The effects of YKL-40 on angiogenic potential of HUVECs are partly mediated by syndecan-4

ObjectiveYKL-40, a secreted glycoprotein, has a role in promoting tumor angiogenesis through syndecan-1 receptor. As one of the members of syndecans family, syndecan-4 is also an important mediator for tube formation. However, the effects of YKL-40 on migration and tube formation of human umbilical vein cells (HUVECs) mediated by syndecan-4 receptor are unknown. MethodsHUVECs were transfected with lentivirus encoding syndecan-4 short hairpin (sh) RNA (lenti-synd4 shRNA) and the efficiency of transfection was measured using reverse transcription quantitative real time polymerase chain reaction (qRT-PCR) and flow cytometry. The effects of recombinant protein of YKL-40 on migration and angiogenesis of HUVECs adjusted by syndecan-4 were determined by wound healing and tube formation assay. The expression of protein kinase C (PKC) and extracellular signal regulated kinases (ERKs) 1 and 2 (ERK1/2) in HUVECs was measured using western blotting. ResultsTransfection of lenti-synd4 shRNA significantly decreased the membrane protein expression of syndecan-4 in HUVECs. HUVECs transfected with lenti-synd4 shRNA remarkably inhibited the migration and tube formation of endothelial cells stimulated by recombinant protein of YKL-40. The levels of PKC and ratio of p-ERK1/2 to ERK1/2 in HUVECs were also down-regulated by silencing syndecan-4. ConclusionThe effects of YKL-40-induced on migration and tube formation of HUVECs may partly be inhibited by knock-downing syndecan-4 through suppressing PKC and ERK1/2 signaling pathways.