Cellular and Molecular Gastroenterology and Hepatology (Jan 2024)
Hepatocyte-specific Epidermal Growth Factor Receptor Deletion Promotes Fibrosis but has no Effect on Steatosis in Fast-food Diet Model of Metabolic Dysfunction-associated Steatotic Liver DiseaseSummary
Abstract
Background & Aims: Metabolic dysfunction-associated steatotic liver disease (MASLD) has become the most prevalent chronic liver disorder, with no approved treatment. Our previous work demonstrated the efficacy of a pan-ErbB inhibitor, Canertinib, in reducing steatosis and fibrosis in a murine fast-food diet (FFD) model of MASLD. The current study explores the effects of hepatocyte-specific ErbB1 (ie, epidermal growth factor receptor [EGFR]) deletion in the FFD model. Methods: EGFRflox/flox mice, treated with AAV8-TBG-CRE to delete EGFR specifically in hepatocytes (EGFR-KO), were fed either a chow-diet or FFD for 2 or 5 months. Results: Hepatocyte-specific EGFR deletion reduced serum triglyceride levels but did not prevent steatosis. Surprisingly, hepatic fibrosis was increased in EGFR-KO mice in the long-term study, which correlated with activation of transforming growth factor-β/fibrosis signaling pathways. Further, nuclear levels of some of the major MASLD regulating transcription factors (SREBP1, PPARγ, PPARα, and HNF4α) were altered in FFD-fed EGFR-KO mice. Transcriptomic analysis revealed significant alteration of lipid metabolism pathways in EGFR-KO mice with changes in several relevant genes, including downregulation of fatty-acid synthase and induction of lipolysis gene, Pnpla2, without impacting overall steatosis. Interestingly, EGFR downstream signaling mediators, including AKT, remain activated in EGFR-KO mice, which correlated with increased activity pattern of other receptor tyrosine kinases, including ErbB3/MET, in transcriptomic analysis. Lastly, Canertinib treatment in EGFR-KO mice, which inhibits all ErbB receptors, successfully reduced steatosis, suggesting the compensatory roles of other ErbB receptors in supporting MASLD without EGFR. Conclusions: Hepatocyte-specific EGFR-KO did not impact steatosis, but enhanced fibrosis in the FFD model of MASLD. Gene networks associated with lipid metabolism were greatly altered in EGFR-KO, but phenotypic effects might be compensated by alternate signaling pathways.
