RESUMEN
Recent structural studies of epidermal growth factor receptor (EGFR) family extracellular regions have identified an unexpected mechanism for ligand-induced receptor dimerization that has important implications for activation and inhibition of these receptors. Here we describe the 2.8 angstroms resolution X-ray crystal structure of the antigen binding (Fab) fragment from cetuximab (Erbitux), an inhibitory anti-EGFR antibody, in complex with the soluble extracellular region of EGFR (sEGFR). The sEGFR is in the characteristic "autoinhibited" or "tethered" inactive configuration. Cetuximab interacts exclusively with domain III of sEGFR, partially occluding the ligand binding region on this domain and sterically preventing the receptor from adopting the extended conformation required for dimerization. We suggest that both these effects contribute to potent inhibition of EGFR activation.
Asunto(s)
Anticuerpos Monoclonales/química , Receptores ErbB/química , Modelos Moleculares , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales Humanizados , Complejo Antígeno-Anticuerpo/química , Antineoplásicos/química , Antineoplásicos/inmunología , Sitios de Unión/genética , Unión Competitiva , Cetuximab , Cristalografía por Rayos X , Factor de Crecimiento Epidérmico/química , Epítopos/química , Epítopos/genética , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/inmunología , Humanos , Fragmentos Fab de Inmunoglobulinas/química , Fragmentos Fab de Inmunoglobulinas/inmunología , Fragmentos Fab de Inmunoglobulinas/farmacología , Mutación/genética , Unión Proteica , Estructura Cuaternaria de Proteína , Estructura Terciaria de Proteína/efectos de los fármacos , Agregación de Receptores/efectos de los fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/inmunología , Factor de Crecimiento Transformador alfa/químicaRESUMEN
Placental growth factor (PlGF), a member of the vascular endothelial growth factor family of proteins regulating angiogenesis, has been shown to have acute vasodilatory effects on human resistance arteries. However, the acute hemodynamic effects of PlGF in vivo are not known. The aim of this study was to report acute cardiovascular changes induced by recombinant human PlGF administered intravenously in male Guinea Pigs with implanted telemeters. PlGF decreased mean arterial blood pressure by 10-20% within minutes. The magnitude of reduction was similar at three dose levels; however, the duration of relative hypotension was dose-dependent. Blood pressure reduction resulted in a compensatory increase in heart rate, or reflex tachycardia. To rule out any direct effect on the heart, PlGF was tested in the ex vivo Langendorff heart preparation, and no cardiac changes were found. Together these results suggest that the PlGF-related changes in blood pressure are largely mediated by its actions in the vasculature.
Asunto(s)
Hipotensión , Factor A de Crecimiento Endotelial Vascular , Animales , Femenino , Cobayas , Hemodinámica , Humanos , Masculino , Neovascularización Patológica/metabolismo , Placenta/metabolismo , Factor de Crecimiento Placentario/metabolismo , Embarazo , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
Therapeutic anticancer strategies that target and inactivate the epidermal growth factor receptor (EGFR) are under intense study in the clinic. Here we describe the mechanism of EGFR inhibition by an antibody drug IMC-11F8. IMC-11F8 is a fully human antibody that has similar antitumor potency as the chimeric cetuximab/Erbitux and might represent a safer therapeutic alternative. We report the X-ray crystal structure of the Fab fragment of IMC-11F8 (Fab11F8) in complex with the entire extracellular region and with isolated domain III of EGFR. We compare this to our previous study of the cetuximab/EGFR interaction. Fab11F8 interacts with a remarkably similar epitope, but through a completely different set of interactions. Both the similarities and differences in binding of these two antibodies have important implications for the development of inhibitors that could exploit this same mechanism of EGFR inhibition.
