RESUMO
Estradiol receptors (ER), ERalpha and ERbeta, are ligand-dependent transcription factors that regulate gene expression. Human and murine genetics suggest that ERalpha is the key target for estradiol action on bone, uterus and breast. To date, the molecular mode of action of estradiol and selective estradiol receptor modulators (SERMs) on bone is not fully understood. This is exemplified by a lack of in vitro assays that reliably predict SERM agonist activities in vivo. We hypothesized that ligand-dependent ERalpha transrepression, via protein-protein interactions at AP1, may predict estrogenic effects on bone. We modeled this using the MMP1 promoter, which encodes an AP1 binding site. We show that ICI-182780, raloxifene, 4-hydroxytamoxifen and estradiol all exhibit differential agonistic activities on the MMP1 promoter by suppressing activity by 20-80%. Transrepression efficacy and potency correlated with both uterotrophic (R(2)=0.98) and osteoprotective (R(2)=0.80) potential in the ovariectomized rat. This identifies MMP1 promoter transrepression as an agonist activity commonly shared by AF2 agonists and "antagonists" alike. Mutation analysis showed that the repression by estradiol and SERMs required correct amino acid sequences in the AF-2 domain. For instance, L540Q AF2 mutation did not alter responses to raloxifene, although it greatly increased responses to ICI-182780 (threefold) and reduced estradiol's effect by 20%. Furthermore, all tested ligands repressed the MMP1 promoter through the L540Q mutant with identical efficacy. Together, these data suggest that estradiol and SERMs share common agonist transcriptional activity via protein-protein interactions at AP1.
Assuntos
Osso e Ossos/efeitos dos fármacos , Receptor alfa de Estrogênio/agonistas , Metaloproteinase 1 da Matriz/genética , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Útero/efeitos dos fármacos , Motivos de Aminoácidos/fisiologia , Animais , Osso e Ossos/metabolismo , Regulação para Baixo/efeitos dos fármacos , Estradiol/farmacologia , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor alfa de Estrogênio/fisiologia , Feminino , Humanos , Metaloproteinase 1 da Matriz/metabolismo , Proteínas Mutantes/fisiologia , Regiões Promotoras Genéticas/efeitos dos fármacos , Estrutura Terciária de Proteína/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Células Tumorais Cultivadas , Útero/metabolismoRESUMO
A novel class of indole ligands for estrogen receptor alpha have been discovered which exhibit potent affinity and high selectivity. Substitution of the bazedoxifene skeleton to the linker present in the HTS lead 1a provided 22b which was found to be 130-fold alpha-selective and acted as an antagonist of estradiol activity in uterine tissue and MCF-7 cancer cells.
Assuntos
Receptor alfa de Estrogênio/antagonistas & inibidores , Indóis/química , Indóis/farmacocinética , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Antagonistas de Estrogênios/química , Antagonistas de Estrogênios/farmacologia , Feminino , Humanos , Concentração Inibidora 50 , Ligantes , Útero/efeitos dos fármacosRESUMO
Estrogen receptor alpha (ERalpha) serine 118 (Ser118) phosphorylation modulates activation function-1 (AF1) function. Correct positioning of helix 12 promotes agonist-dependent recruitment of cyclin-dependent kinase-7 to catalyze this event. In this study we show robust cyclin-dependent kinase-7-independent, AF2 antagonist-induced Ser118 phosphorylation. Estradiol (E2) and ICI-182,780 (ICI-780) induce Ser118 phosphorylation of wild-type ERalpha and either of two helix 12 mutants, suggesting AF2-independent action, probably via shedding of 90-kDa heat shock protein. With E2 treatment, the predominantly nuclear, phosphorylated ERalpha in COS-1 cells is detergent soluble. Although levels of ICI-780-induced phosphorylation are profound, Ser118-phosphorylated ERalpha is aggregated over the nucleus or in the cytoplasm, fractionating with the cell debris and making detection in cleared lysates improbable. Selective ER modulators (SERMs) elicit a mixed response with phosphorylated ERalpha in both detergent-soluble and -insoluble compartments. Apparent ligand-induced loss of ERalpha protein from cleared lysates is thus due to ligand-induced redistribution into the pellet, not degradation. The COS-1 response to ICI-780 can be mimicked in MCF-7 cells treated with a proteasome inhibitor to block authentic ligand-induced degradation. With SERMs and antagonists, the magnitude of Ser118-phosphorylated receptor redistribution into the insoluble fraction of COS-1 cells correlates with the magnitude of authentic ERalpha degradation in MCF-7 cells. A strong inverse correlation with ligand-induced uterotropism in vivo (P < 0.0001) and direct correlation with AF2-independent transrepression of the matrix metalloprotease-1 promoter in endometrial cells in vitro are seen. These data suggest that ligand-induced Ser118 phosphorylation of ERalpha can be AF2 independent. Furthermore, they identify translocation of Ser118-phosphorylated ERalpha out of the nucleus, leading to cytoplasmic aggregation, as an antagonist pathway that may precede receptor degradation.
