Melanoma-associated Antigen Gene Research Articles

Evaluation of variants of melanoma-associated antigen genes and mRNA transcripts in melanomas of dogs

OBJECTIVE-To characterize variability in melanoma-associated antigen (MAA) genes and gene expression in melanomas of dogs. ANIMALS-18 dogs with malignant melanomas and 8 healthy control dogs. PROCEDURES-cDNA was prepared from malignant melanoma biopsy specimens and from pigmented oral mucocutaneous tissues of healthy control dogs. Genomic DNA was extracted from poorly pigmented melanomas. A PCR assay was performed by use of Melan-A, SILV, or tyrosinase-specific primers. RESULTS-Splice variants of Melan-A and SILV were identified in malignant melanomas and also in healthy pigmented tissues, whereas a tyrosinase splice variant was detected in melanoma tissues only. A short interspersed nuclear element (SINE) insertion mutation was identified in the SILV gene in 1 of 10 poorly pigmented melanomas. Six novel exonic single nucleotide polymorphisms (SNPs; 3 synonymous and 3 nonsynonymous) were detected in the tyrosinase gene, and 1 nonsynonymous exonic SNP was detected in the SILV gene. CONCLUSIONS AND CLINICAL RELEVANCE-Variants of MAA mRNA were detected in malignant melanoma tissues of dogs. The importance of MAA alternative transcripts expressed in melanomas and normal pigmented tissues was unclear, but they may have represented a means of regulating melanin synthesis. The tyrosinase splice variant was detected only in melanomas and could potentially be a tumor-specific target for immunotherapy. A SILV SINE insertion mutation was identified in a melanoma from a Great Dane, a breed known to carry this mutation (associated with merle coat color). The nonsynonymous SNPs detected in tyrosinase and SILV transcripts did not appear to affect tumor pigmentation.

Melanoma-associated antigen-A1 expression predicts resistance to docetaxel and paclitaxel in advanced and recurrent gastric cancer

Melanoma-associated antigen (MAGE) genes are cancer-testis antigen genes that serve as immunotherapy targets in several human cancers. Previous studies have revealed that the forced expression of MAGE genes induces a paclitaxel-resistant phenotype. In the present study, we examined whether the expression of MAGE-A1 could predict the response of advanced and recurrent gastric cancers (GCs) to taxan (doce-taxel or paclitaxel)-based chemotherapy. The expression of MAGE-A1 was analyzed by immunostaining in 41 primary GC samples. DNA demethylation was assessed by methylation-specific polymerase chain reaction and the effect of the forced expression of MAGE-A1 on drug resistance to taxan drugs was monitored by MTT assay. The expression of MAGE-A1 in primary GC was observed in 4 (9.8%) of 41 cases. All 4 patients with MAGE-A1-positive GC showed progressive disease, whereas MAGE-A1 expression was not detected in any of the 23 patients showing partial response (P=0.0302). There was no association between MAGE-A1 gene demethylation and response to chemotherapy (P=0.7245). The forced MAGE-A1 expression in the TMK-1 GC cell line increased the sensitivity to paclitaxel and docetaxel. These results suggest that although MAGE-A1 does not participate directly in the drug-resistant phenotype, the expression of MAGE-A1 could be a marker for the prediction of resistance to taxan-based chemotherapies in patients with GC.

Differential expression profile of MAGE family in non-small-cell lung cancer

The expression of the melanoma-associated antigen (MAGE) genes consists of variables in all tumor types, such as lung cancer, which are relevant to be silent in all normal tissues except germ cells. They are considered as tumor-specific antigens, and are ideal targets for cancer immunotherapy. A complete MAGE genes differential expression profile analysis of lung cancer can provide this study not only various target genes for immunotherapy, but also valuable markers for further diagnosis and prognosis. This research has constructed a membrane array, which was consisted 32 MAGE genes, to detect whether the differential expression profile occurred in 52 pairs of non-small-cell lung cancer (NSCLC) samples. Nearly 32 MAGE genes have been differential expressed in NSCLC except MAGE-B1 and -E2. MAGE-B, -C, -D, and subgroup -B6, -D4 have showed prominences in lung adenocarcinoma. High-frequent expression of MAGE-D, and subgroup -A2, -D2 has also been discovered in non-metastasis group (p<0.05). However, there is no significant difference of MAGE genes differential expression shown among different primary tumor (T), nodal involvement (N) and overall stages. Several MAGE subgroup genes, such as MAGE-A5, -A7, -A8, -A9, -A11, -B3, -B4, -B10, -D2, -D3, -F1, -G1, -H1, and -L2, have been first discovered to show differential expression in NSCLC. Although the small size of the sample may limit the diagnostic and prognostic value of MAGE genes, the function of the membrane array can provide this study a high-throughput method to detect the whole MAGE genes differential expression profile.