Asunto(s)
Anticuerpos Monoclonales/química , Antineoplásicos/química , Receptores ErbB/química , Secuencia de Aminoácidos , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/uso terapéutico , Anticuerpos Monoclonales Humanizados , Antineoplásicos/inmunología , Antineoplásicos/uso terapéutico , Sitios de Unión , Cetuximab , Cristalografía por Rayos X , Epítopos/química , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/inmunología , Glicosilación , Fragmentos Fab de Inmunoglobulinas/química , Modelos Moleculares , Datos de Secuencia Molecular , Mutación , Estructura Terciaria de ProteínaRESUMEN
OBJECTIVES: Although epidemiological studies have shown that obesity is associated with increased incidence of hypertension during pregnancy, the mechanisms linking these two comorbidities are not as well studied. Previous investigations detected lower levels of the anti-hypertensive and pregnancy-related factor, placental growth factor (PlGF), in obese hypertensive pregnancies. Therefore, we examined whether obese hypertensive pregnant rats have reduced PlGF and whether increasing its levels by administering recombinant human (rh)PlGF reduces their blood pressure. METHODS: We utilized a genetic model of obesity characterized to be heavier, hypertensive and fertile, namely rats having heterozygous deficiency of the melanocortin-4 receptor (MC4R-def). RESULTS: MC4R-def obese rats had lower circulating levels of PlGF than wild-type lean controls at gestational day 19. Also, assessment of the PlGF receptor, Flt-1, in the vasculature showed that its levels were reduced in aorta and kidney glomeruli but increased in small mesenteric arteries. Chronic intraperitoneal administration of rhPlGF from gestational day 13-19 significantly increased circulating PlGF levels in both obese and lean rats, but reduced blood pressure only in the obese pregnant group. The rhPlGF treatment did not alter maternal body and fat masses or circulating levels of the adipokines, leptin and adiponectin. In addition, this treatment did not impact average foetal weights but increased placental weights regardless of obese or lean pregnancy. CONCLUSION: PlGF is reduced in MC4R-def obese hypertensive pregnant rats, which is similar to findings in obese hypertensive pregnant women, while increasing its levels with exogenous rhPlGF reduces their blood pressure.
Asunto(s)
Presión Sanguínea/efectos de los fármacos , Hipertensión/metabolismo , Obesidad/metabolismo , Factor de Crecimiento Placentario , Proteínas Recombinantes , Animales , Femenino , Humanos , Factor de Crecimiento Placentario/administración & dosificación , Factor de Crecimiento Placentario/farmacología , Embarazo , Ratas , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/farmacologíaRESUMEN
A series of arylphthalazine derivatives were synthesized and evaluated as antagonists of VEGF receptor II (VEGFR-2). IM-094482 57, which was prepared in two steps from commercially available starting materials, was found to be a potent inhibitor of VEGFR-2 in enzymatic, cellular and mitogenic assays (comparable activity to ZD-6474). Additionally, 57 inhibited the related receptor, VEGF receptor I (VEGFR-1), and showed excellent exposure when dosed orally to female CD-1 mice.
Asunto(s)
Ftalazinas/farmacocinética , Receptor 2 de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Administración Oral , Animales , Disponibilidad Biológica , Femenino , Isoquinolinas/síntesis química , Isoquinolinas/farmacocinética , Ratones , Ratones Endogámicos , Ftalazinas/administración & dosificación , Ftalazinas/síntesis química , Piperidinas , Quinazolinas , Receptor 1 de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidoresRESUMEN
Heparanase is an endo-beta-D-glucuronidase that degrades heparan sulfate glycosaminoglycan side chains of the proteoglycans in extracellular matrix and basement membrane. Heparanase enzymatic activity is important in the promotion of tumor angiogenesis, primary tumor growth, invasion, and metastasis. Expression of heparanase in many tumor types conversely correlates with prognosis. Much progress has been made in studying the regulation of heparanase expression, processing and activation. The interaction between heparanase and its substrate heparan sulfate has been well characterized. The fact that heparanase was identified as the single predominant heparan sulfate-degrading enzyme in human cancer sparked considerable interest in developing heparanase inhibitors for potential therapeutic applications. Recent progress in drug development led to several classes of heparanase inhibitors, including chemically modified natural products, small molecule inhibitors, and antibodies. Some of these inhibitors have demonstrated potent activities to inhibit tumor angiogenesis, tumor progress, or tumor metastasis. A leading compound, PI-88, is currently being evaluated in clinical phase II trials in patients with melanoma, liver, or lung cancers. This review summarizes the recent progress in heparanase biochemical research and the development of heparanase antagonists as novel anti-cancer therapeutics.
