Abstract
Estrogen compounds were used to treat mice bearing syngeneic transplants of medroxyprogesterone acetate(MPA)-induced BALB/c mammary adenocarcinomas. Both MPA-dependent and MPA-independent tumor lines were used. These lines expressed estrogen (ER) and progesterone receptors (PR). We demonstrate that different doses of estradiol benzoate (EB) and 17-beta-estradiol (E2) inhibit tumor growth and induce tumor regression in both MPA-independent and -dependent tumors, even in the presence of MPA or progesterone (P). EB was unable to induce regression of (ER-) hormone-independent tumor lines. A few MPA-dependent tumors became resistant to the estrogenic treatment; in subsequent passages some of these tumors retained their MPA-responsiveness, although estrogen sensitivity was not recovered.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenocarcinoma / chemically induced
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Adenocarcinoma / drug therapy*
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Adenocarcinoma / pathology
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Animals
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Cell Division / drug effects
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Delayed-Action Preparations
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Estradiol / administration & dosage
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Estradiol / pharmacology
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Estradiol / therapeutic use*
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Female
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Mammary Neoplasms, Experimental / chemically induced
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Mammary Neoplasms, Experimental / drug therapy*
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Mammary Neoplasms, Experimental / pathology
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Medroxyprogesterone / analogs & derivatives*
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Medroxyprogesterone Acetate
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Mice
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Mice, Inbred BALB C
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Neoplasm Transplantation
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Progesterone / pharmacology
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Receptors, Estrogen / analysis
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Receptors, Progesterone / analysis
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Silicone Elastomers
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Transplantation, Isogeneic
Substances
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Delayed-Action Preparations
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Receptors, Estrogen
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Receptors, Progesterone
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Silicone Elastomers
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Progesterone
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Estradiol
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Medroxyprogesterone Acetate
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Medroxyprogesterone