Neuropilin-2 and vascular endothelial growth factor receptor-3 are up-regulated in human vascular malformations

Abstract

Despite multiple previous studies in the field of vascular anomalies, the mechanism(s) leading to their development, progression and maintenance has remained unclear. In this study, we have characterized the expression levels of vascular endothelial growth factors and their receptors in 33 human vascular anomalies. Analysis with quantitative real-time PCR and gene-specific assays showed higher expression of neuropilin-2 (NRP2) and VEGF-receptor-3 (VEGFR-3) mRNAs in vascular malformations (VascM) as compared to infantile hemangiomas (Hem). In addition, the expression levels of PlGF and VEGF-C mRNA were significantly higher in venous VascM when compared to the other VascM and Hem. Higher expression of NRP2 and VEGFR-3 were confirmed by immunohistochemistry. To further study the importance of NRP2 and VEGFR-3, endothelial cell (EC) cultures were established from vascular anomalies. It was found that NRP2 and VEGFR-3 mRNA levels were significantly higher in some of the VascM ECs as compared to human umbilical vein ECs which were used as control cells in the study. Furthermore, adenoviral delivery of soluble decoy NRP2 prevented the proliferation of ECs isolated from most of the vascular anomalies. Our findings suggest that NRP2 functions as a factor maintaining the pathological vascular network in these anomalies. Thus, NRP2 could become a potential therapeutic target for the diagnosis and treatment of vascular anomalies.

AKT hyper-phosphorylation associated with PI3K mutations in lymphatic endothelial cells from a patient with lymphatic malformation

“…In our study we show that LM-LEC overexpress NRP2 and VEGFR-3 and the VEGFR-3 ligands VEGF-C and VEGF-D. These findings suggest that LM-LECs have a pro-lymphangiogenic phenotype; similarly VEGFR-3/NRP2 overexpression has been described in a subset of vascular malformation ECs (39). VEGFR-3 signaling can activate the PI3K/AKT pathway (40) and this signaling cascade has been shown to be critical for lymphatic development in mice (41) and for LEC migration in vitro (42).…”

Rapamycin reversal of VEGF-C–driven lymphatic anomalies in the respiratory tract

“…VEGF-C is expressed in some human lymphatic anomalies (41,42), and VEGFR-3 and neuropilin-2 are overexpressed in endothelial cells of vascular malformations with lymphatic features (43). However, VEGF-C from epithelial cells may not mimic all consequences of mutations in AKT, PI3K, RAS, or other genetic defects associated with lymphatic malformations in humans (2).…”

Cellular and molecular mechanisms of PIK3CA-related vascular anomalies

“…Patient-derived lymphatic endothelial cells (LM-LEC) exhibit pro-angiogenic properties such as increased proliferation, sprout formation, and VEGF-C and VEGFR-3 overexpression. AKT that is downstream of PI3K is constitutively active in the mutant LM-LEC, while ERK1/2 phosphorylation levels are variable (17,19,20,22). A few animal models of LM have been reported and consist of xenografts generated by injection of LM-LEC (17) or LEC progenitor cells (23).…”