RESUMO
Lymph nodes are initial sites of tumor metastasis, yet whether the lymph node microenvironment actively promotes tumor metastasis remains unknown. We show here that VEGF-C/PI3Kα-driven remodeling of lymph nodes promotes tumor metastasis by activating integrin α4ß1 on lymph node lymphatic endothelium. Activated integrin α4ß1 promotes expansion of the lymphatic endothelium in lymph nodes and serves as an adhesive ligand that captures vascular cell adhesion molecule 1 (VCAM-1)(+) metastatic tumor cells, thereby promoting lymph node metastasis. Experimental induction of α4ß1 expression in lymph nodes is sufficient to promote tumor cell adhesion to lymphatic endothelium and lymph node metastasis in vivo, whereas genetic or pharmacological blockade of integrin α4ß1 or VCAM-1 inhibits it. As lymph node metastases accurately predict poor disease outcome, and integrin α4ß1 is a biomarker of lymphatic endothelium in tumor-draining lymph nodes from animals and patients, these results indicate that targeting integrin α4ß1 or VCAM to inhibit the interactions of tumor cells with the lymph node microenvironment may be an effective strategy to suppress tumor metastasis.
Assuntos
Carcinoma Ductal de Mama/patologia , Endotélio Linfático/metabolismo , Integrina alfa4beta1/metabolismo , Linfonodos/metabolismo , Metástase Neoplásica/fisiopatologia , Fosfatidilinositol 3-Quinases/metabolismo , Molécula 1 de Adesão de Célula Vascular/metabolismo , Análise de Variância , Animais , Adesão Celular/fisiologia , Feminino , Regulação Neoplásica da Expressão Gênica/fisiologia , Humanos , Imuno-Histoquímica , Linfangiogênese/fisiologia , Camundongos , Metástase Neoplásica/prevenção & controle , Molécula 1 de Adesão de Célula Vascular/fisiologiaRESUMO
Angiogenesis is controlled by signals that stimulate motility in endothelial cells at the tips of vascular sprouts while maintaining cell-cell adhesion in the stalks of angiogenic sprouts. We show here that Gs-linked G protein-coupled receptor activation of cAMP-dependent protein kinase (PKA) plays an important role in regulating the switch between endothelial cell adhesion and migration by activating C-terminal Src kinase, leading to inhibition of pp60Src. Activated PKA blocks pp60Src-dependent vascular endot helial-cadherin phosphorylation, thereby stimulating cell-cell adhesion while suppressing endothelial cell polarization, motility, angiogenesis, and vascular permeability. Similar to the actions of Notch and Dll4, PKA activation blocks sprouting in newly forming embryonic blood vessels, while PKA inhibition promotes excessive sprouting in these vessels. These findings demonstrate that G protein-coupled receptors and PKA regulate vascular sprouting during angiogenesis by controlling endothelial cell migration and cell-cell adhesion through their actions on pp60Src.
Assuntos
Adesão Celular/fisiologia , Movimento Celular/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Neovascularização Fisiológica , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Transdução de Sinais , Western Blotting , Proteína Tirosina Quinase CSK , Células Cultivadas , Proteínas Quinases Dependentes de AMP Cíclico/genética , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Humanos , Imunoprecipitação , Fosforilação , Proteínas Tirosina Quinases/genética , Proteínas Proto-Oncogênicas pp60(c-src)/antagonistas & inibidores , Proteínas Proto-Oncogênicas pp60(c-src)/genética , Veias Umbilicais/citologia , Veias Umbilicais/metabolismo , Quinases da Família srcRESUMO
Tumor-associated macrophages promote tumor growth by stimulating angiogenesis and suppressing antitumor immunity. Thus, therapeutics that inhibit macrophage recruitment to tumors may provide new avenues for cancer therapy. In this study, we showed how chemoattractants stromal cell-derived growth factor 1 alpha (SDF-1α) and interleukin 1 beta (IL-1ß) collaborate with myeloid cell integrin-α4ß1 to promote tumor inflammation and growth. We found that SDF-1α and IL-1ß are highly expressed in the microenvironments of murine lung, pancreatic, and breast tumors; surprisingly, SDF-1α was expressed only by tumor cells, whereas IL-1ß was produced only by tumor-derived granulocytes and macrophages. In vivo, both factors directly recruited proangiogenic macrophages to tissues, whereas antagonists of both factors suppressed tumor inflammation, angiogenesis, and growth. Signals induced by IL-1ß and SDF-1α promoted the interaction of talin and paxillin with the cytoplasmic tails of integrin-α4ß1, thereby stimulating myeloid cell adhesion to endothelium in vitro and in vivo. Inhibition of integrin-α4ß1, SDF-1α, or IL-1ß was sufficient to block tumor inflammation and growth, and the combined blockade of these molecules greatly accentuated these effects. Furthermore, antagonists of integrin-α4ß1 inhibited chemotherapy-induced tumor inflammation and acted synergistically with chemotherapeutic agents to suppress tumor inflammation and growth. These results show that targeting myeloid cell recruitment mechanisms can be an effective approach to suppress tumor progression.