Assuntos
Antagonistas de Estrogênios/farmacologia , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor alfa de Estrogênio/metabolismo , Animais , Benzoquinonas , Células COS , Chlorocebus aethiops , Quinases Ciclina-Dependentes/efeitos dos fármacos , Quinases Ciclina-Dependentes/metabolismo , Citoplasma/efeitos dos fármacos , Citoplasma/metabolismo , Endométrio/citologia , Endométrio/efeitos dos fármacos , Estradiol/análogos & derivados , Estradiol/farmacologia , Receptor alfa de Estrogênio/agonistas , Feminino , Fulvestranto , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Proteínas de Choque Térmico HSP90/efeitos dos fármacos , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Lactamas Macrocíclicas , Metaloproteinase 1 da Matriz/efeitos dos fármacos , Metaloproteinase 1 da Matriz/genética , Tamanho do Órgão/efeitos dos fármacos , Fosforilação , Regiões Promotoras Genéticas , Quinonas/farmacologia , Ratos , Ratos Sprague-Dawley , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Serina/metabolismo , Útero/efeitos dos fármacos , Quinase Ativadora de Quinase Dependente de CiclinaRESUMO
Two novel side chains which had previously been found to enhance antagonist activity in the dihydrobenzoxathiin SERM series were applied to three existing platforms. The novel side chains did not improve the antagonist activity of the existing platforms.
Assuntos
Receptor alfa de Estrogênio/antagonistas & inibidores , Oxati-Inas/química , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Animais , Ligantes , RatosRESUMO
An optimized side chain for dihydrobenzoxathiin SERAMs was discovered and attached to four dihydrobenzoxathiin platforms. The novel SERAMs show exceptional estrogen antagonist activity in uterine tissue and an MCF-7 breast cancer cell assay.
Assuntos
Oxati-Inas/síntese química , Receptores de Estrogênio/química , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Antagonistas de Estrogênios/síntese química , Antagonistas de Estrogênios/farmacologia , Feminino , Humanos , Oxati-Inas/farmacologia , Ratos , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacos , Útero/crescimento & desenvolvimentoRESUMO
Estrogens and selective estrogen receptor modulators (SERMs) are prescribed widely in the clinic to alleviate symptoms in postmenopausal women, and they are metabolized to reactive intermediates, which may elicit adverse effects. As part of our efforts to develop safer SERMs, in vitro covalent protein binding of (2S,3R)-(+)-3-(4-hydroxyphenyl)-2-[4-(2-piperidin-1-ylethoxy)phenyl]-2,3-dihydro-1,4-benzoxathiin-6-ol (I) was evaluated. Radioactivity from [3H]I became covalently bound to proteins in a fashion that was both time- and NADPH-dependent in human liver microsomes and reached a value of 1106 pmol equiv/mg protein following a 45 min incubation. At least three pathways are involved in the bioactivation of I, namely, oxidative cleavage of the dihydrobenzoxathiin moiety to give a hydroquinone/para-benzoquinone redox couple, hydroxylation at position 5 or 7 of the benzoxathiin moiety leading to an o-quinone intermediate, and metabolism of the piperidine ring to give an iminium ion. The latter reactive intermediate was identified as its bis-cyano adduct when human liver microsomal incubations were performed in the presence of sodium cyanide. Structural modification of I, including a replacement of the piperidine with a pyrrolidine group, led to (2S,3R)-(+)-3-(3-hydroxyphenyl)-2-[4-(2-pyrrolidin-1-ylethoxy)phenyl]-2,3-dihydro-1,4-benzoxathiin-6-ol (II), which did not form a reactive iminium ion. Following the incubation of II with human liver microsomes, covalent binding to proteins was reduced (461 pmol equiv/mg protein), the residual level of binding apparently due to the formation of a rearranged biphenyl quinone type metabolite. Studies with inhibitory antibodies and chemical inhibitors showed that P450 3A4 was the primary enzyme responsible for oxidative bioactivation of I and II in human liver microsomes. These studies thus demonstrated that gaining an understanding of bioactivation mechanisms may be exploited in terms of guiding structural modifications of drug candidates to minimize covalent protein binding and, hopefully, to lower the potential for drug-mediated adverse effects.
