Evaluation of cell survival and micronucleus formation in clamped and non-clamped solid tumors exposed to carbon-ion beams in comparison to X-rays

Autor: Hirayama, Ryoichi, Uzawa, Akiko, Takase, Nobuhiro, Koda, Kana, Matsumoto, Yoshitaka, Ozaki, Masakuni, Noguchi, Miho, Kase, Yuki, Matsufuji, Naruhiro, Koike, Sachiko, Masunaga, Shinichiro, Ando, Koichi, Okayasu, Ryuichi, Furusawa, Yoshiya
Jazyk: angličtina
Rok vydání: 2012
Popis: The aim of this study was to clarify the RBE (relative biological effectiveness) and OER (oxygen enhancement ratio) for cell killing and micronucleus formation in clamped and non-clamped transplanted solid tumors in mice leg after 290 MeV/n carbon-ion beams and X-rays. Furthermore, single-cell suspensions were prepared by tumors and were used directly to determine the radiation response of oxic cells. Squamous cell carcinoma (SCC VII) cells were transplanted into the right hind legs of syngeneic C3H male mice. Irradiation with either carbon-ion beams with a 6-cm spread-out Bragg peak (46 and 80 keV/µm) or X-rays was delivered to 5-mm diameter tumors. Single-cell suspensions were prepared from excised and trypsinized tumors, and were used for in vivo-in vitro colony formation assay to obtain cell-survival curves. Moreover, a large portion of single-cell suspensions were incubated with cytochalasin-B to examine the dose-response curves for micronucleus (MN) formation. The RBE and OER for cell survival were evaluated by D10 values (the dose required to reduce surviving fraction down to 10%), and the RBE and OER for MN formation were evaluated by D0 values (the dose corresponding to 37% retained binucleated cell without micronuclei. The RBEs for survival and MN formation increased with increasing LET. These maximum values were 1.7-2.4 at an LET of 80 keV/µm. The OERs for in vivo (clamped tumor / non-clamped tumor) were smaller than that for in vitro (clamped tumor / single-cell suspension) in both endpoints, and the dependence of OERs for in vivo toward LET was small in comparison to the OERs for in vitro.
The 10th International Symposium on Chromosomal Aberrations
Databáze: OpenAIRE
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