Asunto(s)
Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Glucuronidasa/antagonistas & inhibidores , Glucuronidasa/fisiología , Neoplasias/tratamiento farmacológico , Biomarcadores/análisis , Diseño de Fármacos , Glucuronidasa/análisis , Humanos , Metástasis de la Neoplasia , Neoplasias/patología , Neovascularización Patológica , Nitrógeno/química , Oxígeno/química , Sulfatos/químicaRESUMEN
Vascular endothelial-cadherin (VE-cadherin) is an endothelial cell-specific adhesion molecule that is localized exclusively at cell-cell contacts referred to as adherens junctions. VE-cadherin-mediated adhesion is crucial for proper assembly of vascular structures during angiogenesis as well as for maintenance of a normal vascular integrity. We have shown previously that a monoclonal antibody (BV13) to VE-cadherin not only inhibits the formation of vascular tubes during tumor angiogenesis but also disrupts adherens junctions of normal vasculature with a concomitant increase in vascular permeability. The goal of the current studies was to block VE-cadherin function during angiogenesis without disrupting existing junctions on normal endothelium. Using in vitro screening assays to test for functional blocking of adherens junction formation and in vivo assays to detect antibody effects on vascular permeability in normal tissues, we have identified a novel blocking antibody (E4G10) that inhibits VE-cadherin function during angiogenesis but does not disrupt existing adherens junctions on normal vasculature. E4G10 inhibited formation of vascular tubes in vivo in the Matrigel plug and corneal micropocket assays. E4G10 also inhibited tumor growth in three models of mouse and human tumors via an antiangiogenic mechanism. Examination of normal mouse and tumor tissues showed that E4G10 bound to endothelial cells in a subset of tumor vasculature but not to normal vasculature. Bromodeoxyuridine labeling experiments showed that E4G10 specifically targeted a subset of tumor endothelium that is undergoing active cell proliferation, which likely reflects the activated, angiogenic endothelium. These findings indicate that VE-cadherin can be selectively targeted during states of pathological angiogenesis, despite its ubiquitous distribution throughout the entire vasculature. Our data also suggest that antibody E4G10 recognizes VE-cadherin epitopes that are only accessible on endothelial cells forming new adherens junctions, such as in angiogenic tumor vasculature.
Asunto(s)
Inhibidores de la Angiogénesis/farmacología , Anticuerpos Monoclonales/farmacología , Cadherinas/inmunología , Endotelio Vascular/inmunología , Neoplasias Cutáneas/irrigación sanguínea , Neoplasias Cutáneas/tratamiento farmacológico , Uniones Adherentes/efectos de los fármacos , Uniones Adherentes/inmunología , Inhibidores de la Angiogénesis/inmunología , Inhibidores de la Angiogénesis/metabolismo , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/metabolismo , Antígenos CD , Permeabilidad Capilar/inmunología , División Celular/inmunología , Córnea/efectos de los fármacos , Endotelio Vascular/citología , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Inhibidores de Crecimiento/inmunología , Inhibidores de Crecimiento/farmacología , Humanos , Ratones , Ratones Desnudos , Neovascularización Patológica/tratamiento farmacológico , Neovascularización Fisiológica/efectos de los fármacos , Neoplasias Cutáneas/inmunología , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Heparanase is an enzyme that cleaves heparan sulfate chains of proteoglycans, and its expression has been associated with increased growth, metastasis, and angiogenesis of some tumors. Because myeloma tumor cells express high levels of the syndecan-1 heparan sulfate proteoglycan and because these tumors grow as highly vascularized aggregates within the bone marrow, we analyzed the activity, expression, and function of heparanase in myeloma patients. Analysis of heparanase activity in the plasma isolated from bone marrow biopsies of 100 patients reveals 86 positive for heparanase activity and 14 negative. The bone marrow samples can be further divided into three categories of heparanase activity, high activity (42 patients), low activity (44 patients), and negative (14 patients). In contrast to the bone marrow plasma, levels of heparanase activity in peripheral blood plasma of 29 myeloma patients were either negative or low, suggesting that in multiple myeloma, heparanase functions in the local microenvironment of the bone marrow and its activity is not significantly elevated systemically. Immunohistochemistry reveals that patients with high levels of heparanase activity often have tumor cells with intense staining for the enzyme. Interestingly, a marked heterogeneity among tumor cells was noted, with clusters of heavily stained cells surrounded by cells with weak or negative staining for heparanase. Analysis of microvessel density reveals a strikingly higher concentration of vessels in patients with high heparanase activity (78.96 vessels/mm(2)) as compared with patients negative for heparanase activity (25.03 vessels/mm(2)). When human myeloma cells transfected with the cDNA for heparanase are implanted in severe combined immunodeficient (SCID) mice, the resulting tumors exhibited a significantly higher microvessel density than did tumors established with control cells. Thus, expression of heparanase appears to play a direct role in enhancing microvessel density in these myeloma tumors. Because heparanase is known to stimulate angiogenesis, and because high microvessel density is associated with poor prognosis in myeloma, we conclude that heparanase expression likely plays an important role in regulating the growth and progression of myeloma, and that therapies designed to block heparanase activity may aid in controlling this cancer.
