RESUMEN
Expression of the cell cycle regulatory gene CDK6 is required for Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) cell growth, whereas expression of the closely related CDK4 protein is dispensable. Moreover, CDK6 silencing is more effective than treatment with the dual CDK4/6 inhibitor palbociclib in suppressing Ph+ ALL in mice, suggesting that the growth-promoting effects of CDK6 are, in part, kinase-independent in Ph+ ALL. Accordingly, we developed CDK4/6-targeted proteolysis-targeting chimeras (PROTACs) that inhibit CDK6 enzymatic activity in vitro, promote the rapid and preferential degradation of CDK6 over CDK4 in Ph+ ALL cells, and markedly suppress S-phase cells concomitant with inhibition of CDK6-regulated phospho-RB and FOXM1 expression. No such effects were observed in CD34+ normal hematopoietic progenitors, although CDK6 was efficiently degraded. Treatment with the CDK6-degrading PROTAC YX-2-107 markedly suppressed leukemia burden in mice injected with de novo or tyrosine kinase inhibitor-resistant primary Ph+ ALL cells, and this effect was comparable or superior to that of the CDK4/6 enzymatic inhibitor palbociclib. These studies provide "proof of principle" that targeting CDK6 with PROTACs that inhibit its enzymatic activity and promote its degradation represents an effective strategy to exploit the "CDK6 dependence" of Ph+ ALL and, perhaps, of other hematologic malignancies. Moreover, they suggest that treatment of Ph+ ALL with CDK6-selective PROTACs would spare a high proportion of normal hematopoietic progenitors, preventing the neutropenia induced by treatment with dual CDK4/6 inhibitors.
Asunto(s)
Quinasa 6 Dependiente de la Ciclina/antagonistas & inhibidores , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Recombinantes de Fusión/farmacología , Animales , Apoptosis/efectos de los fármacos , Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Quinasa 6 Dependiente de la Ciclina/metabolismo , Modelos Animales de Enfermedad , Activación Enzimática/efectos de los fármacos , Perfilación de la Expresión Génica , Genes cdc , Humanos , Ratones , Estructura Molecular , Fosforilación , Leucemia-Linfoma Linfoblástico de Células Precursoras/etiología , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/uso terapéutico , Resultado del Tratamiento , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
A copper iodide-Pyox complex catalyzes the first conjugate addition of diverse sulfur, nitrogen, and carbon nucleophiles to isocyanoalkenes. The anionic addition generates metalated isocyanoalkanes capable of SNi displacements, providing a rapid route to a series of functionalized, cyclic isocyanoalkanes. The Cu(I)I-Pyox complex efficiently catalyzes a first-in-class conjugate addition affording a range of complex, functionalized isocyanoalkanes that are otherwise challenging to synthesize while laying a foundation for catalytic reactions that maintain the isocyanide group.
Asunto(s)
Cobre , Cianuros , Catálisis , Yoduros , AzufreRESUMEN
Substituted imidazoles are readily prepared by condensing the versatile isocyanide Asmic, anisylsulfanylmethylisocyanide, with nitrogenous π-electrophiles. Deprotonating Asmic with lithium hexamethyldisilazide effectively generates a potent nucleophile that efficiently intercepts nitrile and imine electrophiles to afford imidazoles. In situ cyclization to the imidazole is promoted by the conjugate acid, hexamethyldisilazane, which facilitates the requisite series of proton transfers. The rapid formation of imidazoles and the interchange of the anisylsulfanyl for hydrogen with Raney nickel make the method a valuable route to mono- and disubstituted imidazoles.
RESUMEN
Isocyanides are exceptional building blocks, the wide deployment of which in multicomponent and metal-insertion reactions belies their limited availability. The first conjugate addition/alkylation to alkenyl isocyanides is described, which addresses this deficiency. An array of organolithiums, magnesiates, enolates, and metalated nitriles add conjugately to ß- and ß,ß-disubstituted arylsulfonyl alkenyl isocyanides to rapidly assemble diverse isocyanide scaffolds. The intermediate metalated isocyanides are efficiently trapped with electrophiles to generate substituted isocyanides incorporating contiguous tri- and tetra-substituted centers. The substituted isocyanides are ideally functionalized for elaboration into synthetic targets as illustrated by the three-step synthesis of γ-carboline N-methyl ingenineâ B.
