Research

Gene expression profiling by DNA microarray analysis in mouse embryonic fibroblasts transformed by ras^V12 mutated protein and the E1A oncogene

Sophie Vasseur¹ , Cédric Malicet¹ , Ezequiel L Calvo² , Claude Labrie² , Patrice Berthezene¹ , Jean Charles Dagorn¹ and Juan Lucio Iovanna¹

¹  Centre de Recherche INSERM EMI 0116, 163 Avenue de Luminy, BP172, 13009 Marseille, France

²  Molecular Endocrinology and Oncology Research Center, Laval University Medical Center 2705 Laurier Boulevard, Quebec, G1V 4G2, Canada

author email corresponding author email

Molecular Cancer 2003, 2:19doi:10.1186/1476-4598-2-19

Published:	19 March 2003

Abstract

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 ras^V12/E1A-transformed mouse embryonic fibroblasts. Among the ~12,000 genes and ESTs analyzed, 815 showed altered expression in ras^V12/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 ras^V12/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.