The radiation bystander effect and its potential implications for human health.

TitleThe radiation bystander effect and its potential implications for human health.
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2012
AuthorsMancuso, Mariateresa, Pasquali Emanuela, Giardullo Paola, Leonardi Simona, Tanori Mirella, Di Majo V, Pazzaglia Simonetta, and Saran Anna
JournalCurr Mol Med
Date Published2012 Jun
KeywordsAnimals, Bystander Effect, cell communication, DNA damage, Humans, Neoplasms, Radiation, Ionizing

A long-held dogma in radiation biology has been that the biological effects of exposure to ionizing radiation occur as a result of damage in directly irradiated cells and that no effect would occur in neighboring unirradiated cells. This paradigm has been frequently challenged by reports of radiation effects in unirradiated or 'bystander' cells receiving signals from directly irradiated cells, an issue that may have substantial impact on radiation risk assessment and development of radiation-based therapies. Radiation-induced bystander effects have been shown in single-cell systems in vitro for an array of cancer relevant endpoints, and may trigger damage in more complex 3-D tissue systems. They may be mediated by soluble factors released by irradiated cells into the extracellular environment and/or by the passage of mediator molecules through gap-junction intercellular communication. To date, evidence that radiation-associated bystander or abscopal responses are effectual in vivo has been limited, but new data suggest that they may significantly affect tumor development in susceptible mouse models. Further understanding of how the signal/s is transmitted to unirradiated cells and tissues and how it provokes long-range and significant responses is crucial. By summarizing the existing evidence of radiation induced bystander-like effects in various systems with emphasis on in vivo findings, we will discuss the potential mechanisms involved in these observations and how effects in bystander cells contribute to uncertainties in assessing cancer risks associated with radiation exposure.

Alternate JournalCurr. Mol. Med.
PubMed ID22452594