TCPOBOP-Induced Hepatomegaly and Hepatocyte Proliferation are Attenuated by Combined Disruption of MET and EGFR Signaling

Hepatology. 2019 Apr;69(4):1702-1718. doi: 10.1002/hep.30109. Epub 2018 Dec 31.

Abstract

TCPOBOP (1,4-Bis [2-(3,5-Dichloropyridyloxy)] benzene) is a constitutive androstane receptor (CAR) agonist that induces robust hepatocyte proliferation and hepatomegaly without any liver injury or tissue loss. TCPOBOP-induced direct hyperplasia has been considered to be CAR-dependent with no evidence of involvement of cytokines or growth factor signaling. Receptor tyrosine kinases (RTKs), MET and epidermal growth factor receptor (EGFR), are known to play a critical role in liver regeneration after partial hepatectomy, but their role in TCPOBOP-induced direct hyperplasia, not yet explored, is investigated in the current study. Disruption of the RTK-mediated signaling was achieved using MET knockout (KO) mice along with Canertinib treatment for EGFR inhibition. Combined elimination of MET and EGFR signaling [MET KO + EGFR inhibitor (EGFRi)], but not individual disruption, dramatically reduced TCPOBOP-induced hepatomegaly and hepatocyte proliferation. TCPOBOP-driven CAR activation was not altered in [MET KO + EGFRi] mice, as measured by nuclear CAR translocation and analysis of typical CAR target genes. However, TCPOBOP-induced cell cycle activation was impaired in [MET KO + EGFRi] mice due to defective induction of cyclins, which regulate cell cycle initiation and progression. TCPOBOP-driven induction of FOXM1, a key transcriptional regulator of cell cycle progression during TCPOBOP-mediated hepatocyte proliferation, was greatly attenuated in [MET KO + EGFRi] mice. Interestingly, TCPOBOP treatment caused transient decline in hepatocyte nuclear factor 4 alpha expression concomitant to proliferative response; this was not seen in [MET KO + EGFRi] mice. Transcriptomic profiling revealed the vast majority (~40%) of TCPOBOP-dependent genes primarily related to proliferative response, but not to drug metabolism, were differentially expressed in [MET KO + EGFRi] mice. Conclusion: Taken together, combined disruption of EGFR and MET signaling lead to dramatic impairment of TCPOBOP-induced proliferative response without altering CAR activation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle
  • Cell Proliferation
  • Constitutive Androstane Receptor
  • ErbB Receptors / metabolism*
  • Female
  • Forkhead Box Protein M1 / metabolism
  • Gene Expression Profiling
  • Hepatocyte Nuclear Factor 4 / metabolism
  • Hepatocytes / physiology
  • Hepatomegaly / chemically induced
  • Hepatomegaly / metabolism*
  • Hippo Signaling Pathway
  • Mice, Knockout
  • Protein Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins c-met / metabolism*
  • Pyridines
  • Receptors, Cytoplasmic and Nuclear / agonists
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Signal Transduction

Substances

  • Constitutive Androstane Receptor
  • Forkhead Box Protein M1
  • Foxm1 protein, rat
  • Hepatocyte Nuclear Factor 4
  • Pyridines
  • Receptors, Cytoplasmic and Nuclear
  • 1,4-bis(2-(3,5-dichloropyridyloxy))benzene
  • ErbB Receptors
  • Proto-Oncogene Proteins c-met
  • Protein Serine-Threonine Kinases