摘要
Objective： The aim of the study was to investigate the impact of 60Co y-ray on apoptosis, cell cycles and the expression of protein hypoxia-inducible factor-1α （HIF-1α） to Hep-2 cell line in the conditions of normoxia and hypoxia. Methods： Hep-2 cell were divided into 2 groups： group A （normoxia） and group B （hypoxia）. All of the ceils were exposed to y-ray with dosage being 0, 1, 3, 5, 10, 20, and 40 Gy. Flow cytometry was used to measure the protein level of HIF-1α and to detect apoptosis and cell cycles. The protein level of HIF-1α was also determined by immunohistochemistry and Western blotting. Results： The protein level of HIF-1α in group B was significantly higher than that in group A. In group A, low doses （1-5 Gy） of y-ray had caused G0/G1 cell cycle arrest and high doses （10-40 Gy） had caused G2/M cell cycle arrest. In group B, without exposure of y-ray （0 Gy） had caused G0/G1 cell cycle arrest, all of the different dosage of y-ray could cause G2/M cell cycle arrest. The curve of apoptosis rate in group A was a parabola, the apoptotic rate was related to the dosage of y-ray in a dosage dependent manner. The peak was at the point of 5 Gy. The apoptosis rate in group A was significantly higher than that in group B. Conclusion： Different doses of y-ray could cause different cell cycles arrest then make different impact on apoptosis to Hep-2 ceil. The lower apoptosis rate in condition of hypoxia maybe has a relationship with G2/M cell cycle arrest. Up-regulated HIF-1α protein may be one of the reasons for G2/M cell cycle arrest.
