G1 arrest and apoptosis of Bgc-823 cell lines with different p3 status after irradiation

Objective: To assess the role of the p53 tumor suppressor gene (wild-type p53) in G1 arrest and apoptosis after irradiation in human gastric carcinoma 823 cell lines (BGC823). Methods: Three human gastric carcinoma 823 cell lines with different p53 status, i.e. BGC823-wtp53 cells with wild-type p53, BGC823-mutp53 cell with mutant p53 alleles and BGC823-vect without p53 gene, were used. Various cell phase distribution and apoptosis were analyzed by flow cytometry in 0.8 and 24 h following irradiation with 4 Gy. Results: The BGC823-wtp53 cells had strong arrest in G1 phase at 8 and 24 h following radiation with 4 Gy (67.9% and 61.1% of original population, respectively), while the BGC823-mutp53 and BGC823-vect cells had almost no arrest in G1 phase at 8 and 24 h following radiation with 4 Gy. In the BGC823-wtp53 cells, a sub-G1 phase peak of apoptosis could be observed at 8 and 24 h after irradiation with 4 Gy, apoptotic cell rates being 13.0% and 15.3%, respectively, while the BGC823-mutp53 and BGC823-vect cells had no apoptotic response after irradiation with 4 Gy. Conclusion: Wild-type p53 genes promote G1 phase arrest and apoptosis of tumor cells following irradiation, while those with mutant or vect p53 genes abrogate this response to irradiation