不同剂量X射线对同步化HeLaS3细胞周期的影响

目的　研究不同剂量Ｘ射线对同步化ＨｅＬａＳ３ 细胞周期的影响，为进一步探讨其分子调控机理和临床肿瘤放疗提供基础资料。方法　采用胸苷（ＴｄＲ） 双阻断法和流式细胞术（ＦＣＭ） 检测了ＨｅＬａＳ３ 细胞同步化后分别于其细胞周期各时相进行７５ ｍ Ｇｙ 和２－０ Ｇｙ Ｘ 射线照射以及于Ｇ２＋ Ｍ 期进行０－０２５～２－０ Ｇｙ 照射后其细胞周期进程的变化。结果　２－０ Ｇｙ 照射时细胞无论处于Ｇ０／Ｇ１ 、Ｓ期还是Ｇ２ ＋ Ｍ 期，从释放点后９～１５ 小时内均发生明显的Ｓ期延迟和Ｇ２ 阻滞，但其中以Ｇ２ 期照射者阻滞最显著；于Ｇ０／Ｇ１ 和Ｇ２ ＋ Ｍ 期进行７５ ｍ Ｇｙ 照射，分别在９ 和１２ ｈ 时发生一过性的明显的Ｇ２ 阻滞，至１１ 和１５ｈ 时完全从这一阻滞中脱离，甚至促进了其细胞周期的进程；而在Ｓ期进行７５ ｍ Ｇｙ 照射时，并没有发生这种阻滞，反而加速了其细胞周期由Ｇ２ ＋ Ｍ→Ｇ０／Ｇ１ 的移行，其中尤以９ｈ 时最为显著。剂量效应关系研究表明，于Ｇ２ ＋ Ｍ 期进行０－０２５ ～２－０ Ｇｙ 照射后，在释放点后１１ ｈ 时均发生Ｇ０／Ｇ１ 期细胞数减少，Ｇ２ 阻滞，且有剂量依赖性，而Ｓ期细胞数的变化在０－０２５ ～０－１ Ｇｙ 和０－５ ～２－０ Ｇｙ

Changes in cell cycle progression of HeLaS3cells synchronized after X-ray irradiation

Objective\ To observe the effect of different doses of X rays on cell cycle progression of synchronized HeLaS 3 cells. Methods Using a double block method with thymidine and flow cytometric analysis,the changes in cell cycle progression of synchronized HeLaS 3 cells were examined after 75 mGy and 2.0 Gy X irradiation in G 0/G 1,S and G 2 M phases respectively,and the dose response relationship given in G 2/M phase was analyzed after irradiation. Results The S and G 2 phases occurred late 9 15h after the releasing point regardless of whether HeLaS 3 cells were irradiated with 2 Gy in G 0/G 1,S or G 2 M phases.HeLaS 3 cells underwent a G 2 arrest 9 and 12h after the releasing point when 75 mGy irradiation was administered in G 0/G 1 and G 2 M phases,and this delay skipped completely at 12 and 15h,respectively.Moreover,the cell cycle progression was accelerated. However,there was no G 2 delay at 9 and 11h when the cells were irradiated with 75 mGy in S phase,and in this case the cell cycle progression from G 2/M to G 0/G 1 phase was accelerated.A study on the dose effect relationship showed that the number of G 0/G 1 phase cells decreased,and G 2 delayed after 0 025-2 0 Gy irradiation given in G 2/M phase,and the delay was dose dependent.However,the changes in the number of S phase cells were different between low (0 025-0 1 Gy) and higher(0 5-2 0 Gy) doses. Conclusion G 2 delay is a very radiosensitive parameter,which occurs in HeLaS 3 cells after X ray irradiation with a dose as low as 25 mGy when administered in G 0/G 1 and G 2 M phases,but this delay only occurs with doses above 0.1 Gy when the cells are irradiated in S phase.