A WOW!!!!!? I think.
What are the implications of this?
Very foggy with big gaps - but huge me thinks.
What does it say about the realtionship of oestrogen produced externally and oestrogen produced by the tumour and the ranking and control?.
It seems to be saying that localised control is much more important than external supply, if you can find a way of acheiving local aromatase control, and from the summary are the suggestion not that melatonin may be acheiving this??.
One for those facing fertility / treatment decisions to talk to their oncs about?
RB
http://www.ncbi.nlm.nih.gov/entrez/q..._uids=16080194
1: Int J Cancer. 2006 Jan 15;118(2):274-8.Click here to read Links
Melatonin inhibits the growth of DMBA-induced mammary tumors by decreasing the local biosynthesis of estrogens through the modulation of aromatase activity.
* Cos S,
* Gonzalez A,
* Guezmes A,
* Mediavilla MD,
* Martinez-Campa C,
* Alonso-Gonzalez C,
* Sanchez-Barcelo EJ.
Department of Physiology and Pharmacology, School of Medicine, University of Cantabria, Santander, Spain.
Melatonin inhibits the growth of breast cancer cells by interacting with estrogen-responsive pathways, thus behaving as an antiestrogenic hormone. Recently, we described that melatonin reduces aromatase expression and activity in MCF-7 human breast cancer cells, thus modulating the local estrogen biosynthesis. To investigate the in vivo aromatase-inhibitory properties of melatonin in our current study, this indoleamine was administered to rats bearing DMBA-induced mammary tumors, ovariectomized (ovx) and treated with testosterone. In these castrated animals, the growth of the estrogen-sensitive mammary tumors depends on the local aromatization of testosterone to estrogens. Ovariectomy significantly reduced the size of the tumors while the administration of testosterone to ovx animals stimulated tumor growth, an effect that was suppressed by administration of melatonin or the aromatase inhibitor aminoglutethimide. Uterine weight of ovx rats, which depends on the local synthesis of estrogens, was increased by testosterone, except in those animals that were also treated with melatonin or aminoglutethimide. The growth-stimulatory effects of testosterone on the uterus and tumors depend exclusively on locally formed estrogens, since no changes in serum estradiol were appreciated in testosterone-treated rats. Tumors from animals treated with melatonin had lower microsomal aromatase activity than tumors of animals from other groups, and incubation with melatonin decreased the aromatase activity of microsomal fractions of tumors. Animals treated with melatonin had the same survival probability as the castrated animals and significantly higher survival probability than the uncastrated. We conclude that melatonin could exert its antitumoral effects on hormone-dependent mammary tumors by inhibiting the aromatase activity of the tumoral tissue. Copyright 2005 Wiley-Liss, Inc.
PMID: 16080194 [PubMed - indexed for MEDLINE]
Related Links
* Melatonin modulates aromatase activity in MCF-7 human breast cancer cells. [J Pineal Res. 2005] PMID: 15683469
* The effect of estrogen on aromatase and vascular endothelial growth factor messenger ribonucleic acid in the normal nonhuman primate mammary gland. [J Clin Endocrinol Metab. 1999] PMID: 10199791
* The effect of aromatase inhibitor 4-hydroxyandrostenedione on steroid receptors in hormone-dependent tissues of the rat. [J Steroid Biochem Mol Biol. 1995] PMID: 7857875
* Growth and characterization of N-methyl-N-nitrosourea-induced mammary tumors in intact and ovariectomized rats. [Carcinogenesis. 2001] PMID: 11751437
* Antitumor effects of SEF19, a new nonsteroidal aromatase inhibitor, on 7,12-dimethylbenz[a]anthracene-induced mammary tumors in rats. [Anticancer Res. 1998] PMID: 9568073
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