Novel complex of copper and a salicylaldehyde pyrazole hydrazone derivative induces apoptosis through up-regulating integrin beta 4 in vascular endothelial cells.

To determine apoptosis modulators of human umbilical vein endothelial cells (HUVECs), we prepared 9 novel complexes of copper (Cu) and salicylaldehyde pyrazole hydrazone (SPH) derivatives (Cu-SPHs). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay revealed that all of the SPHs and Cu-SPHs effectively inhibited cell growth. Six of the 9 Cu-SPHs induced apoptosis in HUVECs. Among the 9 Cu-SPHs, the complex of Cu and (E)-N'-(2-hydroxybenzylidene)-1-benzyl-3-phenyl-1H-pyrazole-5-carbohydrazide, named Cu-15, was one of the most effective apoptosis inducers and inhibited angiogenesis on Matrigel and HUVEC migration in vitro. We further studied the mechanism of Cu-15 action and found that the protein level of integrin beta 4 increased with 10 microM Cu-15 treatment for 12 or 24 h. Knockdown of integrin beta 4 by RNA interference significantly inhibited apoptosis induced by Cu-15 in HUVECs. Thus, high level of integrin beta 4 could promote apoptosis induced by Cu-15. Cu-15 might be a useful tool for further investigating the functions of integrin beta 4 in regulating angiogenesis and HUVEC apoptosis.