RESUMO
The [18F] isotope-labelled CB1 inverse agonist 3 was elaborated and synthesized for positron emission tomography scanning studies. After immediate purification and calibration with its unlabeled counterpart, compound 3 was intravenously injected in mice and revealed that its distribution percentage in brain over 90-min scans among five region of interests, including brain, liver, heart, thigh muscle and kidney was lower than 1%, thus providing direct evidence to justify itself as a peripherally restricted CB1 antagonist.
Assuntos
Agonistas de Receptores de Canabinoides/farmacologia , Pirazóis/farmacologia , Receptor CB1 de Canabinoide/agonistas , Sulfonamidas/farmacologia , Tiofenos/farmacologia , Animais , Agonistas de Receptores de Canabinoides/síntese química , Agonistas de Receptores de Canabinoides/química , Agonistas de Receptores de Canabinoides/farmacocinética , Agonismo Inverso de Drogas , Radioisótopos de Flúor , Marcação por Isótopo , Masculino , Camundongos Endogâmicos C57BL , Tomografia por Emissão de Pósitrons/métodos , Pirazóis/síntese química , Pirazóis/química , Pirazóis/farmacocinética , Receptor CB1 de Canabinoide/antagonistas & inibidores , Sulfonamidas/síntese química , Sulfonamidas/química , Sulfonamidas/farmacocinética , Tiofenos/química , Tiofenos/farmacocinética , Distribuição TecidualRESUMO
To date, imaging of malignant glioma remains challenging. In positron emission tomography-related diagnostic imaging, differential tumor uptake of 3'-deoxy-3'-[(18)F] fluorothymidine ([(18)F]FLT) has been shown to reflect the levels of cell proliferation and DNA synthesis. However, additional biomarkers for tumors are urgently required. Aberrant levels of glutathione transferase (GST) activity have been hypothesized to constitute such a novel diagnostic marker. Here, a C6 rat glioma tumor model was used to assess the ability of the positron emission tomography tracers, [(18)F]FLT and (18)F-fluorobutyl ethacrynic amide ([(18)F]FBuEA), to indicate reactive oxygen species-induced stress responses as well as detoxification-related processes in tumors. Using a GST activity assay, we were able to demonstrate that FBuEA is more readily catalyzed by GST-π than by GST-α. Furthermore, we showed that FBuEA-GS, a metabolite of FBuEA, elicits greater cytotoxicity in tumor cells than in normal fibroblast cells. Finally, in vitro and in vivo investigation of radiotracer distribution of [(18)F]FBuEA and [(18)F] FBuEA-GS revealed preferential accumulation in C6 glioma tumor cells over normal fibroblast cells for [(18)F]FBuEA-GS but not for [(18)F]FBuEA.
RESUMO
Lipocalin-type prostaglandin D synthase (L-PGDS) has been correlated with the progression of neurological disorders. The present study aimed at evaluating the imaging potency of a glutathione conjugate of fluorine-18-labeled fluorobutyl ethacrynic amide ([18F]FBuEA-GS) for brain tumors. Preparation of [18F]FBuEA-GS has been modified from the -4-tosylate derivative via radiofluorination in 5% radiochemical yield. The mixture of nonradioactive FBuEA-GS derived from a parallel preparation has be resolved to two isomers in a ratio of 9:1 using analytic chiral reversed phase high performance liquid chromatography (RP-HPLC). The two fluorine-18-labeled isomers purified through nonchiral semipreparative RP-HPLC as a mixture were studied by assessing the binding affinity toward L-PGDS through a gel filtration HPLC, by analyzing radiotracer accumulation in C6 glioma cells, and by evaluating the imaging of radiotracer in a C6 glioma rat with positron emission tomography. The inhibition percentage of the production of PGD2 from PGH2 at the presence of 200 µM of FBuEA-GS and 4-Dibenzo[a,d]cyclohepten-5-ylidene-1-[4-(2H-tetrazol-5-yl)butyl]piperidine (AT-56) were 74.1 ± 4.8% and 97.6 ± 16.0%, respectively. [18F]FBuEA-GS bound L-PGDS (16.3-21.7%) but not the isoform, microsomal prostaglandin E synthase 1. No binding to GST-alpha and GST-pi was observed. The binding strength between [18F]FBuEA-GS and L-PGDS has been evaluated using analytic gel filtration HPLC at the presence of various concentrations of the cold competitor FBuEA-GS. The contrasted images indicated that the radiotracer accumulation in tumor lesions is probably related to the overexpression of L-PGDS.
Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Radioisótopos de Flúor , Regulação Neoplásica da Expressão Gênica , Glutationa/química , Oxirredutases Intramoleculares/metabolismo , Lipocalinas/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Amidas/química , Animais , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Glutationa/farmacologia , Masculino , Prostaglandina D2/biossíntese , Prostaglandina H2/metabolismo , Traçadores Radioativos , Radioquímica , Ratos , Ratos Sprague-DawleyRESUMO
This study is concerned with the development of an agent for single photon emission computer tomography (SPECT) for imaging inflammation and tumor progression. [(123)I]Iodooctyl fenbufen amide ([(123)I]IOFA) was prepared from the precursor N-octyl-4-oxo-4-(4'-(trimethylstannyl)biphenyl-4-yl)butanamide with a radiochemical yield of 15%, specific activity of 37 GBq/µmol, and radiochemical purity of 95%. Analysis of the binding of [(123)I]IOFA to COX-1 and COX-2 enzymes by using HPLC and a gel filtration column showed a selectivity ratio of 1:1.3. An assay for the competitive inhibition of substrate transfer showed that IOFA exhibited a comparable IC(50) value compared to fenbufen. In the normal rat liver, a lower level and homogeneous pattern of [(123)I]IOFA radioactivity was observed by SPECT. In contrast, in the rat liver with thioacetamide-induced cholangiocarcinoma, a higher uptake and heterogeneous pattern of [(123)I]IOFA radioactivity was seen as hot spots in tumor lesions by SPECT imaging. Importantly, elevated COX-1 and COX-2 expressions from immunostaining were found in the bile ducts of tumor rats but not of normal rats. Therefore, [(123)I]IOFA was found to exhibit the potential for imaging tumors that over-express COX.
Assuntos
Colangiocarcinoma/diagnóstico por imagem , Colangiocarcinoma/enzimologia , Fenilbutiratos , Prostaglandina-Endoperóxido Sintases/metabolismo , Tomografia Computadorizada de Emissão de Fóton Único , Animais , Bioensaio , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colangiocarcinoma/patologia , Cromatografia Líquida de Alta Pressão , Concentração Inibidora 50 , Ligantes , Masculino , Simulação de Acoplamento Molecular , Fenilbutiratos/síntese química , Fenilbutiratos/química , Fenilbutiratos/farmacologia , Ratos , Ratos Sprague-Dawley , Ovinos , Especificidade por Substrato/efeitos dos fármacosRESUMO
[(18)F]Flurobutyl ethacrynic amide ([(18)F]FBuEA) was prepared from the precursor tosylate N-Boc-N-[4-(toluenesulfonyloxy)butyl]ethacrynic amide with a radiochemical yield of 3%, a specific activity of 48 GBq/µmol and radiochemical purity of 98%. Chemical conjugation of [(18)F]FBuEA with glutathione (GSH) via a self-coupling reaction and enzymatic conjugation under catalysis of glutathiontransferase alpha (GST-α) and π provided about 41% yields of radiochemical conjugated product [(18)F]FBuEA-GSH, 85% and 5-16%, respectively. The catalytic selectivity of this tracer toward GST-alpha was addressed. Positron emission tomography (PET) imaging of [(18)F]FBuEA in normal rats showed that a homogeneous pattern of radioactivity was distributed in the liver, suggesting a catalytic role of GST. By contrast, PET images of [(18)F]FBuEA in rats with thioacetamide-induced cholangiocarcinoma displayed a heterogeneous pattern of radioactive accumulation with cold spots in tumor lesions. PET imaging with [(18)F]FBuEA could be used for early diagnosis of hepatic tumor with a low GST activity as well as liver function.
