RESUMEN
Maintenance of tumor vasculature integrity is indispensable for tumor growth and thus affects tumor progression. Previous studies have identified platelets as major regulators of tumor vascular integrity, as their depletion selectively rendered tumor vessels highly permeable and caused massive intratumoral hemorrhage. While these results established platelets as potential targets for antitumor therapy, their depletion is not a treatment option due to their essential role in hemostasis. Thus, a detailed understanding of how platelets safeguard vascular integrity in tumors is urgently demanded. Here, we show for the first time that functional inhibition of glycoprotein VI (GPVI) on the platelet surface with an antibody (JAQ1) F(ab)2 fragment rapidly induces tumor hemorrhage and diminishes tumor growth similar to complete platelet depletion while not inducing systemic bleeding complications. The intratumor bleeding and tumor growth arrest could be reverted by depletion of Ly6G+ cells, confirming them to be responsible for the induction of bleeding and necrosis within the tumor. In addition, JAQ1 F(ab)2-mediated GPVI inhibition increased intratumoral accumulation of coadministered chemotherapeutic agents, such as Doxil and paclitaxel, thereby resulting in a profound antitumor effect. In summary, our findings identify platelet GPVI as a key regulator of vascular integrity specifically in growing tumors and could serve as a basis for the development of antitumor strategies based on the interference with platelet function.
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Fragmentos Fab de Inmunoglobulinas/farmacología , Neoplasias Experimentales/patología , Glicoproteínas de Membrana Plaquetaria/antagonistas & inhibidores , Animales , Femenino , Hemorragia/patología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Neovascularización PatológicaRESUMEN
Interactions of malignant multiple myeloma (MM) plasma cells (MM-cells) with the microenvironment control MM-cell growth, survival, drug-resistance and dissemination. As in MM microvascular density increases in the bone marrow (BM), we investigated whether BM MM endothelial cells (MMECs) control disease progression via the junctional adhesion molecule A (JAM-A). Membrane and cytoplasmic JAM-A levels were upregulated in MMECs in 111 newly diagnosed (NDMM) and 201 relapsed-refractory (RRMM) patients compared to monoclonal gammopathy of undetermined significance (MGUS) and healthy controls. Elevated membrane expression of JAM-A on MMECs predicted poor clinical outcome. Mechanistically, addition of recombinant JAM-A to MMECs increased angiogenesis whereas its inhibition impaired angiogenesis and MM growth in 2D and 3D in vitro cell culture and chorioallantoic membrane-assays. To corroborate these findings, we treated MM bearing mice with JAM-A blocking mAb and demonstrated impaired MM progression corresponding to decreased MM-related vascularity. These findings support JAM-A as an important mediator of MM progression through facilitating MM-associated angiogenesis. Collectively, elevated JAM-A expression on bone marrow endothelial cells is an independent prognostic factor for patient survival in both NDMM and RRMM. Blocking JAM-A restricts angiogenesis in vitro, in embrio and in vivo and represents a suitable druggable molecule to halt neoangiogenesis and MM progression.
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Molécula A de Adhesión de Unión , Mieloma Múltiple , Animales , Médula Ósea , Ecosistema , Células Endoteliales , Homeostasis , Humanos , Ratones , Mieloma Múltiple/tratamiento farmacológico , Microambiente TumoralRESUMEN
Alternative intronic polyadenylation (IPA) can generate truncated protein isoforms with significantly altered functions. Here, we describe 31 dominant-negative, secreted variant isoforms of receptor tyrosine kinases (RTKs) that are produced by activation of intronic poly(A) sites. We show that blocking U1-snRNP can activate IPA, indicating a larger role for U1-snRNP in RNA surveillance. Moreover, we report the development of an antisense-based method to effectively and specifically activate expression of individual soluble decoy RTKs (sdRTKs) to alter signaling, with potential therapeutic implications. In particular, a quantitative switch from signal transducing full-length vascular endothelial growth factor receptor-2 (VEGFR2/KDR) to a dominant-negative sKDR results in a strong antiangiogenic effect both on directly targeted cells and on naive cells exposed to conditioned media, suggesting a role for this approach in interfering with angiogenic paracrine and autocrine loops.
