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1.
Eur J Cancer ; 51(14): 1865-73, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26199039

RESUMO

BACKGROUND: The phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K-AKT-mTOR) signalling pathway is aberrantly activated in several cancers. Notch signalling maintains cell proliferation, growth and metabolism in part by driving the PI3K pathway. Combining the mTOR inhibitor ridaforolimus with the Notch inhibitor MK-0752 may increase blockade of the PI3K pathway. METHODS: This phase I dose-escalation study (NCT01295632) aimed to define the dose-limiting toxicities (DLTs) and maximum tolerated dose (MTD) of combination oral ridaforolimus (rising doses starting at 20 mg, 5 days/week) and oral MK-0752 (1800 mg once weekly) in patients with solid tumours. No intrapatient dose escalation was permitted. RESULTS: Twenty eight patients were treated on study. Ridaforolimus doses were escalated from 20 to 30 mg/day. Among 14 evaluable patients receiving ridaforolimus 20 mg, one DLT (grade 2 stomatitis, second episode) was reported. Among eight evaluable patients receiving ridaforolimus 30 mg, three DLTs were reported (one each grade 3 stomatitis, grade 3 diarrhoea, and grade 3 asthenia). The MTD was 20 mg daily ridaforolimus 5 days/week+1800 mg weekly MK-0752. The most common drug-related adverse events included stomatitis, diarrhoea, decreased appetite, hyperglycaemia, thrombocytopenia, asthenia and rash. Two of 15 (13%) patients with head and neck squamous cell carcinoma (HNSCC) had responses: one with complete response and one with partial response. In addition, one patient experienced stable disease ⩾6 months. CONCLUSIONS: Combined ridaforolimus and MK-0752 showed activity in HNSCC. However, a high number of adverse events were reported at the MTD, which would require careful management during future clinical development.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Escamosas/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Administração Oral , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Derivados de Benzeno/administração & dosagem , Carcinoma de Células Escamosas/enzimologia , Carcinoma de Células Escamosas/patologia , Esquema de Medicação , Europa (Continente) , Feminino , Neoplasias de Cabeça e Pescoço/enzimologia , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Imagem Multimodal/métodos , Tomografia por Emissão de Pósitrons , Propionatos/administração & dosagem , Inibidores de Proteínas Quinases/administração & dosagem , Transdução de Sinais/efeitos dos fármacos , Sirolimo/administração & dosagem , Sirolimo/análogos & derivados , Carcinoma de Células Escamosas de Cabeça e Pescoço , Sulfonas/administração & dosagem , Fatores de Tempo , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Estados Unidos
2.
Br J Cancer ; 111(10): 1932-44, 2014 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-25290091

RESUMO

BACKGROUND: Two strategies to interrogate the insulin growth factor 1 receptor (IGF-1R) pathway were investigated: vertical inhibition with dalotuzumab and MK-2206 or ridaforolimus to potentiate PI3K pathway targeting and horizontal cross-talk inhibition with dalotuzumab and MK-0752 to exert effects against cellular proliferation, angiogenesis, and stem cell propagation. METHODS: A phase I, multi-cohort dose escalation study was conducted in patients with advanced solid tumours. Patients received dalotuzumab (10 mg kg(-1)) and escalating doses of MK-2206 (90-200 mg) or escalating doses of dalotuzumab (7.5-10 mg kg(-1)) and MK-0752 (1800 mg) weekly. Upon maximum tolerated dose determination, patients with low-RAS signature, high-IGF1 expression ovarian cancer were randomised to dalotuzumab/MK-2206 versus dalotuzumab/ridaforolimus, whereas patients with high IGF1/low IGF2 expression colorectal cancer received dalotuzumab/MK-0752. RESULTS: A total of 47 patients were enrolled: 29 in part A (18 in the dalotuzumab/MK-2206 arm and 11 in the dalotuzumab/MK-0752 arm) and 18 in part B (6 in each arm). Dose-limiting toxicities (DLTs) for dalotuzumab/MK-2206 included grade 4 neutropenia and grade 3 serum sickness-like reaction, maculopapular rash, and gastrointestinal inflammation. For dalotuzumab/MK-0752, DLTs included grade 3 dehydration, rash, and diarrhoea. Seven patients remained on study for >4 cycles. CONCLUSIONS: Dalotuzumab/MK-2206 and dalotuzumab/MK-0752 combinations were tolerable. Further developments of prospectively validated predictive biomarkers to aid in patient selection for anti-IGF-1R therapies are needed.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Derivados de Benzeno/uso terapêutico , Compostos Heterocíclicos com 3 Anéis/uso terapêutico , Neoplasias/tratamento farmacológico , Propionatos/uso terapêutico , Sirolimo/análogos & derivados , Sulfonas/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais/farmacocinética , Anticorpos Monoclonais Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica , Derivados de Benzeno/farmacocinética , Biomarcadores Tumorais/metabolismo , Ensaios Clínicos Fase II como Assunto , Ensaios Clínicos Fase III como Assunto , Estudos de Coortes , Feminino , Seguimentos , Compostos Heterocíclicos com 3 Anéis/farmacocinética , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias/metabolismo , Neoplasias/patologia , Prognóstico , Propionatos/farmacocinética , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Ensaios Clínicos Controlados Aleatórios como Assunto , Receptor IGF Tipo 1/antagonistas & inibidores , Receptores Notch/antagonistas & inibidores , Sirolimo/farmacocinética , Sirolimo/uso terapêutico , Sulfonas/farmacocinética , Serina-Treonina Quinases TOR/antagonistas & inibidores , Distribuição Tecidual
3.
Ann Oncol ; 19(10): 1802-9, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18497430

