@article{oai:repo.qst.go.jp:00043915,
 author = {Hama-Inaba, Hiroko and Bing, Wang and Mori, Masahiko and Matsushima, Tadashi and Saito, Toshiyuki and Takusagawa, Mitsuko and Yamada, Takeshi and Muto, Masahiro and Ohyama, Harumi and 稲葉 浩子 and 王 冰 and 森 雅彦 and 齋藤 俊行 and 田草川 光子 and 武藤 正弘 and 大山 ハルミ},
 journal = {Fundamental and Molecular Mechanisms of Mutagenesis : A Section of Mutation Research},
 month = {Jul},
 note = {3SB, a mouse thymoma cell line, is one of the most radio-sensitive cells (D0 = 0.3 Gy), and its rapid apoptosis (4 h after 5 Gy irradiation, 90% apoptosis) seems to play a decisive role in enhancing the radiosensitivity. To understand the molecular mechanisms underlying extremely high radiosensitivity and rapid apoptosis, we attempted to isolate X-ray-resistant (XR) variants from 3SBH5, a stable subclone of 3SB, by repeating exposure of the cells to 2-5 Gy X-rays. Four independent stable XR variants, R111, R223, R316 and R429, were isolated by the repeated irradiation protocols. All XR cells possessed about 3 times higher D10 values than that of their parental 3SBH5. They were also resistant to apoptosis; only 10% cells underwent apoptosis 4 h after 5 Gy irradiation. The p53 protein was induced in all the cell lines after 5 Gy X-irradiation. These variants showed a cross resistance to a chemical reagent daunorubicin (DNR) that is known to be involved in the ceramide-mediated apoptosis. DNR, as well as C2-ceramide (5 muM) induced apoptosis in parental 3SBH5 cell, but not in two XR variants, R233 and R316 cells. Present result suggests that the induction of X-ray resistance by repeated X-irradiation might be achieved, at least partly, by the enhanced resistance to the ceramide-mediated apoptosis.},
 pages = {85--94},
 title = {Radio-sensitive murine thymoma cell line 3SB: characterization of its apoptosis-resistant variants induced by repeated X-irradiation.},
 volume = {403},
 year = {1998}
}