Asunto(s)
Intrones , Poliadenilación , Proteínas Tirosina Quinasas Receptoras/biosíntesis , Humanos , Neovascularización Fisiológica/fisiología , Poli A/química , Poli A/genética , Isoformas de Proteínas/biosíntesis , Isoformas de Proteínas/química , Isoformas de Proteínas/fisiología , Empalme del ARN , Proteínas Tirosina Quinasas Receptoras/química , Proteínas Tirosina Quinasas Receptoras/fisiología , Ribonucleoproteína Nuclear Pequeña U1/fisiología , Transducción de Señal , Receptor 2 de Factores de Crecimiento Endotelial Vascular/biosíntesis , Receptor 2 de Factores de Crecimiento Endotelial Vascular/química , Receptor 2 de Factores de Crecimiento Endotelial Vascular/fisiologíaRESUMEN
As in the systemic treatment of any disease, it is crucial for anti-cancer drugs to reach their target at a sufficient that is a therapeutically effective dose. However, unlike normal organs, solid tumors have a tendency to be undersupplied and hypoxic. This not only leads to insufficient supply of oxygen and nutrients but also to inefficient transport of drugs into tumors. As a consequence, administered doses have to be raised, resulting in increased side effects and often premature termination of treatment. A better understanding of the mechanisms that hamper transport of drugs into tumors could lead to the development of auxiliary strategies aimed at increasing tumor drug delivery and accumulation and thereby improving the efficacy of anti-cancer drugs at our disposal. The tumor microenvironment (TME), i.e., its vasculature, stroma, extracellular matrix and immune environment affect the transport of drugs to the tumor and their distribution within the tumor tissue in various ways. In this review we will highlight the current research regarding the cellular and molecular mechanisms that remain as an obstacle towards an effective cancer therapy, and also focus on the various strategies to alter the TME to increase tumor drug exposure and thereby treatment efficacy.
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Antineoplásicos/metabolismo , Antineoplásicos/farmacocinética , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Microambiente Tumoral , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/farmacología , Transporte Biológico/efectos de los fármacos , Humanos , Neoplasias/patología , Microambiente Tumoral/efectos de los fármacosRESUMEN
Here we studied the autoantibody specificity elicited by proteolipid protein (PLP) in MP4-induced experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis (MS). In C57BL/6 (B6) mice, antibodies were induced by immunization with one of the two extracellular and by the intracellular PLP domain. Antibodies against extracellular PLP were myelin-reactive in oligodendrocyte cultures and induced mild spinal cord demyelination upon transfer into B cell-deficient J(H)T mice. Remarkably, also antibodies against intracellular PLP showed binding to intact oligodendrocytes and were capable of inducing myelin pathology upon transfer into J(H)T mice. In MP4-immunized mice peptide-specific T(H)1/T(H)17 responses were mainly directed against the extracellular PLP domains, but also involved the intracellular epitopes. These data suggest that both extracellular and intracellular epitopes of PLP contribute to the pathogenesis of MP4-induced EAE already in the setting of intact myelin. It remains to be elucidated if this concept also applies to MS itself.
Asunto(s)
Encefalomielitis Autoinmune Experimental/inmunología , Proteína Básica de Mielina/inmunología , Proteína Proteolipídica de la Mielina/inmunología , Oligodendroglía/inmunología , Proteínas Recombinantes de Fusión/inmunología , Animales , Enfermedades Desmielinizantes/inmunología , Epítopos/inmunología , Ratones , Fragmentos de Péptidos/inmunología , Estructura Terciaria de Proteína , Células TH1/inmunología , Células Th17/inmunologíaRESUMEN
Blood vessels in tumors are often dysfunctional. This impairs the delivery of therapeutic agents to and distribution among the cancer cells. Subsequently, treatment efficacy is reduced, and dose escalation can increase adverse effects on non-malignant tissues. The dysfunctional vessel phenotypes are attributed to aberrant pro-angiogenic signaling, and anti-angiogenic agents can ameliorate traits of vessel dysfunctionality. However, they simultaneously reduce vessel density and thereby impede drug delivery and distribution. Exploring possibilities to improve vessel functionality without compromising vessel density in the tumor microenvironment, we evaluated transcription factors (TFs) involved in epithelial-mesenchymal transition (EMT) as potential targets. Based on similarities between EMT and angiogenic activation of endothelial cells, we hypothesized that these TFs, Snai1 in particular, might serve as key regulators of vessel dysfunctionality. In vitro, experiments demonstrated that Snai1 (similarly Slug and Twist1) regulates endothelial permeability, permissiveness for tumor cell transmigration, and tip/stalk cell formation. Endothelial-specific, heterozygous knock-down of Snai1 in mice improved vascular quality in implanted tumors. This resulted in better oxygenation and reduced metastasis. Notably, the tumors in Snai1KD mice responded significantly better to chemotherapeutics as drugs were transported into the tumors at strongly increased rates and more homogeneously distributed. Thus, we demonstrate that restoring vessel homeostasis without affecting vessel density is feasible in malignant tumors. Combining such vessel re-engineering with anti-cancer drugs allows for strategic treatment approaches that reduce treatment toxicity on non-malignant tissues.
