Involvement of two Ets binding sites in the transcriptional activation of the MAGE1 gene

Abstract

The MAGE1 gene codes for an antigen recognized on melanoma cell line MZ2-MEL by autologous cytolytic T lymphocytes. It is expressed in a number of tumors of different histological origins, but not in normal tissues except in testis. The MAGE1 promoter region was analyzed by performing transient transfections in MZ2-MEL cells with luciferase reporter plasmids. A fragment extending from nucleotide -792 to +118 exhibited high transcriptional activity. By deletional analysis of this fragment, we identified five activating regions designated C, A, B', B, and D. The activity of region A depends on the presence of region B' and vice versa. Two inverted Ets motifs contained in regions B' and B were found to drive 90% of the activity of the MAGE1 promoter in MZ2-MEL cells. Electrophoretic mobility shift assays performed with a nuclear extract from MZ2-MEL cells and with competitor oligonucleotides containing an Ets consensus site showed that nuclear proteins bind to the Ets motif of regions B' and B. Similar experiments suggested that region A binds transcription factors of the Sp1 family. The MAGE1 promoter was found to exert transcriptional activity in tumor cells where the MAGE1 gene is not expressed, suggesting that other mechanisms, such as demethylation, may contribute to the tumor-specific expression of the gene.

Methyl-CpG Binding Domain Proteins and Their Involvement in the Regulation of the MAGE-A1, MAGE-A2, MAGE-A3, and MAGE-A12 Gene Promoters

“…In normal adult tissues, they are silent, except for testicular germ cells (spermatogonia and primary spermatocytes) and placenta (9). Hypermethylation of CpG-rich MAGE-A promoters causes gene silencing and prevents Ets transcription factors from accessing their binding sites (1,10,11), which are responsible for the high transcriptional activation of the MAGE-A1 gene (12).…”

An optimum anti-melanoma response in mice immunized with fibroblasts transfected with DNA from mouse melanoma cells requires the expression of both syngeneic and allogeneic MHC-determinants

“…The products of genes that specify TAAs expressed by melanoma cells, such as BAGE, GAGE-1, MAGE-1, MAGE-2, MAGE-3, gp100 and tyrosinase, among others, have been identified as the targets of CTLs. [5][6][7][8][9][10][11][12][13] It is likely that these TAAs are only several representations of an undefined, and possibly large number of TAAs expressed by different cells that comprise the malignant cell population. Genetic instability is a characteristic phenotype of cancer cells.…”

When MAGE meets RING: insights into biological functions of MAGE proteins

“…Because of the specific expression in tumors and germline cells, but not normal cells, type I MAGE genes have been extensively investigated De Smet et al, 1995;Patard et al, 1995;Bolli et al, 2002;Brichard and Lejeune, 2007). In normal somatic cells, the promoters of such type I MAGE genes are methylated and thus their expression is suppressed (De Smet et al, 1995).…”

“…In normal somatic cells, the promoters of such type I MAGE genes are methylated and thus their expression is suppressed (De Smet et al, 1995). Nevertheless in tumor cells, these genes are aberrantly activated due to the demethylation of their promoters, which is the consequence of a genome-wide demethylation process occurring in many cancers (Miranda, 2010).…”

“…Aberrant expression of MAGE I genes occurs in a wide range of tumors. In addition, type II MAGE genes have also been implicated in many biologic processes, such as neuronal differentiation and apoptosis (Espantman and O'Shea, 2010).Because of the specific expression in tumors and germline De Smet et al, 1995;Patard et al, 1995;Bolli et al, 2002;Brichard and Lejeune, 2007). In normal somatic cells, the promoters of such type I MAGE genes are methylated and thus their expression is suppressed (De Smet et al, 1995).…”