Mechanisms of VEGF Availability in Prostate Cancer
Abstract
Vascular endothelial growth factor (VEGF) is one of the most relevant mediators of capillary recruitment and stimulator of tumor-angiogenesis. Substantial evidence implicates VEGF in the vascularization of tumors, including those related to the prostate gland. Once synthesized and secreted by the normal prostate epithelium, VEGF is frequently bound to extracellular matrix molecules, remaining inaccessible to its receptors present on endothelial cells. Subsequent release of VEGF from extracellular sources is thought to require break-down of matrix proteins by matrix metalloproteinases(MMPs). However, its exact regulation is unknown. We previously found that MMP-3 cleaves VEGF165(^22kDa) directly, releasing two major VE6F165 cleavage products, ^l6kDa and ^6kDa. Here we report that, by western analysis with epitope-specific antibodies, Edman sequencing and MALDI/MS analysis for both fragments to determine the cleavage sites in VEGF, MMP-3 cleaves VEGF165, separating the c-terminal heparin binding domain from the rest of VEGF165 molecule that contains the receptor binding region. The ^l6kDa fragment is functionally active as it phosphorylates VEGFR-2 in porcine aortic endothelial cells at a level comparable by conditioned media from uncleaved VEGF165-expressing cells. The data imply that VEGF may be processed extracellulary releasing bioactive fragments and that this proteolysis might offer an important mode for regulation on VEGF bioavailability.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2003
- Accession Number
- ADA414812
Entities
People
- Arnaud Monvoisin
Organizations
- University of California, Los Angeles