Asunto(s)
Glucuronidasa/metabolismo , Mieloma Múltiple/irrigación sanguínea , Mieloma Múltiple/enzimología , Animales , Médula Ósea/enzimología , Femenino , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Glicoproteínas de Membrana/biosíntesis , Glicoproteínas de Membrana/genética , Ratones , Ratones SCID , Mieloma Múltiple/genética , Mieloma Múltiple/patología , Neovascularización Patológica/enzimología , Neovascularización Patológica/patología , Proteoglicanos/biosíntesis , Proteoglicanos/genética , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Sindecano-1 , SindecanosRESUMEN
The insulin-like growth factor I receptor (IGF-IR) is overexpressed in many diverse tumor types and is a critical signaling molecule for tumor cell proliferation and survival. Therapeutic strategies targeting the IGF-IR may therefore be effective broad-spectrum anticancer agents. Through screening of a Fab phage display library, we have generated a fully human antibody (A12) that binds to the IGF-IR with high affinity (4.11 x 10(-11) M) and inhibits ligand binding with an IC(50) of 0.6-1 nM. Antibody-mediated blockade of ligand binding to the IGF-IR inhibited downstream signaling of the two major insulin-like growth factor (IGF) pathways, mitogen-activated protein kinase and phosphatidylinositol 3'-kinase/Akt, in MCF7 human breast cancer cells. As a result, the mitogenic and proliferative potential of IGF-I and IGF-II were significantly reduced. A12 did not block insulin binding to the insulin receptor but could block binding to atypical IGF-IR in MCF7 cells. In addition, A12 was shown to induce IGF-IR internalization and degradation on specific binding to tumor cells, resulting in a significant reduction in cell surface receptor density. In xenograft tumor models in vivo, IGF-IR blockade by A12 was shown to occur rapidly, resulting in significant growth inhibition of breast, renal, and pancreatic tumors. Histological analysis of tumor sections demonstrated a marked increase in apoptotic tumor cells in antibody-treated animals. These results demonstrate that A12 possesses strong antitumor activity in vitro and in vivo and may therefore be an effective therapeutic candidate for the treatment of cancers that are dependent on IGF-IR signaling for growth and survival.
Asunto(s)
Anticuerpos Monoclonales/farmacología , Receptor IGF Tipo 1/antagonistas & inhibidores , Animales , Especificidad de Anticuerpos , Neoplasias de la Mama/terapia , División Celular/efectos de los fármacos , Femenino , Humanos , Factor I del Crecimiento Similar a la Insulina/antagonistas & inhibidores , Factor I del Crecimiento Similar a la Insulina/metabolismo , Ligandos , Ratones , Ratones Desnudos , Biblioteca de Péptidos , Fosforilación , Receptor IGF Tipo 1/inmunología , Receptor IGF Tipo 1/metabolismo , Proteínas Recombinantes/farmacología , Transducción de Señal/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Platelet-derived growth factor receptor alpha (PDGFRalpha) is a type III receptor tyrosine kinase that is expressed on a variety of tumor types. A neutralizing monoclonal antibody to human PDGFRalpha, which did not cross-react with the beta form of the receptor, was generated. The fully human antibody, termed 3G3, has a Kd of 40 pmol/L and blocks both PDGF-AA and PDGF-BB ligands from binding to PDGFRalpha. In addition to blocking ligand-induced cell mitogenesis and receptor autophosphorylation, 3G3 inhibited phosphorylation of the downstream signaling molecules Akt and mitogen-activated protein kinase. This inhibition was seen in both transfected and tumor cell lines expressing PDGFRalpha. The in vivo antitumor activity of 3G3 was tested in human glioblastoma (U118) and leiomyosarcoma (SKLMS-1) xenograft tumor models in athymic nude mice. Antibody 3G3 significantly inhibited the growth of U118 (P=0.0004) and SKLMS-1 (P <0.0001) tumors relative to control. These data suggest that 3G3 may be useful for the treatment of tumors that express PDGFRalpha.