RESUMEN
Targeting the supportive tumor microenvironment (TME) is an approach of high interest in cancer drug development. However, assessing TME-targeted drug candidates presents a unique set of challenges. We develop a comprehensive screening platform that allows monitoring, quantifying, and ranking drug-induced effects in self-organizing, vascularized tumor spheroids (VTSs). The confrontation of four human-derived cell populations makes it possible to recreate and study complex changes in TME composition and cell-cell interaction. The platform is modular and adaptable for tumor entity or genetic manipulation. Treatment effects are recorded by light sheet fluorescence microscopy and translated by an advanced image analysis routine in processable multi-parametric datasets. The system proved to be robust, with strong interassay reliability. We demonstrate the platform's utility for evaluating TME-targeted antifibrotic and antiangiogenic drugs side-by-side. The platform's output enabled the differential evaluation of even closely related drug candidates according to projected therapeutic needs.
Asunto(s)
Neoplasias de la Mama , Microscopía Fluorescente , Esferoides Celulares , Microambiente Tumoral , Humanos , Microambiente Tumoral/efectos de los fármacos , Esferoides Celulares/efectos de los fármacos , Esferoides Celulares/patología , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Microscopía Fluorescente/métodos , Femenino , Línea Celular Tumoral , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Ensayos de Selección de Medicamentos Antitumorales/métodos , Inhibidores de la Angiogénesis/farmacología , Inhibidores de la Angiogénesis/uso terapéutico , Neovascularización Patológica/tratamiento farmacológico , Neovascularización Patológica/patologíaRESUMEN
In tumor therapy anti-angiogenic approaches have the potential to increase the efficacy of a wide variety of subsequently or co-administered agents, possibly by improving or normalizing the defective tumor vasculature. Successful implementation of the concept of vascular normalization under anti-angiogenic therapy, however, mandates a detailed understanding of key characteristics and a respective scoring metric that defines an improved vasculature and thus a successful attempt. Here, we show that beyond commonly used parameters such as vessel patency and maturation, anti-angiogenic approaches largely benefit if the complex vascular network with its vessel interconnections is both qualitatively and quantitatively assessed. To gain such deeper insight the organization of vascular networks, we introduce a multi-parametric evaluation of high-resolution angiographic images based on light-sheet fluorescence microscopy images of tumors. We first could pinpoint key correlations between vessel length, straightness and diameter to describe the regular, functional and organized structure observed under physiological conditions. We found that vascular networks from experimental tumors diverted from those in healthy organs, demonstrating the dysfunctionality of the tumor vasculature not only on the level of the individual vessel but also in terms of inadequate organization into larger structures. These parameters proofed effective in scoring the degree of disorganization in different tumor entities, and more importantly in grading a potential reversal under treatment with therapeutic agents. The presented vascular network analysis will support vascular normalization assessment and future optimization of anti-angiogenic therapy.