Assuntos
Sistema Enzimático do Citocromo P-450/fisiologia , Microssomos Hepáticos/metabolismo , Oxati-Inas/farmacocinética , Moduladores Seletivos de Receptor Estrogênico/farmacocinética , Benzoquinonas/metabolismo , Biotransformação , Citocromo P-450 CYP3A , Hepatócitos/metabolismo , Humanos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Ligação ProteicaRESUMO
The discovery, synthesis, and SAR of chromanes as ER alpha subtype selective ligands are described. X-ray studies revealed that the origin of the ER alpha-selectivity resulted from a C-4 trans methyl substitution to the cis-2,3-diphenyl-chromane platform. Selected compounds from this class demonstrated very potent in vivo antagonism of estradiol in an immature rat uterine weight assay, effectively inhibited ovariectomy-induced bone resorption in a 42 days treatment paradigm, and lowered serum cholesterol levels in ovx'd adult rat models. The best antagonists 8F and 12F also exhibited potent inhibition of MCF-7 cell growth and were shown to be estrogen receptor down-regulators (SERDs).
Assuntos
Cromanos/química , Cromanos/farmacologia , Receptor alfa de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Animais , Sítios de Ligação , Linhagem Celular , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Ligantes , Modelos Químicos , Estrutura Molecular , Tamanho do Órgão , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Útero/efeitos dos fármacosRESUMO
[reaction: see text] During the course of drug metabolism studies, a major metabolite of compound 1 was detected in rhesus monkeys and assigned structure 4. The intriguing biotransformation of 1 leading to 4 was confirmed by a 19-step total synthesis starting from resorcinol (11), the key feature of which was the construction of the oxygen bridge utilizing a phenolic oxidation and trapping sequence. In addition, the synthesis of a related metabolite (5) is described.
Assuntos
Receptor alfa de Estrogênio/antagonistas & inibidores , Osteoporose/tratamento farmacológico , Oxati-Inas/síntese química , Oxati-Inas/farmacologia , Moduladores Seletivos de Receptor Estrogênico/síntese química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Animais , Biotransformação , Macaca mulatta , Modelos Moleculares , Conformação Molecular , Oxirredução , Oxigênio/química , Resorcinóis/metabolismoRESUMO
The ring oxygen and sulfur analogs of lasofoxifene, 1a and 1b, were synthesized in an attempt to impart ERalpha selectivity, as found in the closely related dihydrobenzoxathiin compound I, recently discovered in these laboratories. The resulting isochroman and isothiochroman compounds were found to exhibit equipotent binding affinities to the ER isoforms and were less active in the inhibition of estradiol-triggered uterine growth when compared to I and lasofoxifene.
Assuntos
Cromanos/síntese química , Cromanos/farmacologia , Receptor alfa de Estrogênio/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Estradiol/farmacologia , Feminino , Humanos , Concentração Inibidora 50 , Ligantes , Modelos Moleculares , Ligação Proteica , Isoformas de Proteínas , Relação Estrutura-Atividade , Útero/efeitos dos fármacos , Útero/crescimento & desenvolvimentoRESUMO
A series of dihydrobenzoxathiin SERAMs with alkylated pyrrolidine side chains or alkylated linkers was prepared. Minor modifications in the side chain or linker resulted in significant effects on biological activity, especially in uterine tissue.