Asunto(s)
Anticuerpos Monoclonales/química , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Animales , Becaplermina , Bioensayo , Línea Celular Tumoral , Relación Dosis-Respuesta Inmunológica , Citometría de Flujo , Humanos , Cinética , Ligandos , Sistema de Señalización de MAP Quinasas , Ratones , Ratones Desnudos , Ratones Transgénicos , Trasplante de Neoplasias , Fosforilación , Factor de Crecimiento Derivado de Plaquetas/química , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Estructura Terciaria de Proteína , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-akt , Proteínas Proto-Oncogénicas c-sis , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/inmunología , Factores de Tiempo , TransfecciónRESUMEN
Preeclampsia is a pregnancy-specific disorder of new-onset hypertension. Unfortunately, the most effective treatment is early delivery of the fetus and placenta. Placental ischemia appears central to the pathogenesis of preeclampsia because placental ischemia/hypoxia induced in animals by reduced uterine perfusion pressure (RUPP) or in humans stimulates release of hypertensive placental factors into the maternal circulation. The anti-angiogenic factor soluble fms-like tyrosine kinase-1 (sFlt-1), which antagonizes and reduces bioavailable vascular endothelial growth factor and placental growth factor (PlGF), is elevated in RUPP rats and preeclampsia. Although PlGF and vascular endothelial growth factor are both natural ligands for sFlt-1, vascular endothelial growth factor also has high affinity to VEGFR2 (Flk-1) causing side effects like edema. PlGF is specific for sFlt-1. We tested the hypothesis that PlGF treatment reduces placental ischemia-induced hypertension by antagonizing sFlt-1 without adverse consequences to the mother or fetus. On gestational day 14, rats were randomized to 4 groups: normal pregnant or RUPP±infusion of recombinant human PlGF (180 µg/kg per day; AG31, a purified, recombinant human form of PlGF) for 5 days via intraperitoneal osmotic minipumps. On day 19, mean arterial blood pressure and plasma sFlt-1 were higher and glomerular filtration rate lower in RUPP than normal pregnant rats. Infusion of recombinant human PlGF abolished these changes seen with RUPP along with reducing oxidative stress. These data indicate that the increased sFlt-1 and reduced PlGF resulting from placental ischemia contribute to maternal hypertension. Our novel finding that recombinant human PlGF abolishes placental ischemia-induced hypertension, without major adverse consequences, suggests a strong therapeutic potential for this growth factor in preeclampsia.
Asunto(s)
Hipertensión Inducida en el Embarazo/tratamiento farmacológico , Isquemia/complicaciones , Placenta/irrigación sanguínea , Preeclampsia/tratamiento farmacológico , Proteínas Gestacionales/farmacología , Preñez , Análisis de Varianza , Animales , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Hipertensión Inducida en el Embarazo/etiología , Isquemia/tratamiento farmacológico , Estrés Oxidativo/fisiología , Placenta/metabolismo , Factor de Crecimiento Placentario , Circulación Placentaria/efectos de los fármacos , Circulación Placentaria/fisiología , Insuficiencia Placentaria , Preeclampsia/etiología , Embarazo , Proteínas Gestacionales/metabolismo , Ratas , Ratas Sprague-Dawley , Valores de Referencia , Medición de RiesgoRESUMEN
Recombinant protein production in plants such as corn is a promising means to generate high product yields at low comparable production cost. The anti-EGFR monoclonal antibody C225, cetuximab, is a well-characterized receptor antagonist antibody recently approved for the treatment of refractory colorectal cancer. We initiated a study to test and compare the functional activity of glycosylated and aglycosylated C225 produced in stable transgenic corn seed. Both corn antibodies were shown to be functionally indistinguishable from mammalian-derived C225 in demonstrating high-affinity binding to the EGF receptor, blocking of ligand-dependent signaling, and inhibiting cell proliferation. In addition, consistent with cetuximab, both corn antibodies possessed strong anti-tumor activity in vivo. Acute dose primate pharmacokinetic studies, however, revealed a marked increase in clearance for the glycosylated corn antibody, while the aglycosylated antibody possessed in vivo kinetics similar to cetuximab. This experimentation established that corn-derived receptor blocking monoclonal antibodies possess comparable efficacy to mammalian cell culture-derived antibody, and offer a cost effective alternative to large-scale mammalian cell culture production.