RESUMO

BACKGROUND: To determine the maximum tolerated dose (MTD), safety, potential pharmacokinetic (PK) interactions, and effect on liver histology of trabectedin in combination with pegylated liposomal doxorubicin (PLD) for advanced malignancies. PATIENTS AND METHODS: Entry criteria for the 36 patients included normal liver function, prior doxorubicin exposure <250 mg/m(2), and normal cardiac function. A 1-h PLD (30 mg/m(2)) infusion was followed immediately by one of six trabectedin doses (0.4, 0.6, 0.75, 0.9, 1.1, and 1.3 mg/m(2)) infused over 3 h, repeated every 21 days until evidence of complete response (CR), disease progression, or unacceptable toxicity. Plasma samples were obtained to assess PK profiles. RESULTS: The MTD of trabectedin was 1.1 mg/m(2). Drug-related grade 3 and 4 toxic effects were neutropenia (31%) and elevated transaminases (31%). Six patients responded (one CR, five partial responses), with an overall response rate of 16.7%, and 14 had stable disease (less than a 50% reduction and less than a 25% increase in the sum of the products of two perpendicular diameters of all measured lesions and the appearance of no new lesions) >4 months (39%). Neither drug had its PK affected significantly by concomitant administration compared with trabectedin and PLD each given as a single agent. CONCLUSION: Trabectedin combined with PLD is generally well tolerated at therapeutic doses of both drugs in pretreated patients with diverse tumor types and appears to provide clinical benefit. These results support the need for additional studies of this combination in appropriate cancer types.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/farmacocinética , Neoplasias/tratamento farmacológico , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Dioxóis/administração & dosagem , Dioxóis/efeitos adversos , Dioxóis/sangue , Dioxóis/farmacocinética , Relação Dose-Resposta a Droga , Doxorrubicina/administração & dosagem , Doxorrubicina/efeitos adversos , Doxorrubicina/análogos & derivados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/sangue , Polietilenoglicóis/administração & dosagem , Polietilenoglicóis/efeitos adversos , Tetra-Hidroisoquinolinas/administração & dosagem , Tetra-Hidroisoquinolinas/efeitos adversos , Tetra-Hidroisoquinolinas/sangue , Tetra-Hidroisoquinolinas/farmacocinética , Trabectedina
6.
Semin Diagn Pathol ; 17(1): 56-65, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10721807

