Binding region and interaction properties of sulfoquinovosylacylglycerol (SQAG) with human vascular endothelial growth factor 165 revealed by biosensor-based assays

Abstract

Sulfoquinovosylacylglycerol (SQAG) is a sulfoglycolipid showing anti-angiogenic and radiosensitizing effects for treatment of solid tumors both in vitro and in vivo. Here we elucidated the interaction of SQAG with various growth factors and their cognate receptors for vascular formation using biosensor-based assays. The structure–binding relationship was also determined. Our results show that βSQDG selectively recognizes heparin binding domain (HBD) in human vascular endothelial growth factor 165 (hVEGF₁₆₅) with an affinity in the order of 10⁻¹¹ M. The presence of both a sulfate moiety and at least one C₁₈ length fatty acid chain is essential for binding. Conversion of anomeric configurations in SQAG did not alter the affinity with hVEGF₁₆₅. This SQAG association inhibited T7 phage-displayed HBD binding to neuropilin-1 (NRP1), a VEGF receptor on the endothelial cell surface of blood vessels that specifically recognizes HBD in hVEGF₁₆₅.