The RBE of 3.4 MeV α-particles and 0.565 MeV neutrons relative to 60Co γ-rays for neoplastic transformation of human hybrid cells and the impact of culture conditions

• Published in: Radiation protection dosimetry 2010-01, Vol.138 (1), p.29-39
• Main Authors: Frankenberg-Schwager, M., Spieren, S., Pralle, E., Giesen, U., Brede, H. J., Thiemig, M., Frankenberg, D.
• Format: Article
• Language: English
• Subjects: Cell Culture Techniques - methods; Cell Transformation, Neoplastic - pathology; Cell Transformation, Neoplastic - radiation effects; Cobalt Radioisotopes; Dose-Response Relationship, Radiation; Gamma Rays; HeLa Cells; Humans; Hybrid Cells - pathology; Hybrid Cells - radiation effects; Neutrons; Radiation Dosage; Relative Biological Effectiveness
• ISSN: 0144-8420; 1742-3406
• DOI: 10.1093/rpd/ncp201

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 (γ-rays, MeV electrons or photons) are in good agreement, whereas for higher doses larger variations are reported. The 60Co γ-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 α-particles (LET = 124 keV/μm) and 0.565 MeV monoenergetic neutrons relative to low doses of 60Co γ-rays, a maximum relative biological effectiveness (RBEM) of 2.8 ± 0.2 and 1.5 ± 0.2, respectively, was calculated. Surprisingly, at higher doses of 60Co γ-rays lower frequencies of neoplastic transformation were observed. This non-monotonic dose relationship for neoplastic transformation by 60Co γ-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.