Potent inhibition of angiogenesis by D,L-peptides derived from vascular endothelial growth factor receptor 2.

Vascular endothelial growth factor (VEGF) is a potent mitogen for endothelial cells and plays a central role in angiogenesis and vasculogenesis. Therefore, VEGF and its receptors VEGFR-1 and VEGFR-2 are prime targets for anti-angiogenic intervention which is thought to be one of the most promising approaches in cancer therapy. Recently, we have discovered a VEGFR-2-derived peptide ((247)RTELNVGIDFNWEYP(261)) representing a potential binding site to VEGF. Using the spot synthesis technique, systematic D-amino acid substitutional analyses of this peptide were conducted and the resulting D,L-peptides inhibit VEGF binding to VEGFR-2 at half maximal concentration of 30 nM. The serum-stable D,L-peptides further inhibited autophosphorylation of the VEGFR-2 at nanomolar concentrations. Testing of the peptides in a spheroid-based angiogenesis assay demonstrated a potent anti-angiogenic effect in vitro. The rational design of potent and stable anti-angiogenic peptide inhibitors from their parent receptors provides a feasible route to develop novel leads for anti-angiogenic medicines

Vascular endothelial growth factor-D induces lymphangiogenesis and lymphatic metastasis in models of ductal pancreatic cancer.

The presence of lymphatic metastases is a strong indicator for poor prognosis in patients with ductal pancreatic cancer. In order to better understand the mechanisms controlling lymphatic growth and lymph node metastasis in human ductal pancreatic cancer, we analyzed the expression pattern of the vascular endothelial growth factor-D (VEGF-D), its receptor VEGF-receptor-3 (VEGFR-3) and the lymphatic endothelium-specific hyaluronan receptor LYVE-1 in a panel of 19 primary human ductal pancreatic tumors and 10 normal pancreas specimens. We further addressed the biological function of VEGF-D for induction of lymphatic metastasis in a nude mouse xenograft model using two human ductal pancreatic cancer cell lines with overexpression of VEGF-D. Compared to normal human pancreas, pancreatic cancer tissue showed overexpression of VEGF-D and VEGFR-3 in conjunction with a high lymphatic vascularization as determined by immunohistochemistry and in situ hybridization. Tumors derived from VEGF-D-overexpressing cells had a higher microvessel density compared to their mock-controls, as determined based on CD31 immunohistochemistry. Importantly, these tumors also revealed a significant induction of intra- and peritumoral lymphatics, as judged from immunohistochemical detection of LYVE-1 expression. This was associated with a significant increase in lymphatic vessel invasion by tumor cells and an increased rate of lymphatic metastases, as indicated by pan-cytokeratin reactive cells in lymph nodes. Our results suggest that VEGF-D plays a pivotal role in stimulating lymphangiogenesis and lymphatic metastasis in human ductal pancreatic cancer, and therefore represents a novel therapeutic target for this devastating disease