Activation of the IGF1 system characterizes cholangiocyte survival during progression of primary biliary cirrhosis

J Histochem Cytochem. 2007 Apr;55(4):327-34. doi: 10.1369/jhc.6R7125.2006. Epub 2006 Dec 12.

Abstract

We evaluated the IGF1 system in cholangiocytes of primay biliary cirrhosis (PBC) patients and investigated the relationships with apoptosis. Biopsies of PBC patients (n=32) and normal subjects (n=5) were investigated by immunohistochemistry for expression in cholangiocytes of IGF1, IGF1-R, pAKT, terminal deoxynucleotide transferase end labeling (TUNEL), Bax (proapoptotic protein), and Bcl2 (antiapoptotic protein). Whereas normal cholangiocytes were almost negative, cholangiocytes of PBC patients showed strong IHC staining for IGF1, IGF1-R, and pAKT, which increases from stage I to stage IV, where >70% of cholangiocytes were positive. Bax/Bcl2 ratio reached the highest value (4.6) in PBC stage III when apoptosis is maximal (24% TUNEL positivity), whereas it declines in stage IV (1.4) when only 7.8% cholangiocytes were TUNEL positive. In PBC stages III and IV, expression of IGF1, IGF1-R, and pAKT in cholangiocytes was directly correlated with the antiapoptotic Bcl2 and inversely correlated with proapoptotic Bax, Bax/Bcl2 ratio, and TUNEL positivity. In conclusion, cholangiocytes of PBC patients showed a marked increase in IGF1, IGF1-R, and pAKT expression involving most cholangiocytes surviving in the terminal ductopenic stage. This was associated and correlated with a balance of pro- and antiapoptotic proteins favoring survival rather than apoptosis, suggesting a major role of IGF1 system in promoting cholangiocyte survival.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Bile Ducts / chemistry*
  • Bile Ducts / cytology
  • Cell Survival
  • Disease Progression
  • Female
  • Humans
  • Immunohistochemistry
  • In Situ Nick-End Labeling
  • Insulin-Like Growth Factor I / analysis*
  • Liver Cirrhosis, Biliary / metabolism*
  • Liver Cirrhosis, Biliary / pathology
  • Middle Aged
  • Proto-Oncogene Proteins c-akt / analysis
  • Proto-Oncogene Proteins c-bcl-2 / analysis
  • bcl-2-Associated X Protein / analysis

Substances

  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • Insulin-Like Growth Factor I
  • Proto-Oncogene Proteins c-akt