RESUMO

In the pancreas, 3 types of morphologically similar lesions may present as "squamous cysts": Lymphoepithelial cysts, dermoid cysts (monodermal teratomas), and epidermoid cysts in intrapancreatic accessory spleen. Lymphoepithelial cysts (LECs) are seen predominantly in men (M/F: 4/1) and in adulthood (mean age, 56, and range, 35 to 74 years). They may occur at any site of the organ (head, body, or tail). LECs are well-delineated cysts that may be multilocular (60%) or unilocular (40%), and they are characterized microscopically by stratified squamous epithelium surrounded by a band of mature lymphoid tissue with intervening well-formed germinal centers. Solid lymphoepithelial clusters are seldom seen. The pathogenesis of LECs is unclear; clinical diseases that are known to be associated with their counterparts in the salivary glands such as Sjogren disease or human immunodeficiency virus have not been documented for the LECs of the pancreas. The second type of squamous-lined cyst in the pancreas is the epidermoid cyst arising in intrapancreatic accessory spleen. These are located almost exclusively in the tail of the pancreas, in the fourth decade of life (mean age = 38). Their mean size is 4.5 cm (range, 2.3 to 6.5). In some cases, the cyst lining may be partly mucinous. Dermoid cysts of the pancreas are also rare. The cases that appear to be true dermoid cysts occur in a younger age group (mean age, 23, range, 2 to 53 years), and in contrast with LEC, there is no gender predominance. Mucinous epithelium, respiratory-type mucosa and sebaceous units are more readily identifiable in dermoid cysts, and they may contain hair. Subepithelial lymphoid tissue is not a feature. They are sometimes complicated by suppurative infections. The importance of these lesions is in their distinction from other cystic neoplasms, especially mucinous cystic tumors.


Assuntos
Coristoma/diagnóstico , Cisto Dermoide/diagnóstico , Cisto Epidérmico/diagnóstico , Linfocele/diagnóstico , Cisto Pancreático/diagnóstico , Pancreatopatias/diagnóstico , Baço , Células Epiteliais/patologia , Feminino , Humanos , Masculino
7.
J Neurosci Res ; 59(3): 436-45, 2000 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-10679781

RESUMO

Previous research has established that the development and function of oligodendrocytes are influenced by glucocorticoids. The enzyme glycerol phosphate dehydrogenase (E.C.1.1.1.8) has been used as a model to study glucocorticoid regulation of gene expression in oligodendrocytes and the C6 glial cell line. In the rat brain this enzyme is exclusively localized to oligodendrocytes. The sequence of the 5' flanking region for the rat gene encoding Glycerol Phosphate Dehydrogenase (GPDH; EC 1.1.1.8) was determined. 4 kb of sequence from the 5' flanking region, exon 1, and part of intron 1 of the rat GPDH gene was compared to the corresponding mouse sequence. Dotplot matrix comparison revealed that the rat sequence is more than 80% similar to the mouse sequence, but differs from the mouse sequence in two regions: the rat sequence is devoid of 200 bp of B1 repeat sequence that is present in the mouse, and the rat sequence has an excess 700 bp of B2 repeat sequence inserted between -0.7 kb and -1. 4 kb that is absent in the mouse. To determine the regulatory activity of the rat GPDH 5' flanking region, various portions of the rat GPDH 5' flanking region were placed in luciferase reporter constructs and tested for transcriptional activity. Transient transfection of reporter constructs into the C6 glial cell line revealed that the distal end of the 5' flanking region was glucocorticoid-inducible. A 385 bp Glucocorticoid Response Unit (GRU) was identified whose glucocorticoid induction was enhanced by dibutyryl-cAMP and reduced by phorbol esters. Sequence analysis of the GRU revealed the presence of four consensus GRE sequences and other putative consensus elements. Results here suggest that the 5' flanking region of the GPDH gene mediates the ligand-inducible regulation of GPDH, and that multiple signaling pathways converge at the 5' regulatory sequence to modulate GPDH gene expression in oligodendrocytes.


Assuntos
Glucocorticoides/fisiologia , Glicerolfosfato Desidrogenase/genética , Oligodendroglia/fisiologia , Animais , Sequência de Bases/genética , AMP Cíclico/metabolismo , Elementos Facilitadores Genéticos/genética , Éxons , Glucocorticoides/farmacologia , Glicerol-3-Fosfato Desidrogenase (NAD+) , Camundongos , Dados de Sequência Molecular , Ratos , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas/efeitos dos fármacos
8.
J Clin Oncol ; 18(2): 421-8, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10637258

