鉄存在下HepG2細胞におけるTNF-α/actinomycin D処理による肝障害モデルの構築

We examained the contribution of iron to the cytotoxicity of tumor necrosis factor (TNF)-a combined with actinomycin D (ActD) as a model of hepatocyte injury in Hep G2 cells. In general,hepatocytes are resistant to TNF-a. However,a transcriptional inhibitor such as ActD can sensitize then to TNF-a. In the present study, we show that low levels of ActD (0.5nM) sensitized HepG2 cells to the cytotoxic effects of TNF-a (20 ng/mL) for 48h. Iron plays a critical role in catalyxing the formation of potent oxidants. To acsses the toxicological significance of this TNF-a/ActD interaction,ferric-nitrilotriacetate (Fe-NTA,2uM) was added to the cells. Treatment with Fe-NTA significantly increased the sensitivity to the TNF-a/ActD-mediated cell death. TNF-a/ActD-mediated cell death in the presence of a lower concentration of iron did not result in DNA fragmentation. We suggest that iron increased the sensitivity to the cytotoxicity of TNF-a/ActD in HepG2 cells. It is likely that TNF-a/ActD/Fe-NTA-mediated cell death contributes to the non-apoptotic death of cells via oxidative stress caused by iron. Our experimental model may be useful for studying hepatic drug metabolism using TNF-a as a hepatocyte injury,especially in HepG2 cells