Melanoma-associated antigens in esophageal adenocarcinoma: Identification of novel MAGE-A10 splice variants

Abstract Introduction: The melanoma-associated antigen gene family (MAGE) encodes tumor-specific antigens recognized by cytotoxic T lymphocytes. In this study, expression of MAGE family A members was investigated during the development of esophageal adenocarcinoma as potential targets for immunotherapy. Methods: MAGE-A mRNA expression was evaluated in 46 samples including Barrett's metaplasia, dysplasia, and esophageal adenocarcinoma using oligonucleotide microarrays. Expression of MAGE-A proteins was confirmed by immunohistochemistry on tissue microarrays containing 59 esophageal adenocarcinoma, 11 dysplasia, and nine Barrett's metaplasia samples and by Western blot. To further evaluate MAGE-A10 expression, RT-PCR products were sequenced and protein expression was determined using a specific antibody. Results: Overexpression of MAGE-A1, 2b, 3, 4, 6, 9, 10, and 12 was found in esophageal adenocarcinomas relative to Barrett's metaplasia on oligonucleotide microarrays. MAGE-A3 overexpression was confirmed by Real-time RT-PCR in 21.4% (6/28) of esophageal tumors. Immunohistochemistry on tissue microarray revealed MAGE-A proteins in 20.3% (12/59) of esophageal adenocarcinomas and MAGE-A10 staining in 16.9% (10/59). MAGE-A expression was confirmed by Western blot in several esophageal tumors and in two esophageal adenocarcinoma cell lines, Flo-1 and Seg-1, while Flo-1 also expressed MAGE-A10. Tumors produced from these cell lines in nude mice retained MAGE-A expression. Interestingly, in primary tumors expressing MAGE-A10 protein, RT-PCR revealed the presence of additional PCR products that were identified as novel MAGE-A10 alternative splice variants using DNA sequencing. Conclusions: This is the first report of these MAGE-A10 alternative splice sequences, and characterization of MAGE-A expression may provide potential targets for immunotherapy in patients with esophageal adenocarcinoma.

Prognostic factors in localized neuroblastoma

The melanoma-associated antigen (MAGE) genes families are found in different cancers, including non-small-cell lung cancers. These genes are silent in normal tissues, except for the testis. The goal of this study was to investigate the differentially expressed profile of the different MAGE genes subclass in non-small-cell lung cancer (NSCLC) tumoral tissue.Formalin-fixed paraffin embedded NSCLC resected tissues were collected from 31 patients hospitalized in our referral hospital, and 29 patients were diagnosed with either squamous cell carcinoma (SCC) or adenocarcinoma (ADC). We used a nested reverse transcriptase–polymerase chain reaction, which comprised independent amplification of MAGE-A1, MAGE-A2, MAGE-A3/6, MAGE-A4, and MAGE-A12, to detect expression frequency of the MAGE-A family in lung tissue biopsies at both tumoral and nontumoral parts of patients' tissues.From 29 patients with diagnosis of either SCC (n = 16) or ADCs (n = 13), 58 samples were prepared. From 58 blocks sampled for this experiment, 37 tumoral tissue samples and 22 nontumoral tissue samples expressed at least one of the MAGE-A genes. MAGE-A4 gene had the highest incidence among all MAGE-A genes in both tumoral and nontumoral gens. In SCC and ADCs, the data showed expression of at least one of the MAGE-A genes in 59.4% and 69.2% of tumoral and nontumoral tissues, respectively.The detection of the MAGE-A genes expression could be a molecular tumor marker for early diagnosis and potential targets for active immunotherapy in NSCLC, particularly in ADCs and SCC. Besides, the frequency of different subtypes of MAGE genes may vary in different regions of world.

Structural characterization and chromosomal localization of the MAGE-E1 gene

Genes of the melanoma-associated antigen ( MAGE) family are characterized by the expression of tumor antigens on a malignant melanoma recognized by autologous cytolytic T lymphocytes. We have previously identified novel members of the MAGE gene family expressed in human glioma and named them MAGE-E1a–c. In the present study, we have revealed the genomic structure of MAGE-E1 by sequence analysis of a human chromosome bacterial artificial chromosome clone containing the MAGE-E1 gene. The MAGE-E1 gene is composed of 13 exons, and three of these (exon 2, exon 3 and exon 12) are alternatively spliced in each variant (E1a–c). The open reading frame encoding the MAGE-E1 peptides initiates in exon 2 and ends in exon 13. We have also demonstrated that the MAGE-E1 gene is located in Xp11 through the analysis of radiation hybrid panels. The genomic structure of MAGE-E1 is markedly similar to that of MAGE-D and its chromosomal locus is also identical to that of MAGE-D, but these features contrast with those of other MAGEs. These results suggest that MAGE-D and - E1 may be evolutionarily distant from other members of the MAGE family, and the two may be ancestral genes for the others.

Cloning of the first invertebrate MAGE paralogue: an epitope that activates T-cells in humans is highly conserved in evolution

The MAGE (Melanoma Associated Antigen) family tumor-specific antigens are shared by a number of histologically different tumors. Till date, only human and mouse MAGE genes have been characterized. Our study describes the first non-mammalian member of MAGE super-family, DMAGE from D. melanogaster. A conceptual translation of the cDNA of DMAGE identifies a putative protein that contains a motif that shares eight out of nine amino acids with the previously identified promiscuous, HLA-A2 restricted antigenic epitope in the C-terminus of human MAGE-B1 and -B2. Similarly, this motif of DMAGE shares seven out of nine amino acids with the same antigenic epitope of human MAGE-A3 and -A12. Thus, the phylogeny of proteins that activate tumor specific T-cells in mammals as unmutated self-proteins began at least 100 million years earlier in evolution than the emergence of the adaptive immune system of higher vertebrates. Northern analysis revealed that DMAGE is a developmentally regulated gene highly expressed in adult fruit fly and in the embryo of D. melanogaster. In contrast, the expression level of the mRNA of DMAGE in fruit fly larva is substantially lower than in embryo and adult fly. We propose that studies of DMAGE on D. melanogaster may help define the function(s) of MAGE super-family genes.