Truly Incomplete and Complex Exchanges in Prematurely Condensed Chromosomes of Human Fibroblasts Exposed In Vitro to Energetic Heavy Ions

• Published in: Radiation research 2003-10, Vol.160 (4), p.418-424
• Main Authors: Wu, Honglu, Durante, Marco, Furusawa, Yoshiya, George, Kerry, Kawata, Tetsuya, Cucinotta, Francis A.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cell Cycle - drug effects; Cell Cycle - radiation effects; Cell Line; Chromosome aberrations; Chromosome Aberrations - statistics & numerical data; Chromosomes; Chromosomes, Human - drug effects; Chromosomes, Human - radiation effects; Chromosomes, Human - ultrastructure; Dose-Response Relationship, Radiation; Fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - radiation effects; Gamma Rays; Gene Frequency - drug effects; Gene Frequency - radiation effects; Heavy Ions; Humans; In Situ Hybridization, Fluorescence - methods; Interphase; Ions; Iron; Life Sciences (General); Linear Energy Transfer; Lymphocytes; Medical sciences; Oxazoles - pharmacology; Radiation damage; Radiation dosage; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); REGULAR ARTICLES; Silicon; Technology. Biomaterials. Equipments. Material. Instrumentation; Telomeres
• ISSN: 0033-7587; 1938-5404
• DOI: 10.1667/RR3061

Wu, H., Durante, M., Furusawa, Y., George, K., Kawata, T. and Cucinotta, F. A. Truly Incomplete and Complex Exchanges in Prematurely Condensed Chromosomes of Human Fibroblasts Exposed In Vitro to Energetic Heavy Ions. Radiat. Res. 160, 418–424 (2003). Confluent human fibroblast cells (AG1522) were irradiated with γ rays, 490 MeV/nucleon silicon ions, or iron ions at either 200 or 500 MeV/nucleon. The cells were allowed to repair at 37°C for 24 h after exposure, and a chemically induced premature chromosome condensation (PCC) technique was used to condense chromosomes in the G2 phase of the cell cycle. Incomplete and complex exchanges were analyzed in the irradiated samples. To verify that chromosomal breaks were truly unrejoined, chromosome aberrations were analyzed using a combination of whole-chromosome specific probes and probes specific for the telomere region of the chromosome. Results showed that the frequency of unrejoined chromosome breaks was higher after irradiation with the heavy ions of high LET, and consequently the ratio of incomplete to complete exchanges increased steadily with LET up to 440 keV/μm, the highest LET included in the present study. For samples exposed to 200 MeV/nucleon iron ions, chromosome aberrations were analyzed using the multicolor FISH (mFISH) technique, which allows identification of both complex and truly incomplete exchanges. Results of the mFISH study showed that 0.7 and 3 Gy iron ions produced similar ratios of complex to simple exchanges and incomplete to complete exchanges; these ratios were higher than those obtained after exposure to 6 Gy γ rays. After 0.7 Gy of iron ions, most complex aberrations were found to involve three or four chromosomes, which is a likely indication of the maximum number of chromosome domains traversed by a single iron-ion track.