The Regulatory Effects Of Indoleamine 2,3-dioxygense On HCC

Background and Objective In a lot of tumor microenvironments.IDO have a important role in enabling tumors to escape the immune system , but the mechanism of this function is still in research. To investigate the change of hepatocyte activation and apoptosis with IDO and Tryptophan calabolism ( L-Kynurenine,Anthranilic acid,Quinolinic acid ).Methods The activity of HepG₂ cells was detected with MTT method after treated with different concentration of IDO.Then investigate the change of the activity after adding 1-MT(the inhibitor of IDO)at the same time. The activity ,apoptosis and necrosis was detected with MTT method and flow cytometry assay after influence of different Tryptophan calabolism.Result The effect of IDO on HepG₂ cells was dependent on the time and concentration obviously. At the density of 0.5 mmol/L and 5 mmol/L ,IDO can accelerate the growth of HepG₂ cells(P<0.05).For example,at the best treated time ,24h,the Optical Density number (OD) of this two groups was 1.28±0.04 and 1.31±0.02 which was higher than control group ,0.73±0.03.The effect of IDO was inhibited by I-MT . Among Tryptophan calabolisms , L-Kynurenine or Anthranilic acid can accelerate the growth of HepG₂ cells and this effect was dependent on the time and concentration obviously. At the density of 0.1 mmol/L and treat 24h, percentages of inhibition was(-32.94±1.05)% and (-65.15±0.46)%. At the density of 1 mmol/L and treat 24h, percentages of inhibition was(-50.58±1.12)%å’Œ(-78.62±0.92)%. Through flow cytometry assay ,these two calabolisms can change cells cycle distribution (shorten G0-G1period and prolong S period). only Quinolinic acid can inhibit the growth of HepG₂ cells by enhancing apoptosis and necrosis when its density is 1mmol/L(P<0.05).The best treated time was 24h.At this time, percentages of apoptosis was (9.01±0.24)%,and percentages of necrosis was (23.43±2.16)%Conclusion IDO can accelerate the growth of HepG₂ cells. I-MT can inhibit the effect of IDO. L-Kynurenine or Anthranilic acid can accelerate the growth of HepG₂ cells(through shortenning G0-G1period and prolonging S period). At a high density,Quinolinic acid can inhibit the growth of HepG₂ cells,the major mechanism was that it can enhance the apoptosis of HepG₂ cells.