Topography of Protein Kinase C ßII in Benign and Malignant Melanocytic Lesions.

ABSTRACT

BACKGROUND: Protein kinase C ßII promotes melanogenesis and affects proliferation of melanocytic cells but is frequently absent or decreased in melanoma cells in vitro. OBJECTIVE: To investigate PKC-ßII expression and spatial distribution within a lesion in various benign and malignant melanocytic proliferations. METHODS: Expression of PKC-ßII was semiquantitatively assessed in the various existing compartments (intraepidermal [not nested], junctional [nested], and dermal) of benign (n = 43) and malignant (n = 28) melanocytic lesions by immunohistochemistry. RESULTS: Melanocytes in the basal layer of normal skin or in lentigo simplex stained strongly for PKC-ßII. Common nevi lacked completely PKC-ßII. All other lesions expressed variably PKC-ßII, with cutaneous melanoma metastases displaying the lowest rate of positivity (14%). In the topographical analysis within a lesion, PKC-ßII expression was largely retained in the intraepidermal and junctional part of all other lesions (dysplastic nevus, lentigo maligna, and melanoma). Reduced expression of PKC-ßII was found in the dermal component of benign and malignant lesions ( P = .041 vs intraepidermal). PKC-ßII expression in the various compartments did not differ significantly between benign and malignant lesions. CONCLUSIONS: The current study revealed a significant correlation between PKC-ßII expression and spatial localization of melanocytes, with the lowest expression found in the dermal compartment and the highest in the epidermal compartment.