RESUMO

PURPOSE: Quality of life (QOL) is increasingly recognized as a critical cancer-treatment outcome measure, but little is known about the impact of QOL on the patient decision-making process. A pilot study was conducted in an effort to (1) measure the expectations of patients, physicians, and research nurses regarding the potential benefits and toxicities from experimental and standard therapies, and (2) determine the relationship of QOL to patient perceptions regarding treatment options. METHODS: Thirty cancer patients enrolling in phase I clinical trials, their physicians, and their research nurses were administered questionnaires that assessed demographics, QOL, and treatment expectations. RESULTS: Compared with their physicians, patients overestimated potential benefits and toxicities from experimental therapy (mean expected benefit, 59.8% v 23.8%, P <.01; mean expected toxicity, 29.8% v 16.0%, P <.01). Patients estimated a greater potential for benefit (59.8% v 36.8%, P <.01) and less potential for toxicity (29.8% v 45.6%, P =.01) for experimental therapy, compared with standard therapy. Short Form-36 general health perception correlated with patient perception of potential benefit from experimental therapy (r =.48, P =.01). CONCLUSION: Participants in phase I clinical trial have high expectations regarding the success of experimental therapy and discount potential toxicity. Patient QOL may affect the expectation of benefit from experimental therapy and, ultimately, treatment choice. Understanding the interactions between QOL and patient expectations may guide the development of improved strategies to present appropriate information to patients considering early-phase clinical trials.


Assuntos
Ensaios Clínicos Fase I como Assunto , Consentimento Livre e Esclarecido , Satisfação do Paciente , Qualidade de Vida , Adulto , Idoso , Antineoplásicos/efeitos adversos , Tomada de Decisões , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias/terapia , Relações Médico-Paciente , Projetos Piloto , Resultado do Tratamento
9.
Semin Oncol Nurs ; 16(4 Suppl 1): 2-12, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11151455

RESUMO

OBJECTIVES: To review the immune response and tumor immunology, and to provide an update on the success and obstacles to targeted therapy using monoclonal antibodies and antibody conjugates. DATA SOURCES: Research articles and textbooks. CONCLUSIONS: Ongoing studies are exploiting the targeting properties of the immune system to improve anticancer therapy. Both monoclonal antibodies and immunoconjugates have shown promise in treatment of specific diseases. IMPLICATIONS FOR NURSING PRACTICE: The rapid growth of molecular techniques has allowed for the development of new anticancer therapies. Since nurses are intimately involved in the delivery of such therapy as well as in educating patients regarding risks and benefits, they must be knowledgeable.


Assuntos
Anticorpos Monoclonais/uso terapêutico , Imunoterapia , Neoplasias/enfermagem , Neoplasias/terapia , Humanos , Metástase Neoplásica , Neoplasias/patologia , Enfermagem Oncológica
10.
Clin Cancer Res ; 5(5): 1057-62, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10353738

RESUMO

The cyclin-dependent kinase inhibitors (CDIs) p27kip1 and p21waf1/cip1 are key cell cycle-negative regulatory enzymes. The objective of this study was to correlate expression of p27kip1 and p21waf1/cip1 with survival, chemotherapy responsiveness, and expression of the proliferation marker Ki-67 in patients with advanced colorectal cancer. Immunohistochemistry was performed with antibodies to p27kip1, p21waf1/cip1, and Ki-67 on samples from 66 patients with metastatic colorectal carcinoma. Interpretation was performed by visual inspection and automated image analysis. Patients who obtained a response to chemotherapy had greater p21waf1/cip1 tumor staining with a mean of 10.0 positive cells/high-powered field, compared with 4.5 positive cells/high-powered field for nonresponders (P = 0.03). A positive Spearman correlation was seen between Ki-67 and p27kip1 (r = 0.48; P = 0.0001), as well as between Ki-67 and p21waf1/cip1 (r = 0.48; P = 0.0001). A trend toward shorter survival was seen in patients with positive specimens (median survival of 10 months for patients with both p27kip1- and p21waf1/cip1-positive specimens, compared with 22 months for patients with neither p27kip1- nor p21waf1/cip1-positive specimens). In contrast to that previously reported in normal colonic mucosa or early-stage colorectal cancer, we observed positive correlations of Ki-67 with both p27kip1 and p21waf1/cip1, a trend toward greater CDI staining indicating worse prognosis, and greater p21waf1/cip1 staining in tumors that were chemosensitive. These findings suggest that in the metastatic setting, CDIs may show altered function, compared with their role in the normal cell cycle.


