Expression of endothelin-1 and endothelin receptors in cultured human glioblastoma cells

Production and secretion of endothelin-1 (ET-1) by a human glioblastoma cel l line, T98G, were studied by radioimmunoassay and Northern blot analysis. Immunoreactive ET was detected in the culture medium of T98G (17.6 +/- 0.6 fmol/10(5) cells/24 h, mean +/- SEM, n = 5). Reverse-phase high-performance liquid chromatography (HPLC) of immunoreactive ET in the culture medium ex tract showed a single peak eluting in the position of ET-1. Northern blot a nalysis showed expression of ET-1 mRNA in T98G cells. Treatment with interf eron-gamma decreased the expression of ET-1. Treatment with TNF alpha or in terleukin-1 beta (IL-1 beta) increased the expression of ET-1. Furthermore, reverse transcriptase polymerase chain reaction (RT-PCR) showed expression of endothelin-A- and -B- (ETA and ETB) receptor mRNAs in T98G glioblastoma cells. These findings indicate that glioblastoma cells produce and secrete ET-1, and express ET receptor mRNAs. ET-1 secreted by glioblastoma cells m ay act locally on tumor cells, possibly as a growth modulator.