1. ¹Department of Pathology, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
2. ²Department of Dermatology, Hospital Universitari Germans Trias i Pujol, Barcelona, Spain
3. ³Department of Dermatology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Barcelona, Spain

Correspondence: Maria Teresa Fernandez-Figueras, M.D., Department of Pathology, Hospital Universitari Germans Trias i Pujol, Ctra. de Canyet, s/n, 08916 Badalona, Barcelona, Spain. e-mail: mtferfig@ns.hugtip.scs.es; fax: 34-93-4978843

Accepted 15 August 2002.

Abstract

F-Box protein p45^SKP2 is the substrate-specific receptor of ubiquitin-protein ligase SCF/p45^SKP2 and is involved in the degradation of p27^Kip1 through the ubiquitin/proteasome pathway. In addition, p45^SKP2 facilitates proteolysis of other molecules related to the cell cycle, is frequently over-expressed in transformed cells, and induces S phase in quiescent cells. The aim of this study was to determine whether p45^SKP2 expression is altered in aggressive lesions of Kaposi's sarcoma and its relation to p27^KIP1down-regulation. We performed immunohistochemistry using antibodies directed to p45^SKP2, p27^KIP1, and Ki67 on paraffin blocks corresponding to 47 cases of Kaposi's sarcoma (8 macules, 10 plaques, 12 tumors, and 15 extracutaneous lesions). p45^SKP2 nuclear over-expression was present in all Kaposi's sarcoma stages, being significantly increased in skin tumors (mean 95% confidence interval: 39.2 18.8) and extracutaneous lesions (25.8 17.3) as compared with macules (18.9 8.2) and plaques (29.2 12.0; P = .0199). On the other hand, Kaposi's sarcoma progression was associated with a decrease in p27^KIP1 expression and Ki67 immunoreactivity was independent of disease stage. No statistically significant differences were found in regard to patients' sex and human immunodeficiency virus status and regression analysis failed to show a correlation among p45^SKP2, p27^KIP1 and Ki67 immunostaining scores. These findings suggest that p45^SKP2 is involved in Kaposi's sarcoma progression, not only by promoting the degradation of p27^KIP1 but also through other mechanisms still unknown.