Effects of ionizing radiation in nonirradiated cells
- William F. Morgan*,† and
- Marianne B. Sowa‡
- *Radiation Oncology Research Laboratory and Marlene and Stewart Greenebaum Cancer Center, University of Maryland, BRB 7-011, Baltimore, MD 21201-1509; and‡Chemical Structure and Dynamics, Pacific Northwest National Laboratory, Richland, WA 99352
Implicit in understanding the biological effects of ionizing radiation and subsequent risks associated with such exposure is that only cells “hit” by the radiation are likely to carry the legacy of radiation damage. When a cell is hit, the deposition of energy can result in direct damage to the genetic material or indirect damage to critical nuclear targets through the radiolysis of water (Fig. 1). The subsequent action of DNA repair processes either removes the lesion(s) or misrepairs the induced damage such that all surviving progeny of an irradiated cell carry the burden of radiation exposure, e.g., a gene mutation and/or a chromosomal rearrangement (Fig. 1, diagram A). This central tenet in our understanding of the biological effects of ionizing radiation has now been called into question by the description of a number of nontargeted effects associated with radiation exposure. These effects can occur in the progeny of irradiated cells generations after the initial exposure, and/or in cells that were not directly traversed by ionizing radiation but were some distance from the hit cells (reviewed in refs. 1 and 2) (Fig. 1, diagram B).
Ionizing radiation induces direct DNA damage and indirect damage through the radiolysis of water. This damage is either eliminated or fixed in the cell as a mutation or chromosomal rearrangement by DNA repair processes. After release by cell cycle checkpoint control mechanisms, an irradiated surviving cell (blue) may …
