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通过对小鼠乳腺癌放射敏感细胞SX 9照射前、后细胞周期分布及其 p5 3基因状态等研究 ,初步探讨其放射敏感性与照射后细胞周期阻滞的关系。方法 利用克隆形成法比较SX 9与SR 1细胞照射后细胞存活份数及流式细胞术研究其细胞周期分布的差异 ;RT PCR克隆并鉴定p5 3基因 ;DNA电泳、流式细胞术和苔盼蓝染色研究细胞死亡方式。 结果 SX 9细胞对γ射线高度敏感 ,照射后G1 期阻滞消失 ,但仍存在G2 期阻滞 ;其 p5 3基因第 5外显子存在突变 ,DNA电泳检测不到DNAladder;苔盼蓝染色检测到的细胞死亡比例与对照组无显著差异。结论 γ射线照射放射敏感细胞SX 9细胞周期改变与其亲本细胞SR 1明显不同。SX 9亲本细胞SR 1细胞存在G1 ,G2 期阻滞。DNA电泳及苔盼蓝染色检测结果与SX 9细胞相同。结果表明SX 9细胞对放射敏感不是由于照射后细胞凋亡所致 ,而是由于其失去增殖能力引起增殖死亡的结果。
The relationship between radiosensitivity and cell cycle arrest after irradiation was investigated by studying the distribution of the cell cycle and the p53 gene status of mouse breast cancer radiosensitive cells SX9 before and after irradiation. Methods The number of cell survival after irradiation with SX 9 and SR 1 cells was compared by cloning method and the difference of cell cycle distribution was studied by flow cytometry. The p53 gene was cloned and identified by RT PCR; DNA electrophoresis, flow cytometry and lyp Blue staining was used to study cell death patterns. RESULTS: SX9 cells were highly sensitive to γ-rays and disappeared after G1 arrest, but G2 arrest was still present. There was a mutation in exon 5 of the p53 gene, and DNA ladder could not be detected by DNA electrophoresis; The proportion of cell deaths reached was not significantly different from the control group. Conclusion The change of cell cycle of SX 9 irradiated by γ-rays is obviously different from that of parental cell SR 1 . There was G1 in the SX9 parental cell SR1 cells and G2 arrest. The result of DNA electrophoresis and trypan blue staining was the same as that of SX 9 cells. The results showed that SX9 cells are not sensitive to radiation due to apoptosis after irradiation, but due to their loss of proliferation, resulting in proliferation and death.