PubMed · 1629913
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E Blume. 1992-06-17. Scientists, activists discuss DES issues.. https://doi.org/10.1093/jnci%2F84.12.925
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Although current hormonal therapy of prostate cancer may not appear to have altered survival appreciably, there have been considerable changes that may significantly affect the future management of this disease. A number of new hormonal agents have been introduced that still require definition of their therapeutic efficacy. Megestrol acetate, a hormonal agent with multiple sites of action in androgen metabolism, has recently been investigated in the treatment of patients with metastatic and locally advanced disease, and in those patients whose disease progresses with other hormonal therapies. Megestrol acetate plus mini-dose diethylstilbestrol (DES) is associated with fewer side effects than standard-dose DES and has equivalent therapeutic efficacy in the treatment of patients with metastatic disease. In patients with locally advanced disease that may benefit from hormonal cytoreduction, megestrol acetate is effective and well tolerated. Megestrol acetate has a role in the palliation of patients with progressive disease despite initial hormonal therapy. Considerable controversy surrounds the therapy of carcinoma of the prostate; further studies are required to define optimal hormonal therapy.
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Metabolic redox cycling between the stilbene estrogen diethylstilbestrol (DES) and diethylstilbestrol-4',4"-quinone (DES Q) has been demonstrated previously. The xanthine and xanthine oxidase-catalyzed reduction of estrogen quinone has been studied in this work to understand the role of metabolic redox cycling in estrogen metabolism. Xanthine and xanthine oxidase catalyzed the reduction of DES Q to 44% Z-DES and 9% E-DES. This reaction was inhibited by the addition of superoxide dismutase or by a lack of oxygen (under anaerobic conditions). DES Q was also reduced in a non-enzymatic reaction by superoxide radicals generated by potassium superoxide and crown ether. The reaction between the O2-. and DES Q was also investigated by an electron spin resonance spin-trapping technique. The superoxide anion generated in an oxygen-saturated xanthine and xanthine oxidase system was detected as 5,5-dimethyl-1-pyrroline-1-oxide-superoxide adduct. The addition of DES Q or 2,3-estradiol quinone totally inhibited the formation of this adduct. The reduction of DES Q by superoxide radicals was taken as evidence that this reaction was one possible mechanism of xanthine and xanthine oxidase-mediated reduction. In addition, reduction of DES Q by direct electron transfer to quinone by the enzyme may also occur. The intermediate formation of semiquinone free radicals in the reduction is implied by the nature of the single electron transfer reactions and, in addition, has been demonstrated for the catechol estrogen by electron spin resonance measurements. It is concluded that the reduction of estrogen quinones to their hydroquinones by xanthine oxidase occurs by both one electron transfer to the quinone and by formation of superoxide which then reduces the quinone.