Fig. 2.
Induction of apoptotic chromatin condensation in neuronal PC12 cells by camptothecin. PC12 cells were neuronally differentiated by treatment with serum-free RPMI 1640 medium containing NGF (100 ng/ml) for 10 d. Cells were then cultured with serum-free RPMI medium containing NGF in the presence or absence of 10 μm camptothecin for 72 hr, with or without flavopiridol (0.5 μm) or olomoucine (200 μm), then fixed and stained with DAPI to visualize nuclear chromatin. Images were captured under differential interference contrast (A,C, E, G, I,K) or fluorescence (B,D, F, H, J,L) optics. Condition depicted are no additives (A, B), camptothecin alone (C, D), camptothecin and flavopiridol (E, F), camptothecin and olomoucine (G, H), flavopiridol alone (I, J), and olomoucine alone (K, L). Camptothecin produced a significant degree of cell death, characterized by blebbing (C, arrow) and apoptotic chromatin condensation (D, arrow), which could be inhibited by both flavopiridol (E,F) and olomoucine (G,H). However, both flavopiridol and olomoucine, in combination with camptothecin or alone, were able to induce partial changes in chromatin structure (H,arrowhead). Scale bar (shown in L), 20 μm.