Chromosomal instability induced by heavy ion irradiation.
OBJECTIVE
To establish the dose-response relationship for the induction of chromosomal instability in GM10115 cells exposed to high-energy iron ions (1 GeV/nucleon, mean LET 146 keV/microm) and gold ions (11 GeV/nucleon, mean LET 1450 keV/microm). Past work has established that sparsely ionizing X-rays can induce a long-lived destabilization of chromosomes in a dose-dependent manner at an incidence of approximately 3% per gray. The present investigation assesses the capacity of High-Z and High-energy (HZE) particles to elicit this same endpoint.


METHODS
Clonal populations derived from single progenitor cells surviving heavy-ion irradiation were analyzed cytogenetically to identify those clones showing a persistent destablization of chromosomes.


RESULTS
Dose-response data, with a particular emphasis at low dose (< 1.0 Gy), indicate a frequency of approximately 4% per gray for the induction of chromosomal instability in clones derived from single progenitor cells surviving exposure to iron ions. The induction of chromosomal instability by gold ions was, however, less responsive to applied dose, as the observed incidence of this phenotype varied from 0 to 10% over 1-8 Gy. Both iron and gold ions gave dose-dependent increases in the yield of chromosomal aberrations (both chromosome- and chromatid-type) measured at the first mitosis following irradiation, as well as shoulderless survival curves having D0=0.87 and 1.1 Gy respectively.


CONCLUSIONS
Based on the present dose-response data, the relative biological effectiveness of iron ions is 1.3 for the induction of chromosomal instability, and this indicates that heavy ions are only slightly more efficient than X-rays at eliciting this delayed phenotype.
Limoli
C L
CL
Department of Radiology, University of California, San Francisco 94103-0806, USA. Limoli@itsa.ucsf.edu
Ponnaiya
B
B
Corcoran
J J
JJ
Giedzinski
E
E
Morgan
W F
WF
D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000528:radiation effects*; D006224:Cricetinae; D003582:Cytogenetics; D004307:Dose-Response Relationship, Radiation; D006049:Gold Isotopes / Q000009:adverse effects; D020450:Heavy Ions; D017404:In Situ Hybridization, Fluorescence; D007503:Iron Isotopes / Q000009:adverse effects; D008677:Metaphase; D010641:Phenotype; D014965:X-Rays
D006049:Gold Isotopes; D007503:Iron Isotopes