RESUMO
BACKGROUND: Neurofibroma, the hallmark of neurofibromatosis, is a cutaneous or subcutaneous lesion, with a variable clinical presentation. Histologically, neurofibroma consists of proliferation of nerve derived cellular elements, together with an abundant, collagenous extracellular matrix. Specifically, neurofibroma has been shown to contain 30-50% collagen in its matrix. Objective 5. METHODS: We examined the expression of extracellular matrix genes (collagen, fibronectin, laminin), TGF-b mRNA and Ha-ras oncogene mRNA by using Northern and slot-blot hybridization and immunoperoxidase stains. Result: In Northern blot analysis, Ha-ras and TGF-b genes revealed respectively, 8.8kb and 2. 5kb sized mRNA transcripts in neurofibroma. These parameters were normal in the control. The expression of these genes were 1.9, 2.0 fold increased in neurofibroma. In slot-blot analysis, expression of type I collagen showed fibronectin genes to be 2,401+210, 540+43, respectively, in neurofibroma. So there were 3.7 fold, 2.1 fold, differences respectively, compared to the normal control. However, there were no significant changes of type IV collagen and laminin Bl mRNA levels between neurofibroma and normal skin tissues. Irnmunoperoxidase staining by rnonoclonal anti type IV collagen antibody in neurofibroma showed type IV collagen to be diffusely and weakly stained in tissue. On staining by monoclonal anti-laminin antibody, laminin was stained in a matrix and around vessels. CONCLUSION: The increased expression of extracellular matrix genes may suggest that there is a subpopulation of fibroic cells in neurofibroma which are stimulated by TGF-b. Ha-ras genes which might have accumulated with the differentiation of neural tissue may be related to the pathogenesis of neurofibroma tissue formation. Further studies are needed to determine whether the other factors are related to the pathogenesis of neurofibroma.