@article{oai:repo.qst.go.jp:00049575,
 author = {Oonishi, Kazuhiko and Cui, Xing and Hirakawa, Hirokazu and Fujimori, Akira and Kamijo, Takehiko and Yamada, Shigeru and Yokosuka, Osamu and Kamada, Tadashi and Tsujii, Hirohiko and Sai, Sei and Hirakawa, Hirokazu and Fujimori, Akira and Kamijo, Takehiko and Yamada, Shigeru and Yokosuka, Osamu and Kamada, Tadashi},
 issue = {2},
 journal = {Radiotherapy and Oncology},
 month = {Sep},
 note = {Purpose: The effects of a carbon ion beam and X-rays on human pancreatic cancer stem-like cells were examined from the point of view of clonogenic survival and DNA repair.
Materials and methods: Human pancreatic cancer stem-like cells were treated with and without carbon ion and X-ray irradiation, and then colony, spheroid and tumor formation assays as well as rH2AX foci formation assay were performed.

Results: The relative biological effectiveness (RBE) values of a carbon ion beam relative to X-ray for the MIA PaCa-2 and BxPc-3 cells at the D10 values were 1.85–2.10. The ability for colony, spheroid formation, and tumorigenicity from cancer stem-like CD44+/CD24+ cells is significantly higher than that from noncancer stem-like CD44-/CD24-cells. FACS data showed that CD44+/CD24+ cells were more highly enriched after X-rays compared to carbon ion irradiation at isoeffective doses. 
The RBE values for the carbon ion beam relative to X-ray at the D10 levels for CD44+/CD24+ cells were 2.0–2.19.The number of rH2AX foci in CD44-/CD24-cells was higher than that of CD44+/CD24+ cells after irradiation with either X-ray or carbon ion beam. The number of rH2AX foci in CD44+/CD24+ cells was almost the same in the early time, but it persists significantly longer in carbon ion beam irradiated cells compared to X-rays.
Conclusions: Carbon ion beam has superior potential to kill pancreatic cancer stem cell-like cells, and prolonged induction of DNA damage might be one of the pivotal mechanisms of its high radiobiological effects compared to X-rays.},
 pages = {258--265},
 title = {Different effects of carbon ion beams and  X-rays on clonogenic survival and DNA Repair in human pancreatic cancer stem-like cells},
 volume = {105},
 year = {2012}
}