Disease relevance of MLANA

• We have shown previously that peripheral blood lymphocytes (PBL) of patients with metastatic melanoma include cytotoxic T-cell clones that recognize Melan-A/MART-1 in a HLA-A2-restricted fashion [1].
• Metastases increasing in size over time showed a loss of Melan A/MART-1 expression in the presence of CTL in one patient [2].
• Our study shows that angiomyolipomas express the melanocyte-associated antigens Melan-A and gp-100 at the protein and at the mRNA level, suggesting a true expression of these antigens rather than cross-reacting epitopes [3].
• Our results demonstrate that Melan-A and tyrosinase are sensitive and specific markers to distinguish epithelioid melanocytic nevi from epithelioid histiocytic tumors [4].
• CONCLUSION: The sclerotic/desmoplastic and hypopigmented blue nevi were uniformly positive for Melan-A, while the vast majority of DMM were negative in their spindle cell compartments [5].
• Even the short Melan-A/MART-1(26-35(A27L)) peptide was recognized by CD4 T cells from HLA-DQ6+ and HLA-DR3+ melanoma patients [6].

High impact information on MLANA

• We identified circulating CD8+ T-cell populations specific for the tumor-associated antigens (TAAs) MART-1 (27-35) or tyrosinase (368-376) in six of eleven patients with metastatic melanoma using peptide/HLA-A*0201 tetramers [7].
• Postthymic replicative history of Melan-A/MART-1-specific CD8 T cells was independently assessed by quantifying T cell receptor excision circles and telomere length ex vivo [8].
• Here, we report an unexpected high frequency of T cells specific for the self-antigen Melan-A/MART-1 in CD8 single-positive thymocytes from human histocompatibility leukocyte antigen-A2 healthy individuals, which is maintained in the peripheral blood of newborns and adults [8].
• Current strategies for the immunotherapy of melanoma include augmentation of the immune response to tumor antigens represented by melanosomal proteins such as tyrosinase, gp100, and MART-1 [9].
• In contrast to skin biopsies obtained from the patient before T cell infusion, postinfusion biopsies demonstrated loss of MART-1 expression, evidence of melanocyte damage, and the complete absence of melanocytes in affected regions of the skin [9].

Chemical compound and disease context of MLANA

• Their SLNs were assessed for tyrosinase (Tyr) and melanoma antigens recognized by T-cells (MART-1) mRNA expression using RT-PCR, in parallel with hematoxylin and eosin staining and immunohistochemistry [10].
• Analysis of melanoma cells in peripheral blood by reverse transcription-polymerase chain reaction for tyrosinase and MART-1 after mononuclear cell collection with cell preparation tubes: a comparison with the whole blood guanidinium isothiocyanate RNA isolation method [11].
• The discriminatory immunostaining pattern with the 'MCW Melanoma Cocktail' (a mixture of MART-1 {1:500}, Melan- A {1:100}, and Tyrosinase {1:50} monoclonal antibodies) allows intraoperative immunocytochemical evaluation of imprint smears of SLNs for melanoma metastases [12].
• Originally studied as a melanoma marker, Melan-A, as detected by the murine monoclonal antibody, A103, has gained recent attention as a marker for steroid-producing cells [13].
• We compared the new melanoma markers, Melan-A (clone A103) and MART-1 (clone M2-7C10), with S-100 protein and HMB-45, by examining 77 formalin-fixed paraffin-embedded sections of sentinel lymph nodes from 13 cases of primary cutaneous melanoma [14].

Biological context of MLANA

• By HLA-tetramer analysis, in a tumor-invaded lymph node, >50% of mutant Prdx5-specific CD8(+) T cells (frequency 0.37%/CD8(+)) showed a CCR7(+/-) CD45RA(-) "T(CM)" or "T(EM)" phenotype, as found in Melan-A/MART-1-specific T cells (frequency 0.68%/CD8(+)) in the same tissue [15].
• DNA methylation patterns at the Melan-A/MART-1 promoter region were investigated by methylation-sensitive restriction enzyme digestion and subsequent Southern blot analysis [16].
• Exogenous promoter activity was assessed in all 20 melanoma cell lines to correlate the DNA methylation patterns with Melan-A/MART-1 expression [16].
• Newly established clear cell sarcoma (malignant melanoma of soft parts) cell line expressing melanoma-associated Melan-A antigen and overexpressing C-MYC oncogene [17].
• Immunologic assays showed no consistent immunization to the MART-1 or gp100 transgenes expressed by the recombinant adenoviruses [18].

Anatomical context of MLANA

• Recent studies have revealed that MITF, an essential transcription factor for melanocyte development, directly regulates expression of MLANA [19].
• Heterogeneous expression of immunotherapy candidate proteins gp100, MART-1, and tyrosinase in human melanoma cell lines and in human melanocytic lesions [20].
• Four of ten HLA-A2-restricted melanoma specific CTL that were derived from tumor-infiltrating lymphocytes (TIL) and administered to patients recognized the gp100 melanoma Ag and nine of ten recognized the MART-1 Ag [21].
• MART-1 is required for the function of the melanosomal matrix protein PMEL17/GP100 and the maturation of melanosomes [22].
• The CTLs exhibited up to 74% specific lysis against peptide-pulsed autologous EBV-transformed B cells, with Melan-A-specific CTLs yielding the greatest lytic activity [23].

