Detection of phenotypic changes in malignant melanoma. Immunohistochemical study of c-Myc, PDGF, bFGF and nestin expression in benign and malignant cutaneous melanocytic lesions

Malignant melanomas are highly aggressive tumours characterised by a rapidly increasing incidence and unpredictable prognosis. Tumour progression is typified by aberrant proliferation of malignant cells associated with alterations to cell growth and cell regulation. We analyzed expression of growth factors PDGF, bFGF, c-Myc oncogene and nestin belonging to a newly identified intermediate filament associated with highly malignant neuroectodermal tumours in primary malignant skin melanomas as well as benign nevi. Formalin-fixed and paraffin-embedded tissue sections of 11 nodular melanomas (NM), 12 superficial melanomas (SSM), 9 dysplastic and 10 benign nevi were examined by indirect immunohistochemistry using EnVision visualisation system. In groups of superficial and nodular melanomas an increased expressions of c-Myc and PDGF in comparison to benign and dysplastic nevi were observed. The results for nestin expression were interesting: the protein was slighly increased in SSM but strongly so in a group of NM. A higher FGF positivity of FGF was detected in NM compared to SSM and dysplastic nevi. This protein was also present in benign nevi and this could be caused by the gradual maturation of cells. We conclude that melanoma progression is characterized by aberrant angiogenesis associated with alteration of growth factors PDGF, bFGF, c-Myc oncogene and nestin protein. Nestin therefore may be a useful marker of malignant progression and grade of tumour differentiation. The work was supported by MSM 6198959216.