IADR Abstract Archives
Glucose, Glutamine and Glutamate Metabolism of OSCC Cells and pH
Objectives: We have already shown that the metabolic activities of both oral squamous cell carcinoma (OSCC) and normal cells were decreased as the environmental pH was lowered. However, details about metabolic properties were still unclear. Therefore, we tried to elucidate differences in metabolic system between OSCC and normal cells by comparing the lactate and ammonia production.
Methods: OSCC cells (HSC-2, HSC-3) and a normal cell (HaCaT) were used. The cultured cells were suspended in saline, and mixed with substrates (5 mM glucose, glutamine or glutamate) at 37°C and pH 6.5, 7.0, 7.5 or 8.0. The whole acid production was monitored with pH-stat. The production of lactate and ammonia was measured with CE-TOFMS and ammonia meter, respectively.
Results: The whole acid production from glucose was decreased as the environmental pH was lowered in all cells. The proportion of lactate in the whole acid production increased at acidic pH in OSCC cells (41.2±12.5% at pH 8.0 to 58.4±3.9% at pH 6.5 in HSC-2, 37.1±13.1% to 47.5±11.9% in HSC-3), while that in normal cells was stable around 40%. The whole acid production and the ammonia production from glutamine were decreased at acidic pH in all cells. Normal cells showed a similar tendency with ammonia production in glutamate metabolism. However, cancer cells showed no ammonia production from glutamate.
Conclusions: The increase of the lactate proportion in OSCC cells at acidic pH indicates that cancer cells shift their glucose metabolism to anaerobic glycolysis at acidic pH. No ammonia production from glutamate in OSCC cells suggests that glutamate can transfer amino group to 2-oxoacids and synthesize various amino acids in cancer cells. The enrichment of amino acid pool, as well as the metabolic shift to anaerobic glycolysis might be advantageous for continuous cell growth in OSCC cells.
Methods: OSCC cells (HSC-2, HSC-3) and a normal cell (HaCaT) were used. The cultured cells were suspended in saline, and mixed with substrates (5 mM glucose, glutamine or glutamate) at 37°C and pH 6.5, 7.0, 7.5 or 8.0. The whole acid production was monitored with pH-stat. The production of lactate and ammonia was measured with CE-TOFMS and ammonia meter, respectively.
Results: The whole acid production from glucose was decreased as the environmental pH was lowered in all cells. The proportion of lactate in the whole acid production increased at acidic pH in OSCC cells (41.2±12.5% at pH 8.0 to 58.4±3.9% at pH 6.5 in HSC-2, 37.1±13.1% to 47.5±11.9% in HSC-3), while that in normal cells was stable around 40%. The whole acid production and the ammonia production from glutamine were decreased at acidic pH in all cells. Normal cells showed a similar tendency with ammonia production in glutamate metabolism. However, cancer cells showed no ammonia production from glutamate.
Conclusions: The increase of the lactate proportion in OSCC cells at acidic pH indicates that cancer cells shift their glucose metabolism to anaerobic glycolysis at acidic pH. No ammonia production from glutamate in OSCC cells suggests that glutamate can transfer amino group to 2-oxoacids and synthesize various amino acids in cancer cells. The enrichment of amino acid pool, as well as the metabolic shift to anaerobic glycolysis might be advantageous for continuous cell growth in OSCC cells.