Some features of the energy metabolism of primary cell cultures of sarcomas.

e23540 Background: Cellular bioenergetic profiles are critical determinants of tumor biology and can vary significantly between different malignancies. Characterizing the metabolic dependencies of primary sarcoma cultures is essential for understanding their pathophysiology and potential therapeutic vulnerabilities. This study aimed to define the energetic phenotypes of primary sarcoma cell cultures by assessing their metabolic response to glucose. Methods: Five primary sarcoma cell cultures were established from patient samples via enzymatic dissociation with collagenase I and cultured in DMEM medium supplemented with 10% FBS, ITS, and NEAA. Metabolic profiling of adherent cells was performed using a Seahorse XFp analyzer. Assays included the mitochondrial stress test, FCCP titration, and the glycolytic stress test according to the manufacturer's protocols, utilizing media optimized for specific energetic substrates to accurately measure cellular respiration and glycolysis. Results: Analysis of the respiratory response to glucose addition revealed two distinct metabolic phenotypes. Group 1 (three cultures) exhibited a low mitochondrial ATP production rate (<5% of total respiration linked to ATP synthesis) but high reserve respiratory capacity (>150% of baseline) and glycolytic reserve (>1600% of baseline). As expected, these cultures increased oxygen consumption upon glucose addition, proportional to their high reserve capacities. In contrast, Group 2 (two cultures) demonstrated a high mitochondrial ATP production rate (>10%) but low reserve respiratory capacity (<90%) and low glycolytic reserve (<700%). These cultures decreased oxygen consumption following glucose addition, corresponding to a reduction in their spare metabolic capacities. Conclusions: Primary sarcoma cultures display two distinct energetic phenotypes: a "high-reserve" phenotype with low baseline mitochondrial ATP production but substantial capacity to upregulate both oxidative phosphorylation and glycolysis in response to glucose; and a "low-reserve" phenotype with high baseline mitochondrial ATP dependence but limited ability to further enhance metabolism with increased glucose. This phenotypic stratification may reflect underlying biological heterogeneity in sarcomas and could inform strategies for metabolic targeting.