Global gene expression in Ha‐ras and B‐raf mutated mouse liver tumors

Chemically‐induced mouse liver tumors harbor mutations in different oncogenes. About 50% of tumors contain activating mutations in the Ha‐ras gene contain and about 20% of tumors show point mutations in the B‐raf oncogene. We have investigated the gene expression profiles in tumors of the 2 genotypes by microarray analysis. In total, ∼500 genes or expressed sequences were aberrantly expressed in tumors relative to normal liver tissue. Around two/thirds of them were significantly altered in both Ha‐ras and B‐raf mutated liver tumors, and most of the remaining genes showed at least qualitatively comparable changes in both tumor types. Several functional clusters were hypothesized in tumors of the 2 genotypes which involve alterations in a battery of genes encoding enzymes of lipid metabolism. The similarity in the patterns of global gene expression of Ha‐ras and B‐raf mutated liver tumors suggests that mutational activation of the 2 oncogenes results in activation of a common set of transcriptional regulators. © 2007 Wiley‐Liss, Inc.