Expression of melanocyte-associated markers gp-100 and melan-A/MART-1 in angiomyolipomas : An immunohistochemical and rt-PCR analysis

• Published in: Virchows Archiv : an international journal of pathology Vol. 434; no. 5; pp. 429 - 435
• Main Authors: JUNGBLUTH, A. A, IVERSEN, K, COPLAN, K, WILLIAMSON, B, CHEN, Y.-T, STOCKERT, E, OLD, L. J, BUSAM, K. J
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-05-1999
• Subjects: Angiomyolipoma - chemistry; Angiomyolipoma - metabolism; Angiomyolipoma - pathology; Antigens, Neoplasm; Biological and medical sciences; Biomarkers, Tumor - biosynthesis; Biomarkers, Tumor - genetics; gp100 Melanoma Antigen; Humans; Immunohistochemistry; Kidney Neoplasms - metabolism; Kidney Neoplasms - pathology; Kidneys; Liver Neoplasms - metabolism; Liver Neoplasms - pathology; MART-1 Antigen; Medical sciences; Melanocytes - chemistry; Melanocytes - metabolism; Melanocytes - pathology; Membrane Glycoproteins - biosynthesis; Membrane Glycoproteins - genetics; Neoplasm Proteins - biosynthesis; Neoplasm Proteins - genetics; Nephrology. Urinary tract diseases; Reverse Transcriptase Polymerase Chain Reaction; Staining and Labeling; Tumors of the urinary system; Kidney disease; Angiomyoma; Human; Immunohistochemistry; Urinary system disease; Melanocyte; Biological marker; Reverse transcription; Gene expression; Kidney; Polymerase chain reaction; Pathology; Tumor; Diagnosis; Angiomyolipoma; Molecular biology; Lipoma
• ISSN: 0945-6317; 1432-2307
• DOI: 10.1007/s004280050362

Angiomyolipomas are tumours of uncertain histogenesis, most often occurring in association with the kidney. A characteristic finding is their reactivity with HMB-45, a monoclonal antibody to the melanocyte-associated antigen gp-100. We tested 18 angiomyolipomas for their reactivity with A103, a monoclonal antibody to Melan-A (MART-1), another melanocyte-associated marker, and compared it with HMB-45. All cases were positive with both antibodies, yet most cases showed a more homogeneous staining pattern with A103. Normal kidney was immunohistochemically negative for both antibodies. We also performed RT-PCR assays for gp-100 and Melan-A in 4 of the 18 angiomyolipoma samples and in three normal kidney samples. All 4 angiomyolipoma specimens revealed mRNA for both melanocyte differentiation markers. gp-100 mRNA was found in the samples of normal kidney, but Melan-A mRNA was not. 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. Based on the mRNA expression pattern, immunohistochemical analysis is the preferred method for the detection of gp-100, while Melan-A can be used at the protein and mRNA levels. Our study demonstrates that A103 is a useful marker for the diagnosis of angiomyolipomas.