RESUMEN
SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily A member 2 (SMARCA2), also known as Brahma homologue (BRM), is a Snf2-family DNA-dependent ATPase. BRM and its close homologue Brahma-related gene 1 (BRG1), also known as SMARCA4, are mutually exclusive ATPases of the large ATP-dependent SWI/SNF chromatin-remodeling complexes involved in transcriptional regulation of gene expression. No small molecules have been reported that modulate SWI/SNF chromatin-remodeling activity via inhibition of its ATPase activity, an important goal given the well-established dependence of BRG1-deficient cancers on BRM. Here, we describe allosteric dual BRM and BRG1 inhibitors that downregulate BRM-dependent gene expression and show antiproliferative activity in a BRG1-mutant-lung-tumor xenograft model upon oral administration. These compounds represent useful tools for understanding the functions of BRM in BRG1-loss-of-function settings and should enable probing the role of SWI/SNF functions more broadly in different cancer contexts and those of other diseases.
Asunto(s)
Antineoplásicos/administración & dosificación , Antineoplásicos/farmacología , ADN Helicasas/genética , Diseño de Fármacos , Mutación , Proteínas Nucleares/genética , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genética , Administración Oral , Animales , Antineoplásicos/química , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Humanos , Ratones , Modelos Moleculares , Conformación Proteica , Relación Estructura-Actividad , Factores de Transcripción/química , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
From a high content in vivo screen for modulators of developmental patterning in embryonic zebrafish, we previously identified eggmanone (EGM1, 3) as a Hedgehog (Hh) signaling inhibitor functioning downstream of Smoothened. Phenotypic optimization studies for in vitro probe development utilizing a Gli transcription-linked stable luciferase reporter cell line identified EGM1 analogs with improved potency and aqueous solubility. Mechanistic profiling of optimized analogs indicated two distinct scaffold clusters: PDE4 inhibitors able to inhibit downstream of Sufu, and PDE4-independent Hh inhibitors functioning between Smo and Sufu. Each class represents valuable in vitro probes for elucidating the complex mechanisms of Hh regulation.
Asunto(s)
Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/metabolismo , Proteínas Hedgehog/antagonistas & inhibidores , Inhibidores de Fosfodiesterasa 4/farmacología , Pirimidinonas/farmacología , Transducción de Señal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Células HEK293 , Humanos , Estructura Molecular , Inhibidores de Fosfodiesterasa 4/síntesis química , Inhibidores de Fosfodiesterasa 4/química , Pirimidinonas/síntesis química , Pirimidinonas/química , Proteínas Represoras/antagonistas & inhibidores , Proteínas Represoras/deficiencia , Receptor Smoothened/antagonistas & inhibidores , Relación Estructura-ActividadRESUMEN
RATIONALE: The lack of measurable single-cell contractility of human-induced pluripotent stem cell-derived cardiac myocytes (hiPSC-CMs) currently limits the utility of hiPSC-CMs for evaluating contractile performance for both basic research and drug discovery. OBJECTIVE: To develop a culture method that rapidly generates contracting single hiPSC-CMs and allows quantification of cell shortening with standard equipment used for studying adult CMs. METHODS AND RESULTS: Single hiPSC-CMs were cultured for 5 to 7 days on a 0.4- to 0.8-mm thick mattress of undiluted Matrigel (mattress hiPSC-CMs) and compared with hiPSC-CMs maintained on a control substrate (<0.1-mm thick 1:60 diluted Matrigel, control hiPSC-CMs). Compared with control hiPSC-CMs, mattress hiPSC-CMs had more rod-shape morphology and significantly increased sarcomere length. Contractile parameters of mattress hiPSC-CMs measured with video-based edge detection were comparable with those of freshly isolated adult rabbit ventricular CMs. Morphological and contractile properties of mattress hiPSC-CMs were consistent across cryopreserved hiPSC-CMs generated independently at another institution. Unlike control hiPSC-CMs, mattress hiPSC-CMs display robust contractile responses to positive inotropic agents, such as myofilament calcium sensitizers. Mattress hiPSC-CMs exhibit molecular changes that include increased expression of the maturation marker cardiac troponin I and significantly increased action potential upstroke velocity because of a 2-fold increase in sodium current (INa). CONCLUSIONS: The Matrigel mattress method enables the rapid generation of robustly contracting hiPSC-CMs and enhances maturation. This new method allows quantification of contractile performance at the single-cell level, which should be valuable to disease modeling, drug discovery, and preclinical cardiotoxicity testing.
