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Cummings J, Willmott N, Hoey BM, et al. The consequences of doxorubicin quinone reduction in vivo in tumour tissue. Biochem Pharmacol. 1992;44(11):2165-74doi: 10.1016/0006-2952(92)90343-h.
Cummings, J., Willmott, N., Hoey, B. M., Marley, E. S., & Smyth, J. F. (1992). The consequences of doxorubicin quinone reduction in vivo in tumour tissue. Biochemical pharmacology, 44(11), 2165-74. https://doi.org/10.1016/0006-2952(92)90343-h
Cummings, J, et al. "The consequences of doxorubicin quinone reduction in vivo in tumour tissue." Biochemical pharmacology vol. 44,11 (1992): 2165-74. doi: https://doi.org/10.1016/0006-2952(92)90343-h
Cummings J, Willmott N, Hoey BM, Marley ES, Smyth JF. The consequences of doxorubicin quinone reduction in vivo in tumour tissue. Biochem Pharmacol. 1992 Dec 01;44(11):2165-74. doi: 10.1016/0006-2952(92)90343-h. PMID: 1472081.
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Elsevier Science

Biochem Pharmacol. 1992 Dec 01;44(11):2165-74. doi: 10.1016/0006-2952(92)90343-h.

The consequences of doxorubicin quinone reduction in vivo in tumour tissue.

Biochemical pharmacology

J Cummings, N Willmott, B M Hoey, E S Marley, J F Smyth

Affiliations

  1. Imperial Cancer Research Fund, Western General Hospital, Edinburgh, U.K.

PMID: 1472081 DOI: 10.1016/0006-2952(92)90343-h

Abstract

A clear role for quinone reduction in the mechanism of action of doxorubicin has still to be established. There are three possible outcomes of this form of doxorubicin metabolism: (1) drug free radical formation, redox cycling and generation of reactive oxygen species (ROS) resulting in lipid peroxidation and DNA damage; (2) covalent binding of reactive drug intermediates to DNA; and (3) formation of an inactive 7-deoxyaglycone metabolite. In this work, the occurrence of each of these pathways has been studied in vivo in a subcutaneously growing rat mammary carcinoma (Sp 107). Doxorubicin was administered by direct intratumoural injection either as the free drug or incorporated in albumin microspheres (10-40 microns diameter). There was no evidence of an increase in lipid peroxidation over background after either treatment at any time point studied. In fact, doxorubicin administration resulted in a statistically significant reduction in lipid peroxidation at the later time points studied compared to control (no drug treatment), e.g. 24 hr: control, 21.7 +/- 2.8 SD nmol malondialdehyde/g tissue; free doxorubicin (70 micrograms drug), 14.5 +/- 4.0 SD nmol/g (P < 0.01 Student's t-test) and doxorubicin microspheres (70 micrograms drug), 17.4 +/- 1.1 nmol/g (P < 0.05). Covalent binding to DNA was measured by a 32P-post-labelling technique. Low levels of four putative drug-DNA adducts were detected; however, there were no qualitative or quantitative differences in profiles between free drug and microspheres. High 7-deoxyaglycone metabolite concentrations comparable to the parent drug itself were detected after administration of microspheres (3.0 micrograms/g +/- 1.7 SD at 24 hr and 3.1 micrograms/g +/- 1.1 SD at 48 hr). In contrast, these metabolites were present at levels close to the limit of detection of our HPLC assay after free drug (0.04 microgram/g +/- 0.03 SD at 24 hr and 0.02 microgram/g +/- 0.03 SD at 48 hr). Thus, 7-deoxyaglycone metabolite formation can occur in tumour tissue (indicating active drug quinone reduction) without concomitant increases in the level of lipid peroxidation or the levels of drug-DNA adducts. In conclusion, the main biological consequence of doxorubicin quinone reduction in vivo in tumour tissue would appear to be drug inactivation to a 7-deoxyaglycone metabolite rather than drug activation to DNA reactive species or ROS.

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