Fig. 1.

RKD containing cyclic peptides derived from the AMOP domain of ISM trigger apoptosis but not necrosis of HUVECs in culture. (a) GR01 and GR16 and peptide analogues derived from them induce apoptosis in HUVECS. Cells were treated with 100 μM of GR01, GR16 and analogues for 24 h and apoptosis were determined with Cell Death Detection ELISA (Roche). GR16, BC66, BC70, BC71, BC72, BC74, BC75, BC81, BC83 and BC84 induced apoptosis with relative fold change over 1.4. (b, c) BC51, BC71 and BC84 reduced HUVEC viability at 24 h post-treatment. HUVECs were treated with 100 μM of for 24 h and 48 h treatment. MTT assay was used to determine the cell viability. Significant viability reduction is indicated by *. (d, e) No necrosis was induced by any peptide analogue. The necrotic effects of peptide analogues at 100 μM were determined at 24 h and 48 h post-treatment using the LDH secretion assay in HUVECs. For clarity of presentation, data were normalized with that of non-treated (VEGF only) cells, which was set as 1. Data are expressed as mean ± standard error of the mean. The results are representative of at least three independent experiments. Statistical significance was determined using ANOVA. *P < 0.05; **P < 0.01, n ≥ 3.