NDRG1 and FOXO1 regulate endothelial cell proliferation in infantile haemangioma

The etiopathogenesis of infantile haemangioma has not been well understood, and it is accepted that angiogenic mediator dysregulation is the main contributor to the abnormal haemangioma capillary formation. The role of NDRG1, a hypoxia-inducible protein; FOXOs, which are tumor suppressor proteins; and the mTOR complex 2 pathway in infantile haemangioma have not been studied yet. The purpose of this study was to investigate NDRG1 and FOXO1 expression in the infantile haemangioma and the correlation of these proteins with proliferation and involution. Primary endothelial cells were obtained, with parental agreement, from 12 infantile haemangioma patients during surgery; 6 patients had proliferating infantile haemangiomas and 6 had involuting IHs. We compared the infantile haemangioma tissues and primary endothelial cells with human vein endothelial cells using microarrays, real-time PCR, Western blotting and immunohistochemical staining. Our data indicated that FOXO1 expression was downregulated in proliferating infantile haemangioma tissue. We found that the expression of NDRG1, a molecule upstream of the FOXO1 pathway, increased during haemangioma proliferation. NDRG1 knockdown decreased haemangioma endothelial cell proliferation and downregulated c-MYC oncoprotein levels. Our findings suggest that NDRG1 positively regulates haemangioma proliferation. FOXO1 dysregulation plays an important role in infantile haemangiomas pathogenesis.