Aberrant Notch3 and Notch4 expression in human hepatocellular carcinoma.
BACKGROUND
Notch signalling is altered in several solid tumours and it plays a role in growth inhibition and apoptosis of hepatocellular carcinoma (HCC)-derived cell lines, bile duct development and hepatocyte regeneration.


OBJECTIVE
This study aims to analyse the expression of Notch3, Notch4 and HES1 and HES6 as Notch-target genes in HCC, matched non-neoplastic tissue and HEPG2 cells.


RESULTS
Notch3 and Notch4 are not expressed in normal liver and in chronic hepatitis surrounding HCC. Cirrhotic tissue stains negative for Notch3, while Notch4 is expressed by hepatocytes at the edge of regenerative nodules and in cell planes adjacent to fibrous septa. HCC tissue displays Notch3 and Notch4 abnormal accumulation, respectively, in 78% and 68% of the cases. The endothelium of hepatic veins with neoplastic permeation is frequently Notch4 positive. An upregulation of Notch3 mRNA was found in 95% of HCCs vs cirrhosis (P=0.0001), while Notch4 mRNA was downregulated in 80% of HCCs. HES6 mRNA expression was higher in HCC tissue when compared with cirrhosis (P=0.007), paralleling Notch3 mRNA expression. The HEPG2 cell line displays high Notch3 and low Notch4 protein and mRNA levels.


CONCLUSIONS
These descriptive findings suggest an aberrant expression of Notch3 and Notch4 in HCC and allow the hypothesis of an activation of Notch signalling by Notch3.
Gramantieri
Laura
L
Center for Applied Biomedical Research (CRBA), University of Bologna and St Orsola-Malpighi University Hospital, Bologna, Italy. gramantieri@aosp.bo.it
Giovannini
Catia
C
Lanzi
Arianna
A
Chieco
Pasquale
P
Ravaioli
Matteo
M
Venturi
Annamaria
A
Grazi
Gian Luca
GL
Bolondi
Luigi
L
D000368:Aged; D000369:Aged, 80 and over; D051792:Basic Helix-Loop-Helix Proteins / Q000032:analysis; D026481:Blotting, Far-Western; D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019694:Hepatitis B, Chronic / Q000235:genetics / Q000378:metabolism; D019698:Hepatitis C, Chronic / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D008103:Liver Cirrhosis / Q000235:genetics / Q000378:metabolism; D008113:Liver Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011518:Proto-Oncogene Proteins / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D000071656:Receptor, Notch3; D000074562:Receptor, Notch4; D051880:Receptors, Notch / Q000032:analysis* / Q000235:genetics; D012097:Repressor Proteins / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D000072056:Transcription Factor HES-1
D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D000071656:Receptor, Notch3; D000074562:Receptor, Notch4; D051880:Receptors, Notch; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; C411859:HES6 protein, human; C499374:NOTCH3 protein, human; C106075:NOTCH4 protein, human; C078493:HES1 protein, human