Chloroquine induces apoptosis in cultured glioma cells. (A and B) Time-dependent activation of caspase-3 by chloroquine in U87MG cells. Untreated or chloroquine-treated cells were stained for the cleaved form of caspase-3 and counterstained by DAPI. The inset in (A) shows the characteristic nuclear morphology of chloroquine-treated cells. (C) Summary of the caspase-3 activation assessment in glioma cells lines with different status of p53. The percentage of cells positive for cleaved caspase-3 was determined by counting a minimum of 500 cells in 5–10 microscopic fields in replicates of 3 for each condition. (D) Assessment of apoptosis in U87MG cells by TUNEL. A propidium iodide (PI) counterstain was used. (E) The effects of chloroquine on the mitochondrial membrane potential integrity assessed by measurements of the mitochondrial accumulation of fluorescent JC-1 in glioma cells with wtp53 (U87MG) or mutp53 (G112). The ratio of red/green JC-1 fluorescence was determined in cells untreated or treated with chloroquine for 24 or 48 hours.