Fas (APO-1/CD95) signaling pathway is intact in radioresistant human glioma cells

Radiation induced apoptosis can be mediated through pathways initiated by e ither DNA damage or ceramide-induced Pas signaling. Glioblastoma multiforme is a primary brain tumor that is highly resist-ant to irradiation, and U-8 7 MG, SF126, and T98G are glioblastoma-derived cell lines that mimic this c haracteristic. We found that these radioresistant glioma cells are suscepti ble to Pas-mediated cell death induced by treatment with either anti-Pas an tibody or exogenous ceramide, Pas-mediated cell death in these cell lines i s p53-independent. These data demonstrate that apoptosis can he induced by ceramide and mediated through the Pas pathway in glioma cells, although hig h-dose ionizing radiation fails to trigger this pathway.