Effect of low doses of radiation 169Yb- on proliferation and cell death in human cells in culture

Abstract

In this work we study the effect of sources of 169Yb- on the proliferation, progression of the cell cycle, apoptotic death and the level of chromosome aberrations in carcinoma (HeLa G63) and endothelial (ECV304) human cells in culture. It has been shown that exposure of cells by 169 Yb- with doses 0.33—1.2 Gy leads to cell blocking in G2/M phases of the cell cycle. We found that the blocking the progression of cells is dose dependent and become irreversible, resulting in repopulation changes. The169Yb radiation also inhibited the growth of cells in a dose dependent manner. We found that the level of the chromosome aberrations induced in HeLa G63cells by the ytterbium exposure of 1.1 Gy was close to the same level induced by X-rays exposure of 1 Gy. Morphological analysis of the cells identified of apoptotic form of cellular death, not only and not so much in irradiated cells, as their descendants. In the latter case we also recorded an abnormal mitosis, a damage of the mitotic apparatus of cell division. Necrotic form of cellular death was registered only after prolonged exposure of ytterbium irradiation. Observation of the irradiation effects for several cellular generations indicates that low doses of radiation induce systemic change of cellular metabolism, which was accompanied by activation of mechanism of «check-point» control and apoptosis. The observed manifestation of the damaging effect late after the irradiation by ytterbium sources may significantly contribute to the total effect of treatment, which is important in clinical practice.