中国生物工程杂志

Objective:To explore after indoleamine-2,3-dioxygenase(IDO)gene transfection the influence of the hepatocellular carcinoma cells’ apoptosis and the related cellular immune mechanisms by cell culture and in vivo. Methods: By cell culture and gene transfection technology,T-lymphocytes freshly isolated from healthy people and hepatocellular carcinoma cells were cocultured. The experiments were divided into six groups: T-lymphocytes and HepG2 cells group, T-lymphocytes and pcDNA3.1-HepG2 cells group, T-lymphocytes and pcDNA3.1-IDO-HepG2 cells group,and the three intervention groups which were added to IDO inhibitor 1-MT(1-methyl-tryptophan) on the basis of the above three groups. After two days of combine reaction, the apoptosisrate of HepG2 cell and the cytotoxicity of T-lymphocyte against HepG2 cell were examined by flow cytometer and MTT assay. After five days in mixed culture,the percentage of regulatory T cells(Treg) were analyzed by flow cytometer. Through establishment of the mouse model of human liver cancer cells, the percentage of Treg cells in peripheral blood of mouse was analyzed by flow cytometer. Results: 1.After two days of combine reaction, the apoptosis rate of HepG2 cell and the cytotoxicity of T-lymphocyte against HepG2 cell in IDO-HepG2 group were significantly lower than which in pcDNA3.1-HepG2 and HepG2 groups. They were respectively (1.65 ±0. 14) % and (35.00±2.20)% (p<0.05). With 1-MT groups, the above indexes were significantly higher than before the intervention (p<0.05). 2.After five days in mixed culture,the percentage of Treg cells in IDO-HepG2 group was significant higher and that was(10.53±1.05)%,it was considered statistically significant compared with the control group without 1-MT. In adding 1-MT groups, it decreased significantly (p<0.05). 3.In the mouse model of human liver cancer cells, the percentage of Treg cells in peripheral blood of IDO-HepG2 group increased significantly, that is (15.33 ±1.18)% and compared with the other two groups was statistically significant (p<0.05). Conclusion: 1.Though increasing the percentage of Treg cells in T-lymphocytes, IDO can suppress the apoptosis rate of hepatocellular carcinoma cells and the cytotoxicity of T-lymphocyte. 1-MT can reverse the role of IDO. 2.In vivo test, it can be confirmed that over-expression of IDO can increase the proportion of Treg cells in peripheral blood.