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

Production and secretion of endothelin-1 (ET-1) by a human glioblastoma cell 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/10⁵ cells/24 h, mean ± SEM, n = 5). Reverse-phase high-performance liquid chromatography (HPLC) of immunoreactive ET in the culture medium extract showed a single peak eluting in the position of ET-1. Northern blot analysis showed expression of ET-1 mRNA in T98G cells. Treatment with interferon-γ decreased the expression of ET-1. Treatment with TNFα or interleukin-1β (IL-1β) increased the expression of ET-1. Furthermore, reverse transcriptase polymerase chain reaction (RT-PCR) showed expression of endothelin-A- and -B- (ET(A) and ET(B)) 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 may act locally on tumor cells, possibly as a growth modulator.