Assuntos
Adenocarcinoma/química , Proteínas de Ciclo Celular , Neoplasias Colorretais/química , Ciclinas/análise , Proteínas Associadas aos Microtúbulos/análise , Proteínas de Neoplasias/análise , Proteínas Supressoras de Tumor , Adenocarcinoma/tratamento farmacológico , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Adenocarcinoma/cirurgia , Adenocarcinoma Mucinoso/química , Adenocarcinoma Mucinoso/tratamento farmacológico , Adenocarcinoma Mucinoso/mortalidade , Adenocarcinoma Mucinoso/patologia , Adenocarcinoma Mucinoso/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Ciclo Celular , Diferenciação Celular , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Inibidor de Quinase Dependente de Ciclina p21 , Inibidor de Quinase Dependente de Ciclina p27 , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Antígeno Ki-67/análise , Tábuas de Vida , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estadiamento de Neoplasias , Análise de Sobrevida , Resultado do Tratamento
11.
Am J Surg Pathol ; 23(6): 656-61, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10366147

RESUMO

Patients infected with HIV often have unusual manifestations of common infections and neoplasms. One such example is "mycobacterial pseudotumor," an exuberant spindle cell lesion induced in lymph nodes by mycobacteria. Kaposi sarcoma also produces a spindle cell proliferation in lymph nodes of HIV-positive patients. These two entities must be differentiated from one another because of differences in treatment and prognosis. We report here, however, three cases of intranodal Kaposi sarcoma with simultaneous mycobacterial infection, the occurrence of which has not been clearly documented. For comparison, we also studied three cases of mycobacterial pseudotumor, of which 14 cases have been described to date. There was considerable histologic overlap between these two lesions. Acid-fast bacilli were present in all cases, predominantly in the more epithelioid histiocytes in the cases of Kaposi sarcoma, and in spindle and epithelioid cells in the cases of mycobacterial pseudotumor. The morphologic features that favored Kaposi sarcoma over mycobacterial pseudotumor were the prominent fascicular arrangement of spindle cells and slitlike spaces, the lack of granular, acidophilic cytoplasm, and the presence of mitoses. Immunohistochemistry was a reliable adjunct study in the differential diagnosis, as the spindle cells in mycobacterial pseudotumor were positive for S-100 protein and CD68 whereas those of Kaposi sarcoma were CD31- and CD34-positive but negative for S-100 protein and CD68. Awareness that Kaposi sarcoma may coexist with mycobacterial infection in the same biopsy specimen is important because these lesions may be misdiagnosed as mycobacterial pseudotumor. The clinical impact of distinguishing between Kaposi sarcoma with mycobacteria and mycobacterial pseudotumor is significant because the presence of Kaposi sarcoma alters treatment and prognosis.


Assuntos
Soropositividade para HIV/patologia , Linfonodos/patologia , Doenças Linfáticas/patologia , Infecção por Mycobacterium avium-intracellulare/patologia , Sarcoma de Kaposi/patologia , Adulto , Idoso , Biomarcadores/análise , Diagnóstico Diferencial , Soropositividade para HIV/metabolismo , Soropositividade para HIV/microbiologia , Humanos , Técnicas Imunoenzimáticas , Linfonodos/metabolismo , Linfonodos/microbiologia , Doenças Linfáticas/metabolismo , Doenças Linfáticas/microbiologia , Masculino , Pessoa de Meia-Idade , Complexo Mycobacterium avium/isolamento & purificação , Infecção por Mycobacterium avium-intracellulare/metabolismo , Infecção por Mycobacterium avium-intracellulare/microbiologia , Sarcoma de Kaposi/metabolismo , Sarcoma de Kaposi/microbiologia
12.
Inflamm Res ; 46(5): 168-79, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9197987