Asunto(s)
Neoplasias , Neovascularización Patológica , Humanos , Neovascularización Patológica/diagnóstico por imagen , Neovascularización Patológica/tratamiento farmacológico , Neovascularización Patológica/patología , Neoplasias/diagnóstico por imagen , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Inmunoterapia , Inhibidores de la Angiogénesis/farmacología , Inhibidores de la Angiogénesis/uso terapéuticoRESUMEN
Blocking tumor vascularization has not yet come to fruition to the extent it was hoped for, as angiogenesis inhibitors have shown only partial success in the clinic. We hypothesized that under-appreciated vascular wall-resident stem and progenitor cells (VW-SPCs) might be involved in tumor vascularization and influence effectiveness of anti-angiogenic therapy. Indeed, in patient samples, we observed that vascular adventitia-resident CD34+ VW-SPCs are recruited to tumors in situ from co-opted vessels. To elucidate this in detail, we established an ex vivo model using concomitant embedding of multi-cellular tumor spheroids (MCTS) and mouse aortic rings (ARs) into collagen gels, similar to the so-called aortic ring assay (ARA). Moreover, ARA was modified by removing the ARs' adventitia that harbors VW-SPCs. Thus, this model enabled distinguishing the contribution of VW-SPCs from that of mature endothelial cells (ECs) to new vessel formation. Our results show that the formation of capillary-like sprouts is considerably delayed, and their number and network formation were significantly reduced by removing the adventitia. Substituting iPSC-derived neural spheroids for MCTS resulted in distinct sprouting patterns that were also strongly influenced by the presence or absence of VW-SPCs, also underlying the involvement of these cells in non-pathological vascularization. Our data suggest that more comprehensive approaches are needed in order to block all of the mechanisms contributing to tumor vascularization.
Asunto(s)
Adventicia/patología , Neoplasias/irrigación sanguínea , Neoplasias/patología , Células Madre/patología , Animales , Antígenos CD34/metabolismo , Aorta/patología , Capilares/patología , Humanos , Ratones , Modelos Biológicos , Neovascularización Patológica , Neovascularización Fisiológica , Ratas , Receptores de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Receptores de Factores de Crecimiento Endotelial Vascular/metabolismoRESUMEN
The long plasma half-life of IgG, while allowing for enhanced tumor uptake of tumor-targeted IgG conjugates, also results in increased background activity and normal-tissue toxicity. Therefore, successful therapeutic uses of conjugated antibodies have been limited to the highly sensitive and readily accessible hematopoietic tumors. We report a therapeutic strategy to beneficially alter the pharmacokinetics of IgG antibodies via pharmacological inhibition of the neonatal Fc receptor (FcRn) using high-dose IgG therapy. IgG-treated mice displayed enhanced blood and whole-body clearance of radioactivity, resulting in better tumor-to-blood image contrast and protection of normal tissue from radiation. Tumor uptake and the resultant therapeutic response was unaltered. Furthermore, we demonstrated the use of this approach for imaging of tumors in humans and discuss its potential applications in cancer imaging and therapy. The ability to reduce the serum persistence of conjugated IgG antibodies after their infusion can enhance their therapeutic index, resulting in improved therapeutic and diagnostic efficacy.
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Antígenos de Histocompatibilidad Clase I/metabolismo , Inmunoglobulina G/inmunología , Inmunoglobulina G/uso terapéutico , Neoplasias/patología , Neoplasias/terapia , Receptores Fc/metabolismo , Actinio/química , Animales , Femenino , Humanos , Inmunoglobulina G/administración & dosificación , Inmunoglobulina G/efectos adversos , Inmunoterapia , Radioisótopos de Indio/química , Inyecciones Intravenosas , Radioisótopos de Yodo , Ratones , Neoplasias/inmunología , Neoplasias/metabolismo , Tomografía de Emisión de Positrones , Factores de TiempoRESUMEN
Solid tumors are complex organ-like structures that consist not only of tumor cells but also of vasculature, extracellular matrix (ECM), stromal, and immune cells. Often, this tumor microenvironment (TME) comprises the larger part of the overall tumor mass. Like the other components of the TME, the ECM in solid tumors differs significantly from that in normal organs. Intratumoral signaling, transport mechanisms, metabolisms, oxygenation, and immunogenicity are strongly affected if not controlled by the ECM. Exerting this regulatory control, the ECM does not only influence malignancy and growth of the tumor but also its response toward therapy. Understanding the particularities of the ECM in solid tumor is necessary to develop approaches to interfere with its negative effect. In this review, we will also highlight the current understanding of the physical, cellular, and molecular mechanisms by which the pathological tumor ECM affects the efficiency of radio-, chemo-, and immunotherapy. Finally, we will discuss the various strategies to target and modify the tumor ECM and how they could be utilized to improve response to therapy.
