ABSTRACT
ObjectiveTo investigate the inhibitory effect of 1-methyl-tryptophan (1-MT) on transplanted hepatocellular carcinoma in mice.MethodsHuman hepatocellular carcinoma subcutaneous tumor models were established in mice,and the mice were divided into hepG2 group,empty plasmid group,indoleamine 2,3-dioxygenase (IDO) saline group,IDO) 5-fluoropyrimidine (5-FU) group,IDO 1-MT group,and the group combining IDO 1-MT with 5-FU treatment (n=8 in each group).The tumor growth,tumor volume and pathological examination were observed and the expression of IDO in tumor tissues was determined by immunohistochemistry.ResultsCompared with hepG2 and the empty vector saline groups,IDO saline group had bigger tumor,faster growth,and the differences were statistically significant (P＜0.05).Compared with IDO saline group,5-FU group,1-MT group and combination treatment groups showed smaller tumor volume and weight,and the tumor inhibitory rates were 86.54％,79.95％,94.46％,respectively.There were significant differences between these groups (P＜0.05).However,there were no significant differences in tumor volumes between 5-FU group and 1-MT group (P＞0.05).HE pathological observation of ceils in each treatment group showed reduced density,increased necrotic area and significant decrease in peripheral blood alpha-fetoprotein (P＜0.05).ConclusionsIDO can promote the growth of liver cancer cells involved in immune escape.1-MT can inhibit the transplanted tumor growth in mice,and therefore may enhance the chemotherapeutic efficacy.
ABSTRACT
Clonal suppression induced by CD4+ CD25+ regulatory T cells is one of the principal factors to evoke the immune tolerance in tumor. Through the activation of CD4+ CD25+ regulatory T cells, the indoleamine 2,3-dioxygenase (IDO) reduces the immune response in tumor micro-environment of various systems , and induces the formation of host immune tolerance. IDO inhibitor 1-MT is expected to become a new target for cancer treatment.