Assuntos
Oxati-Inas/farmacologia , Pirrolidinas/química , Receptores de Estrogênio/efeitos dos fármacos , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Ligantes , Modelos Moleculares , Oxati-Inas/química , Receptores de Estrogênio/metabolismoRESUMO
A series of benzoxathiin SERAMs with bicyclic amine side chains was prepared. Minor modifications in the side chain resulted in significant effects on biological activity, especially in uterine tissue.
Assuntos
Compostos Bicíclicos com Pontes/química , Ligantes , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/metabolismo , Animais , Compostos Bicíclicos com Pontes/farmacologia , Feminino , Cinética , Modelos Moleculares , Conformação Molecular , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacosRESUMO
A series of benzoxathiin SERAMs with heteroatom-substituted amine side chains was prepared. Minor modifications in the side chain resulted in significant effects on biological activity, especially in uterine tissue.
Assuntos
Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/metabolismo , Animais , Feminino , Cinética , Ligantes , Modelos Moleculares , Conformação Molecular , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacosRESUMO
Dihydrobenzodithiin compounds (1-6) were prepared to explore the expansion of the dihydrobenzoxathiin lead compounds I-III as SERAMs (Selective Estrogen Receptor Alpha Modulators). The dihydrobenzodithiin compounds generally maintained a high degree of selectivity for ERalpha over ERbeta, however, they lacked the in vivo antagonism/agonism activity exhibited by the lead class in an immature rat uterine growth model.
Assuntos
Compostos Heterocíclicos com 2 Anéis/síntese química , Piperidinas/síntese química , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Sítios de Ligação , Células Cultivadas , Receptor alfa de Estrogênio , Receptor beta de Estrogênio , Feminino , Compostos Heterocíclicos com 2 Anéis/farmacologia , Concentração Inibidora 50 , Ligantes , Modelos Biológicos , Piperidinas/farmacologia , Ratos , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacos , Útero/metabolismoRESUMO
Dihydrobenzoxathiin analogs (1-11) with modifications on the basic side chain region were prepared and evaluated for estrogen/anti-estrogen activity in both in vitro and in vivo models. The compounds generally maintained a high degree of selectivity for ERalpha over ERbeta, similar to the original lead compound I. Many of the compounds also maintained high potency in the inhibition of human carcinoma MCF-7 cell growth. However, all were less potent in the inhibition of estradiol-triggered uterine growth. This work demonstrates the sensitive nature of modification to the antagonist basic side chain region.
Assuntos
Antagonistas de Estrogênios/síntese química , Oxati-Inas/síntese química , Receptores de Estrogênio/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Antagonistas de Estrogênios/farmacologia , Receptor alfa de Estrogênio/antagonistas & inibidores , Receptor beta de Estrogênio/antagonistas & inibidores , Humanos , Ligantes , Oxati-Inas/farmacologia , Relação Estrutura-AtividadeRESUMO
A series of estrogen receptor ligands based on a dihydrobenzoxathiin scaffold is described and evaluated for estrogen/anti-estrogen activity in both in vitro and in vivo models. The most active analogue, 22, was found to be 40-fold ERalpha selective in a competitive binding assay, and 22 demonstrated very potent in vivo antagonism of estradiol driven proliferation in an immature rat uterine weight gain assay.
Assuntos
Receptor alfa de Estrogênio/química , Oxati-Inas/farmacologia , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Ligação Competitiva , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Receptor beta de Estrogênio/química , Feminino , Compostos Heterocíclicos de 4 ou mais Anéis/síntese química , Compostos Heterocíclicos de 4 ou mais Anéis/farmacocinética , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Ligantes , Tamanho do Órgão , Oxati-Inas/síntese química , Oxati-Inas/farmacocinética , Ligação Proteica , Ratos , Ratos Sprague-Dawley , Moduladores Seletivos de Receptor Estrogênico/farmacocinética , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Relação Estrutura-Atividade , Útero/efeitos dos fármacosRESUMO
The discovery and synthesis of dihydrobenzoxathiins as potent, ERalpha subtype selective ligands are described. The most active analogue, 4-D, was found to be 50-fold selective in a competitive binding assay and 100-fold selective in a transactivation assay in HEK-293 cells. The alpha selectivity was postulated to lie in the interaction of the sulfur atom of the benzoxathiin ring with the two discriminating residues in the binding pocket of the receptor isoforms.
