Harming Bystanders

Abstract

Irradiation of cells is known to cause damage to neighboring cells that are not directly exposed to the radiation. Such bystander responses are important when considering the potential damage caused by environmental exposure to radiation or to radiation used in cancer treatment. Although it is known that cells whose nuclei are exposed to radiation can trigger the bystander response, Shao et al. show that even radiation delivered to the cytoplasm of a single cell suffices. The bystander response was measured by the increase of micronuclei (a measure of chromosomal damage) in the cell population when single human glioblastoma T98G cells were exposed to single 3He2+ ions. The bystander response was blocked by the addition of a nitric oxide (NO) scavenger to the medium, and disruption of glycosphingolipid-enriched membrane microdomains (GEMs) with filipin also blocked the bystander response, suggesting that NO, produced through a process that requires GEMs, appears to mediate a signal that leads to chromosomal damage in neighboring cells. — NG