Zusammenfassung
Geprüft wurde, ob die Freisetzung von Acrolein aus Oxazaphosphorinan-Cytostatika zur cytotoxischen Wirkung und Spezifität beiträgt. Zu diesem Zwecke wurde die Cytotoxizität von 4-Hydroperoxycyclophosphamid, 4-Hydroperoxy-semi-cyclophosphamid, 4-Hydroperoxy-dechloro-cyclophosphamid und von Acrolein auf L 1210 Tumorzellen in vitro durch Bestimmung der mittleren Überlebenszeit nach Transplantation der Tumorzellen auf DBA2/Han-Mäuse miteinander verglichen. Wir fanden, daß nur 4-Hydroperoxycyclophosphamid, das neben Acrolein auch das alkylierende Spaltprodukt N-Lost-Phosphorsäurediamid freisetzt, die Transplantabilität der L 1210 Zellen vermindert. Dagegen waren die Strukturanalogen 4-Hydroperoxy-semi-cyclophosphamid und 4-Hydroperoxy-dechloro-cyclophosphamid, die nur Acrolein aber kein Alkylans freisetzen, unwirksam. Zusatz von Acrolein in Konzentrationen, die dem während der Inkubationszeit aus den Oxazaphosphorinan-Derivaten abgespaltenen Acrolein entsprechen, verringerte die Transplantabilität der L 1210 Zellen nur unwesentlich, unterschied sich aber qualitativ durch verstärkte Zell-Lyse (Trypanblaufärbung) von dem intrazellulär aus 4-Hydroperoxy-oxazaphosphorinan-Verbindungen freigesetzten Acrolein. Die Versuche zeigen, daß die cytotoxische Wirkung von aktiviertem Cyclophosphamid auf Reaktionen des alkylierenden Molekülteils beruht, und daß weder die 4-Hydroperoxy-Funktion, der aktivierte Oxazaphosphorinanring als solcher, noch das während der Giftung intrazellulär freigesetzte Acrolein direkt cytotoxisch auf L 1210 Zellen wirken und dadurch die höhere cytotoxische Spezifität von aktiviertem CP im Vergleich zu anderen Stickstoff-Lost-Cytostatika verursachen.
Summary
To determine whether the release of acrolein from oxazaphosphorinane-cytostatics contributes to their cytotoxic action, the effect of 4-hydroperoxycyclophosphamide, 4-hydroperoxy-semi-cyclophosphamide, 4-hydroperoxy-dechloro-cyclophosphamide, and acrolein on murine L 1210 leukemia cells in vitro was compared by measuring the median survival time (MST) after transplantation of the tumor cells in DBA2/Han mice. We found that only 4-hydroperoxycyclophosphamide, which is able to release both acrolein and the alkylating metabolite phosphoramide-mustard, decreased the transplantability of L 1210 cells, while the structurally analogous 4-hydroperoxy-dechloro-cyclophosphamide and 4-hydroperoxy-semi-cyclophosphamide, which under physiological conditions only release acrolein but no alkylating split products, showed no cytotoxicity. Acrolein itself showed only a marginal effect, when administered in concentrations equivalent to the release of acrolein from the oxazaphosphorinane-derivatives in test. In this case, however, significant lysis of the L 1210 cells was observed by estimating dye exclusion, while acrolein released intracellularly from 4-hydroperoxy-oxazaphosphorinane-compounds did not. This points to a different mechanism of the cytotoxic action of extracellular acrolein and acrolein released intracellularly from activated oxazaphosphorinane-compounds. The results suggest that the cytotoxic effect of activated cyclophosphamide is based on the alkylating moiety of the molecule. Neither the 4-hydroperoxy-group nor the activated oxazaphosphorinane-ring itself, nor acrolein released intracellularly during toxification of activated cyclophosphamide exert a direct cytotoxic effect. Thus, the release of acrolein from activated CP apparently does not contribute to the cytotoxicity of CP in vivo.
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Our studies were supported by the Deutsche Forschungsgemeinschaft Bonn-Bad Godesberg, FRG
This paper contains results of the Ph. D. Dissertation of E. Wrabetz to be submitted to the Fachbereich Biologie, University of Frankfurt, 1980
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Wrabetz, E., Peter, G. & Hohorst, H.J. Does acrolein contribute to the cytotoxicity of cyclophosphamide?. J Cancer Res Clin Oncol 98, 119–126 (1980). https://doi.org/10.1007/BF00405956
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DOI: https://doi.org/10.1007/BF00405956