RESUMO
We have recently generated lipophilic D-xylose derivatives that increase the rate of glucose uptake in cultured skeletal muscle cells in an AMP-activated protein kinase (AMPK)-dependent manner. The derivative 2,4:3,5-dibenzylidene-D-xylose-diethyl dithioacetal (EH-36) stimulated the rate of glucose transport by increasing the abundance of glucose transporter-4 in the plasma membrane of cultured myotubes. The present study aimed at investigating potential antihyperglycaemic effects of EH-36 in animal models of diabetes. Two animal models were treated subcutaneously with EH-36: streptozotocin-induced diabetes in C57BL/6 mice (a model of insulin-deficient type 1 diabetes), and spontaneously diabetic KKAy mice (Kuo Kondo rats carrying the A(y) yellow obese gene; insulin-resistant type 2 diabetes). The in vivo biodistribution of glucose in control and treated mice was followed with the glucose analogue 2-deoxy-2-[(18) F]-D-glucose; the rate of glucose uptake in excised soleus muscles was measured with [(3) H]-2-deoxy-D-glucose. Pharmacokinetic parameters were determined by non-compartmental analysis of the in vivo data. The effective blood EH-36 concentration in treated animals was 2 µM. It reduced significantly the blood glucose levels in both types of diabetic mice and also corrected the typical compensatory hyperinsulinaemia of KKAy mice. EH-36 markedly increased glucose transport in vivo into skeletal muscle and heart, but not to adipose tissue. This stimulatory effect was mediated by Thr(172) -phosphorylation in AMPK. Biochemical tests in treated animals and acute toxicological examinations showed that EH-36 was well tolerated and not toxic to the mice. These findings indicate that EH-36 is a promising prototype molecule for the development of novel antidiabetic drugs.
Assuntos
Acetais/uso terapêutico , Compostos de Benzilideno/uso terapêutico , Compostos Bicíclicos Heterocíclicos com Pontes/uso terapêutico , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Tioglicosídeos/uso terapêutico , Quinases Proteína-Quinases Ativadas por AMP , Acetais/administração & dosagem , Animais , Compostos de Benzilideno/administração & dosagem , Transporte Biológico/efeitos dos fármacos , Glicemia/análise , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Células Cultivadas , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Transportador de Glucose Tipo 4/biossíntese , Coração/efeitos dos fármacos , Hipoglicemiantes/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Proteínas Quinases/metabolismo , Ratos , Ratos Wistar , Tioglicosídeos/administração & dosagem , TrítioRESUMO
In a continued effort to find a suitable PET tracer for visualization of angiogenic processes, we explored the 3,4-diarylmaleimide family, known to have high affinity and selectivity towards the VEGFR-TKs. One previously reported agent and three new halogen-containing 3,4-diarylmaleimide derivatives were synthesized. The four maleimide derivatives were evaluated for their affinity and selectivity towards the VEGFRs and exhibited promising results. An automated carbon-11 radiolabeling route with a total synthesis time of 50min successfully labeled the lead compound, resulting in 1.55+/-0.15GBq of tracer with a radiochemical yield of 20+/-2%, 96% radiochemical purity and a SA of 111+/-22GBq/micromol (EOB, n=5). The tracer possessed high stability in in vitro blood stability tests and specific VEGFR-TK binding profiles in intact cell binding experiments. Tracer lipophilicity was evaluated in an n-octanol/phosphate buffer system giving a LogD(7.4) of 1.99+/-0.04. For the in vivo experiments, two animal models were used. The first was a U87 glioma tumor model, frequently reported in the literature and the second, a newly developed 293/KDR tumor model. Both models were validated for VEGFR-2 expression and used in in vivo biodistribution studies. These studies revealed low accumulation and rapid washout of the tracer from tumor tissue. High accumulation of activity in the liver prompted us to examine the tracer's in vitro stability to liver microsomes, revealing low resistance to P450 metabolism. In spite of encouraging in vitro results, the labeled lead tracer failed to accumulate in VEGFR-2 overexpressing tumors. It is possible that poor resistance to P450 metabolism reduces tracer's circulation leading to low tumor accumulation.
