachment culture, macrophage phagocytosis was observed with phagocytosing neutral red method; spleen macrophage killing capability and NK(Natural killer) cell activity were measured by MTT method, the levels of serum TNF-a and IL-2were detected with enzyme linked immunosorbent assay(ELISA); T lymphocyte subsets in peripheral blood were analyzed by flow cytometry.Results①Compared with normal control group, the induced hepatic carcinoma rats gain weight slower, at the16th week, the weights of rats of group E was obviously increased when compared to model group B(P<0.05);②The serum ALT,AST,and GGT of the induced hepatic carcinoma rats, especially in model group, increased significantly when compared to those of the normal control group, with the increase of the SJAMP intervention dose, the above indicators decreased gradually, and there were significant differences compared with model group;③The thymus index of model group decreased (P<0.05), while the spleen index increased(P<0.05) when compared to normal group; with the implement of the SJMAP intervention, these two indicators incresed significantly(P<0.05), and a dose-response relationship has been presented;④ith the implement of the SJAMP intervention,The occurrence of liver tumors was significantly inhibited and the number of tumor nodules was obviously reduced, the number of nodules of SJAMP intervention group greater than3mm or5mm in diameter were significantly less than model group (P<0.05), and the average volume of the largest nodule was less than the model group (P<0.01);⑤The ability of phagocytosis of macrophagocytes of the model group and SJAMP intervention groups increased(P<0.05) when compared to normal group, SJAMP intervention groups increased more significantly, there were statistical differences among group D, group E and group C (P<0.01);⑥The killing capacity of macrophages of rats in model group reduced (P<0.01) compared to the normal group, however, the killing capacity of macrophages in the SJAMP intervention group increased when compared with model group(P<0.01);⑦ompared with normal group, natural killer cell activity decreased significantly (P<0.01), SJAMP intervention can enhance natural killer cell activity of the induced hepatic carcinoma rats(P<0.05);⑧Serum TNF-a level of rats in model group and SJAMP intervention group were higher than normal control group(P<0.01), suggesting that liver injuries have occurred in all the DEN induced hepatic carcinoma rats, there were statistical differences when compare group D and E with model group(P<0.01);⑨Serum IL-2level of model group was was significantly lower (P<0.01) than the normal control group, while the level of SJAMP intervention groups increased compared to model group(P<0.01);⑩D3+, CD4+T lymphocytes and CD4+/of CD8+ratio of model group were significantly lower than normal group(P<0.05), however, with the increase of the SJAMP intervention dose, CD3+CD4+, CD8+T lymphocytes and CD4+/CD8+ratio of the induced hepatic carcinoma rats were gradually increased.Conclusion Although the occurrence of liver cancer can not be completely blocked, but can be significantly inhibited by SJAMP. The possible mechanisms may be: SJAMP can stimulate the immune organs and tissues, protect the normal liver cells, cahance cell-mediated immunity ability of macrophage, natural killer and T lymphocytes, regulate cytokines which have anti-tumor effect,such as TNF-a and IL-2. |
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