Assuntos
Oxati-Inas/síntese química , Moduladores Seletivos de Receptor Estrogênico/síntese química , Animais , Sítios de Ligação , Ligação Competitiva , Linhagem Celular , Cristalografia por Raios X , Receptor alfa de Estrogênio , Receptor beta de Estrogênio , Feminino , Humanos , Ligantes , Modelos Moleculares , Conformação Molecular , Tamanho do Órgão/efeitos dos fármacos , Oxati-Inas/química , Oxati-Inas/farmacologia , Receptores de Estrogênio/efeitos dos fármacos , Receptores de Estrogênio/metabolismo , Moduladores Seletivos de Receptor Estrogênico/química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Ativação Transcricional , Útero/efeitos dos fármacosRESUMO
A series of 3-alkyl, 3-cycloalkyl, and 3-heteroaryl dihydrobenzoxathiin analogs 1 were prepared and evaluated for estrogen/anti-estrogen activity in both in vitro and in vivo models. In general, the compounds were found to exhibit a high degree of selectivity for ER alpha over ER beta, but were less potent than the original lead compound 1a in the inhibition of estradiol-driven uterine proliferation.
Assuntos
Receptores de Estrogênio/antagonistas & inibidores , Moduladores Seletivos de Receptor Estrogênico/síntese química , Moduladores Seletivos de Receptor Estrogênico/farmacologia , Animais , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Feminino , Compostos Heterocíclicos de 4 ou mais Anéis/síntese química , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Humanos , Concentração Inibidora 50 , Ligantes , Tamanho do Órgão/efeitos dos fármacos , Ratos , Relação Estrutura-Atividade , Útero/citologiaRESUMO
A class of flavanoids exhibiting a high degree of selectivity for ERalpha over ERbeta has been discovered. The most active analogue 6 was found to be 66-fold ERalpha-selective and demonstrated uterine estradiol antagonism.
Assuntos
Flavonoides/química , Flavonoides/metabolismo , Receptores de Estrogênio/metabolismo , Animais , Feminino , Humanos , Ligação Proteica/fisiologia , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Útero/metabolismoRESUMO
Raloxifene is a selective estrogen receptor modulator which is effective in the treatment of osteoporosis in postmenopausal women. We report herein that cytochrome P450 (P450)3A4 is inhibited by raloxifene in human liver microsomal incubations. The nature of the inhibition was irreversible and was NADPH- and preincubation time-dependent, with K(I) and k(inact) values estimated at 9.9 microM and 0.16 min(-1), respectively. The observed loss of P450 3A4 activity was attenuated partially by glutathione (GSH), implying the involvement of a reactive metabolite(s) in the inactivation process. Subsequently, GSH adducts of raloxifene were identified in incubations with human liver microsomes; substitution with GSH occurred at the 5- or 7-position of the benzothiophene moiety or at the 3'-position of the phenol ring, with the 7-glutathionyl derivative being most abundant based on LC/MS and NMR analyses. These adducts are postulated to derive from addition of GSH to raloxifene arene oxides followed by dehydration and aromatization. Alternatively, raloxifene may be oxidized to an extended quinone intermediate, which then is trapped by GSH conjugation. The bioactivation of raloxifene most likely is catalyzed by P450 3A4, since the formation of GSH adducts was almost abolished when liver microsomes were pretreated with ketoconazole or with an inhibitory anti-P450 3A4 IgG. The GSH adducts also were detected in incubations of raloxifene with rat or human hepatocytes, while the corresponding N-acetylcysteine adducts were identified in the bile and urine from rats treated orally with the drug at 5 mg/kg. Taken together, these data indicate that P450 3A4-mediated bioactivation of raloxifene in vitro is accompanied by loss of enzyme activity. The significance of these findings with respect to the clinical use of raloxifene remains to be determined.