Keywords: low–dose rate radiation, cell adhesion, adaptive response, HL60, MCF7, low radiation, gamma irradiation, ionising radiation, tumour growth
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.