RESUMO
Delta-like 4 (DLL4)-mediated Notch signalling has emerged as an attractive target for cancer therapy. However, the potential side effects of blocking this pathway remain uncertain. Here we show that chronic DLL4 blockade causes pathological activation of endothelial cells, disrupts normal organ homeostasis and induces vascular tumours, raising important safety concerns.
Assuntos
Antineoplásicos/efeitos adversos , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Proteínas de Membrana/antagonistas & inibidores , Neoplasias Vasculares/induzido quimicamente , Proteínas Adaptadoras de Transdução de Sinal , Animais , Antineoplásicos/farmacologia , Proteínas de Ligação ao Cálcio , Doença Hepática Induzida por Substâncias e Drogas/patologia , Doença Hepática Induzida por Substâncias e Drogas/fisiopatologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/patologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macaca fascicularis , Proteínas de Membrana/metabolismo , Camundongos , Ratos , Receptores Notch/metabolismo , Transdução de SinaisRESUMO
The Notch signaling pathway plays a fundamental role during blood vessel development. Notch signaling regulates blood vessel morphogenesis by promoting arterial endothelial differentiation and providing spatial and temporal control over "tip cell" phenotype during angiogenic sprouting. Components of the Notch signaling pathway have emerged as potential regulators of lymphatic development, joining the increasing examples of blood vessel regulators that are also involved in lymphatic development. However, in mammals a role for the Notch signaling pathway during lymphatic development remains to be demonstrated. In this report, we show that blockade of Notch1 and Dll4, with specific function-blocking antibodies, results in defective postnatal lymphatic development in mice. Mechanistically, Notch1-Dll4 blockade is associated with down-regulation of EphrinB2 expression, been shown to be critically involved in VEGFR3/VEGFC signaling, resulting in reduced lymphangiogenic sprouting. In addition, Notch1-Dll4 blockade leads to compromised expression of distinct lymphatic markers and to dilation of collecting lymphatic vessels with reduced and disorganized mural cell coverage. Finally, Dll4-blockade impairs wound closure and severely affects lymphangiogenesis during the wound healing in adult mouse skin. Thus, our study demonstrates for the first time in a mammalian system that Notch1-Dll4 signaling pathway regulates postnatal lymphatic development and pathologic lymphangiogenesis.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Linfangiogênese , Vasos Linfáticos/metabolismo , Proteínas de Membrana/metabolismo , Receptor Notch1/metabolismo , Transdução de Sinais , Proteínas Adaptadoras de Transdução de Sinal , Animais , Proteínas de Ligação ao Cálcio , Linhagem Celular , Efrina-B2/genética , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Vasos Linfáticos/citologia , Vasos Linfáticos/ultraestrutura , CamundongosRESUMO
In vertebrates, endothelial cells form 2 hierarchical tubular networks, the blood vessels and the lymphatic vessels. Despite the difference in their structure and function and genetic programs that dictate their morphogenesis, common signaling pathways have been recognized that regulate both vascular systems. ALK1 is a member of the transforming growth factor-beta type I family of receptors, and compelling genetic evidence suggests its essential role in regulating blood vascular development. Here we report that ALK1 signaling is intimately involved in lymphatic development. Lymphatic endothelial cells express key components of the ALK1 pathway and respond robustly to ALK1 ligand stimulation in vitro. Blockade of ALK1 signaling results in defective lymphatic development in multiple organs of neonatal mice. We find that ALK1 signaling regulates the differentiation of lymphatic endothelial cells to influence the lymphatic vascular development and remodeling. Furthermore, simultaneous inhibition of ALK1 pathway increases apoptosis in lymphatic vessels caused by blockade of VEGFR3 signaling. Thus, our study reveals a novel aspect of ALK1 signaling in regulating lymphatic development and suggests that targeting ALK1 pathway might provide additional control of lymphangiogenesis in human diseases.
Assuntos
Receptores de Activinas Tipo II/metabolismo , Receptores de Ativinas Tipo I/metabolismo , Diferenciação Celular/fisiologia , Células Endoteliais/metabolismo , Linfangiogênese/fisiologia , Vasos Linfáticos/metabolismo , Animais , Animais Recém-Nascidos , Apoptose/fisiologia , Células Cultivadas , Humanos , Ligantes , Camundongos , Transdução de Sinais , Receptor 3 de Fatores de Crescimento do Endotélio Vascular/antagonistas & inibidores , Receptor 3 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
PURPOSE: Although agents targeting Delta-like ligand 4 (DLL4) have shown great promise for angiogenesis-based cancer therapy, findings in recent studies have raised serious safety concerns. To further evaluate the potential for therapeutic targeting of the DLL4 pathway, we pursued a novel strategy to reduce toxicities related to DLL4 inhibition by modulating the pharmacokinetic (PK) properties of an anti-DLL4 antibody. EXPERIMENTAL DESIGN: The F(ab')2 fragment of anti-DLL4 antibody (anti-DLL4 F(ab')2) was generated and assessed in efficacy and toxicity studies. RESULTS: Anti-DLL4 F(ab')2 enables greater control over the extent and duration of DLL4 inhibition, such that intermittent dosing of anti-DLL4 F(ab')2 can maintain significant antitumor activity while markedly mitigating known toxicities associated with continuous pathway inhibition. CONCLUSIONS: PK modulation has potentially broad implications for development of antibody-based therapeutics. Our safety studies with anti-DLL4 F(ab')2 also provide new evidence reinforcing the notion that the DLL4 pathway is extremely sensitive to pharmacologic perturbation, further underscoring the importance of exercising caution to safely harness this potent pathway in humans.