RESUMEN
Pluripotent stem cells give rise to reproductively enabled offsprings by generating progressively lineage-restricted multipotent stem cells that would differentiate into lineage-committed stem and progenitor cells. These lineage-committed stem and progenitor cells give rise to all adult tissues and organs. Adult stem and progenitor cells are generated as part of the developmental program and play critical roles in tissue and organ maintenance and/or regeneration. The ability of pluripotent stem cells to self-renew, maintain pluripotency, and differentiate into a multicellular organism is highly dependent on sensing and integrating extracellular and extraorganismal cues. Proteins perform and integrate almost all cellular functions including signal transduction, regulation of gene expression, metabolism, and cell division and death. Therefore, maintenance of an appropriate mix of correctly folded proteins, a pristine proteome, is essential for proper stem cell function. The stem cells' proteome must be pristine because unfolded, misfolded, or otherwise damaged proteins would interfere with unlimited self-renewal, maintenance of pluripotency, differentiation into downstream lineages, and consequently with the development of properly functioning tissue and organs. Understanding how various stem cells generate and maintain a pristine proteome is therefore essential for exploiting their potential in regenerative medicine and possibly for the discovery of novel approaches for maintaining, propagating, and differentiating pluripotent, multipotent, and adult stem cells as well as induced pluripotent stem cells. In this review, we will summarize cellular networks used by various stem cells for generation and maintenance of a pristine proteome. We will also explore the coordination of these networks with one another and their integration with the gene regulatory and signaling networks.
RESUMEN
Organoids derived from human pluripotent stem cells are interesting models to study mechanisms of morphogenesis and promising platforms for disease modeling and drug screening. However, they mostly remain incomplete as they lack stroma, tissue resident immune cells and in particular vasculature, which create important niches during development and disease. We propose, that the directed incorporation of mesodermal progenitor cells (MPCs) into organoids will overcome the aforementioned limitations. In order to demonstrate the feasibility of the method, we generated complex human tumor as well as neural organoids. We show that the formed blood vessels display a hierarchic organization and mural cells are assembled into the vessel wall. Moreover, we demonstrate a typical blood vessel ultrastructure including endothelial cell-cell junctions, a basement membrane as well as luminal caveolae and microvesicles. We observe a high plasticity in the endothelial network, which expands, while the organoids grow and is responsive to anti-angiogenic compounds and pro-angiogenic conditions such as hypoxia. We show that vessels within tumor organoids connect to host vessels following transplantation. Remarkably, MPCs also deliver Iba1+ cells that infiltrate the neural tissue in a microglia-like manner.
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Vasos Sanguíneos/fisiología , Células Madre Pluripotentes Inducidas/citología , Mesodermo/citología , Organoides/citología , Diferenciación Celular , HumanosRESUMEN
The potential of altering the tumor ECM to improve drug response remains fairly unexplored. To identify targets for modification of the ECM aiming to improve drug response and overcome resistance, we analyzed expression data sets from pre-treatment patient cohorts. Cross-evaluation identified a subset of chemoresistant tumors characterized by increased expression of collagens and collagen-stabilizing enzymes. We demonstrate that strong collagen expression and stabilization sets off a vicious circle of self-propagating hypoxia, malignant signaling, and aberrant angiogenesis that can be broken by an appropriate auxiliary intervention: Interfering with collagen stabilization by inhibition of lysyl oxidases significantly enhanced response to chemotherapy in various tumor models, even in metastatic disease. Inhibition of collagen stabilization by itself can reduce or enhance tumor growth depending on the tumor type. The mechanistical basis for this behavior is the dependence of the individual tumor on nutritional supply on one hand and on high tissue stiffness for FAK signaling on the other.