Assuntos
Neoplasias dos Ductos Biliares/diagnóstico por imagem , Ductos Biliares Intra-Hepáticos/diagnóstico por imagem , Colangiocarcinoma/diagnóstico por imagem , Glutationa Transferase/metabolismo , Isoenzimas/metabolismo , Compostos Radiofarmacêuticos/síntese química , Amidas/química , Animais , Neoplasias dos Ductos Biliares/induzido quimicamente , Neoplasias dos Ductos Biliares/diagnóstico , Ductos Biliares Intra-Hepáticos/patologia , Colangiocarcinoma/induzido quimicamente , Colangiocarcinoma/diagnóstico , Radioisótopos de Flúor , Glutationa/química , Fígado/diagnóstico por imagem , Fígado/patologia , Tomografia por Emissão de Pósitrons , Ratos , Distribuição TecidualRESUMO
As one of the most intensively studied probes for imaging of the cellular proliferation, [(18)F]FLT was investigated whether the targeting specificity of thymidine kinase 1 (TK1) dependency could be enhanced through a synergistic effect mediated by herpes simplex type 1 virus (HSV1) tk gene in terms of the TK1 or TK2 expression. 5-[(123)I]Iodo arabinosyl uridine ([(123)I]IaraU) was prepared in a radiochemical yield of 8% and specific activity of 21 GBq/µmol, respectively. Inhibition of the cellular uptake of these two tracers was compared by using the arabinosyl uridine analogs such as 5-iodo, 5-fluoro and 5-(E)-iodovinyl arabinosyl uridine along with 2'-fluoro-5-iodo arabinosyl uridine (FIAU). Due to potential instability of the iodo group, accumulation index of 1.6 for [(123)I]IaraU by HSV1-TK vs. control cells could virtually be achieved at 1.5 h, but dropped to 0.2 compared to 2.0 for [(18)F]FLT at 5 h. The results from competitive inhibition by these nucleosides against the accumulation of [(18)F]FLT implied that FLT exerted a mixed TK1- and TK2-dependent inhibition with HSV1-tk gene transfection because of the shifting of thymidine kinase status. Taken together, the combination of [(18)F]FLT and HSV1-TK provides a synergistic imaging potency.
Assuntos
Didesoxinucleosídeos/farmacocinética , Fibrossarcoma/diagnóstico por imagem , Herpesvirus Humano 1/enzimologia , Timidina Quinase/metabolismo , Uridina/análogos & derivados , Animais , Processos de Crescimento Celular , Linhagem Celular Tumoral , Didesoxinucleosídeos/química , Fibrossarcoma/enzimologia , Fibrossarcoma/genética , Herpesvirus Humano 1/genética , Humanos , Radioisótopos do Iodo/química , Radioisótopos do Iodo/metabolismo , Camundongos , Cintilografia , Compostos Radiofarmacêuticos/farmacocinética , Timidina Quinase/antagonistas & inibidores , Timidina Quinase/genética , Transfecção , Uridina/química , Uridina/farmacocinéticaRESUMO
The derivatives with fenbufen and ethacrynic acid core compounds was synthesized through a facial preparation of 1-amino-4-azidobutane. The subsequent coupling with 102 members of carboxylic acids afforded amide products. The in situ screening using colorimetric assay with 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide showed that fenbufen but not ethacrynic acid butyl amide members displayed the cytotoxicities to tumor cells substantially, including two human cell lines (MCF7 and A549) and two murine cell lines (C26 and TRAMP-C1). Three fenbufen analogs were found to have a good anti-tumor activity comparable to cisplatin.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Inibidores Enzimáticos/química , Ácido Etacrínico/química , Fenilbutiratos/química , Bibliotecas de Moléculas Pequenas , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Ácido Etacrínico/farmacologia , Humanos , Concentração Inibidora 50 , Camundongos , Estrutura Molecular , Neoplasias/tratamento farmacológico , Fenilbutiratos/farmacologiaRESUMO
We constructed a minilibrary using a solution-phase synthesis through coupling of three core amino compounds (5'-amino-5'-deoxy uridine, 5'-amino-2',5'-di-deoxy arabinosyl uridine, and butan-1-amine) with 30 carboxylic acids via amide bond formation. The simplified structural core compound butan-1-amine was selectively coupled with 9 carboxylic acids as control. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay of the crude mixtures showed that analogues derived from fenbufen, butylfenbufen C15; ethacrynic acid, butyl ethacrynic amide C18; and sphingosines, Sph-1, Sph-2 and U27 had an increased cytotoxicity against MCF-7 cells as well as A549 cells. Structural elucidation with molecular docking suggested that cytotoxicity of these compounds is mainly due to the inhibition of enzymes regulating cellular apoptosis.