TM208 and TM209,dithiocarbamate derivatives with potential anti-cancer effects,were evaluated in reversible and time-dependent cytochrome P450(CYP)3A inhibition assays in rat liver microsomes using testosterone as pro...TM208 and TM209,dithiocarbamate derivatives with potential anti-cancer effects,were evaluated in reversible and time-dependent cytochrome P450(CYP)3A inhibition assays in rat liver microsomes using testosterone as probe substrate.Both compounds were found to be weak reversible inhibitors and moderate mechanism-based inhibitors of rat CYP3A.For reversible inhibition on rat CYP3A,the Ki values of competitive inhibition model were 12.10±1.75 and 13.94±1.31 μM,respectively.For time-dependent inhibition,the inactivation constants(K_(l))were 31.93±12.64 and 32.91±15.58 μM,respectively,and the maximum inactivation rates(kinact)were 0.0349770.0069 and 0.0725970.0172 min^(-1) respectively.These findings would provide useful in vitro information for future in vivo DDI studies on TM208 or TM209。展开更多
UDP-glucuronosyltransferase 1A9(UGT1A9) is a major phase II enzyme responsible for elimination of drugs and endogenous molecules.Clinical data have shown increased elimination of UGT1A9 substrates in pregnant women or...UDP-glucuronosyltransferase 1A9(UGT1A9) is a major phase II enzyme responsible for elimination of drugs and endogenous molecules.Clinical data have shown increased elimination of UGT1A9 substrates in pregnant women or oral contraceptive users,but the role of estrogen in the regulation of UGT1A9 expression remains unknown.In this study,we investigated the effect of 17β-estradiol(E2) on UGT1A9 expression and the role of ERα in the transcriptional regulation of UGT1A9.E2 significantly increased UGT1A9 promoter activity in Hep G2 cells in the presence of ERα.UGT1A9 induction by E2 was abrogated by antiestrogen ICI182,780 in Hep G2 cells that constitutively express ERα.Results from transient transfection of ERα mutants into Hep G2 cells demonstrated that mutation at DNA-binding domain of ERα abrogates increased UGT1A9 promoter activity by E2.Deletion and mutation assays of UGT1A9 promoter revealed a putative ERE located within -2262/-1987 region.Examination of healthy human liver tissues revealed significantly higher UGT1A9 expression in women as compared to men.Together,these findings provide a mechanistic basis for the previous clinical reports and may shed a light on identifying sources for inter-individual variability in UGT1A9-mediated drug metabolism.展开更多
基金supported by the funds of Peking University Comprehensive Center of Drug Discovery and Development(2009ZX09301-010)from China Ministry of Science and Technology。
文摘TM208 and TM209,dithiocarbamate derivatives with potential anti-cancer effects,were evaluated in reversible and time-dependent cytochrome P450(CYP)3A inhibition assays in rat liver microsomes using testosterone as probe substrate.Both compounds were found to be weak reversible inhibitors and moderate mechanism-based inhibitors of rat CYP3A.For reversible inhibition on rat CYP3A,the Ki values of competitive inhibition model were 12.10±1.75 and 13.94±1.31 μM,respectively.For time-dependent inhibition,the inactivation constants(K_(l))were 31.93±12.64 and 32.91±15.58 μM,respectively,and the maximum inactivation rates(kinact)were 0.0349770.0069 and 0.0725970.0172 min^(-1) respectively.These findings would provide useful in vitro information for future in vivo DDI studies on TM208 or TM209。
基金supported by the U.S. National Institute of Health (Grants HD065532 and GM112746)
文摘UDP-glucuronosyltransferase 1A9(UGT1A9) is a major phase II enzyme responsible for elimination of drugs and endogenous molecules.Clinical data have shown increased elimination of UGT1A9 substrates in pregnant women or oral contraceptive users,but the role of estrogen in the regulation of UGT1A9 expression remains unknown.In this study,we investigated the effect of 17β-estradiol(E2) on UGT1A9 expression and the role of ERα in the transcriptional regulation of UGT1A9.E2 significantly increased UGT1A9 promoter activity in Hep G2 cells in the presence of ERα.UGT1A9 induction by E2 was abrogated by antiestrogen ICI182,780 in Hep G2 cells that constitutively express ERα.Results from transient transfection of ERα mutants into Hep G2 cells demonstrated that mutation at DNA-binding domain of ERα abrogates increased UGT1A9 promoter activity by E2.Deletion and mutation assays of UGT1A9 promoter revealed a putative ERE located within -2262/-1987 region.Examination of healthy human liver tissues revealed significantly higher UGT1A9 expression in women as compared to men.Together,these findings provide a mechanistic basis for the previous clinical reports and may shed a light on identifying sources for inter-individual variability in UGT1A9-mediated drug metabolism.
