A chronic very low dose of gamma-rays alters cell adhesion

The biological effects of very low doses of ionising radiation are difficult to assess. We previously observed a delay of death by lymphoma in two different mouse strains continuously irradiated ( γ -rays) with a dose rate of 10 cGy year −1 . Cellular mechanisms likely to lead to slowing tumour growth were explored. Human lymphoid and epithelial cell lines (HL60 and MCF7) were irradiated in vitro at very low dose rate of 4 cGy month −1 . Proliferation was not modified in HL60 and MCF7 cells. However, irradiated MCF7 adherent cells showed a lower cell attachment to support partly related to a slight decrease in expression levels of α6 and β4 integrins. We also observed a transient adaptive response during at least two weeks after the beginning of the irradiation in both cell lines. These results demonstrate the ability of tiny amounts of gamma-irradiation to alter cell attachment to support and to induce an adaptive response.