Figure 3.

Nuclear DNA fragments and FACS analysis in proton beam-irradiated cancer cells. (A) Representative pictures at 24 h showed an apoptotic morphology in LLC and HepG2 cells irradiated with proton beam (100 Gy) (each upper pictures). At 24 h after the irradiation, LLC and HepG2 cells were observed for DAPI stained nucleus (each lower pictures) with microscope (× 200). Arrows indicate fragmented and condensed DNA in the nucleus. Boxes in the corner show large magnification of representative nucleus (× 400). (B) DNA fragmentation assay was performed at 24 h after irradiated with proton beam in HepG2 (proton beam sensitive) and Molt-4 (proton beam insensitive) cells. DNA fragments were clearly visible in 2% agarose gel and showed apoptotic cell death induced by proton beam. (C) At 24 h after irradiated with proton beam (100 Gy), LLC cells were fixed with ethanol and stained with FITC-Annexin V to detect cell death phenomena. Y axis shows PI labeled population and X axis shows FITC-labeled Annexin-V positive cells. Proton beam increased early apoptosis as well as late apoptosis and necrotic phase.