Inflammation-Driven Downregulation of CYP2E1 Is Associated with Attenuated Diethylnitrosamine (DEN)-Induced Hepatocarcinogenesis

Inflammation is widely viewed as a driver of hepatocellular carcinoma (HCC), yet inflammatory signaling also reshapes hepatic xenobiotic metabolism. Here, we established transgenic (Tg) IKKβΔhep mice (Tg-IKKβΔhep), which combine hepatocyte-specific IKKβ deletion with liver expression of a nuclear, kinase-inactive IKKβ mutant (NLS-IKKβKN). Tg-IKKβΔhep mice developed spontaneous chronic hepatitis and progressive fibrosis but were strikingly resistant to diethylnitrosamine (DEN)-induced hepatocarcinogenesis, with markedly reduced tumor multiplicity and total tumor burden. Despite persistent inflammatory injury, DEN-triggered oxidative DNA damage and p53 activation were markedly attenuated, compatible with reduced tumor initiation. Transcriptomic and biochemical analyses revealed broad repression of xenobiotic-metabolizing cytochrome P450 genes, including the pericentral enzyme CYP2E1, accompanied by reduced CYP2E1 protein abundance. This was associated with impaired HNF4α–PXR–CAR transcriptional output and reduced HNF4α occupancy at target promoters. Acute TNFα or IL-1β exposure recapitulated this repression, in part through reduced PGC-1α expression and decreased RNA polymerase II recruitment to target promoters. In parallel, pericentral xenobiotic metabolism was blunted, a change that could plausibly diminish DEN bioactivation and genotoxic stress. Together, these findings support a “metabolic gatekeeping” model in which chronic inflammation can constrain chemical hepatocarcinogenesis by attenuating carcinogen-metabolizing capacity.