Discipline of Medical Biochemistry, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
Discipline of Human Physiology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.
Exp Mol Pathol. 2018 Dec;105(3):334-344. doi: 10.1016/j.yexmp.2018.09.006. Epub 2018 Oct 2.
Rapamycin (sirolimus) is employed as an immunosuppressant following liver transplant, to inhibit the re-growth of cancer cells following liver resection for hepatocellular carcinoma (HCC), and for the treatment of advanced HCC. Rapamycin also induces the expression of antioxidant enzymes in the liver, suggesting that pretreatment with the drug could provide a potential strategy to reduce ischemia reperfusion injury following liver surgery. The aim of this study was to further investigate the actions of rapamycin in inducing expression of the antioxidant enzymes heme oxygenase-1 (HO-1) and peroxiredoxin-1 (Prx-1) in normal liver and in tumorigenic liver cells. A rat model of segmental hepatic ischemia and reperfusion, cultured freshly-isolated rat hepatocytes, and tumorigenic H4IIE rat liver cells in culture were employed. Expression of HO-1 and Prx-1 was measured using quantitative PCR and western blot. Rapamycin pre-treatment of normal liver in vivo or normal hepatocytes in vitro led to a substantial induction of mRNA encoding HO-1 and Prx-1. The dose-response curve for the action of rapamycin on mRNA expression was biphasic, showing an increase in expression at 0 - 0.1 μM rapamycin but a decrease from maximum at concentrations greater than 0.1 μM. By contrast, in H4IIE cells, rapamycin inhibited the expression of HO-1 and Prx-1 mRNA. Oltipraz, an established activator of transcription factor Nrf2, caused a large induction of HO-1 and Prx-1 mRNA. The dose response curve for the inhibition by rapamycin of HO-1 and Prx-4 mRNA expression, determined in the presence of oltipraz, was monophasic with half maximal inhibition at about 0.01 μM. It is concluded that, at concentrations comparable to those used clinically, pre-treatment of the liver with rapamycin induces the expression of HO-1 and Prx-1. However, the actions of rapamycin on the expression of these two antioxidant enzymes in normal hepatocytes are complex and, in tumorigenic liver cells, differ from those in normal hepatocytes. Further studies are warranted to evaluate preconditioning the livers of patients subject to liver resection or liver transplant with rapamycin as a viable strategy to reduce IR injury following liver surgery.
雷帕霉素（西罗莫司）在肝移植后被用作免疫抑制剂，以抑制肝癌（HCC）肝切除术后癌细胞的再生，并用于治疗晚期 HCC。雷帕霉素还诱导肝脏中抗氧化酶的表达，这表明药物预处理可能为减少肝手术后缺血再灌注损伤提供一种潜在策略。本研究旨在进一步研究雷帕霉素在诱导正常肝脏和肿瘤细胞中的抗氧化酶血红素加氧酶-1（HO-1）和过氧化物还原酶-1（Prx-1）表达中的作用。采用大鼠肝节段性缺血再灌注模型、新鲜分离的大鼠肝细胞培养物和培养的肿瘤源性 H4IIE 大鼠肝细胞。使用定量 PCR 和 Western blot 测量 HO-1 和 Prx-1 的表达。雷帕霉素预处理体内正常肝或体外正常肝细胞导致 HO-1 和 Prx-1 的 mRNA 编码大量诱导。雷帕霉素对 mRNA 表达作用的剂量反应曲线呈双相性，在 0-0.1 μM 雷帕霉素时表达增加，但在浓度大于 0.1 μM 时表达减少。相比之下，在 H4IIE 细胞中，雷帕霉素抑制 HO-1 和 Prx-1 mRNA 的表达。奥替普拉，一种已建立的转录因子 Nrf2 激活剂，引起 HO-1 和 Prx-1 mRNA 的大量诱导。在奥替普拉存在下，雷帕霉素抑制 HO-1 和 Prx-4 mRNA 表达的剂量反应曲线呈单相性，半最大抑制浓度约为 0.01 μM。结论是，在与临床使用浓度相当的浓度下，用雷帕霉素预处理肝脏可诱导 HO-1 和 Prx-1 的表达。然而，雷帕霉素对正常肝细胞中这两种抗氧化酶表达的作用是复杂的，并且在肿瘤源性肝细胞中与正常肝细胞中的作用不同。需要进一步研究评估将雷帕霉素预处理接受肝切除术或肝移植的患者的肝脏作为减少肝手术后缺血再灌注损伤的可行策略。