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Colágeno/metabolismo , Resistencia a Antineoplásicos/fisiología , Proteínas de la Matriz Extracelular/metabolismo , Matriz Extracelular/metabolismo , Proteína-Lisina 6-Oxidasa/metabolismo , Animales , Línea Celular Tumoral , Femenino , Humanos , Ratones , Ratones Endogámicos C57BL , Transducción de Señal/fisiologíaRESUMEN
Tumors are characterized by a rigid, highly cross-linked extracellular matrix (ECM), which impedes homogeneous drug distribution and potentially protects malignant cells from exposure to therapeutics. Lysyl oxidases are major contributors to tissue stiffness and the elevated expression of these enzymes observed in most cancers might influence drug distribution and efficacy. We examined the effect of lysyl oxidases on drug distribution and efficacy in 3D in vitro assay systems. In our experiments elevated lysyl oxidase activity was responsible for reduced drug diffusion under hypoxic conditions and consequently impaired cytotoxicity of various chemotherapeutics. This effect was only observed in 3D settings but not in 2D-cell culture, confirming that lysyl oxidases affect drug efficacy by modification of the ECM and do not confer a direct desensitizing effect. Both drug diffusion and efficacy were strongly enhanced by inhibition of lysyl oxidases. The results from the in vitro experiments correlated with tumor drug distribution in vivo, and predicted response to therapeutics in murine tumor models. Our results demonstrate that lysyl oxidase activity modulates the physical barrier function of ECM for small molecule drugs influencing their therapeutic efficacy. Targeting this process has the potential to significantly enhance therapeutic efficacy in the treatment of malignant diseases.
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Antineoplásicos/farmacología , Inhibidores Enzimáticos/farmacocinética , Proteínas de Neoplasias/antagonistas & inhibidores , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/enzimología , Proteína-Lisina 6-Oxidasa/antagonistas & inhibidores , Animales , Línea Celular Tumoral , Sinergismo Farmacológico , Femenino , Humanos , Ratones , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Controversy surrounds neutrophil function in cancer because neutrophils were shown to provide both pro- and antitumor functions. We identified a heterogeneous subset of low-density neutrophils (LDNs) that appear transiently in self-resolving inflammation but accumulate continuously with cancer progression. LDNs display impaired neutrophil function and immunosuppressive properties, characteristics that are in stark contrast to those of mature, high-density neutrophils (HDNs). LDNs consist of both immature myeloid-derived suppressor cells (MDSCs) and mature cells that are derived from HDNs in a TGF-ß-dependent mechanism. Our findings identify three distinct populations of circulating neutrophils and challenge the concept that mature neutrophils have limited plasticity. Furthermore, our findings provide a mechanistic explanation to mitigate the controversy surrounding neutrophil function in cancer.
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Neoplasias/patología , Neutrófilos/citología , Animales , Línea Celular , Células Cultivadas , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Neoplasias/inmunologíaRESUMEN
Primary tumors have been shown to prepare distal organs for later colonization of metastatic cells by stimulating organ-specific infiltration of bone marrow derived cells. Here we demonstrate that neutrophils accumulate in the lung prior to the arrival of metastatic cells in mouse models of breast cancer. Tumor-entrained neutrophils (TENs) inhibit metastatic seeding in the lungs by generating H(2)O(2) and tumor secreted CCL2 is a critical mediator of optimal antimetastatic entrainment of G-CSF-stimulated neutrophils. TENs are present in the peripheral blood of breast cancer patients prior to surgical resection but not in healthy individuals. Thus, whereas tumor-secreted factors contribute to tumor progression at the primary site, they concomitantly induce a neutrophil-mediated inhibitory process at the metastatic site.
