Cell cycle alteration and cell growth inhibition induced by 60 Co γ-irradiation in HepG 2 cell line

Objective To study the cell cycle alterations in cells of human liver cancer cell line HepG_2 in vitro after 60 Co γ-irradiation, in order to investigate further the role of p27 kip1 protein on cell cycle and proliferation. Methods The effect on proliferation of HepG_2 cell line by irradiation with 1.0-6.0 Gy γ-rays was evaluated with MTT assay. The cell cycle profile and apoptosis were analyzed by FACS,and the expression and subcellular localization of p27 kip1 in the cells were detected by laser confocal microscopy. Results 60 Co γ-irradiation inhibited the growth of HepG_2 cell line in a dose-dependent manner. The HepG_2 cell line cells were arrested in G_2/M 48 hours after 3.0 Gy γ-ray exposure. The expression of p27 kip1 was down-regulated as compared to HepG_2 cell line cells without γ- radiation exposure,Furthermore the p27 kip1 was redistributed to cytoplasm after γ-irradiation. Conclusion The low expression and cytoplasmic localization of p27 kip1 might be due to the G_2/M phase arrest induced by gamma- irradiation of HepG_2 cell line cells.