Abstract
IkappaB kinase beta (IKKbeta), required for NF-kappaB activation, links chronic inflammation with carcinogenesis. We investigated whether IKKbeta is involved in chemically induced liver cancer, a model not involving overt inflammation. Surprisingly, mice lacking IKKbeta only in hepatocytes (Ikkbeta(Deltahep) mice) exhibited a marked increase in hepatocarcinogenesis caused by diethylnitrosamine (DEN). This correlated with enhanced reactive oxygen species (ROS) production, increased JNK activation, and hepatocyte death, giving rise to augmented compensatory proliferation of surviving hepatocytes. Brief oral administration of an antioxidant around the time of DEN exposure blocked prolonged JNK activation and compensatory proliferation and prevented excessive DEN-induced carcinogenesis in Ikkbeta(Deltahep) mice. Decreased hepatocarcinogenesis was also found in mice lacking IKKbeta in both hepatocytes and hematopoietic-derived Kupffer cells. These mice exhibited reduced hepatocyte regeneration and diminished induction of hepatomitogens, which were unaltered in Ikkbeta(Deltahep) mice. IKKbeta, therefore, orchestrates inflammatory crosstalk between hepatocytes and hematopoietic-derived cells that promotes chemical hepatocarcinogenesis.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Carcinogens
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Cell Death / drug effects
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Cell Death / physiology*
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Cell Proliferation / drug effects
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Cell Transformation, Neoplastic / chemically induced
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Cell Transformation, Neoplastic / genetics
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Cell Transformation, Neoplastic / metabolism*
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Cytokines / metabolism*
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Diethylnitrosamine
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Disease Models, Animal
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Female
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Hepatocytes / drug effects
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Hepatocytes / metabolism*
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Hepatocytes / pathology
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I-kappa B Kinase
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Inflammation / chemically induced
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Inflammation / genetics
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Inflammation / metabolism
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JNK Mitogen-Activated Protein Kinases / drug effects
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JNK Mitogen-Activated Protein Kinases / metabolism
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Kupffer Cells / metabolism
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Liver Neoplasms, Experimental / chemically induced
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Liver Neoplasms, Experimental / genetics
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Liver Neoplasms, Experimental / metabolism*
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Liver Regeneration / drug effects
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Liver Regeneration / genetics
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Male
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Mice
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Mice, Inbred C57BL
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Mice, Knockout
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Mice, Transgenic
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Oxidative Stress / drug effects
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Oxidative Stress / genetics
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Protein Serine-Threonine Kinases / genetics*
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Protein Serine-Threonine Kinases / metabolism
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Reactive Oxygen Species / antagonists & inhibitors
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Reactive Oxygen Species / metabolism
Substances
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Carcinogens
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Cytokines
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Reactive Oxygen Species
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Diethylnitrosamine
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Protein Serine-Threonine Kinases
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Chuk protein, mouse
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I-kappa B Kinase
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Ikbkb protein, mouse
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Ikbke protein, mouse
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JNK Mitogen-Activated Protein Kinases