Chetrite GS, Cortes-Prieto J, Pasqualini JR. Effect of tibolone and its principal metabolites (3α- and 3β-hydroxy, 3α-sulfate, and 4-ene derivatives) on estrone sulfatase activity in normal and cancerous human breast tissue.
Horm Mol Biol Clin Investig 2011;
8:491-8. [PMID:
25961347 DOI:
10.1515/hmbci.2011.121]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 11/07/2011] [Indexed: 11/15/2022]
Abstract
BACKGROUND
Tibolone (Org-OD14) is the active substance of Livial®, a synthetic steroid with the structure 7α,17α-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-yn-3-one, possessing weak tissue-specific estrogenic, progestogenic, and androgenic properties, used to treat menopausal complaints. After oral administration, tibolone is extensively metabolized into the 3α-(Org-4904) and 3β-(Org-30126) hydroxy derivatives with estrogenic properties, its 4-ene (Org-OM38) isomer with progestogenic/androgenic activities, and the 3α-sulfate (Org-34322) derivative, a major biologically inactive circulating form. We compared the dose response of tibolone and its metabolites on estrone sulfatase activity [conversion of estrone sulfate (E1S) to estrone (E1)] in normal and cancerous human breast tissues.
MATERIALS AND METHODS
Tissue minces were incubated with physiological concentrations of [3H]-E1S (5×10-9M) alone or in the presence of tibolone and its metabolites (concentration range: 5×10-7to 5×10-5M) for 4 h. Tritiated E1, estradiol (E2), and E1S were separated and evaluated quantitatively by thin-layer chromatography.
RESULTS
The sulfatase activity was significantly higher in cancerous breast but strongly inhibited by tibolone and the different metabolites, whereas 3α- and 3β-hydroxy derivatives were the most potent inhibitors.
CONCLUSION
This very significant inhibitory effect of tibolone and its principal metabolites on the enzyme involved in E2biosynthesis in the human breast provides interesting perspectives to study the biological responses of these compounds in trials with breast cancer patients.
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