Asunto(s)
Anticuerpos Monoclonales/biosíntesis , Anticuerpos Monoclonales/farmacología , Antineoplásicos/aislamiento & purificación , Antineoplásicos/farmacología , Receptores ErbB/antagonistas & inhibidores , Receptores ErbB/inmunología , Zea mays/genética , Zea mays/inmunología , Animales , Anticuerpos Monoclonales/farmacocinética , Anticuerpos Monoclonales Humanizados , Citotoxicidad Celular Dependiente de Anticuerpos , Antineoplásicos/farmacocinética , Cetuximab , Femenino , Humanos , Técnicas In Vitro , Cinética , Macaca fascicularis , Masculino , Ratones , Neoplasias Experimentales/inmunología , Neoplasias Experimentales/terapia , Plantas Modificadas Genéticamente , Unión Proteica , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/farmacología , Trasplante HeterólogoRESUMEN
The anti-VEGF receptor 2 antibody IMC-1121B is a promising antiangiogenic drug being tested for treatment of breast and gastric cancer. We have determined the structure of the 1121B Fab fragment in complex with domain 3 of VEGFR2, as well as the structure of a different neutralizing anti-VEGFR2 antibody, 6.64, also in complex with VEGFR2 domain 3. The two Fab fragments bind at opposite ends of VEGFR2 domain 3; 1121B directly blocks VEGF binding, whereas 6.64 may prevent receptor dimerization by perturbing the domain 3:domain 4 interface. Mutagenesis reveals that residues essential for VEGF, 1121B, and 6.64 binding are nonoverlapping among the three contact patches.
Asunto(s)
Inhibidores de la Angiogénesis/química , Anticuerpos Monoclonales/química , Receptor 2 de Factores de Crecimiento Endotelial Vascular/química , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Anticuerpos Monoclonales Humanizados , Especificidad de Anticuerpos , Sitios de Unión de Anticuerpos , Cristalografía por Rayos X , Ensayo de Inmunoadsorción Enzimática , Modelos Moleculares , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Unión Proteica , Estructura Cuaternaria de Proteína , Estructura Terciaria de Proteína , Receptor 2 de Factores de Crecimiento Endotelial Vascular/genética , RamucirumabRESUMEN
Microtubules are a well-validated target for anticancer therapy. Molecules that bind tubulin affect dynamic instability of microtubules causing mitotic arrest of proliferating cells, leading to cell death and tumor growth inhibition. Natural antitubulin agents such as taxanes and Vinca alkaloids have been successful in the treatment of cancer; however, several limitations have encouraged the development of synthetic small molecule inhibitors of tubulin function. We have previously reported the discovery of two novel chemical series of tubulin polymerization inhibitors, triazoles (Ouyang et al. Synthesis and structure-activity relationships of 1,2,4-triazoles as a novel class of potent tubulin polymerization inhibitors. Bioorg Med Chem Lett. 2005; 15:5154-5159) and oxadiazole derivatives (Ouyang et al. Oxadiazole derivatives as a novel class of antimitotic agents: synthesis, inhibition of tubulin polymerization, and activity in tumor cell lines. Bioorg Med Chem Lett. 2006; 16:1191-1196). Here, we report on the anticancer effects of a lead oxadiazole derivative in vitro and in vivo. In vitro, IMC-038525 caused mitotic arrest at nanomolar concentrations in epidermoid carcinoma and breast tumor cells, including multidrug-resistant cells. In vivo, IMC-038525 had a desirable pharmacokinetic profile with sustained plasma levels after oral dosing. IMC-038525 reduced subcutaneous xenograft tumor growth with significantly greater efficacy than the taxane paclitaxel. At efficacious doses, IMC-038525 did not cause substantial myelosuppression or peripheral neurotoxicity, as evaluated by neutrophil counts and changes in myelination of the sciatic nerve, respectively. These data indicate that IMC-038525 is a promising candidate for further development as a chemotherapeutic agent.
