The radiation-induced bystander effect (bystander effect) is the phenomenon in which unirradiated cells exhibit irradiated effects as a result of signals received from nearby irradiated cells. In November 1992, Hatsumi Nagasawa and John B. Little first reported this radiobiological phenomenon.[1]
There is evidence that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells.[2][3] Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population.[4][5] Similarly, when cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation.[6][7] This is also attributed to the bystander effect.
Demonstration
The demonstration of a bystander effect in 3D human tissues[8] and, more recently, in whole organisms[9] have clear implication of the potential relevance of the non-targeted response to human health.
Consequences
This effect may also contribute to the final biological consequences of exposure to low doses of radiation.[10][11] However, there is currently insufficient evidence to suggest that the bystander effect promotes carcinogenesis in humans at low doses.[12]
Notes
Note that the bystander effect is not the same as the abscopal effect. The abscopal effect is a phenomenon where the response to radiation is seen in an organ/site distant to the irradiated organ/area, that is, the responding cells are not juxtaposed with the irradiated cells. T-cells and dendritic cells have been implicated to be part of the mechanism.[13]
In suicide gene therapy, the "bystander effect" is the ability of the transfected cells to transfer death signals to neighboring tumor cells.[14]
References
↑ Nagasawa, H; Little, J. B. (1992). "Induction of sister chromatid exchanges by extremely low doses of alpha-particles". Cancer Research. 52 (22): 6394–6. PMID1423287.
↑ Prise KM, Belyakov OV, Folkard M, Michael BD (December 1998). "Studies of bystander effects in human fibroblasts using a charged particle microbeam". International Journal of Radiation Biology. 74 (6): 793–8. doi:10.1080/095530098141087. PMID9881726.
↑ Wideł M, Przybyszewski W, Rzeszowska-Wolny J (2009). "[Radiation-induced bystander effect: the important part of ionizing radiation response. Potential clinical implications]". Postepy Higieny i Medycyny Doswiadczalnej. 63: 377–88. PMID19724078.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.