LMO2 promotes angiogenesis probably by up-regulation of bFGF in endothelial cells: an implication of its pathophysiological role in infantile haemangioma

Aims: Infantile haemangiomas (IHs) are common benign vascular tumours distinctive for their perinatal presentation, rapid growth during the first year of life and subsequent slow involution. Recent research has indicated that endothelial cells of haemangiomas express LIM-only protein 2 (LMO2). The aim of this study was to investigate the role of LMO2 in the pathogenesis of IHs was investigated. Methods and results: Immunoreactivity of LMO2 was assessed in specimens of 19 IH. Stable transfection of LMO2 into human endothelial cell lines (EAhy926) was performed to evaluate the role of LMO2 in terms of the change in cell proliferation, cell cycle and cell migration as well as the expression level of angiogenic factors. Immunoreactivity for LMO2 was detected in all IH specimens, specifically in the nucleus of the endothelial cells. The intensity of LMO2 immunostaining decreased significantly from proliferative to involuting stages. Furthermore, the overexpression of LMO2 enhanced the proliferation and migration of the endothelial cells and promoted G0/G1-S-phase transition in vitro, together with an up-regulation of bFGF expression. Conclusions: LMO2 probably promotes angiogenesis by up-regulation of bFGF expression and thereby consequently influences progression of IH.