Oxidative Stress and Iron Addiction: A Comparative Study of 1321N1 Astrocytoma and T98G Glioblastoma Cells with Differential Expression of L-Cysteine-Metabolizing Enzymes

Gliomas are central nervous system primary tumors that are distinguished by heterogeneity, broad-based infiltration, and metabolic reprogramming that sustains proliferation, invasion, and therapy refractoriness. Oxidative stress-a state of imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense-and disturbed iron metabolism are central drivers of glioma biology. The aim of this study was to evaluate ROS production, sulfane sulfur levels, the expression of proteins with antioxidant properties, such as L-cysteine-metabolizing enzymes (cystathionine β-synthase, CBS; cysteine dioxygenase 1, CDO1; cystathionine γ-lyase, CTH; 3-mercaptopyruvate sulfurtransferase, MPST; thiosulfate sulfurtransferase, TST) and non-enzymatic proteins (p53; transferrin receptor 1, TfR1), in human brain cancer cells differing in malignancy: 1321N1 astrocytoma and T98G glioblastoma. Western blotting analysis demonstrated that the expression of CBS, CDO1, and TfR1 was significantly increased in T98G cells, while CTH, MPST, TST, and p53 were comparably expressed in both cell lines. Quantitative assays revealed that T98G cells harbored significantly higher sulfane sulfur levels and higher numbers of ROS-positive cells compared to 1321N1 cells. Our results suggest that glioblastoma but not astrocytoma cells adapt sulfur and iron metabolism to provide proliferation capacity against chronic oxidative stress. It seems that CBS as well as CDO1 may significantly increase the antioxidant potential of T98G cells. In summary, this study suggests a differing metabolic vulnerability identifiable only in high-grade glioma cells and provides a potential novel molecular target for therapy.