title: Sulfation of tibolone and tibolone metabolites by expressed human cytosolic sulfotransferases.
abstract: Tibolone is an important therapeutic agent used in the treatment of menopausal symptoms in many countries and has beneficial effects on menopausal and postmenopausal vasomotor, bone, vaginal and mood symptoms without affecting the endometrial, breast or cardiovascular systems. The rapid metabolism of tibolone to active metabolites including 3alpha-OH-tibolone, 3beta-OH-tibolone and Delta(4)-tibolone may be important in its tissue-specific effects. Sulfation also has a major role in the metabolism and regulation of the tissue-specific activity of tibolone and its metabolites. The ability of seven major expressed human sulfotransferase (SULT) isoforms to sulfate tibolone and its three metabolites was examined. Expressed human SULT2A1 was capable of sulfating tibolone and all three metabolites with the highest affinity for 3alpha-OH-tibolone. SULT1E1 conjugated both 3-OH-tibolone metabolites and tibolone itself slightly. SULT2B1b sulfated both 3-OH metabolites but not tibolone or Delta(4)-tibolone. SULT isoforms 1A1, 1A3, 1B1 and 1C1 did not demonstrate detectable activity. Sulfation of tibolone and its metabolites by human tissue cytosols was analyzed to determine whether the pattern of tibolone sulfation corresponded to the known expression of SULT isoforms in each tissue. The tissue-specific effects of tibolone may be regulated in part by the inactivation of tibolone and its metabolites by specific human SULT isoforms.
authors.affiliation: Department of Pharmacology and Toxicology, University of Alabama at Birmingham, 1670 University Boulevard, Volkder Hall G133M, Birmingham, AL 35294, USA. charles.falany@ccc.uab.edu
authors.forename: Josie L
authors.initials: JL
authors.lastname: Falany
authors.forename: Nancy
authors.initials: N
authors.lastname: Macrina
authors.forename: Charles N
authors.initials: CN
authors.lastname: Falany
mesh_terms: D000311:Adrenal Glands / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology*; D006801:Humans; D007422:Intestines / Q000201:enzymology; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D013058:Mass Spectrometry; D009652:Norpregnenes / Q000032:analysis / Q000378:metabolism*; D013431:Sulfates; D015238:Sulfotransferases / Q000032:analysis / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D007527:Isoenzymes; D009652:Norpregnenes; D013431:Sulfates; D015238:Sulfotransferases; C027385:tibolone