Assuntos
Indutores da Angiogênese/análise , Biomarcadores Tumorais/análise , Maleimidas/análise , Tomografia por Emissão de Pósitrons/métodos , Indutores da Angiogênese/metabolismo , Animais , Biomarcadores Tumorais/metabolismo , Humanos , Masculino , Maleimidas/síntese química , Maleimidas/química , Maleimidas/metabolismo , Camundongos , Camundongos Nus , Neoplasias Experimentais , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Relação Estrutura-Atividade , Especificidade por Substrato , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Senescence, perceived as a cancer barrier, is paradoxically associated with inflammation, which promotes tumorigenesis. Here, we characterize a distinct low-grade inflammatory process in stressed epithelium that is related to para-inflammation; this process either represses or promotes tumorigenesis, depending on p53 activity. Csnk1a1 (CKIα) downregulation induces a senescence-associated inflammatory response (SIR) with growth arrest in colorectal tumors, which loses its growth control capacity in the absence of p53 and instead, accelerates growth and invasiveness. Corresponding processes occur in CKIα-deleted intestinal organoids, assuming tumorigenic transformation properties ex vivo, upon p53 loss. Treatment of organoids and mice with anti-inflammatory agents suppresses the SIR and prevents p53-deficient organoid transformation and mouse carcinogenesis. SIR/para-inflammation suppression may therefore constitute a key mechanism in the anticarcinogenic effects of nonsteroidal anti-inflammatory drugs.
Assuntos
Transformação Celular Neoplásica/patologia , Inflamação/patologia , Neoplasias/patologia , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Senescência Celular/efeitos dos fármacos , Senescência Celular/genética , Senescência Celular/fisiologia , Inflamação/genética , Camundongos , Camundongos Knockout , Neoplasias/genéticaRESUMO
BACKGROUND: Due to the limited availability of suitable positron emission tomography (PET) tracers, the majority of myocardial perfusion imaging (MPI) scans is performed using SPECT rather than PET. AIM: The aim of this study is to design and synthesize carbon-11-labeled ammonium salt derivatives and explore their structureactivity relationship (SAR) and their potential as PETMPI agents. METHODS AND RESULTS: Three carbon-11-labeled ammonium salts were developed. SAR of the labeled compounds were explored vis-à-vis the effects of charge density and lipophilicity on the distribution kinetics in mice. These studies pointed at [11C]4 as the lead compound. Comparative microPET/CT scans in healthy rats, using both [11C]4 and [13 N]NH3, substantiated the potential of [11C]4 ([11C]-DMDPA). A proof of concept for the potential of radiolabeled ammonium salts as MPI agents has been demonstrated in a newly developed swine model of permanent partial coronary artery occlusion. CONCLUSIONS: SAR studies of 11C-labeled ammonium salts suggest that both lipophilicity and charge density affect the performance of these compounds as MPI probes. In a swine model, the labeled lead successfully visualized the defect regions in the myocardium. The data presented call for the development of fluorine-18 analogues, to increase clinical impact.
Assuntos
Radioisótopos de Carbono , Marcação por Isótopo , Imagem de Perfusão do Miocárdio , Tomografia por Emissão de Pósitrons , Compostos de Amônio Quaternário/química , Sais , Animais , Radioisótopos de Carbono/farmacocinética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Infarto do Miocárdio/diagnóstico por imagem , Isquemia Miocárdica/diagnóstico por imagem , Ratos , Sais/química , Relação Estrutura-Atividade , Sus scrofa , Fatores de Tempo , Distribuição TecidualRESUMO
BACKGROUND: Positron emission tomography (PET) has clear advantages over single photon emission computed tomography (SPECT) in the field of myocardial perfusion scintigraphy (MPS); however, there are just a small number of efficient PET tracers available today for MPS. We sought to develop and perform a preliminary biological evaluation of novel carbon-11-labeled ammonium salts as potential MPS PET agents. METHODS AND RESULTS: Three potential tracers were labeled and evaluated via biodistribution in mice and PET imaging in both rats and rabbits, and the results obtained were also compared to agents that are routinely used in the clinical practice. CONCLUSIONS: The results designated carbon-11-labeled ammonium salts as having great potential as MPS PET agents. Specifically, carbon-11-labeled trimethyl-phenyl-ammonium iodide ([(11)C]2) and homologues of higher lipophilicity/charge warrant further studies in larger animals and humans such as measurements of myocardial uptake at rest and stress under both normal and pathological coronary flow conditions.