Zusammenfassung
Unter anaeroben Kulturbedingungen, (95% Argon 5% CO2) stieg der Gesamtlipidgehalt in Ehrlich Ascites Tumorzellen etwas stärker an als unter aeroben Bedingungen (20% O2, 75% N2, 5% CO2). In Abwesenheit von Sauerstoff war der Einbau von [U-14C]Acetat in die Gesamtlipidfraktion als auch in einzelne Lipidklassen, deutlich erhöht, wohingegen ein drastischer Abfall der Einbauraten aus [U-14C]Pyruvat und [1-14C]Oktanoat sowie eine signifikante Verminderung des Einbaus von 3H-Wasser unter diesen Kulturbedingungen beobachtet wurde. Da die spezifische Aktivität von intrazellulärem Wasser auch unter tiefgreifenden Änderungen des metabolischen Zustandes der Zellen praktisch konstant bleibt, wird 3H-Wasser als die zuverlässigste Vorstufe zur Messung der Lipidbiosynthese unter aeroben und anaeroben Kulturbedingungen angesehen.
Aus den Ergebnissen wird geschlossen, daß Ehrlich Ascites Tumorzellen nicht, wie es für Normalgewebe angenommen wird, in der Lage sind, NADH/NADPH bei Ausschluß von Sauerstoff durch erhöhte Fettsäuresynthese zu, reoxidieren. Der beobachtete Anstieg im Gesamtlipidgehalt von anaerob kultivierten Zellen erklärt sich wahrscheinlich durch ein Ungleichgewicht zwischen normaler Aufnahme und gehemmtem Abbau von exogenen Lipiden.
Summary
Anaerobic culture conditions (95% argon/5% CO2) caused a slightly greater increase in total lipids of Ehrlich ascites tumor cells than a gas phase of 20% O2, 75% N2, 5% CO2. Whereas the rate of [U-14C]acetate incorporation into total lipids and lipid-subclasses rose markedly in the absence of oxygen, a drastic decrease of [U-14C]pyruvate and [1-14C]octanoate incorporation as well as a 30% reduction of 3H incorporation into lipids from tritiated water were observed under these conditions.
Since profound changes in the metabolic state of cells cause alterations in the specific activity of the acetyl-CoA pool but do not alter the specific activity of intracellular water, this precursor is considered to be an adequate monitor for lipogenesis under aerobic and anaerobic culture conditions.
Therefore, it is concluded that Ehrlich ascites tumor cells are not able to reoxidize NADH/NADPH in the absence of oxygen by a stimulation of biosynthesis of fatty acids as is discussed to be the case in normal cells. The slight increase in total lipids of anaerobically cultured cells seems to be the result of an imbalance between normal uptake and impaired utilization of lipids from serum-supplemented culture medium.
Abbreviations
- EAT cells:
-
Ehrlich ascites tumor cells
- Acetyl-CoA synthetase:
-
acetate: CoA ligase (AMP), EC 6.2.1.1.
- Pyruvate dehydrogenase:
-
Pyruvate: flpoate oxidoreductase, EC 1.2.4.1.
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This study was supported by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich “Zellenergetik und Zelldifferenzierung”
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Löffler, M., Schneider, F. Lipogenesis in Ehrlich ascites tumor cells under anaerobic culture conditions. J. Cancer Res. Clin. Oncol. 95, 115–122 (1979). https://doi.org/10.1007/BF00401005
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DOI: https://doi.org/10.1007/BF00401005