The Bystander Effect

Monday, October 17, 2005 10:15 AM-12:00 PM Room No. 702
Chair(s): Hall, Eric

(SY029) The role of intercellular communication and oxidative metabolism in the propagation of low-level radiation effects.

Azzam, Edouard*,1, Little, John2, 1 Department of Radiology/Division of Radiation Research, Newark, NJ, USA2 Center for Radiation Sciences and Environmental Health, Boston, MA, USA

ABSTRACT- Evidence accumulated over the past two decades has indicated that exposure of cell populations to ionizing radiation results in significant biological effects occurring in both irradiated and non-irradiated cells in the population. This phenomenon, termed the "bystander response", has been shown to occur both in vitro and in vivo. Genetic alterations, changes in gene expression and lethality have been shown to occur in bystander cells that neighbor directly irradiated cells. The amplification of stress by the bystander effect has been postulated to impact cancer risk induction by ionizing radiation. To elucidate the mechanisms underlying bystander effects, we have been characterizing molecular/biochemical steps related to intercellular communication and oxidative metabolism that have been shown to mediate expression of these effects. Recent data that describe i) the role of gap-junctions that permit intercellular communication of molecules with specific characteristics in the propagation or mitigation of damaging effects; ii) persistent perturbations in oxidative metabolism and modulation of mitochondrial function in bystander cells and their progeny; iii) the effect of radiation dose on the capacity of exposed cells to release factors that induce stressful effects in bystander cells will be discussed. (Supported by Research Grant 1R01CA92262-01A1 from the NIH and FG02-98ER62685 from the US Department of Energy)

Key words: Bystander effect, Gap-junctions, Oxidative metabolism, secreted diffusible factors

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2005 RRS