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Hypoxia triggers a proangiogenic pathway involving cancer cell microvesicles and PAR-2-mediated heparin-binding EGF signaling in endothelial cells.
Svensson, Katrin J; Kucharzewska, Paulina; Christianson, Helena C; Sköld, Stefan; Löfstedt, Tobias; Johansson, Maria C; Mörgelin, Matthias; Bengzon, Johan; Ruf, Wolfram; Belting, Mattias.
Afiliación
  • Svensson KJ; Department of Clinical Sciences, Section of Oncology, Lund University, SE-221 85 Lund, Sweden.
Proc Natl Acad Sci U S A ; 108(32): 13147-52, 2011 Aug 09.
Article en En | MEDLINE | ID: mdl-21788507
Highly malignant tumors, such as glioblastomas, are characterized by hypoxia, endothelial cell (EC) hyperplasia, and hypercoagulation. However, how these phenomena of the tumor microenvironment may be linked at the molecular level during tumor development remains ill-defined. Here, we provide evidence that hypoxia up-regulates protease-activated receptor 2 (PAR-2), i.e., a G-protein-coupled receptor of coagulation-dependent signaling, in ECs. Hypoxic induction of PAR-2 was found to elicit an angiogenic EC phenotype and to specifically up-regulate heparin-binding EGF-like growth factor (HB-EGF). Inhibition of HB-EGF by antibody neutralization or heparin treatment efficiently counteracted PAR-2-mediated activation of hypoxic ECs. We show that PAR-2-dependent HB-EGF induction was associated with increased phosphorylation of ERK1/2, and inhibition of ERK1/2 phosphorylation attenuated PAR-2-dependent HB-EGF induction as well as EC activation. Tissue factor (TF), i.e., the major initiator of coagulation-dependent PAR signaling, was substantially induced by hypoxia in several types of cancer cells, including glioblastoma; however, TF was undetectable in ECs even at prolonged hypoxia, which precludes cell-autonomous PAR-2 activation through TF. Interestingly, hypoxic cancer cells were shown to release substantial amounts of TF that was mainly associated with secreted microvesicles with exosome-like characteristics. Vesicles derived from glioblastoma cells were found to trigger TF/VIIa-dependent activation of hypoxic ECs in a paracrine manner. We provide evidence of a hypoxia-induced signaling axis that links coagulation activation in cancer cells to PAR-2-mediated activation of ECs. The identified pathway may constitute an interesting target for the development of additional strategies to treat aggressive brain tumors.
Asunto(s)

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Transducción de Señal / Péptidos y Proteínas de Señalización Intercelular / Células Endoteliales / Receptor PAR-2 / Exosomas / Neovascularización Patológica Tipo de estudio: Prognostic_studies Límite: Humans Idioma: En Revista: Proc Natl Acad Sci U S A Año: 2011 Tipo del documento: Article País de afiliación: Suecia Pais de publicación: Estados Unidos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Transducción de Señal / Péptidos y Proteínas de Señalización Intercelular / Células Endoteliales / Receptor PAR-2 / Exosomas / Neovascularización Patológica Tipo de estudio: Prognostic_studies Límite: Humans Idioma: En Revista: Proc Natl Acad Sci U S A Año: 2011 Tipo del documento: Article País de afiliación: Suecia Pais de publicación: Estados Unidos