Background: Retinoids are candidate differentiation-inducing agents for glial tumors. Differentiation therapy is an attractive approach to cancers that resist surgery, irradiation and chemotherapy.
Methods: We examined the effects of retinoids on proliferation, morphology and sensitivity to apoptosis in human malignant glioma and neuroblastoma cell lines.
Results: In contrast to neuroblastoma cells, retinoids are devoid of acute cytotoxic effects and have only moderate antiproliferative effects on human glioma cell lines upon long-term exposure at high concentrations. Electron microscopy fails to reveal features of differentiation or apoptosis in retinoid-treated glioma cells and untransformed rat astrocytes. Retinoids do not modulate CD95 or CD95L expression or susceptibility to CD95-mediated apoptosis and fail to act in synergy with interferon (IFN)-alpha or IFN-gamma or cancer chemotherapy drugs to promote growth inhibition or apoptosis.
Conclusion: Glioma cell lines are refractory to the induction of differentiation or apoptosis by retinoids.
Copyright 2000 S. Karger AG, Basel.