Asunto(s)
Diferenciación Celular/fisiología , Células Madre Pluripotentes Inducidas/fisiología , Miocitos Cardíacos/fisiología , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Colágeno/administración & dosificación , Combinación de Medicamentos , Humanos , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Laminina/administración & dosificación , Contracción Miocárdica/efectos de los fármacos , Contracción Miocárdica/fisiología , Miocitos Cardíacos/efectos de los fármacos , Células Madre Pluripotentes/efectos de los fármacos , Células Madre Pluripotentes/fisiología , Proteoglicanos/administración & dosificaciónRESUMEN
Hedgehog (Hh) signaling plays an integral role in vertebrate development, and its dysregulation has been accepted widely as a driver of numerous malignancies. While a variety of small molecules target Smoothened (Smo) as a strategy for Hh inhibition, Smo gain-of-function mutations have limited their clinical implementation. Modulation of targets downstream of Smo could define a paradigm for treatment of Hh-dependent cancers. Here, we describe eggmanone, a small molecule identified from a chemical genetic zebrafish screen, which induced an Hh-null phenotype. Eggmanone exerts its Hh-inhibitory effects through selective antagonism of phosphodiesterase 4 (PDE4), leading to protein kinase A activation and subsequent Hh blockade. Our study implicates PDE4 as a target for Hh inhibition, suggests an improved strategy for Hh-dependent cancer therapy, and identifies a unique probe of downstream-of-Smo Hh modulation.
Asunto(s)
Proteínas Quinasas Dependientes de AMP Cíclico/biosíntesis , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/metabolismo , Inhibidores de Fosfodiesterasa 4/administración & dosificación , Pirimidinonas/química , Receptores Acoplados a Proteínas G/genética , Tiofenos/química , Proteínas de Pez Cebra/genética , Animales , Proteínas Quinasas Dependientes de AMP Cíclico/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/química , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/genética , Proteínas Hedgehog/antagonistas & inhibidores , Proteínas Hedgehog/genética , Inhibidores de Fosfodiesterasa 4/química , Inhibidores de Fosfodiesterasa 4/aislamiento & purificación , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/administración & dosificación , Bibliotecas de Moléculas Pequeñas/química , Receptor Smoothened , Activación Transcripcional/efectos de los fármacos , Pez Cebra , Proteínas de Pez Cebra/antagonistas & inhibidoresRESUMEN
The effective identification, selection, and implementation of small molecules for the interrogation of biological systems require an intricate understanding of the chemical principles underlying their cellular activities. While much has been published regarding the use of screening techniques in forward chemical genetics platforms and on small-molecule target identification, less emphasis has been placed on detailed strategies for evaluating, selecting, and optimizing screening hits. This chapter provides practical tools for identifying and developing promising screening hit compounds into effective tools for biological discovery.
Asunto(s)
Descubrimiento de Drogas/métodos , Técnicas de Sonda Molecular , Sondas Moleculares , Bibliotecas de Moléculas Pequeñas , Descubrimiento de Drogas/normas , Proteínas Hedgehog/metabolismo , Humanos , Ligandos , Unión Proteica , Transducción de Señal/efectos de los fármacosRESUMEN
Efforts toward the synthesis of the decalin ring system common to the hibarimicin shunt metabolite HMP-Y1 and parent aglycone hibarimicinone are reported herein. An intramolecular Diels-Alder cyclization rapidly generated the decalin framework. Two approaches toward completion of the AB decalin were vetted. Incorporation of a phenylsulfonyl leaving group ß- to both a ketone and a γ-lactone followed by base-induced elimination of sulfinate led to the undesired α,ß-unsaturated lactone. Methanolysis of the γ-lactone followed by elimination produced the unexpected bridged cyclic ether by way of an intramolecular oxy-Michael addition of the endo oriented C13 alcohol.
