title: Epigenetic and genetic factors in the cellular response to radiations and DNA-damaging chemicals.
abstract: DNA-damaging agents are widely used as therapeutic tools for a variety of disease states. Many such agents are considered to produce detrimental side effects. Thus, it is important to evaluate both therapeutic efficacy and potential risk. DNA-damaging agents can be so evaluated by comparison to agents whose therapeutic benefit and potential hazards are better known. We propose a framework for such comparison, demonstrating that a simple transformation of cytotoxicity-dose response patterns permits a facile comparison of variation between cells exposed to a single DNA-damaging agent or to different cytotoxic agents. Further, by transforming data from experiments which compare responses of 2 cell populations to an effects ratio, different patterns for the changes in cytotoxicity produced by epigenetic and genetic factors were compared. Using these transformations, we found that there is a wide variation (a factor of 4) between laboratories for a single agent (UVC) and only a slightly larger variation (factor of 6) between normal cell response for different types of DNA-damaging agents (x-ray, UVC, alkylating agents, crosslinking agents). Epigenetic factors such as repair and recovery appear to be a factor only at higher dose levels. Comparison in the cytotoxic effect of a spectrum of DNA-damaging agents in xeroderma pigmentosum, ataxia telangiectasia, and Fanconi's anemia cells indicates significantly different patterns, implying that the effect, and perhaps the nature, of these genetic conditions are quite different.
mesh_terms: D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects*; D003603:Cytotoxins; D004247:DNA / Q000235:genetics / Q000528:radiation effects*; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans
chemical_list: D003603:Cytotoxins; D004247:DNA