Immunohistochemical Alterations of Basement Membrane Components and Fibronectin Receptor in Malignant Melanoma

To investigate alterations in the basement membrane （BM） and of fibronectin receptor （FNR） in malignant melanoma （MM）, the tumor were studied immunohistochemically by double immunofluorescent staining using monoclonal antibodies to the core protein of heparan sulfate proteoglycan（HSPG）, collagen type III（C-3）and chondroitin 6-sulfate （C6S） as well as antiserum to laminin, collagen type IV （C-4）, fibronectin and fibronectin receptor. In MM in situ, C-4, laminin and HSPG were preserved as a continuous linear band on the dermo-epidermal junction （DEJ）, while C6S is extensively lost from the DEJ and fibronectin is remarkably decreased in the papillary dermis compared with the normal skin. In invasive, MM, although the distribution pattern was varied case by case, the BM components were not decreased. The cases were divided into two groups by the distribution pattern; a great amount of each BM component were localized on the surface of tumor cells, or surrounded tumor nests, forming the large nests. In all but one cases examined, however, C6S was absent from the BM zone of the melanoma nests in the dermis. These data indicates that although C6S was absent, the other BM components were actively synthesized by tumor cells, and that the BM components were altered in phase of MM in situ. Intensity of FNR of melanoma cells were generally more fainter than those of infiltrating lymphocytes in the dermis, basal cells of the epidermis and endothelial cells of small vessels. There were no significant differences in their intensity of melanoma cells between each tumor progression phase. Therefore, the present study may reveal that these receptors do not relate to invasion or metastasis of the tumor