Do Glioblastoma Cancer Cells Need Vitamins? The Role of Vitamin B1

Background/Objectives: In this study, we investigated whether targeting thiamine (vitamin B1) metabolism could be useful in the treatment of glioblastoma. Methods: The study was conducted using LN-229 and T98G glioblastoma cell lines, as well as glioblastoma tissue samples obtained from up to 30 patients. The effects of thiamine and the thiamine antimetabolites oxythiamine and amprolium on cell viability were assessed using the MTT assay. The effects of hypoxia and temozolomide (TMZ), as well as gene expression in tissue samples, were analyzed using qRT-PCR. The expression of SLC19A2, SLC19A3, TPK1, SLC25A19, SLC35F3, and SLC44A4 was evaluated. Results: Higher thiamine concentrations increased the MTT metabolic activity of glioblastoma cells. Oxythiamine and amprolium reduced MTT metabolic activity, although their inhibitory effects reached a plateau and neither compound enhanced the effect of TMZ. Chronic hypoxia reduces thiamine metabolism. The expression of proteins involved in thiamine metabolism is lower in glioblastoma tissue than in peritumoral tissue. Conclusions: Overall, targeting thiamine metabolism does not appear to improve the efficacy of TMZ-based glioblastoma treatment. However, the observed viability-promoting effect of higher thiamine concentrations indicates that excessive thiamine intake or supplementation in patients with glioblastoma should be approached with caution and requires further clinical investigation.