Platelet-derived VEGF, Flt-1, angiopoietin-1 and P-selectin in breast and prostate cancer: further evidence for a role of platelets in tumour angiogenesis

BACKGROUND: Cancer is a complex multi-factorial disorder that may commonly show abnormal angiogenesis in such patients. Recently, platelets have been postulated to have a major role in both these processes, suggesting that antiplatelet strategies may be useful in cancer treatment. MATERIALS AND METHODS: To further investigate the role of platelets in angiogenesis, we used a novel platelet lysate assay to analyse platelet contents in breast cancer (n = 30) and prostate cancer (n = 30) patients and age- and sex-matched controls (n = 60). Markers of angiogenesis (vascular endothelial growth factor (VEGF), angiopoietin-1 and-2 (Ang-1, -2), and their respective receptors (Flt-1 and Tie-2) plus a marker of platelet activation (P-selectin (P-sel)), were all measured in platelet lysate by enzyme-linked immunsorbent assay. RESULTS: Platelet lysate from breast cancer patients contained higher levels of VEGF (P < 0.0001). Ang-1 (P = 0.0186) and P-sel (P = 0.0002), compared to healthy controls. Platelet lysate from prostate cancer patients had elevated VEGF (P = 0.008) but not Ang-1 or P-sel. There were no significant differences between levels of Flt-1 between patients and controls, and both Ang-2 and Tie-2 were undetectable in both patient groups and control platelet lysate. CONCLUSION: We have shown that our previously developed platelet lysate technique could be used to measure indices of angiogenesis, and their respective receptors, and that this assay can be applied to patients with cancer. Our study also provides further evidence that platelets may influence angiogenic abnormalities in human cancer. The platelet may be a useful target in anti-cancer strategies.