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  • Title: Increased cytochrome P-450 2E1 expression sensitizes hepatocytes to c-Jun-mediated cell death from TNF-alpha.
    Author: Liu H, Jones BE, Bradham C, Czaja MJ.
    Journal: Am J Physiol Gastrointest Liver Physiol; 2002 Feb; 282(2):G257-66. PubMed ID: 11804847.
    Abstract:
    The mechanisms underlying hepatocyte sensitization to tumor necrosis factor-alpha (TNF-alpha)-mediated cell death remain unclear. Increases in hepatocellular oxidant stress such as those that occur with hepatic overexpression of cytochrome P-450 2E1 (CYP2E1) may promote TNF-alpha death. TNF-alpha treatment of hepatocyte cell lines with differential CYP2E1 expression demonstrated that overexpression of CYP2E1 converted the hepatocyte TNF-alpha response from proliferation to apoptotic and necrotic cell death. Death occurred despite the presence of increased levels of nuclear factor-kappaB transcriptional activity and was associated with increased lipid peroxidation and GSH depletion. CYP2E1-overexpressing hepatocytes had increased basal and TNF-alpha-induced levels of c-Jun NH(2)-terminal kinase (JNK) activity, as well as prolonged JNK activation after TNF-alpha stimulation. Sensitization to TNF-alpha-induced cell death by CYP2E1 overexpression was inhibited by antioxidants or adenoviral expression of a dominant-negative c-Jun. Increased CYP2E1 expression sensitized hepatocytes to TNF-alpha toxicity mediated by c-Jun and overwhelming oxidative stress. The chronic increase in intracellular oxidant stress created by CYP2E1 overexpression may serve as a mechanism by which hepatocytes are sensitized to TNF-alpha toxicity in liver disease.
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