Overexpression of immediate early gene X-1 (IEX-1) enhances gamma-radiation-induced apoptosis of human glioma cell line, U87-MG.

Malignant gliomas are usually incurable even if adjuvant therapy is delivered after neurosurgical treatment. Therefore, to enhance their radiation-induced apoptosis, it is important to detect the mechanism(s) leading to the death of malignant glioma cells. We report that apoptosis was induced in a time-dependent manner after gamma-radiation and that irradiated U87-MG cells (human glioblastoma cell line) expressed immediate early gene X-1 (IEX-1) with p53. We also document that their apoptotic sensitivity to gamma-radiation was enhanced by the overexpression of IEX-1. Our findings suggest that IEX-1 may represent a new factor for the enhancement of radiation-induced apoptosis of human glioma cells.