MULTIMERIN2 binds VEGF-A primarily via the carbohydrate chains exerting an angiostatic function and impairing tumor growth

Abstract

Angiogenesis is a key process occurring under both physiological and pathological conditions and is a hallmark of cancer. We have recently demonstrated that the extracellular matrix (ECM) molecule MULTIMERIN2 exerts an angiostatic function through the binding to VEGF-A. In this study we identify the region of the molecule responsible for the binding and demonstrate that the interaction involves the carbohydrate chains. MULTIMERIN2 interacts with other VEGF-A isoforms and VEGF family members such as VEGF-B, -C, -D and PlGF-1 suggesting that the molecule may function as a reservoir for different cytokines. In response to VEGF-A165, we show that MULTIMERIN2 impairs the phosphorylation of VEGFR2 at both Y1175 and Y1214 residues, halts SAPK2/p38 activation and negatively affects endothelial cell motility. In addition, MULTIMERIN2 and its active deletion mutant decrease the availability of the VEGFR2 receptor at the EC plasma membrane. The ectopic expression of MULTIMERIN2 or its active deletion mutant led to a striking reduction of tumor-associated angiogenesis and tumor growth. In conclusion, these data pinpoint MULTIMERIN2 as a key angiostatic molecule and disclose the possibility to develop new prognostic tools and improve the management of cancer patients.

Extracellular Matrix, a Hard Player in Angiogenesis

“…This depends on its ability to sequester VEGF-A and inhibit VEGFR-2 activation [224,225]. The binding capability has been pinpointed in a region towards the N-terminus of the molecule [225].…”

“…This depends on its ability to sequester VEGF-A and inhibit VEGFR-2 activation [224,225]. The binding capability has been pinpointed in a region towards the N-terminus of the molecule [225]. The VEGF-binding activity primarily occurs through the carbohydrate chains, since their removal significantly compromises, the binding [225].…”

“…The binding capability has been pinpointed in a region towards the N-terminus of the molecule [225]. The VEGF-binding activity primarily occurs through the carbohydrate chains, since their removal significantly compromises, the binding [225]. In addition, the molecule seems also to affect the redistribution of VEGFR2 receptor at the EC surface and to be the reservoir of different members of the VEGF family of cytokines including VEGF-C, VEGF-D and Placental Growth Factor (PlGF) [225].…”

“…The VEGF-binding activity primarily occurs through the carbohydrate chains, since their removal significantly compromises, the binding [225]. In addition, the molecule seems also to affect the redistribution of VEGFR2 receptor at the EC surface and to be the reservoir of different members of the VEGF family of cytokines including VEGF-C, VEGF-D and Placental Growth Factor (PlGF) [225]. When over-expressed in the tumor microenvironment the molecule and its active fragment display a potent anti-tumoral effect [224,225].…”

Carbohydrate-binding protein CLEC14A regulates VEGFR-2– and VEGFR-3–dependent signals during angiogenesis and lymphangiogenesis

“…Previously, we found that CLEC14A is upregulated during the morphogenesis of endothelial progenitor cells into endothelial cells (ECs) (14). Recently, SILAC-based (stable isotope labeling with amino acids in cell culture-based) proteomics revealed that CLEC14A expression is enhanced in ECs during tubule morphogenesis and regulates cell-extracellular matrix adhesion to multimerin 2 (MMRN2), a suppressor of VEGF/VEGFR signaling during angiogenesis (15). Moreover, CLEC14A expression was significantly higher in the blood vessels of the tumor than in those of adjacent normal tissue (16), along with robust detection in tumor ECs and Controlled angiogenesis and lymphangiogenesis are essential for tissue development, function, and repair.…”