MITOTIC CYCLINS AND CYCLIN-DEPENDENT KINASES IN MELANOCYTIC LESIONS

Recent evidence has implicated cyclins and cyclin-dependent kinases in the evolution and progression of various malignancies. We studied the immunohistochemical expression of cyclin A, cyclin B, and cyclin-depe ndent kinase p34cdc2 in a broad spectrum of benign and malignant melan ocytic lesions. Formalin-embedded, parrafin-fixed tissue sections from 66 malignant melanomas (MM) and 60 benign nevi were examined for the expression of these cell-cycle proteins. The results were compared wit h the standard proliferative marker Ki-67 and mitotic index. MM showed significantly higher immunoreactivity for cyclin A, cyclin B, p34cdc2 , and Ki-67 compared with benign nevi. Cyclin A, p34cdc2, and Ki-67 di splayed strong coexpression in MM. Overexpression of cyclin A and p34c dc2 correlated with histological type, mitotic activity, Ki-67 index, tumor thickness, Clark's level, and clinical outcome in MM. In invasiv e MM, increased immunostaining of cyclin A and Ki-67 were associated w ith decreased patient survival. These findings indicate potential role s of mitotic cyclins and cyclin-dependent kinases in the pathogenesis and progression of malignant melanoma. Copyright (C) 1998 by W.B. Saun ders Company.