EFFECTS OF IFN-GAMMA, TNF-ALPHA AND EGF ON THE EXPRESSION OF HLA CLASS-I ANTIGEN AND THE PROLIFERATION OF HUMAN HEPATOCELLULAR-CARCINOMA HEPG2 CELLS

In this study, the effects of IFN gamma, TNF alpha and EGF on the expr ession of HLA class I antigen and the proliferation of human hepatocel lular carcinoma-HepG2 cells were investigated. In response to IFN gamm a or TNF alpha stimulation, the expression of HLA class I mRNA in HepG 2 cells was increased by 2-4 fold. Cell surface HLA class I antigen wa s also increased, but in comparison, the increase was not as high as H LA class I mRNA expression. This is probably due to the limitation of protein translation and post-translation processing. The enhancing eff ect of EGF on cell surface HLA class I antigen could be noted but was not very significant. IFN gamma and TNF alpha could also inhibit the p roliferation of HepG2 cells. Interestingly, the effect of EGF on the p roliferation of HepG2 cells depended on its concentration. At low conc entrations, EGF increased cell proliferation in terms of thymidine inc orporation. However, if the concentration of EGF was relatively high, it could also exert an inhibitory effect on thymidine incorporation in to the HepG2 cells. The remarkable morphological alteration was observ er when HepG2 cells were exposed to EGF at concentrations higher than 5 ng/ml. This morphological alteration might be associated with the in hibitory effect of EGF at high concentrations on the proliferation of HepG2 cells.