Assuntos
Quimiocina CXCL12/antagonistas & inibidores , Inflamação/prevenção & controle , Integrina alfa4beta1/antagonistas & inibidores , Interleucina-1beta/antagonistas & inibidores , Neoplasias/terapia , Animais , Antígeno CD11b/análise , Movimento Celular , Quimiocina CXCL12/fisiologia , Integrina alfa4beta1/fisiologia , Interleucina-1beta/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Células Mieloides/fisiologia , Neoplasias/patologia , Paxilina/fisiologia , Talina/fisiologiaRESUMO
Tumor inflammation promotes angiogenesis, immunosuppression, and tumor growth, but the mechanisms controlling inflammatory cell recruitment to tumors are not well understood. We found that a range of chemoattractants activating G protein-coupled receptors (GPCRs), receptor tyrosine kinases (RTKs) and Toll-like/IL-1 receptors (TLR/IL1Rs) unexpectedly initiate tumor inflammation by activating the PI3-kinase isoform p110γ in Gr1+CD11b+ myeloid cells. Whereas GPCRs activate p110γ in a Ras/p101-dependent manner, RTKs and TLR/IL1Rs directly activate p110γ in a Ras/p87-dependent manner. Once activated, p110γ promotes inside-out activation of a single integrin, α4ß1, causing myeloid cell invasion into tumors. Pharmacological or genetic blockade of p110γ suppressed inflammation, growth, and metastasis of implanted and spontaneous tumors, revealing an important therapeutic target in oncology.
Assuntos
Classe Ib de Fosfatidilinositol 3-Quinase/fisiologia , Inflamação/etiologia , Neoplasias/patologia , Receptores Proteína Tirosina Quinases/fisiologia , Receptores de Interleucina-1/fisiologia , Receptores Toll-Like/fisiologia , Animais , Adesão Celular , Movimento Celular , Progressão da Doença , Humanos , Integrina alfa4beta1/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Metástase Neoplásica , Neoplasias/prevenção & controle , Proteínas ras/fisiologiaRESUMO
Recent studies have shown that lymphangiogenesis or the growth of lymphatic vessels at the periphery of tumors promotes tumor metastasis to lymph nodes. We show here that the fibronectin-binding integrin alpha4beta1 and its ligand fibronectin are novel functional markers of proliferative lymphatic endothelium. Tumors and lymphangiogenic growth factors, such as vascular endothelial growth factor-C (VEGF-C) and VEGF-A, induce lymphatic vessel expression of integrin alpha4beta1. Integrin alpha4beta1 then promotes growth factor and tumor-induced lymphangiogenesis, as genetic loss of integrin alpha4beta1 expression in Tie2Cre+ alpha4(loxp/loxp) mice or genetic loss of alpha4 signaling in alpha4Y991A knock-in mice blocks growth factor and tumor-induced lymphangiogenesis, as well as tumor metastasis to lymph nodes. In addition, antagonists of integrin alpha4beta1 suppress lymphangiogenesis and tumor metastasis. Our studies show that integrin alpha4beta1 and the signals it transduces regulate the adhesion, migration, invasion, and survival of proliferating lymphatic endothelial cells. As suppression of alpha4beta1 expression, signal transduction, or function in tumor lymphatic endothelium not only inhibits tumor lymphangiogenesis but also prevents metastatic disease, these results show that integrin alpha4beta1-mediated tumor lymphangiogenesis promotes metastasis and is a useful target for the suppression of metastatic disease.
Assuntos
Integrina alfa4beta1/biossíntese , Linfangiogênese , Neoplasias/metabolismo , Transdução de Sinais , Animais , Adesão Celular , Movimento Celular , Proliferação de Células , Células Endoteliais/citologia , Feminino , Humanos , Ligantes , Melanoma Experimental , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Metástase Neoplásica , Neoplasias/patologiaRESUMO
Blood vessels promote tumour growth, and both blood and lymphatic vessels facilitate tumour metastasis by serving as conduits for the transport of tumour cells to new sites. Angiogenesis and lymphangiogenesis are regulated by integrins, which are members of a family of cell surface receptors whose ligands are extracellular matrix proteins and immunoglobulin superfamily molecules. Select integrins promote endothelial cell migration and survival during angiogenesis and lymphangiogenesis, whereas other integrins promote pro-angiogenic macrophage trafficking to tumours. Several integrin-targeted therapeutic agents are currently in clinical trials for cancer therapy. Here, we review the evidence implicating integrins as a family of fundamental regulators of angiogenesis and lymphangiogenesis.