Angiogenesis, the growth of new blood vessels from pre-existing vasculature, is a key process in several pathological conditions, including tumour growth and age-related macular degeneration. Vascular endothelial growth factors (VEGFs) stimulate angiogenesis and lymphangiogenesis by activating VEGF receptor (VEGFR) tyrosine kinases in endothelial cells. VEGFR-3 (also known as FLT-4) is present in all endothelia during development, and in the adult it becomes restricted to the lymphatic endothelium. However, VEGFR-3 is upregulated in the microvasculature of tumours and wounds. Here we demonstrate that VEGFR-3 is highly expressed in angiogenic sprouts, and genetic targeting of VEGFR-3 or blocking of VEGFR-3 signalling with monoclonal antibodies results in decreased sprouting, vascular density, vessel branching and endothelial cell proliferation in mouse angiogenesis models. Stimulation of VEGFR-3 augmented VEGF-induced angiogenesis and sustained angiogenesis even in the presence of VEGFR-2 (also known as KDR or FLK-1) inhibitors, whereas antibodies against VEGFR-3 and VEGFR-2 in combination resulted in additive inhibition of angiogenesis and tumour growth. Furthermore, genetic or pharmacological disruption of the Notch signalling pathway led to widespread endothelial VEGFR-3 expression and excessive sprouting, which was inhibited by blocking VEGFR-3 signals. Our results implicate VEGFR-3 as a regulator of vascular network formation. Targeting VEGFR-3 may provide additional efficacy for anti-angiogenic therapies, especially towards vessels that are resistant to VEGF or VEGFR-2 inhibitors.

CRP alone is a strong prognostic factor, following curative resection of colorectal liver metastases and should be taken into consideration when selecting treatment strategies in CRLM patients. J. Surg. Oncol. 2016;114:895-899. © 2016 2016 Wiley Periodicals, Inc.

<b><i>Introduction:</i></b> The liver metastases of colorectal cancer (CRC) can be surgically treated in selected cases, with continuously improving results. Matrix metalloproteinases (MMPs) contribute to cancer invasion by degrading the extracellular matrix, and elevated levels of MMP-2, MMP-8, and MMP-9 have been detected in several malignancies. Myeloperoxidase (MPO) is a mediator of tissue damage that can oxidatively activate latent MMPs. We evaluated the prognostic value of MMP-2, MMP-8, and MMP-9 in tissue samples of primary tumors and liver metastases and the pre- and postoperative serum levels of MMP-8, MMP-9, and MPO in CRC patients undergoing liver resection. <b><i>Methods:</i></b> Tissue and serum samples were obtained from 111 patients who had primary colorectal tumors and their liver metastases surgically treated at the Helsinki University Hospital between 1988 and 2007. Tissue expression of MMP-2, MMP-8, and MMP-9 in primary tumors and liver metastases was evaluated by immunohistochemistry. Pre- and postoperative serum concentrations of MMP-8, MMP-9, and MPO were determined using a time-resolved immunofluorometric assay or commercially available enzyme-linked immunosorbent assay kits. Clinical data were retrieved from patient records and the Central Statistical Office of Finland. Associations with disease-free survival (DFS) and overall survival (OS) were estimated using Cox regression analysis and the Kaplan-Meier method. <b><i>Results:</i></b> High expression of MMP-9 in colorectal tumor tissue was associated with better DFS (<i>p</i> = 0.010), and high preoperative MPO in serum with improved DFS and OS (<i>p</i> &#x3c; 0.001 and <i>p</i> = 0.014, respectively). The prognostic significance varied according to gender, age, and the synchronicity of liver metastases. <b><i>Conclusion:</i></b> Low preoperative MPO in serum might identify patients at high risk of recurrence and death after resection of colorectal liver metastases. Elevated preoperative MPO and high expression of MMP-9 in colorectal tumor tissue indicate an improved prognosis. The use of these biomarkers should be adjusted according to clinical characteristics.