RESUMO

OBJECTIVE AND DESIGN: The effect of tenidap on the metabolism of arachidonic acid via the 5-lipoxygenase (5-LO) pathway was investigated in vitro and in vivo. MATERIALS AND TREATMENT: In vitro (cells). Arachidonic acid (AA) stimulated rat basophilic leukemia, (RBL) cells; A23817 activated neutrophils (human rat, and rabbit), macrophages (rat), and blood (human). In vitro (enzyme activity). RBL-cell homogenate; purified human recombinant 5-LO. In vivo: Rat (Sprague-Dawley) models in which peritoneal leukotriene products were measured after challenge with zymosan (3 animals per group), A23187 (11 animals per group), and immune complexes (3-5 animals per group), respectively. METHODS: 5-Hydroxyeicosatetraenoic acid (5-HETE) and dihydroxyeicosatetraenoic acids (diHETEs, including LTB4) were measured as radiolabeled products (derived from [14C]-AA) or by absorbance at 235 or 280 nm, respectively, after separation by HPLC. Radiolabeled 5-HPETE was measured by a radio-TLC analyser after separation by thin layer chromatography (TLC). Deacylation of membrane bound [14C]-AA was determined by measuring radiolabel released into the extracellular medium. 5-LO translocation from cytosol to membrane was assessed by western analysis. Rat peritoneal fluid was assayed for PGE, 6-keto-PGF1 alpha, LTE4 or LTB4 content by EIA and for TXB2 by RIA. RESULTS: Tenidap suppressed 5-LO mediated product production in cultured rat basophilic leukemia (RBL-1) cells from exogenously supplied AA, and in human and rat neutrophils, and rat peritoneal macrophages stimulated with A23187 (IC50, 5-15 microM). In addition, tenidap was less potent in inhibiting the release of radiolabeled AA from RBL-1 cells (IC50, 180 microM), suggesting that the decrease in 5-LO derived products could not be explained by an effect on cellular mobilization of AA (i.e., phospholipase). Tenidap blocked 5-hydroxyeicosatetraenoic acid (5-HETE) production by dissociated RBL-1 cell preparations (IC50, 7 microM), as well as by a 100000 x g supernatant of 5-LO/hydroperoxidase activity, suggesting a direct effect on the 5-LO enzyme itself. In addition, tenidap impaired 5-LO translocation from cytosol to its membrane-bound docking protein (FLAP) which occurs when human neutrophils are stimulated with calcium ionophore, indicating a second mechanism for inhibiting the 5-LO pathway. Surprisingly, tenidap did not block the binding of radiolabeled MK-0591, an indole ligand of FLAP, to neutrophil membranes. Although its ability to inhibit the cyclooxygenase pathway was readily observed in whole blood and in vivo, tenidap's 5-LO blockade could not be demonstrated by ionophore stimulated human blood, nor after oral dosing in rat models in which peritoneal leukotriene products were measured after challenge with three different stimuli. The presence of extracellular proteins greatly reduced the potency of tenidap as a 5-LO inhibitor in vitro, suggesting that protein binding is responsible for loss of activity in animal models. CONCLUSIONS: Tenidap inhibits 5-lipoxygenase activity in vitro both directly and indirectly by interfering with its translocation from cytosol to the membrane compartment in neutrophils. A potential mechanism for the latter effect is discussed with reference to tenidap's ability to lower intracellular pH. Tenidap did not inhibit 5-LO pathway activity in three animal models.


Assuntos
Anti-Inflamatórios não Esteroides/toxicidade , Inibidores de Ciclo-Oxigenase/toxicidade , Indóis/toxicidade , Inibidores de Lipoxigenase , 6-Cetoprostaglandina F1 alfa/metabolismo , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Araquidonato 5-Lipoxigenase/sangue , Araquidonato 5-Lipoxigenase/metabolismo , Ácido Araquidônico/metabolismo , Ácido Araquidônico/toxicidade , Calcimicina/toxicidade , Fatores Quimiotáticos/metabolismo , Cromatografia Líquida de Alta Pressão , Inibidores de Ciclo-Oxigenase/administração & dosagem , Eritrócitos/efeitos dos fármacos , Eritrócitos/enzimologia , Humanos , Ácidos Hidroxieicosatetraenoicos/metabolismo , Técnicas Imunoenzimáticas , Indóis/administração & dosagem , Ionóforos/toxicidade , Leucemia Basofílica Aguda/enzimologia , Leucemia Basofílica Aguda/patologia , Leucotrieno B4/metabolismo , Leucotrieno E4/metabolismo , Ativação de Neutrófilo/efeitos dos fármacos , Neutrófilos/citologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/enzimologia , Oxindóis , Coelhos , Radioimunoensaio , Ratos , Ratos Sprague-Dawley , Tromboxano B2/metabolismo , Zimosan/toxicidade
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