Decreased secretion of vascular endothelial growth factor is associated with increased apoptosis in vascular tumor derived endothelial cells

Abstract

Bleomycin is an antineoplastic drug that has recently been employed to treat haemangiomas, the most common vascular tumors of infancy, with very good results. To better understand the mechanism of bleomycin in accelerating haemangioma regression, we have investigated the effects of the drug on vascular tumor inducing endothelial cells (sEnd.2 cells). Cell growth studies were undertaken using crystal violet staining, while morphological studies were undertaken employing transmission electron microscopy. The cells were analyzed for possible apoptosis employing flow cytometry. The expression of Bcl-2 and p53 were investigated using Western blot analysis. In addition, the production of vascular endothelial growth factor was measured using ELISA. Results showed that bleomycin inhibited the growth of these endothelial cells, even in the presence of vascular endothelial growth factor, a proangiogenic growth factor. Further, there was increased endothelial cell apoptosis, as evidenced by morphological analysis, increased acridine orange staining of cell nuclei and annexin V staining. Apoptosis was associated with an increase in the expression of p53 and a decrease in the expression of the antiapoptotic protein Bcl-2.