Expression of the transcription factor Klf6 in cirrhosis, macronodules, and hepatocellular carcinoma.
OBJECTIVE
Macronodules (MN) occurring in cirrhosis are considered to be precursor lesions for hepatocellular carcinoma (HCC). However, early molecular events in hepatocellular carcinogenesis are poorly understood. The aim of this study was to compare gene expression profiling between cirrhotic tissues, MN, and HCC, to identify genes early involved in liver carcinogenesis.


METHODS
Tissues were obtained from explanted livers: nine cirrhosis, 10 MN, and seven HCC. Total RNAs were extracted by RNeasy and reverse transcribed with labelled [(33)P]-alpha ATP. Hybridations were performed on Atlas Human Cancer 1.2 membranes (1176 genes).


RESULTS
A two-way hierarchical clustering algorithm successfully isolated specific gene expression profiles when comparing MN, cirrhosis, and HCC. A total of 16 and 14 genes were up- and down-expressed, respectively, in HCC as compared to cirrhotic tissues. The molecular signature of MN was characterized by the down-expression of 23 and 42 genes as compared to cirrhosis and HCC, respectively. Among them, Klf6 was down-expressed in all MN samples whereas it was over-expressed in cirrhosis and HCC. This result was confirmed at RNA level by quantitative real time-polymerase chain reaction and at protein level by Western blotting. However, no mutation in the exon 2 of Klf6 was detected.


CONCLUSIONS
We identified a molecular signature of MN characterized by a down-expression of several genes. One of them, Klf6 was found to be down-expressed in all MN without evidence of somatic mutations in the exon 2. This gene could be involved at an early stage of hepatocarcinogenesis.
Bureau
Christophe
C
INSERM U858, Fédération Digestive Purpan, CHU Toulouse, Toulouse, France. bureau.c@chu-toulouse.fr
Péron
J M
JM
Bouisson
Michèle
M
Danjoux
Marie
M
Selves
Janick
J
Bioulac-Sage
Paulette
P
Balabaud
Charles
C
Torrisani
Jérome
J
Cordelier
Pierre
P
Buscail
Louis
L
Vinel
Jean Pierre
JP
D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D008103:Liver Cirrhosis / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics*
C105465:KLF6 protein, human; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D011518:Proto-Oncogene Proteins