Associations of MLANA with chemical compounds

• According to the authors' experience the antibody against KBA 62 has shown to be the most effective antibody followed by the antibodies against MART-1 (Melan A) and NKI/C3 [24].
• Stably growing hybrid antigen-presenting cells (HAPC) expressing HLA-DR and HLA-A2 (or HLA-A30/31), and melanoma-associated antigens (MART-1, gp100) were selected by a double strategy of immunomagnetic MACS and neomycin selection [25].
• The tumor cells strongly expressed S100 protein, gp100 (HMB-45), melan A, and tyrosine antibodies (Fig. 2C,D) [26].
• Indium-111 labeling of Melan-A-specific CTL demonstrated localization of transferred CTL to metastatic sites as early as 48 h after injection [27].
• Here we show that Melan-A is a single-pass membrane protein with an NH(2) terminus exposed to the lumen of the exocytic compartment [28].

Physical interactions of MLANA

• We show that MART-1 forms a complex with Pmel17 and affects its expression, stability, trafficking, and the processing which is required for melanosome structure and maturation [22].
• We point out the differences between the cutaneous and renal forms of angiomyolipoma, and conclude that the cutaneous lesion is distinct from a renal lesion in several aspects, including tuberous sclerosis complex association and immunoreactivity to both HMB-45 and MART-1 [29].

Regulatory relationships of MLANA

• Instead, when CD8+ cells from the same patient were sampled shortly (14 days) after an additional vaccination only IL-2 was able to promote the expansion of Melan-A/MART-1(27-35) tetramer positive cells [30].
• In melanoma patients, Melan-A-specific T cells up-regulated 2B4 in parallel with in vivo differentiation [31].
• In addition, some of the markers may identify patients likely to respond better to a new type of therapy (e.g., anti-angiogenic therapy in a patient whose tumor is overexpressing VEGF or immunotherapy for a patient whose tumor is expressing high levels of MART-1) [32].
• To study the requirements for expansion of naive melan-A CTL from healthy donors, we set up an in vitro priming protocol and, using tetramer assays, we demonstrate that the activity and phenotype of the expanded melan-A CTL are profoundly influenced by the type of APC used [33].
• However, these IL-10-grown DC can efficiently activate the epitope-specific CD8(+) T cells when they are made to present the epitope following transduction with an adenoviral vector expressing the MART-1 antigen [34].

Other interactions of MLANA

• In recent years, it has become evident that T cells can recognize peptides of melanocytic lineage antigens such as gp100, MART-1, and tyrosinase at the tumor cell surface and can subsequently destroy these cells [20].
• Additional samples of Melan-A/MART-1-positive, gp100-positive primary melanomas from six non-HLA-A2 patients and four autologous normal skin controls failed to reveal a TCRBV14 predominance in such tissues [1].
• Finally, we demonstrate that brain metastasis-derived cell cultures significantly overexpress Melan-A and MAGE-3, compared to primary tumours and other metastatic sites (P-value range: 0.05-0.001) [35].
• Our data show induction of CD8+ T cells specific for the melanosomal peptides MART-1/Melan-A(27-35) or tyrosinase(1-9), as well as IFN-gamma-releasing KLH-specific T cells, in two of six vaccinated melanoma patients, but do not support an association between the induction of these T cells and clinical responses [36].
• Surprisingly, Mart-1 identified rare melanocytes in 67% of vitiligo cases and a significantly larger pool of melanocytes in LS and controls other than those labeled by Mel-5 [37].

Analytical, diagnostic and therapeutic context of MLANA

• METHODS: The expression of the MAA Melan-A/MART-1 was analyzed in 10 uveal and 10 cutaneous patient-derived melanoma cell lines by Western blot analysis and RT-PCR [16].
• Generation of peptide-specific CTL was documented against Melan A/MART-1-derived peptide epitopes, the tyrosinase signal peptide and the influenza matrix peptide after vaccination [38].
• In five out of six cases high numbers of CD8(+)/tetramer(+) cells could be detected by flow cytometry, and in four patients lymphocyte populations specific for two different melanoma antigens (Melan-A/MART1 and tyrosinase) were contemporaneously present [39].
• Especially where these peptides may be used in human clinical trials for the treatment or prevention of cancer, there is substantial need for direct evaluation of HLA-A*0201-associated peptides from MART-1 and gp100 that are naturally processed and presented [40].
• By hematoxylin-eosin staining and immunocytochemistry for Mel-5 and Mart-1, LS had a lower mean count of melanocytes than acute scars, LP, and normal skin per 200 basal keratinocytes [37].

References