Topography of Protein Kinase C βII in Benign and Malignant Melanocytic Lesions

Abstract

Background. Protein kinase C βII promotes melanogenesis and affects proliferation of melanocytic cells but is frequently absent or decreased in melanoma cells in vitro. Objective. To investigate PKC-βII expression and spatial distribution within a lesion in various benign and malignant melanocytic proliferations. Methods. Expression of PKC-βII 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-βII. Common nevi lacked completely PKC-βII. All other lesions expressed variably PKC-βII, with cutaneous melanoma metastases displaying the lowest rate of positivity (14%). In the topographical analysis within a lesion, PKC-βII expression was largely retained in the intraepidermal and junctional part of all other lesions (dysplastic nevus, lentigo maligna, and melanoma). Reduced expression of PKC-βII was found in the dermal component of benign and malignant lesions (P = .041 vs intraepidermal). PKC-βII expression in the various compartments did not differ significantly between benign and malignant lesions. Conclusions. The current study revealed a significant correlation between PKC-βII expression and spatial localization of melanocytes, with the lowest expression found in the dermal compartment and the highest in the epidermal compartment.