RESUMEN
OBJECTIVE: To investigate whether agonist anti-platelet-derived growth factor receptor alpha (anti-PDGFRalpha) antibodies are present in the serum of patients with systemic sclerosis (SSc; scleroderma). METHODS: Sera were obtained from healthy subjects and scleroderma patients. An electrochemiluminescence binding assay was performed for detection of serum autoantibodies to PDGFRalpha, PDGFRbeta, epidermal growth factor receptor (EGFR), and colony-stimulating factor receptor 1 (CSFR1). Serum immunoglobulin was purified by protein A/G chromatography. To assess Ig agonist activity, PDGFRalpha-expressing cells were incubated with pure Ig and the level of receptor phosphorylation determined in an enzyme-linked immunoassay, as well as by Western blotting. Ig agonist activity was also assessed in a mitogenic assay and by MAP kinase activation in a PDGFRalpha-expressing cell line. RESULTS: Sera from 34.3% of the healthy subjects and 32.7% of the SSc patients contained detectable autoantibodies to PDGFRalpha and PDGFRbeta, but not EGFR or CSFR1. Purified Ig from these sera was shown to retain PDGFR binding activity and, at 200-1,000 microg/ml, exhibited no agonist activity in a cell-based PDGFRalpha phosphorylation assay and did not stimulate a mitogenic response or MAP kinase activation in a PDGFRalpha-expressing cell line. Two purified Ig samples that were unable to bind PDGFRalpha did exhibit binding activity to a nonglycosylated form of PDGFRalpha. CONCLUSION: Although approximately one-third of sera from scleroderma patients contained detectable autoantibodies to PDGFR, these antibodies were not specific to scleroderma, since they were also detected in a similar percentage of samples from normal subjects. PDGFRalpha agonist activity was not demonstrated when purified Ig from these sera was tested in cell-based assays.
Asunto(s)
Especificidad de Anticuerpos , Autoanticuerpos/inmunología , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/inmunología , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Esclerodermia Sistémica/inmunología , Adulto , Anciano , Autoanticuerpos/sangre , Autoanticuerpos/farmacología , Línea Celular , Femenino , Humanos , Sistema de Señalización de MAP Quinasas/inmunología , Masculino , Persona de Mediana Edad , Mitógenos/inmunología , Fosforilación/inmunología , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas/agonistas , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/inmunologíaRESUMEN
We generated three fully human monoclonal antibody antagonists against fibroblast growth factor receptor-1 (FGFR1) that potently block FGF signaling. We found that antibodies targeting the c-splice form of the receptor (FGFR1c) were anorexigenic when administered intraperitoneally three times weekly to mice, resulting in rapid, dose-dependent weight loss that plateaued (for doses>4 mg/kg) at 35-40% in 2 wk. Animals appeared healthy during treatment and regained their normal body weights and growth trajectories upon clearance of the antibodies from the bloodstream. Measurements of food consumption and energy expenditure indicated that the rapid weight loss was induced primarily by decreased energy intake and not by increased energy expenditure or cachexia and was accompanied by a greater reduction in fat than lean body mass. Hypophagia was not caused through malaise or illness, as indicated by absence of conditioned taste aversion, pica behavior, and decreased need-induced salt intake in rats. In support of a hypothalamic site of action, we found that, after intraperitoneal injections, anti-FGFR1c (IMC-A1), but not a control antibody, accumulated in the median eminence and adjacent mediobasal hypothalamus and that FGFR1c is enriched in the hypothalamus of mice. Furthermore, a single intracerebroventricular administration of 3 microg of IMC-A1 via the 3rd ventricle to mice caused an approximately 36% reduction in food intake and an approximately 6% weight loss within the ensuing 24 h. Our data suggest that FGF signaling through FGFR1c may play a physiological role in hypothalamic feeding circuit and that blocking it leads to hypophagia and weight loss.
Asunto(s)
Anticuerpos Monoclonales/farmacología , Ingestión de Alimentos/efectos de los fármacos , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/antagonistas & inhibidores , Receptor Tipo 1 de Factor de Crecimiento de Fibroblastos/inmunología , Pérdida de Peso/efectos de los fármacos , Animales , Anticuerpos Monoclonales/efectos adversos , Especificidad de Anticuerpos , Composición Corporal/efectos de los fármacos , Sistema Nervioso Central/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Femenino , Macaca fascicularis , Masculino , Ratones , Ratones Endogámicos C57BL , Isoformas de Proteínas/inmunología , Ratas , Ratas Sprague-DawleyRESUMEN
A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.