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Neoplasias de la Mama/patología , Neoplasias Pulmonares/secundario , Pulmón/inmunología , Neutrófilos/inmunología , Neutrófilos/metabolismo , Animales , Células de la Médula Ósea , Neoplasias de la Mama/inmunología , Línea Celular Tumoral , Quimiocina CCL2/metabolismo , Citotoxicidad Inmunológica , Femenino , Factor Estimulante de Colonias de Granulocitos/metabolismo , Humanos , Peróxido de Hidrógeno/metabolismo , Pulmón/patología , Neoplasias Pulmonares/inmunología , Neoplasias Pulmonares/patología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Invasividad Neoplásica , Interferencia de ARN , ARN Interferente Pequeño , Especies Reactivas de Oxígeno/metabolismo , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Antiangiogenic therapies are frequently used with concomitantly administered cancer chemotherapy to improve outcomes, but the mechanism for the benefit of the combination is uncertain. We describe a mechanism by which a specific, cytotoxic antivascular agent causes vascular remodeling and improved chemotherapy results. By selectively killing tumor neovasculature using short-ranged α-particles targeted to vascular endothelial (VE)-cadherin on vascular endothelial cells (by use of 225Ac-labeled E4G10 antibody) we were able both to reduce tumor growth and to increase the efficacy of chemotherapy, an effect seen only when the chemotherapy was administered several days after the vascular targeting agent, but not if the order of administration was reversed. Immunohistochemical and immunofluorescence studies showed that the vasculature of 225Ac-E4G10-treated tumors was substantially depleted; the remaining vessels appeared more mature morphologically and displayed increased pericyte density and coverage. Tumor uptake and microdistribution studies with radioactive and fluorescent small molecule drugs showed better accumulation and more homogenous distribution of the drugs within 225Ac-E4G10-treated tumors. These results show that 225Ac-E4G10 treatment leads to ablation and improvement of the tumor vascular architecture, and also show that the resulting vascular remodeling can increase tumor delivery of small molecules, thus providing a process for the improved outcomes observed after combining antivascular therapy and chemotherapy. This study directly shows evidence for what has long been a speculated mechanism for antiangiogenic therapies. Moreover, targeting the vessel for killing provides an alternative mode of improving chemotherapy delivery and efficacy, potentially avoiding some of the drawbacks of targeting a highly redundant angiogenic pathway.
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Anticuerpos Monoclonales/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Neoplasias/tratamiento farmacológico , Neovascularización Patológica/prevención & control , Inhibidores de la Angiogénesis/farmacología , Animales , Línea Celular Tumoral , Didesoxinucleósidos/farmacocinética , Sinergismo Farmacológico , Femenino , Radioisótopos de Flúor/farmacocinética , Fluorouracilo/administración & dosificación , Humanos , Radioisótopos de Indio/farmacocinética , Leucovorina/administración & dosificación , Ratones , Ratones Desnudos , Neoplasias/irrigación sanguínea , Neoplasias/patología , Tomografía de Emisión de Positrones/métodos , Carga Tumoral/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
BACKGROUND Blood vessels are formed either by sprouting of resident tissue endothelial cells (angiogenesis) or by recruitment of bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs, vasculogenesis). Neovascularization has been implicated in tumor growth and inflammation, but its roles in graft-vs-host disease (GVHD) and in tumors after allogeneic BM transplantation (allo-BMT) were not known. METHODS We analyzed neovascularization, the contribution of endothelial cells and EPCs, and the ability of anti-vascular endothelial-cadherin antibody, E4G10, to inhibit neovascularization in mice with GVHD after allo-BMT using immunofluorescence microscopy and flow cytometry. We examined survival and clinical and histopathologic GVHD in mice (n = 10-25 per group) in which GVHD was treated with the E4G10 antibody using immunohistochemistry, flow cytometry, and cytokine immunoassay. We also assessed survival, the contribution of green fluorescent protein-marked EPCs to the tumor vasculature, and the ability of E4G10 to inhibit tumor growth in tumor-bearing mice (n = 20-33 per group) after allo-BMT using histopathology and bioluminescence imaging. All statistical tests were two-sided. RESULTS We found increased neovascularization mediated by vasculogenesis, as opposed to angiogenesis, in GVHD target tissues, such as liver and intestines. Administration of E4G10 inhibited neovascularization by donor BM-derived cells without affecting host vascularization, inhibited both GVHD and tumor growth, and increased survival (at 60 days post-BMT and tumor challenge with A20 lymphoma, the probability of survival was 0.29 for control antibody-treated allo-BMT recipients vs 0.7 for E4G10-treated allo-BMT recipients, 95% confidence interval = 0.180 to 0.640, P < .001). CONCLUSIONS Therapeutic targeting of neovascularization in allo-BMT recipients is a novel strategy to simultaneously ameliorate GVHD and inhibit posttransplant tumor growth, providing a new approach to improve the overall outcome of allogeneic hematopoietic stem cell transplantation.