Mechanism of the HIF‐1α/VEGF/VEGFR‐2 pathway in the proliferation and apoptosis of human haemangioma endothelial cells

Abstract Haemangiomas (HAs) are prevalent vascular endothelial cell tumours. With respect to the possible involvement of HIF‐1α in HAs, we have explored its role in haemangioma endothelial cell (HemEC) proliferation and apoptosis. shRNA HIF‐1α and pcDNA3.1 HIF‐α were manipulated into HemECs. HIF‐α, VEGF, and VEGFR‐2 mRNA and protein levels were assessed by qRT‐PCR and Western blotting. Cell proliferation and viability, cell cycle and apoptosis, migration and invasion, and ability to form tubular structures were assessed by colony formation assay, CCK‐8, flow cytometry, Transwell assay, and tube formation assay. Cell cycle‐related protein levels, and VEGF and VEGFR‐2 protein interaction were detected by Western blot and immunoprecipitation assays. An Haemangioma nude mouse model was established by subcutaneous injection of HemECs. Ki67 expression was determined by immunohistochemical staining. HIF‐1α silencing suppressed HemEC neoplastic behaviour and promoted apoptosis. HIF‐1α facilitated VEGF/VEGFR‐2 expression and the VEGF had interacted with VEGFR‐2 at protein ‐ protein level. HIF‐1α silencing arrested HemECs at G0/G1 phase, diminished Cyclin D1 protein level, and elevated p53 protein level. VEGF overexpression partially abrogated the effects of HIF‐1α knockdown on inhibiting HemEC malignant behaviours. Inhibiting HIF‐1α in nude mice with HAs repressed tumour growth and Ki67‐positive cells. Briefly, HIF‐1α regulated HemEC cell cycle through VEGF/VEGFR‐2, thus promoting cell proliferation and inhibiting apoptosis.