Alterations in estradiol metabolism in MCF-7 cells induced by treatment with indole-3-carbinol and related compounds.
In mammals, estradiol (E2) metabolism primarily involves mutually exclusive hydroxylation at either C-2 or C-16 alpha. We have previously reported a consistent increase in the C-16 alpha hydroxylation activity in human breast cancer and in mouse strains with high levels of mammary tumors. Here we show that the dietary compound indole-3-carbinol (I3C) increases C-2 hydroxylation five-fold in MCF-7 cells in culture but has minimal effect on the reaction at C-16 alpha. Because I3C-induced changes in E2 metabolism result in a metabolite ratio inverse to that observed in women with breast cancer we have separately examined whether this shift conferred an anti-tumorigenic advantage to estrogen target cells. The preferential changes induced by I3C on estradiol metabolism in MCF-7 cells parallel its anti-tumorigenicity in mice. These results suggest that changes in the metabolism of estradiol via the C-2 pathway might play a significant role in decreasing risk for breast cancer in women. Indole-2-carbinol is readily available as a chemical and as a dietary component of cruciferous vegetables. Feasible dietary changes show promise of having clinical utility in the prevention of breast cancer and other hormone-dependent cancers.
Niwa
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Rockefeller University, New York, New York 10021.
Swaneck
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Bradlow
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HL
D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D004958:Estradiol / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D016588:Anticarcinogenic Agents; D004965:Estrogen Antagonists; D007211:Indoles; D004958:Estradiol; C016517:indole-3-carbinol