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

Inflammation is widely viewed as a driver of hepatocellular carcinoma (HCC), yet inflammatory signaling also reshapes hepatic xenobiotic metabolism. Here, we established transgenic (Tg) IKKβ^Δhep mice (Tg-IKKβ^Δhep), which combine hepatocyte-specific IKKβ deletion with liver expression of a nuclear, kinase-inactive IKKβ mutant (NLS-IKKβKN). Tg-IKKβ^Δhep 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.