Asunto(s)
Carbanilidas/farmacología , Inhibidores Enzimáticos/farmacología , Glucuronidasa/antagonistas & inhibidores , Neoplasias Pulmonares/tratamiento farmacológico , Melanoma Experimental/tratamiento farmacológico , Animales , Carbanilidas/síntesis química , Carbanilidas/clasificación , Línea Celular Tumoral , Diseño de Fármacos , Ensayos de Selección de Medicamentos Antitumorales , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/clasificación , Técnicas In Vitro , Melanoma Experimental/secundario , Ratones , Estructura Molecular , Peso Molecular , Metástasis de la Neoplasia/tratamiento farmacológico , Relación Estructura-ActividadRESUMEN
A novel class of N-(4-{[4-(1H-benzoimidazol-2-yl)-arylamino]-methyl}-phenyl)-benzamides are described as inhibitors of the endo-beta-glucuronidase heparanase. Among them are N-(4-{[4-(1H-benzoimidazol-2-yl)-phenylamino]-methyl}-phenyl)-3-bromo-4-methoxy-benzamide (15h), and N-(4-{[5-(1H-benzoimidazol-2-yl)-pyridin-2-ylamino]-methyl}- phenyl)-3-bromo-4-methoxy-benzamide (23) which displayed good heparanase inhibitory activity (IC(50) 0.23-0.29 microM), with the latter showing oral exposure in mice.
Asunto(s)
Benzamidas/farmacología , Bencimidazoles/farmacología , Inhibidores Enzimáticos/farmacología , Glucuronidasa/antagonistas & inhibidores , Administración Oral , Animales , Benzamidas/administración & dosificación , Benzamidas/química , Bencimidazoles/administración & dosificación , Bencimidazoles/química , Conformación de Carbohidratos , Secuencia de Carbohidratos , Diseño de Fármacos , Evaluación Preclínica de Medicamentos , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/química , Técnicas In Vitro , Ratones , Modelos Animales , Datos de Secuencia Molecular , Estructura Molecular , Peso Molecular , Relación Estructura-ActividadRESUMEN
Although widespread skeletal dissemination is a critical step in the progression of myeloma, little is known regarding mechanisms that control metastasis of this cancer. Heparanase-1 (heparanase), an enzyme that cleaves heparan sulfate chains, is expressed at high levels in some patients with myeloma and promotes metastasis of some tumor types (eg, breast, lymphoma). Using a severe combined immunodeficient (SCID) mouse model, we demonstrate that enhanced expression of heparanase by myeloma cells dramatically up-regulates their spontaneous metastasis to bone. This occurs from primary tumors growing subcutaneously and also from primary tumors established in bone. Interestingly, tumors formed by subcutaneous injection of cells metastasize not only to bone, but also to other sites including spleen, liver, and lung. In contrast, tumors formed by injection of cells directly into bone exhibit a restricted pattern of metastasis that includes dissemination of tumor to other bones but not to extramedullary sites. In addition, expression of heparanase by myeloma cells (1) accelerates the initial growth of the primary tumor, (2) increases whole-body tumor burden as compared with controls, and (3) enhances both the number and size of microvessels within the primary tumor. These studies describe a novel experimental animal model for examining the spontaneous metastasis of bone-homing tumors and indicate that heparanase is a critical determinant of myeloma dissemination and growth in vivo.
Asunto(s)
Huesos/patología , División Celular/fisiología , Glucuronidasa/metabolismo , Mieloma Múltiple/patología , Metástasis de la Neoplasia/patología , ADN Complementario/análisis , Glucuronidasa/genética , Humanos , Proteínas Recombinantes , Transfección , Células Tumorales CultivadasRESUMEN
VE-cadherin is an adhesion molecule localized at the adherens junctions of endothelial cells. It is crucial for the proper assembly of vascular structures during angiogenesis and maintaining vascular integrity. We have studied 3 monoclonal antibodies (mAbs) against murine VE-cadherin that inhibit angiogenesis and tumor growth. Two of these, BV13 and 10G4, also disrupted normal vessels, resulting in severe vascular leakage, whereas the third, E4G10, did not. The goal of the current report was to identify the epitope of E4G10 and distinguish it from those of the disruptive mAbs. We mapped the epitope of E4G10 to within the first 10 amino acids of mature VE-cadherin and demonstrated that conserved tryptophan residues in this sequence are required for VE-cadherin-mediated trans-adhesion. The disruptive mAbs target a different epitope within amino acids 45 to 56, which structural homology modeling suggests is not involved in trans-adhesion. From our studies, we hypothesize that E4G10 can only bind the neovasculature, where VE-cadherin has not yet engaged in trans-adhesion and its epitope is fully exposed. Thus, E4G10 can inhibit junction formation and angiogenesis but is unable to target normal vasculature because its epitope is masked. In contrast, BV13 and 10G4 bind an epitope that is accessible regardless of VE-cadherin interactions, leading to the disruption of adherens junctions. Our findings establish the immediate N-terminal region of VE-cadherin as a novel target for inhibiting angiogenesis.