RESUMEN
Lysophosphatidic acid acyltransferase beta (LPAAT-beta) is an intrinsic membrane protein that catalyzes the synthesis of phosphatidic acid (PA) from lysoPA. Given that PA is a cofactor in a number of signaling cascades that are constitutively active in tumors, we evaluated the role of PA produced by LPAAT-beta in Xenopus oocyte meiotic maturation assays and an isoform-specific inhibitor of LPAAT-beta in mammalian cell assays. We found that ectopic overexpression of LPAAT-beta cooperates in activation of the Ras/Raf/Erk pathway in Xenopus oocytes and that inhibition of LPAAT-beta inhibits signaling in both the Ras/Raf/Erk and PI3K/Akt pathways. When LPAAT-beta activity is suppressed by CT32228 (N-(4-bromo-phenyl)-6-(5-chloro-2-methyl-phenyl)-[1,3,5]triazine-2,4-diamine), an isoform-specific noncompetitive inhibitor, tumor cells undergo mitotic catastrophe while most normal cells simply arrest or become quiescent. The data presented here suggest that PA produced by LPAAT-beta plays an important role in signaling pathways critical to tumor cell survival.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Aciltransferasas/química , Apoptosis , Animales , División Celular , Línea Celular Tumoral , Membrana Celular/metabolismo , Supervivencia Celular , Células Cultivadas , Relación Dosis-Respuesta a Droga , Citometría de Flujo , Humanos , Immunoblotting , Concentración 50 Inhibidora , Sistema de Señalización de MAP Quinasas , Mitosis , Modelos Químicos , Oocitos/metabolismo , Fosforilación , Isoformas de Proteínas , Transporte de Proteínas , Transducción de Señal , Fracciones Subcelulares , XenopusRESUMEN
Poly-alpha-(l-glutamic acid) (PG) conjugates of 20(S)-camptothecin (1, CPT) displayed improved aqueous solubility compared to CPT, were stable in aqueous solution at neutral pH, and were potent antitumor agents in vivo. Evaluation of PG molecular weight, CPT loading, aqueous solubility, and CPT equivalent dosing with respect to in vivo antitumor potencies of various linked conjugates led to identification of a preferred conjugate composition.
Asunto(s)
Antineoplásicos/síntesis química , Camptotecina/análogos & derivados , Camptotecina/síntesis química , Ácido Poliglutámico/análogos & derivados , Ácido Poliglutámico/síntesis química , Animales , Antineoplásicos/farmacología , Camptotecina/farmacología , Estabilidad de Medicamentos , Concentración de Iones de Hidrógeno , Ratones , Ratones Endogámicos C57BL , Ratones Desnudos , Ácido Poliglutámico/farmacología , Soluciones , Relación Estructura-Actividad , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Cyclization of (S,S)-alpha-[(1-phenylethyl)amino]-alpha-(2-iodophenyl)acetonitrile with (COCl)(2) in toluene or chlorobenzene afforded the atropisomeric pyrazinone (aS,S) 6-(2-alpha-iodophenyl)-3,5-dichloro-1-(1-phenylethyl)-2(1H)-pyrazinone in 57% yield. With smaller ortho substituents (F, Cl, CH(3), CF(3), OCH(3)) on the aromatic ring, mixtures of atropisomers were obtained from the cyclization reaction. All of the individual atropisomers prepared were stable at room temperature. All but the o-fluoro-substituted atropisomers were stable at elevated temperatures. This paper describes a stereoselective synthesis of pyrazinones and suggests a mechanism for formation via an interesting transfer of chirality.
RESUMEN
2,4-Diamino-N(4),6-diarylpyrimidines were identified as potent, isoform specific inhibitors of lysophosphatidic acid acyltransferase-beta (LPAAT-beta). Active inhibitors also blocked proliferation of tumor cell lines in vitro. The effect of 2j in an in vivo tumor model was investigated.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Pirimidinas/síntesis química , Pirimidinas/farmacología , División Celular/efectos de los fármacos , Línea Celular Tumoral , Humanos , Isomerismo , Relación Estructura-ActividadRESUMEN
Phosphatidic acid (PA) is a component of cellular membranes that is also a mediator of certain cell signalling functions associated with oncogenesis. These include ras/raf/Erk and Akt/mTor [1-3]. The authors have investigated whether it would be possible to interrupt these known oncogenic pathways through the inhibition of lysophosphatidic acid acyltransferase (LPAAT), an enzyme that catalyses the biosynthesis of PA. The expression and activity of the LPAAT-beta isoform are elevated in human tumours, and the respective gene displays transforming capacity when overexpressed in vitro. Inhibition by either genetic means or by isoform-specific small molecules results in a block to cell signalling pathways and apoptosis. Furthermore, the small-molecule inhibitors of LPAAT-beta are not cytotoxic to a number of normal cell types, including primary bone marrow progenitors, indicating a differential dependence of tumour cells on LPAAT-beta function. These discoveries indicate that LPAAT-beta represents a potential novel cancer therapy target.