Effects of retinoic acid and tumor necrosis factor alpha on GL-15 glioblastoma cells

Glioblastomas are particularly resistant to classical antitumor treatments. Retinoids, which proved effective in the treatment of promyelocytic leukem ia, have been used for clinical assays on glioma tumors with only moderate effects; however in some cases they were active in combination with another therapy. These observations prompted us to analyse the efficacy of combini ng retinoic acid (RA) with a cytokine on a clonal human glioma cell line. O n GL-15 cells, RA and tumor necrosis factor alpha (TNF alpha) both reduced the glial fibrillary acidic protein level and DNA synthesis and induced apo ptotic pathways, but they were significantly more effective when used toget her. The up-regulation of the p55 TNF receptors observed during RA exposure might explain this cooperative effect. NeuroReport 11:389-393 (C) 2000 Lip pincott Williams & Wilkins.