Effect of ionizing radiation in combination with 5-flurouracil on cell cycle uncoupling of EL-4 cell line

Objective: To observe the dose-and time-effect of ionizing radiation in combination with 5-flurouracil(5-FU) on the cell cycle uncoupling of EL-4 cell line. Methods: EL-4 cells were collected after irradiation with 0,1.0,2.0 and 4.0 Gy X-irradiation and treatment with 5-FU(0.001,0.010,0.100 and 1.000 mg·L-1) for 0,4,8,16,24 and 48 h.The regularity in the polyloid cells was analyzed by flow cytometry(FCM) following staining cells with propidium iodide(PI). Results: As compared with sham-irradiation group,the percentage of diploid EL-4 cells increased significantly at 8-24 h and returned to normal level at 48 h after irradiation with 2.0 Gy X-rays(P< 0.05 or P< 0.01); the percentage of tetraploid cells began to decrease at 8 h and still to remain lower level at 48 h(P< 0.05 or P< 0.01); the percentage of octoploid cells decreased obviously at 16-24 h (P< 0.05).As compared with sham-irradiation group,the percentage of diploid EL-4 cells increased significantly 16 h after irradiation with 1.0-4.0 Gy X-rays (P< 0.05 or P< 0.01), while that of tetraploid cells decreased in a dose-dependent manner (P< 0.01), the percentage of octoploid cells had no marked changes. As compared with 0 mg·L-1 group, the percentage of diploid cells decreased obviously at 16-48 h after treatment with 0.100 mg·L-1 5-FU(P< 0.01); the percentage of tetraploid cells increased significantly at 8-24 h and returned to normal level at 48 h; the percentage of octoploid cells increased obviously at 4-16 h (P< 0.05). As compared with 0 mg·L-1 group, the percentage of diploid cells decreased significantly 16 h after treatment with different doses 5-FU(P< 0.05 or P< 0.01); while that of tetraploid cells increased significantly (P< 0.05 or P< 0.01), they displayed in a dose-dependent manner in 0.001-1.000 mg·L-1; the percentage of octoploid cells increased significantly after treatment with 0.010 and 0.100 mg·L-1 5-Fu(P< 0.01). Conclusion: The cell cycle uncoupling of EL-4 cell line couldn't be induced by 1.0-4.0 Gy X-rays, but could be induced by 0.010 and 0.100 mg·L-1 5-FU. (authors)