Asunto(s)
Alquenos/química , Carbolinas/síntesis química , Cianuros/química , Carbolinas/química , Estructura MolecularRESUMEN
Triple-negative breast cancers (TNBC) frequently inactivate p53, increasing their aggressiveness and therapy resistance. We identified an unexpected protein vulnerability in p53-inactivated TNBC and designed a new PROteolysis TArgeting Chimera (PROTAC) to target it. Our PROTAC selectively targets MDM2 for proteasome-mediated degradation with high-affinity binding and VHL recruitment. MDM2 loss in p53 mutant/deleted TNBC cells in two-dimensional/three-dimensional culture and TNBC patient explants, including relapsed tumors, causes apoptosis while sparing normal cells. Our MDM2-PROTAC is stable in vivo, and treatment of TNBC xenograft-bearing mice demonstrates tumor on-target efficacy with no toxicity to normal cells, significantly extending survival. Transcriptomic analyses revealed upregulation of p53 family target genes. Investigations showed activation and a required role for TAp73 to mediate MDM2-PROTAC-induced apoptosis. Our data, challenging the current MDM2/p53 paradigm, show MDM2 is required for p53-inactivated TNBC cell survival, and PROTAC-targeted MDM2 degradation is an innovative potential therapeutic strategy for TNBC and superior to existing MDM2 inhibitors. SIGNIFICANCE: p53-inactivated TNBC is an aggressive, therapy-resistant, and lethal breast cancer subtype. We designed a new compound targeting an unexpected vulnerability we identified in TNBC. Our MDM2-targeted degrader kills p53-inactivated TNBC cells, highlighting the requirement for MDM2 in TNBC cell survival and as a new therapeutic target for this disease. See related commentary by Peuget and Selivanova, p. 1043. This article is highlighted in the In This Issue feature, p. 1027.
Asunto(s)
Quimera Dirigida a la Proteólisis , Proteínas Proto-Oncogénicas c-mdm2 , Neoplasias de la Mama Triple Negativas , Proteína p53 Supresora de Tumor , Humanos , Animales , Ratones , Línea Celular Tumoral , Proteínas Proto-Oncogénicas c-mdm2/genética , Proteínas Proto-Oncogénicas c-mdm2/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Neoplasias de la Mama Triple Negativas/fisiopatología , Antineoplásicos/química , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Quimera Dirigida a la Proteólisis/química , Quimera Dirigida a la Proteólisis/farmacología , Quimera Dirigida a la Proteólisis/uso terapéutico , Regulación hacia Arriba/efectos de los fármacos , Análisis de Supervivencia , Apoptosis/efectos de los fármacos , Proteína Tumoral p73/metabolismo , Xenoinjertos , Proteolisis/efectos de los fármacos , FemeninoRESUMEN
Oxazoles are rapidly assembled through a sequential deprotonation-condensation of Asmic, anisylsulfanylmethylisocyanide, with esters followed by sulfanyl-lithium exchange-trapping. Deprotonating Asmic affords a metalated isocyanide that efficiently traps esters to afford oxazoles bearing a versatile C-4 anisylsulfanyl substituent. Interchange of the anisylsulfanyl substituent is readily achieved through a first-in-class sulfur-lithium exchange-electrophilic trapping sequence whose versatility is illustrated in the three-step synthesis of the bioactive natural product streptochlorin.
RESUMEN
Photocatalytic degradation of lignin was studied with the use of catalysts TiO(2) and Pt/TiO(2). The influence of several experimental parameters, i.e. pH, catalyst dosage and illumination on lignin degradation was investigated. The results showed that application of UV irradiation alone has almost no effect on the reduction of dissolved organic carbon (DOC) and American Dye Manufacture Institute value (ADMI). However, the addition of TiO(2) and Pt/TiO(2) reduced the original DOC (251 mg l(-1)) by more than 40% within 30 min of treatment and the reaction can be simulated with pseudo-first order kinetics. Rapid degradation of lignin was observed in acidic solution using either TiO(2) or Pt/TiO(2) as the catalyst compared to high pH cases. The content of Pt in the Pt/TiO(2) catalyst is 1%. In addition, too much catalyst addition has not increased the DOC and ADMI reduction proportionally. The investigation also indicated that the photocatalytic degradation rates could be enhanced 1-6 times faster after doping TiO(2) with Pt in different pH cases. A modified Nernst type model was adopted to simulate the decoloring process using TiO(2) and Pt/TiO(2) based on the profiles of oxidation reduction potential during the photocatalytic reaction. The developed equation can be used to predict the color removal efficiency of lignin wastewater by the photocatalytic process.
Asunto(s)
Lignina/química , Platino (Metal)/química , Titanio/química , Eliminación de Residuos Líquidos/métodos , Catálisis , Concentración de Iones de Hidrógeno , Cinética , Oxígeno/análisis , FotoquímicaRESUMEN
Asmic addresses the long-standing challenge of alkylating isocyanides, providing access to isocyanides with diverse substitution patterns. The o-anisylsulfanyl group serves a critical dual role by facilitating deprotonation-alkylation and providing a latent nucleophilic site through an unusual arylsulfanyl-lithium exchange.
