Human malignant glioma cell lines are refractory to retinoic acid-mediated differentiation and sensitization to apoptosis
F Schmidt1, P Groscurth, J Dichgans
1Laboratory of Molecular Neuro-Oncology, Department of Neurology, University of Tübingen, School of Medicine, Tübingen, Germany.
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.
Insights
Retinoids do not effectively induce differentiation or apoptosis in human glioma cells, unlike neuroblastoma cells. Glioma cells appear resistant to retinoid treatments, limiting their use in differentiation therapy for these tumors.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Retinoids are explored as differentiation-inducing agents for challenging cancers like glial tumors.
- Differentiation therapy offers a promising strategy for cancers resistant to conventional treatments.
Purpose of the Study:
- To investigate the effects of retinoids on human malignant glioma and neuroblastoma cell lines.
- To assess retinoid impact on cell proliferation, morphology, and apoptosis sensitivity.
Main Methods:
- Exposure of human glioma and neuroblastoma cell lines to retinoids.
- Evaluation of cell proliferation, morphology, and apoptosis.
- Electron microscopy to observe cellular changes.
- Assessment of CD95/CD95L expression and apoptosis susceptibility.
- Testing synergy with interferons (IFN-alpha, IFN-gamma) and chemotherapy drugs.
Main Results:
- Retinoids showed minimal cytotoxic and moderate antiproliferative effects on glioma cells, even at high concentrations and long-term exposure.
- No evidence of differentiation or apoptosis was observed in retinoid-treated glioma cells or astrocytes via electron microscopy.
- Retinoids did not alter CD95/CD95L expression or sensitivity to CD95-mediated apoptosis.
- Retinoids did not enhance the effects of interferons or chemotherapy drugs on glioma cell growth inhibition or apoptosis.
Conclusions:
- Human glioma cell lines are resistant to retinoid-induced differentiation.
- Glioma cells do not undergo apoptosis when treated with retinoids.