Biomedical subjects

Ezequiel L Calvo

Publications and source records attributed to Ezequiel L Calvo.

4 recordsLinked to original sources

PubMed2005

Gene expression profiling of tumours derived from rasV12/E1A-transformed mouse embryonic fibroblasts to identify genes required for tumour development.

BACKGROUND: In cancer, cellular transformation is followed by tumour development. Knowledge on the mechanisms of transformation, involving activation of proto-oncogenes and inactivation of tumour-suppressor genes has considerably improved whereas tumour development remains poorly understood. An interesting way of gaining information on tumour progression mechanisms would be to identify genes whose expression is altered during tumour formation. We used the Affymetrix-based DNA microarray technology to analyze gene expression profiles of tumours derived from rasV12/E1A-transformed mouse embryo fibroblasts in order to identify the genes that could be involved in tumour development. RESULTS: Among the 12,000 genes analyzed in this study, only 489 showed altered expression during tumour development, 213 being up-regulated and 276 down-regulated. The genes differentially expressed are involved in a variety of cellular functions, including control of transcription, regulation of mRNA maturation and processing, regulation of protein translation, activation of interferon-induced genes, intracellular signalling, apoptosis, cell growth, angiogenesis, cytoskeleton, cell-to-cell interaction, extracellular matrix formation, metabolism and production of secretory factors. CONCLUSIONS: Some of the genes identified in this work, whose expression is altered upon rasV12/E1A transformation of MEFs, could be new cancer therapeutic targets.

Adenovirus E1A Proteins↗

PubMed2003

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.

Adenovirus E1A Proteins↗

PubMed2002

Cloning and expression of the rat vacuole membrane protein 1 (VMP1), a new gene activated in pancreas with acute pancreatitis, which promotes vacuole formation.

To characterize the emergency program set up by pancreatic cells in response to pancreatitis, we established the phenotype of the pancreatitis-affected pancreas by characterizing a large number of its transcripts. In this report, we describe the cloning, sequencing, and expression pattern of a new gene, named VMP1 (vacuole membrane protein 1). The VMP1 mRNA codes for a putative protein of 406 amino acids. In situ hybridization studies revealed that pancreatic expression of VMP1 mRNAs was restricted to the acinar cells. Interestingly, VMP1 mRNA was also overexpressed in kidney after transient ischemic injury. However, many healthy tissues express VMP1 mRNA. Structure analysis suggested that VMP1 is a transmembrane protein with six hydrophobic regions. VMP1/EGFP fusion protein was located to the Golgi apparatus and the endoplasmic reticulum area. Expression of this protein promoted the formation of intracytoplasmatic vacuoles and VMP1/EGFP was located to the membranes of these vacuoles. Cells overexpressing this protein died after 48 h. In conclusion, we have identified a new stress-induced gene which codes for a transmembrane protein that, when overexpressed, promotes formation of intracellular vacuoles followed by cell death.

Acute Disease↗

PubMed2002

P53-dependent expression of the stress-induced protein (SIP).

The mouse stress-induced protein (SIP) mRNA is activated in the pancreas with acute pancreatitis and in several cell lines in response to various stress agents. The SIP gene is alternatively spliced, generating two proteins (SIP'8 and SIP27). Both proteins, located mainly in the nucleus, promote cell death when overexpressed in vitro. We show that induction by stress agents of the expression of SIP18 and SIP27 mRNAs, observed in human- and mouse-derived cell lines, is absent from cells with deleted, mutated or inactive p53, suggesting that regulation of SIP gene expression is dependent on p53. That hypothesis is consistent with the presence of a functional p53-response element within the promoter region of the mouse SIP gene and confirmed by the induction of SIP mRNA expression in mouse embryo fibroblasts upon activation of a p53-dependent pathway by transfection with rasV12 or rasV12/E1A. In conclusion, SIP being a proapoptotic gene induced through p53 activation could be a stress-induced gene with antitumour properties.

Amino Acid Sequence↗