Effects of low priming dose of radiation on cell cycle arrest of tumor cells caused by high dose of radiation

Effects of low priming dose of radiation on cell cycle progression in hep G2 and HeLa cells have been investigated. For both,cell lines, cells in the G(2)/M phase are accumulated temporarily after 5cGy gamma-ray exposing, and the proliferation of tumor cells is significantly promoted by low dose radiation. When exposing to 3Gy gamma-ray, only the G(2) phase arrest occurred for hep G(2) cells, and both S and G(2) arrest occurred for HeLa cells. In contrast to treatment with high dose of radiation, when high dose was delivered 4hr after priming dose, pretreatment facilitates the accumulation of hep G2 cells in G(2)/M phase, however, pretreatment does not significantly change the cell cycle progression of HeLa cells. It is concluded that alterations of the cell cycle progression by pretreatment with low dose of radiation are dependent on the type of tumor cell lines.