Frequent downregulation of Fas (CD95) expression and function in melanoma.
Membrane-bound Fas ligand (FasL, Apo-1L, CD95L) induces rapid apoptosis of Fas (CD95)-sensitive cells on interaction with Fas, and is an important effector molecule of cytolytic T lymphocytes (CTLs). Melanomas are immunogenic and induce the production of specific CTLs, but are usually able to escape immune destruction. We investigated Fas expression and function in 53 cutaneous melanocytic lesions and 13 melanoma cell lines grown in vitro. Immunohistochemical analysis of Fas expression in cutaneous melanocytic lesions showed moderate to high levels of Fas in common benign melanocytic naevi, but low to undetectable levels in atypical naevi, primary (superficial spreading melanoma, nodular melanoma) and cutaneous melanoma metastases. Fluorescence-activated cell sorting (FACS) analysis of Fas expression in melanoma cell lines revealed undetectable or low levels of cell surface Fas expression in five of the 13 melanoma cell lines. Analysis of Fas signalling by quantification of cell death following exposure to recombinant FasL showed that a reduction in Fas expression results in resistance to FasL-mediated cell death. Furthermore, two of the 13 melanoma cell lines were found to be resistant to FasL-mediated cell death despite conserved Fas expression. Thus seven of the 13 melanoma cell lines were found to have impaired Fas signalling. Taken together, our results indicate that downregulation of Fas expression and resistance to Fas-mediated apoptosis are frequent in melanoma.
Department of Dermatology, Geneva University Medical School, 24 rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland.
R R
RR
Bullani
P
P
Wehrli
I
I
Viard-Leveugle
D
D
Rimoldi
J-C
JC
Cerottini
J-H
JH
Saurat
J
J
Tschopp
L E
LE
French
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D015536:Down-Regulation; D053222:Fas Ligand Protein; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008544:Melanocytes / Q000378:metabolism; D008545:Melanoma / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology / Q000556:secondary; D008562:Membrane Glycoproteins / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D009508:Nevus, Pigmented / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured / Q000378:metabolism; D019014:fas Receptor / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011994:Recombinant Proteins; D019014:fas Receptor