Solanum nigrum polysaccharide inhibits tumor growth in H22-bearing mice through regulation of caspase-3 and bcl-2

The objective of this study was to investigate the effect of Solanum nigrum polysaccharides (SNPs) on tumor growth in H22 hepatocarcinoma cells bearing mice and explore the mechanism by focusing on the regulation of the expression of caspase-3 and bcl-2.Totally, 50 mice bearing with H22 cells were randomly divided into five groups: Model group, cyclophosphamide group (CTX, 30 mg/kg), SNP groups with low, medium, and high doses of SNP (30, 60, and 120 mg/kg). Twenty-four hours after inoculation of H22 cells, CTX or SNP were given by gavage once a day for 10 days. The growth of tumor was observed. The tumor inhibition rate, indexes of the spleen and thymus were calculated. The immunohistochemical method was used for the determination of caspase-3 and bcl-2 expression in the tumor tissue.SNP (30, 60, and 120 mg/kg) reduced the average tumor weight compared with that in model group in a dose-dependent manner, and the tumor inhibition rates were 37.73%, 38.24%, and 42.60%, respectively. In addition, SNP dose dependently increased the index of the thymus compared with that of the CTX group. Immunohistochemistry results showed that the protein expression of caspase-3 in SNP groups was higher, but the expression of bcl-2 was lower than that in model group in a dose-dependent manner.SNP inhibited the growth of tumor in H22-bearing mice and protected the immune organ. The mechanism underlying the inhibition of tumor might be related to the upregulation of caspase-3 and downregulation of bcl-2.