Circulating soluble Fas (sFas) and expression of Fas-ligand on cancer cells
are mechanisms of immune escape. The aim of the present study was to inves
tigate expression and production of Fas and Fas-Ligand on bladder cancer ce
ll lines of different grade as a basic mechanism of their secretion in vivo
. sFas and sFas-ligand serum levels of patients with different stage of bla
dder cancer were examined to determine the possible clinical use of these m
olecules as tumor markers. Bladder cancer cell lints RT4 (G1). RT112 (G1),
T24 (G3) and SUP (G4) were analyzed by flowcytometry for Fas and Fas-ligand
expression. To determine if the fas-ligand gene is transcribed in these bl
adder cancer cell lines, RT-PCR was performed on mRNA extracted from these
cell lines. Production of sFas and sFas-ligand was examined in cell culture
supernatants of the cancer cells as well as in the serum of 62 patients wi
th bladder cancer by a specific ELISA test. We demonstrate that Fas is expr
essed in similar levels on all human bladder carcinoma cell lines. In T24 (
G3) and SUP (G4) cell lines we were able to detect the Fas-ligand protein,
whereas no Fas-ligand protein could be found in RT4 and RT112 (G1) cells. F
as-ligand mRNA was expressed in all bladder cancer cell lines. Furthermore,
all bladder cancer cell lines produce sFas but no sFas-ligand in spite of
mRNA expression. The range of sFas levels in the serum of all patients with
bladder cancer was large and did not show a correlation to the histopathol
ogical stage of bladder cancer. Although there is in vitro evidence that sF
as and Fas-ligand play a role in bladder cancer, no correlation between the
sFas and sFas-ligand serum levels and the histopathological stage of bladd
er cancer could be found. Therefore, serum sFas and sFas-ligand have to dat
e limited clinical relevance. (C) 2001 Elsevier Science Inc. All rights res
erved.