MAGE-1 (96-104)

AIRE is involved in susceptibility to melanoma perhaps regulating T cell immunity against melanoma antigens (MA). To address this issue, AIRE and MAGEB2 expressions were measured by real time PCR in medullary thymic epithelial cells (mTECs) from two strains of C57BL/6 mice bearing either T or C allelic variant of the rs1800522 AIRE SNP. Moreover, the extent of apoptosis induced by mTECs in MAGEB2-specific T cells and the susceptibility to in vivo melanoma B16F10 cell challenge were compared in the two mouse strains.The C allelic variant, protective in humans against melanoma, induced lower AIRE and MAGEB2 expression in C57BL/6 mouse mTECs than the T allele. Moreover, mTECs expressing the C allelic variant induced lower extent of apoptosis in MAGEB2-specific syngeneic T cells than mTECs bearing the T allelic variant (p < 0.05). Vaccination against MAGEB2 induced higher frequency of MAGEB2-specific CTL and exerted higher protective effect against melanoma development in mice bearing the CC AIRE genotype than in those bearing the TT one (p < 0.05). These findings show that allelic variants of one AIRE SNP may differentially shape the MA-specific T cell repertoire potentially influencing susceptibility to melanoma.

Cutaneous melanomas have been found to express several immunogenic differentiation melanoma-associated antigens (MAAs) that have been suggested to play an important role in disease outcome. Adaptive host immunity to MAAs has shown some level of control on melanoma progression. To date, there has been no definitive report correlating the level of differentiated MAAs gene expression in melanomas with overall disease outcome. Metastasis of melanoma to distant visceral organ sites usually indicates a survival of less than 1 year; however, a subset of patients who undergo cytoreductive surgery of distant metastases survive for a longer period. We hypothesized that the gene expression level of differentiation MAAs in metastatic melanoma (AJCC stage IV) lesions would be predictive of survival. We focused on three known differentiation MAAs: tyrosinase (TYR), TYR-related protein 2 (TRP-2), and melanoma antigen recognized by T cells 1 (MART-1); all three of them are known to induce immune responses in melanoma patients and are frequently expressed in melanomas. A quantitative reverse-transcriptase RealTime PCR (qRT) assay was developed for these MAAs to assess mRNA expression in metastatic melanoma tumors obtained from cytoreductive surgery of AJCC stage IV melanoma patients (n = 35). Patients were followed up for over 60 months. There was a variation in mRNA copy levels for individual MAAs in melanoma tumors. Elevated MAA mRNA copy levels of TYR and TRP-2 significantly (P < 0.03 and < 0.009, respectively) correlated with improved overall survival. Patients having at least one MAA expressed in their tumors had a significantly (P = 0.01) better overall survival (median 16 months). These studies demonstrate that levels of differentiated MAA mRNA expression of advanced-stage metastatic melanomas can be used as molecular predictive factors of disease outcome. The studies also imply that an assessment of melanoma tumor MAAs may provide a stratification factor targeted for active-specific immunotherapy.

Objectives: To investigate the expression of melanoma-associated antigen 1 (MAGE-1) in Chinese hepatocellular carcinoma (HCC) patients and to determine the existence and distribution of single nucleotide polymorphisms (SNP) of MAGE-1 gene. Methods: Total RNA was extracted from cancer tissues and adjacent tissues from 19 HCC patients and the expression of MAGE-1 mRNA was examined by using RT-PCR. The PCR products were sequenced to analysis the gene variation. Genomic DNA was extracted from cancer tissues, adjacent tissues and peripheral blood cells of 19 HCC patients, as well as from peripheral blood cells of 23 healthy donors. The PCR product of MAGE-1 DNA was sequenced to determine the existence and distribution of SNPs of MAGE-1 gene. Results: 9 of 19 (47.4%) tumor tissues and none of adjacent tissue from HCC patients expressed MAGE-1 mRNA. There were three kinds of gene variations of cDNA in 9 MAGE-1 mRNA positive patients. One type was named type I including 1 patient, which sequence is as same as that of the GenBank M77481. The other was named TGA type including 5 patients, which involved three nucleotide changes (C159T, A272G and G393A) and result in two amino acid changes (T32A and R72Q). Another one was named GTG type including 3 patients, which involved three nucleotide changes (A272G, C991T, A1125G) and result in only one amino acid changes (T32A). According to the analysis of genomic DNA, above three types were not specific mutations of tumor tissue, but were SNPs. These SNPs types were distributed in HCC patients and normal donors with the frequencies of 26.3% (5/19) and 60.9% (14/23) for type I, 57.9% (11/19) and 47.8% (11/23) for TGA type, and 21.1% (4/19) and 21.7% (5/23) for GTG type, respectively. The sequences of two new SNPs had been deposited in GenBank with the accession numbers of AF463515 and AY148486. In male population, the distributions of SNPs were not correlated to HCC suffering or MAGE-1 expression. Several new HLA-restricted epitopes were probably resulted from SNPs existing. The three-dimensional models of MAGE-1 proteins of type I and TGA type was established by using computer software. Conclusion: The expression rate of MAGE-1 gene in Chinese HCC patients is high. Three SNP types of MAGE-1 gene exist in Chinese population. The three-dimensional models of MAGE-1 proteins were obtained by computer processing. These results will be helpful to developing MAGE-1 peptide-vaccine for HCC immunotherapy.