RESUMEN
A stereochemical feature of the hibarimicins is a central biaryl (HMP-Y6) or aryl-quinone (hibarimicinone) incorporated as a single atropodiastereomer. Herein, a chiral resolution and deracemization process to access optically enriched biaryls aR-3 and aS-3 is described. From these atropoenantiomers the BCD-EFG ring system of HMP-Y6 is constructed [(+)-aR-7]. Comparison of CD spectra of aR-7 to HMP-Y6 leads to the assignment of HMP-Y6 and hibarimicin B atropoisomers as aR and aS, respectively.
Asunto(s)
Glicósidos/química , Glicósidos/síntesis química , Naftacenos/química , Naftacenos/síntesis química , Conformación Molecular , EstereoisomerismoAsunto(s)
Bases de Datos Factuales , Ecología , Suelo , Agricultura , Clima , Ecosistema , Ambiente , Humanos , Suelo/análisisRESUMEN
Studies directed at the synthesis of lamellarin G trimethyl ether and ningalin B via vinylogous iminium salt derivatives are described. The successful strategy relies on the formation of a 2,4-disubstituted pyrrole or a 1,2,3,4-tetrasubstituted pyrrole from a vinylogous iminium salt or vinylogous iminium salt derivative. Subsequent transformations of these highly substituted pyrroles lead to efficient and regiocontrolled formal syntheses of the respective pyrrole containing natural products.
RESUMEN
Studies directed at the synthesis of polycitone and storniamide natural products via vinylogous iminium salts and microwave accelerated Vilsmeier-Haack formylations are described. The successful strategy relies on the formation of a 2,4-disubstituted pyrrole or a 2,3,4-trisubstituted pyrrole from a vinamidinium salt or vinamidinium salt derivative followed by formylation at the 5-position of the pyrrole. Subsequent transformations of the selectively formylated pyrroles lead to efficient and regiocontrolled relay syntheses of the respective pyrrole containing natural products.
RESUMEN
We studied the mechanism of action of 3,5-dibromo-4-(3,4-dimethoxyphenyl)-1H-pyrrole-2-carboxylic acid ethyl ester (JG-03-14) and found that it is a potent microtubule depolymerizer. JG-03-14 caused a dose-dependent loss of cellular microtubules, formation of aberrant mitotic spindles, accumulation of cells in the G(2)/M phase of the cell cycle, and Bcl-2 phosphorylation. These events culminated in the initiation of apoptosis, as evidenced by the caspase 3-dependent cleavage of poly(ADP-ribose) polymerase (PARP). JG-03-14 has antiproliferative activity against a wide range of cancer cell lines, with an average IC(50) value of 62 nM, and it is a poor substrate for transport by P-glycoprotein. JG-03-14 inhibited the polymerization of purified tubulin in vitro, consistent with a direct interaction between the compound and tubulin. JG-03-14 potently inhibited the binding of [(3)H]colchicine to tubulin, suggesting that it bound to tubulin at a site overlapping the colchicine site. JG-03-14 had antitumor effects in the PC3 xenograft model, in which it caused greater than 50% reduction in tumor burden after 14 days of treatment. Molecular modeling studies indicated that the dimethoxyphenyl group of JG-03-14 occupies a space similar to that of the trimethoxyphenyl group of colchicine. However, the 2,3,5-trisubstituted pyrrole group, which is connected to the dimethoxyphenyl moiety, interacted with both alpha and beta tubulin in space not shared with colchicine, suggesting significant differences compared with colchicine in the mechanism of binding to tubulin. Our results suggest that this tetransubstituted pyrrole represents a new, biologically active chemotype for the colchicine site on tubulin.