title: The RBE of 3.4 MeV alpha-particles and 0.565 MeV neutrons relative to 60Co gamma-rays for neoplastic transformation of human hybrid cells and the impact of culture conditions.
abstract: The neoplastic transformation of human hybrid CGL1 cells is affected by perturbations from external influences such as serum batch and concentration, the number of medium changes during the 21-day expression period and cell seeding density. Nevertheless, for doses up to 1.5 Gy, published transformation frequencies for low linear energy transfer (LET) radiations (gamma-rays, MeV electrons or photons) are in good agreement, whereas for higher doses larger variations are reported. The (60)Co gamma-ray data here for doses up to 1.5 Gy, using a low-yield serum batch and only one medium change, are in agreement with published frequencies of neoplastic transformation of human hybrid cells. For 3.4 MeV alpha-particles (LET = 124 keV/mum) and 0.565 MeV monoenergetic neutrons relative to low doses of (60)Co gamma-rays, a maximum relative biological effectiveness (RBE(M)) of 2.8 +/- 0.2 and 1.5 +/- 0.2, respectively, was calculated. Surprisingly, at higher doses of (60)Co gamma-rays lower frequencies of neoplastic transformation were observed. This non-monotonic dose relationship for neoplastic transformation by (60)Co gamma-rays is likely due to the lack of a G2/M arrest observed at low doses resulting in higher transformation frequencies per dose, whereas the lower frequencies per dose observed for higher doses are likely related to the induction of a G2/M arrest.
authors.affiliation: Abteilung Nuklearmedizin im Zentrum Radiologie, Universität Göttingen, Von-Siebold-Str. 3, 37075 Göttingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Frankenberg-Schwager
authors.forename: S
authors.initials: S
authors.lastname: Spieren
authors.forename: E
authors.initials: E
authors.lastname: Pralle
authors.forename: U
authors.initials: U
authors.lastname: Giesen
authors.forename: H J
authors.initials: HJ
authors.lastname: Brede
authors.forename: M
authors.initials: M
authors.lastname: Thiemig
authors.forename: D
authors.initials: D
authors.lastname: Frankenberg
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods*; D002471:Cell Transformation, Neoplastic / Q000473:pathology* / Q000528:radiation effects*; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D006367:HeLa Cells; D006801:Humans; D006822:Hybrid Cells / Q000473:pathology* / Q000528:radiation effects*; D009502:Neutrons; D011829:Radiation Dosage; D012062:Relative Biological Effectiveness
chemical_list: D003037:Cobalt Radioisotopes