Asunto(s)
Alcanos/síntesis química , Cianuros/química , Alcanos/química , Alquilación , Litio/química , Estructura Molecular , Compuestos Organometálicos/química , Compuestos de Sulfhidrilo/químicaRESUMEN
The ozonation reaction is accomplished into two pathways: direct ozone oxidation and indirect free hydroxyl radical oxidation. Both reactions are proceeding simultaneously, thus, it is difficult to separate them and study their respective reaction mechanisms. Carbonate and bicarbonate react with free radicals that will effectively inhibit the indirect free radical oxidation without affecting the direct oxidation reaction. The feasibility of using these chemicals as scavengers to inhibit the hydroxyl radicals so that the direct ozone oxidation reaction and indirect free hydroxyl radical oxidation reaction can be differentiated is presented in this paper. The results will assist in achieving a better understanding of the ozone reaction mechanism in oxidizing organic substances. In this study, synthetic samples made of commercially available humic substance are used to carry out the inhibited and non-inhibited ozone oxidation experiments. The intersecting point of the ORP (oxidation reduction potential) time series curves of the inhibited and un-inhibited reactions, occurring at 120s after the onset of the oxidation reaction, marks the turning point at which all added scavenger chemicals have been completely exhausted. Based on the measured A(254) values, percentage distributions of direct ozone oxidation and indirect hydroxyl radical oxidation are estimated. The results indicate that the contribution of indirect reaction decreases with increasing amounts of inhibiting scavengers. The on-line ORP measurement results are simulated using a modified form of the Nernst equation expressed as ORP=11852-1196 pH+130 ln [(A(254,0)-A(254,t))(A(254,t))(-1)] with R(2) value of 0.99. In this equation, A(254) is the absorbance at 254 nm used to index the humic substance concentration while subscript 0 and t denote the initial and the final time, respectively.
Asunto(s)
Sustancias Húmicas , Ozono/química , Concentración de Iones de Hidrógeno , Radical Hidroxilo/química , Oxidación-ReducciónRESUMEN
Metalated arylmethylisonitriles readily add to 2-chloropyridines to afford imidazo[1,5-a]pyridines. Analogous additions to imidoyl chlorides and a chloroquinoline provide imidazoles and an imidazo[1,5-a]quinolone which, like imidazo[1,5-a]pyridines, are valuable heterocycles for pharmaceutical synthesis.
Asunto(s)
Imidazoles/síntesis química , Nitrilos/química , Piridinas/síntesis química , Alquilación , Imidazoles/química , Estructura Molecular , Piridinas/químicaRESUMEN
Copper iodide catalyzes the conjugate addition of organometallic and heteroatom nucleophiles to isocyano enones to afford oxazoles. A range of enolates, metalated nitriles, amines, and thiols undergo catalyzed conjugate addition to cyclic and acyclic oxoalkene isocyanides. Mechanistic studies suggest that copper complexation facilitates the nucleophilic attack on the isocyano enone to generate an enolate that cyclizes onto the isocyanide leading to a variety of substituted acyclic or ring-fused oxazoles.
Asunto(s)
Cianuros/química , Oxazoles/síntesis química , Catálisis , Cobre/química , Ciclización , Yoduros/química , Malonatos/química , Estructura MolecularRESUMEN
Studies on applying the photochemical UV/TiO2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l(-1) TiO2. When 10 g l(-1) TiO2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO2 process.
Asunto(s)
Lignina/química , Modelos Químicos , Fotoquímica , Titanio/química , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Color , Concentración de Iones de Hidrógeno , Oxidación-Reducción , Espectrofotometría , Factores de Tiempo , Rayos UltravioletaRESUMEN
In this paper, various forms of Nernst equations have been developed based on the real stoichiometric relationship of biological nitrification and denitrification reactions. Instead of using the Nernst equation based on a one-to-one stoichiometric relation for the oxidizing and the reducing species, the basic Nernst equation is modified into slightly different forms. Each is suitable for simulating the redox potential (ORP) variation of a specific biological nitrification or denitrification process. Using the data published in the literature, the validity of these developed Nernst equations has been verified by close fits of the measured ORP data with the calculated ORP curve. The simulation results also indicate that if the biological process is simulated using an incorrect form of Nernst equation, the calculated ORP curve will not fit the measured data. Using these Nernst equations, the ORP value that corresponds to a predetermined degree of completion for the biochemical reaction can be calculated. Thus, these Nernst equations will enable a more efficient on-line control of the biological process.