Propranolol inhibits proliferation and induces apoptosis of hemangioma-derived endothelial cells via Akt pathway by down-regulating Ang-2 expression

Abstract

Hemangioma is one of the commonest benign vascular tumors among children. Propranolol is the first-line therapeutic drug for hemangioma. However, the effects and mechanisms of propranolol in hemangioma have not been thoroughly elaborated. In this study, the effects and mechanisms of propranolol were explored using hemangioma-derived endothelial cells (HemECs). The expression of GLUT1 were determined by immunofluorescence staining. qRT-PCR assay was conducted to detect the mRNA expressions of angiopoietin-2 (Ang-2) and Tie-2. Western blot assay was carried out to measure the protein levels of Ang-2, Tie-2, protein kinase-B (Akt) and phospholyrated-Akt (p-Akt). Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay and Western blot of Ki67 protein level. Cell apoptosis was measured by flow cytometry analysis and Western blot of Bax and Bcl-2 levels. We found that propranolol inhibited proliferation and induced apoptosis in human umbilical vein endothelial cells (HUVECs) and HemECs. Moreover, propranolol inhibited the expressions of Ang-2 and Tie-2 in HUVECs and HemECs. Functional analysis revealed that Ang-2 attenuated the effects of propranolol on HemEC proliferation and apoptosis. Mechanistical analysis showed that propranolol inhibited the Akt pathway by regulating Ang-2 expression in HemECs. Futhermore, inhibition of the Akt pathway attenuated the effects of Ang-2 on proliferation and apoptosis in HemECs. In conclusion, propranolol inhibited proliferation and induced apoptosis of HemECs via Akt pathway by down-regulating Ang-2 expression, which contributes to our understanding on the pathogenesis of hemangioma and promotes the development of therapeutic approaches for hemangioma.