Proliferation and cell death of human glioblastoma cells after carbon-ion beam exposure; Morphologic and morphometric analyses

Oishi, Takuma*; Sasaki, Atsushi*; Hamada, Nobuyuki*; Ishiuchi, Shogo*; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko; Nakano, Takashi*; Nakazato, Yoichi*

Using CGNH-89 cells exposed to 0-10 Gy of X-ray (140 kVp) or carbon-ions (18.3 MeV/nucleon, LET = 108 keV/m), we performed conventional histology and immunocytochemistry with MIB-1 antibody, transmission electron microscopy, and computer-assisted, nuclear size measurements. After carbon-ion and X-ray exposure, living cells showed decreased cell number, nuclear condensation, increased atypical mitotic figures, and a tendency of cytoplasmic enlargement at the level of light microscopy. The deviation of the nuclear area size increased during 48 hours after irradiation, while the small cell fraction increased in 336 hours. In glioblastoma cells of the control, 5 Gy carbon-beam, and 10 Gy carbon-beam, and MIB-1 labeling index decreased in 24 hours but increased in 48 hours. Ultrastructurally, cellular enlargement seemed to depend on vacuolation, swelling of mitochondria, and increase of cellular organelles, such as the cytoskeleton and secondary lysosome. We could not observe apoptotic bodies in the CGNH-89 cells under any conditions. We conclude that carbon-ion irradiation induced cell death and senescence in a glioblastoma cell line with mutant TP53. Our results indicated that the increase of large cells with enlarged and bizarre nuclei, swollen mitochondria, and secondary lysosome occurred in glioblastoma cells after carbon-beam exposure.