Mechanisms of Anthracycline-Enhanced Reactive Oxygen Metabolism in Tumor Cells

Table 9

Requirements for doxorubicin-stimulated hydroxyl radical formation by detergent-treated Ehrlich carcinoma cells. Hydroxyl radical production by Ehrlich carcinoma cells was determined by measurements of formaldehyde production from DMSO; the standard reaction mixture contained 100 mM DMSO, 100 μM EDTA, 50 μM FeS0₄, 1 mM NADPH, 0.1% Triton X-100, 10⁷ tumor cells/ml, and the indicated concentration of doxorubicin in a final volume of 7 ml of PBS at pH 7.2. Data are expressed as the of formaldehyde production for the 2 hr reaction interval in each experimental group; the total number of experiments for each group () is given in parentheses.

Experimental system	Hydroxyl radical production (nmol formaldehyde/10^7 cells)
Control	()^a
Doxorubicin (250 μM)	()^b
Minus cells	()^c
Heat denatured cells^d	()^c
Minus DMSO	()^c
Minus EDTA	()^c
Minus FeS04	()^c
Using 1 μM rather than 50 μM FeS04	()^c
Using FeC13 (50 μM) rather than FeS04	()^b
Minus NADPH	()^c
Minus NADPH plus NADH (1 mM)	()^e
Minus NADPH plus succinate (5 mM)	()^c
Minus Triton X-100	()^c

^a; ^bsignificantly different from the control group (); ^csignificantly different from complete reaction mixture containing doxorubicin and 50 μM FeS0₄ (); ^dtumor cells autoclaved for 60 min; ^esignificantly different from control and from complete reaction mixture containing NADPH ().