Murine cirrhosis induces hepatocyte epithelial mesenchymal transition and alterations in survival signaling pathways

Takashi Nitta, Jae Sung Kim, Dagmara Mohuczy, Kevin E. Behrns

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

Abstract

Hepatocytes that reside in a chronically-injured liver have altered growth responses compared to hepatocytes in normal liver. Transforming growth factor beta (TGFβ) is upregulated in the cirrhotic liver, and cirrhotic hepatocytes, unlike normal hepatocytes exposed to this cytokine, exhibit decreased apoptosis. In fetal hepatocytes, TGFβ also induces epithelial-mesenchymal transition (EMT and signaling changes in cell survival pathways. Here, chronic murine liver injury was induced by twice-weekly carbon tetrachloride administration for 8 weeks. Normal liver-derived hepatocytes (NLDH) and cirrhotic liver-derived hepatocytes (CLDH) were examined for EMT and the small mothers against decapentaplegic homolog (Smad), phosphatidylinositol-3-kinase (Pl3K/ Akt), and mitogen activated protein kinase (MAPK) pathways were investigated. Immunofluorescence imaging of cirrhotic livers demonstrated increased vimentin expression, which was confirmed by immunoblot analysis. In vitro, CLDH exhibited increased vimentin and type 1 collagen expression within cellular extensions consistent with EMT. Treatment with TGFβ augmented the EMT response in CLDH. In contrast, untreated NLDH did not display features of EMT but responded to TGFβ with increased vimentin expression and EMT characteristics. In response to P13K/Akt inhibition, CLDH had decreased basal and insulin-stimulated p-Akt expression and decreased apoptosis compared to NLDH. In both NLDH and CLDH, vimentin expression was dependent on P13K/ Akt activity. CLDH demonstrated increased basal P-extracellular signal regulated kinase expression that was independent of Smad and P13K/Akt signaling. Inhibition of the MAPK pathway produced a marked increase in CLDH apoptosis. Conclusion: CLDH have increased vimentin and type 1 collagen expression and morphologic features consistent with EMT. In addition, compared to NLDH, the cellular signaling phenotype of CLDH changes from a MAPK-independent pathway to a MAPK-dependent cell survival pathway. These findings may have clinical implications for chemoprevention of hepatocellular carcinoma in the cirrhotic liver.

Original languageEnglish
Pages (from-to)909-919
Number of pages11
JournalHepatology
Volume48
Issue number3
DOIs
StatePublished - Sep 2008

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