1. ^*Department of Dermatology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
2. ^†Department of Cardiology and Pneumology, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany
3. ^‡Division of Surgical Oncology, University of Pittsburgh Cancer Institute, PB02 Cancer Pavilion, Pittsburgh, Pennsylvania, USA

Correspondence: Jürgen Eberle PhD, Department of Dermatology, Charité-Universitätsmedizin Berlin Campus Benjamin Franklin, Fabeckstrasse 60-62, 14195 Berlin, Germany. Email: juergen.eberle@charite.de

Received 28 May 2004; Revised 23 September 2004; Accepted 28 September 2004; Published online 21 December 2004.

Abstract

Induction of apoptosis has been demonstrated previously by overexpression of CD95 ligand (CD95L) in cultured human melanoma cells. For in vivo approaches based on CD95L, however, targeted expression is a prerequisite and tyrosinase promoters have been considered for selection. Luciferase reporter gene assays performed for a representative panel of melanoma cell lines characterized by strong (SK-Mel-19), moderate (SK-Mel-13, MeWo), weak (A-375), and missing expression (M-5) of endogenous tyrosinase revealed high tyrosinase promoter activities in SK-Mel-19, SK-Mel-13, and MeWo, but only weak activities in A-375 and M-5 as well as in non-melanoma cell lines. After transfection of a CMV promoter CD95L expression construct, melanoma cells were found highly sensitive, as compared with non-melanoma cells. By applying a tyrosinase promoter CD95L construct, apoptosis was selectively induced in SK-Mel-19, SK-Mel-13, MeWo as well as in A-375, which was characterized by high CD95 surface expression and high sensitivity to agonistic CD95 activation. M5 and non-melanoma cell lines remained uninfluenced. Also, resistance to agonistic CD95 activation seen in MeWo characterized by weak CD95 surface expression was overcome by overexpression of CD95L. Our investigations provide evidence that tyrosinase promoter CD95L constructs may be of value for selective induction of apoptosis in therapeutic strategies for melanoma.