Fibroblast Activation Protein: Differential Expression and Serine Protease Activity in Reactive Stromal Fibroblasts of Melanocytic Skin Tumors

• Published in: Journal of investigative dermatology Vol. 120; no. 2; pp. 182 - 188
• Main Authors: Huber, Margit A., Schubert, Roland D., Peter, Ralf U., Kraut, Norbert, Park, John E., Rettig, Wolfgang J., Garin-Chesa, Pilar
• Format: Journal Article
• Language: English
• Published: Danvers, MA Elsevier Inc 01.02.2003; Nature Publishing; Elsevier Limited
• Subjects: Antigens, Neoplasm - biosynthesis; Antigens, Neoplasm - metabolism; Biological and medical sciences; Biomarkers, Tumor - biosynthesis; Biomarkers, Tumor - metabolism; Dermatology; Fibroblasts - enzymology; Gelatinases; Humans; Medical sciences; melanoma; Melanoma - metabolism; Melanoma - secondary; Membrane Proteins; metastasis; Neoplasms - metabolism; Neoplasms - pathology; Nevus, Pigmented - metabolism; Nevus, Pigmented - pathology; Serine Endopeptidases - biosynthesis; Serine Endopeptidases - metabolism; Skin Neoplasms - metabolism; Skin Neoplasms - pathology; Stromal Cells - enzymology; tumor progression; tumor stroma; Tumors of the skin and soft tissue. Premalignant lesions; melanoma; tumor progression; tumor stroma; metastasis; Human; Immunohistochemistry; Skin disease; melanoma/metastasis/tumor progression/tumor stroma; Serine endopeptidases; Enzyme; Metastasis; Peptidases; Pathology; Malignant melanoma; Tumor progression; Hydrolases; Tumor; Skin; Fibroblast
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1046/j.1523-1747.2003.12035.x

Growth and metastasis of solid neoplasms require the recruitment of a supporting tumor stroma. A highly consistent trait of tumor stromal fibroblasts in most epithelial cancers is the induction of fibroblast activation protein (FAP), a member of the serine protease family. Recently it was demonstrated that FAP has both dipeptidyl peptidase and collagenolytic activity capable of degrading gelatin and type I collagen. In this study, we describe the expression and enzyme activity of FAP in benign and malignant melanocytic skin tumors. FAP-positive fibroblasts were detected immunohistochemically in the reactive stroma of all melanocytic nevi tested. In primary and metastatic melanomas an upregulation of FAP expression in the reactive mesenchyme could be observed. Whereas 30% of the nevi revealed additional FAP expression on subsets of melanocytic cells, melanoma cells from primary and metastatic melanomas were FAP negative. This may indicate a possible role for FAP in the control of tumor cell growth and proliferation during melanoma carcinogenesis. Consistent with this in vivo expression pattern FAP enzyme activity could be detected by a specific immunocapture assay in extracts of melanocytic nevi and melanoma metastases, whereas no significant activity was detectable in normal adult skin. Strong protein expression of FAP was observed in patterned structures restricted to a subset of the melanoma metastases. Our findings that these FAP-positive structures showed no overlap with endothelial cell surface markers, nor with various melanoma antigens, suggest that FAP is a marker for specific stromal-cell-derived patterns in cutaneous melanoma metastases.