FIGURE 6.

Squalamine suppresses the toxicity associated with Aβ₄₂ oligomeric species to neuroblastoma cells. (A) Aβ-derived diffusible ligands (ADDLs) of Aβ₄₂ (denoted Aβ₄₂ oligomers) were resuspended in cell culture medium at a concentration of 1 μM (in monomer equivalents) and incubated with or without increasing concentrations (0.1, 0.33, 1, 3, and 10 μM) of SQ (red bars) for 1 h at 37°C and then added to the cell culture medium of SH-SY5Y cells for 24 h. The cells were also treated with the same concentrations of SQ pre-incubated in the absence of oligomers for 1 h at 37°C (white bars). (B) Representative confocal scanning microscopy images of the apical planes of cells treated for 15 min with Aβ₄₂ oligomers (1 μM in monomer equivalents) in the absence or presence of 10 μM SQ. Red and green fluorescence indicates the cell membranes and the Aβ₄₂ oligomers, respectively. Scale bar = 10 μm. (C) The histogram shows the percentage of colocalization on regions of interest (12–22 cells). In all panels, data represent mean ± s.e.m. of three independent experiments, the symbols ** and *** indicate p < 0.01 and 0.001, respectively, relative to untreated cells, and the symbol °°° indicates p < 0.001 relative to cells treated with oligomers. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) data were analyzed by one-way ANOVA followed by Bonferroni’s post comparison test. Cell binding data were analyzed using an unpaired, two-tailed Student’s t-test.