Molecular mechanisms of liver carcinogenesis in the mdr2-knockout mice.
Mouse models of hepatocellular carcinoma (HCC) simulate specific subgroups of human HCC. We investigated hepatocarcinogenesis in Mdr2-knockout (Mdr2-KO) mice, a model of inflammation-associated HCC, using gene expression profiling and immunohistochemical analyses. Gene expression profiling showed that although Mdr2-KO mice differ from other published murine HCC models, they share several important deregulated pathways and many coordinately differentially expressed genes with human HCC data sets. Analysis of genome positions of differentially expressed genes in liver tumors revealed a prolonged region of down-regulated genes on murine chromosome 8 in three of the six analyzed tumor samples. This region is syntenic to human chromosomal regions that are frequently deleted in human HCC and harbor multiple tumor suppressor genes. Real-time reverse transcription-PCR analysis of 16 tumor samples confirmed down-regulation of several tumor suppressors in most tumors. We show that in the aged Mdr2-KO mice, cyclin D1 nuclear level is increased in dysplastic hepatocytes that do not form nodules; however, it is decreased in most dysplastic nodules and in liver tumors. We found that this decrease is mostly at the protein, rather than the mRNA, level. These findings raise the question on the role of cyclin D1 at early stages of hepatocarcinogenesis in the Mdr2-KO HCC model. Furthermore, we show that most liver tumors in Mdr2-KO mice were characterized by the absence of beta-catenin activation. In conclusion, the Mdr2-KO mouse may serve as a model for beta-catenin-negative subgroup of human HCCs characterized by low nuclear cyclin D1 levels in tumor cells and by down-regulation of multiple tumor suppressor genes.
Katzenellenbogen
Mark
M
Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Kiryat Hadassah, P.O. Box 12000, Jerusalem 91120, Israel.
Mizrahi
Lina
L
Pappo
Orit
O
Klopstock
Naama
N
Olam
Devorah
D
Jacob-Hirsch
Jasmine
J
Amariglio
Ninette
N
Rechavi
Gideon
G
Domany
Eytan
E
Galun
Eithan
E
Goldenberg
Daniel
D
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D019938:Cyclin D1 / Q000378:metabolism; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D016147:Genes, Tumor Suppressor; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D051176:beta Catenin / Q000378:metabolism; D000097202:ATP-Binding Cassette Sub-Family B Member 4
D018435:ATP Binding Cassette Transporter, Subfamily B; D019938:Cyclin D1; D051176:beta Catenin; D000097202:ATP-Binding Cassette Sub-Family B Member 4