Microphthalmia transcription factor. A sensitive and specific melanocyte marker for MelanomaDiagnosis.
Malignant melanomas do not uniformly retain expression of melanocytic gene products-an observation associated with diagnostic dilemmas. Microphthalmia transcription factor (Mitf) is a melanocytic nuclear protein critical for the embryonic development and postnatal viability of melanocytes. It serves as a master regulator in modulating extracellular signals, such as those triggered by alpha-MSH and c-Kit ligand. Because of its central role in melanocyte survival and to assess its potential use as a histopathological marker for melanoma, Mitf expression was examined in histologically confirmed human melanoma specimens. Western blot analysis of melanoma cell lines revealed consistent expression of two Mitf protein isoforms differing by MAP kinase-mediated phosphorylation. In a series of 76 consecutive human melanoma surgical specimens, 100% stained positively for Mitf with a nuclear pattern of reactivity. In a side-by-side comparison, Mitf staining was positive in melanomas that failed to stain for either HMB-45 or S-100, the most common currently used melanoma markers. Of 60 non-melanoma tumors, none displayed nuclear Mitf staining and two displayed cytoplasmic staining. Although Mitf does not distinguish benign from malignant melanocytic lesions, for invasive neoplasms it appears to be a highly sensitive and specific histopathological melanocyte marker for melanoma.
King
R
R
Department of Dermatopathology, Albany Medical Center, Albany, New York, USA.
Weilbaecher
K N
KN
McGill
G
G
Cooley
E
E
Mihm
M
M
Fisher
D E
DE
D000818:Animals; D000951:Antigens, Neoplasm / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000096:biosynthesis; D015153:Blotting, Western; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D008544:Melanocytes / Q000378:metabolism*; D008545:Melanoma / Q000175:diagnosis / Q000378:metabolism*; D058950:Melanoma-Specific Antigens; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor; D009363:Neoplasm Proteins / Q000378:metabolism; D009506:Nevus / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D009418:S100 Proteins / Q000378:metabolism; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; C497234:MITF protein, human; D058950:Melanoma-Specific Antigens; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D009363:Neoplasm Proteins; D009418:S100 Proteins; D014157:Transcription Factors