Gene expression profiling by DNA microarray analysis in mouse embryonic fibroblasts transformed by rasV12 mutated protein and the E1A oncogene.
BACKGROUND
Ras is an area of intensive biochemical and genetic studies and characterizing downstream components that relay ras-induced signals is clearly important. We used a systematic approach, based on DNA microarray technology to establish a first catalog of genes whose expression is altered by ras and, as such, potentially involved in the regulation of cell growth and transformation.


RESULTS
We used DNA microarrays to analyze gene expression profiles of rasV12/E1A-transformed mouse embryonic fibroblasts. Among the approximately 12,000 genes and ESTs analyzed, 815 showed altered expression in rasV12/E1A-transformed fibroblasts, compared to control fibroblasts, of which 203 corresponded to ESTs. Among known genes, 202 were up-regulated and 410 were down-regulated. About one half of genes encoding transcription factors, signaling proteins, membrane proteins, channels or apoptosis-related proteins was up-regulated whereas the other half was down-regulated. Interestingly, most of the genes encoding structural proteins, secretory proteins, receptors, extracellular matrix components, and cytosolic proteins were down-regulated whereas genes encoding DNA-associated proteins (involved in DNA replication and reparation) and cell growth-related proteins were up-regulated. These data may explain, at least in part, the behavior of transformed cells in that down-regulation of structural proteins, extracellular matrix components, secretory proteins and receptors is consistent with reversion of the phenotype of transformed cells towards a less differentiated phenotype, and up-regulation of cell growth-related proteins and DNA-associated proteins is consistent with their accelerated growth. Yet, we also found very unexpected results. For example, proteases and inhibitors of proteases as well as all 8 angiogenic factors present on the array were down-regulated in transformed fibroblasts although they are generally up-regulated in cancers. This observation suggests that, in human cancers, proteases, protease inhibitors and angiogenic factors could be regulated through a mechanism disconnected from ras activation.


CONCLUSIONS
This study established a first catalog of genes whose expression is altered upon fibroblast transformation by rasV12/E1A. This catalog is representative of the genome but not exhaustive, because only one third of expressed genes was examined. In addition, contribution to ras signaling of post-transcriptional and post-translational modifications was not addressed. Yet, the information gathered should be quite useful to future investigations on the molecular mechanisms of oncogenic transformation.
Vasseur
Sophie
S
Centre de Recherche INSERM EMI 0116, 163 Avenue de Luminy, BP172, 13009 Marseille, France. vasseur@marseille.inserm.fr
Malicet
Cédric
C
Calvo
Ezequiel L
EL
Labrie
Claude
C
Berthezene
Patrice
P
Dagorn
Jean Charles
JC
Iovanna
Juan Lucio
JL
D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000166:cytology*; D020224:Expressed Sequence Tags; D005347:Fibroblasts / Q000378:metabolism*; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D017500:Adenovirus E1A Proteins; D015689:Oncogene Protein p21(ras)