Biology subjects

Duraj, T.

Publications and source records attributed to Duraj, T..

3 recordsLinked to original sources

bioRxiv2025

Lactate cannot replace glucose for maintaining the viability of mouse and human glioma cells

ObjectivesAerobic lactic acid fermentation (the "Warburg effect") is associated with OxPhos insufficiency and altered energy metabolism in most cancers. Whether lactate is a major fuel in cancer cells remains debated. This study investigated whether lactate could serve as a metabolic fuel in glioma cells and replace glucose to support viability. MethodsA bioluminescence ATP assay and calcein-AM/EthD-III double-staining were used to measure ATP content and viability in mouse (VM-M3, CT-2A) and human (U-87MG) glioma cells differing in cell biology and genetic background. Viability was assessed in thioglycollate-elicited peritoneal macrophages (TPMs) from VM/Dk and C57BL/6J mice, used as syngeneic non-neoplastic controls for VM-M3 and CT-2A gliomas, respectively. Oxygen consumption rate (OCR) was determined using the Resipher system. ResultsLactate alone failed to sustain ATP content and viability in all glioma cell lines. ATP content and viability were lower in cancer cells cultured in glutamine and lactate than in glucose and glutamine. In contrast, lactate alone sustained over 45% viability in both TPM models. Moreover, viability was similar between TPMs cultured in glutamine and lactate and in glucose and glutamine. In human U-87MG, lactate addition under severe glucose restriction increased OCR and viability. A low dose of the glycolysis inhibitor 2-deoxy-D-glucose abolished both increases. ConclusionsOur results suggest non-neoplastic mouse TPMs utilize lactate more effectively than mouse glioma cells. In U-87MG, lactate utilization appears glycolysis-dependent, given its sensitivity to 2-deoxy-D-glucose. In conclusion, our data does not support lactate as a major oxidative fuel for viability in mouse and human glioma cells.

cancer biology↗

bioRxiv2025

The differential effect of glutamine supplementation on the orthotopic and subcutaneous growth of two syngeneic murine models of glioma

Glutamine serves as a major fuel source for tumor cell proliferation while simultaneously playing an essential role in maintaining gastrointestinal health and immune function. Controversy exists regarding glutamine supplementation for cancer patients undergoing chemotherapy and radiation, with concerns that it may stimulate cancer growth. The present study is the first to examine the effects of dietary glutamine supplementation (0.4g/kg/day) on the growth of malignant gliomas, which utilize large amounts of glutamine to satisfy metabolic demands. Brain bioluminescence and subcutaneous tumor volumes were used to assess the influence of glutamine supplementation on the growth of the syngeneic VM-M3 and CT-2A preclinical models of glioma. Glutamine supplementation had no significant effect on the orthotopic growth of the VM-M3 or the CT-2A gliomas when compared to non-supplemented controls. However, glutamine supplementation significantly increased tumor volume by 28% in the VM-M3 and by 166% in the CT-2A tumors when grown subcutaneously outside the central nervous system (CNS) relative to controls. Additionally, glutamine supplementation increased serum glutamine despite a localized decrease in intratumoral glutamine concentrations. Caution is warranted when considering glutamine supplementation in patients with glutamine-dependent malignancies. Further studies are needed to better understand the potential risks and benefits of glutamine supplementation in cancer therapy.

cancer biology↗

bioRxiv2024

Amino Acid and Glucose Fermentation Maintain ATP Content in Mouse and Human Malignant Glioma Cells

Energy is necessary for tumor cell viability and growth. Aerobic glucose-driven lactic acid fermentation is a common metabolic phenotype seen in most cancers including malignant gliomas. This metabolic phenotype is linked to abnormalities in mitochondrial structure and function. A luciferin-luciferase bioluminescence ATP assay was used to measure the influence of amino acids, glucose, and oxygen on ATP content and viability in mouse (VM-M3 and CT-2A) and human (U-87MG) glioma cells that differed in cell biology, genetic background, and species origin. Oxygen consumption was measured using the Resipher system. Extracellular lactate and succinate were measured as end products of the glycolysis and glutaminolysis pathways, respectively. The results showed that: 1) glutamine was a source of ATP content irrespective of oxygen. No other amino acid could replace glutamine in sustaining ATP content and viability; 2) ATP content persisted in the absence of glucose and under hypoxia, ruling out substantial contribution through either glycolysis or oxidative phosphorylation (OxPhos) under these conditions; 3) Mitochondrial complex IV inhibition showed that oxygen consumption was not an accurate measure for ATP production through OxPhos. The glutaminase inhibitor, 6-diazo-5-oxo-L-norleucine (DON), reduced ATP content and succinate export in cells grown in glutamine. The data suggests that mitochondrial substrate level phosphorylation in the glutamine-driven glutaminolysis pathway contributes to ATP content in these glioma cells. A new model is presented highlighting the synergistic interaction between the high-throughput glycolysis and glutaminolysis pathways that drive malignant glioma growth and maintain ATP content through the aerobic fermentation of both glucose and glutamine. Summary statementMalignant gliomas, regardless of cell of origin or species, rely on fermentation mechanisms for ATP production due to OxPhos insufficiency. Glucose and glutamine together are necessary and sufficient for dysregulated tumor cell growth, whereas OxPhos is neither necessary nor sufficient.

cancer biology↗