p53在调控DNA损伤所致MDA-MB-231细胞死亡中的作用及其机制

目的：研究p53在调控DNA损伤所致乳腺癌MDA-MB-231细胞死亡中发挥的作用及其相关机制。方法：采用5 J/m²短波紫外线UVC体外照射MDA-MB-231细胞建立DNA损伤模型，通过Western blot检测磷酸化H2AX以鉴定DNA损伤程度，并采用Westernblot检测细胞死亡相关蛋白p21、PARP、磷酸化p53和p53，以及核因子NF-90表达的变化。结果：与对照组比较，5 J/m² UVC处理细胞0.5 h后即检测到明显的H2AX磷酸化（P < 0.05），表明成功建立了DNA损伤模型；同时，p21发生降解并持续保持低表达状态，p53开始发生磷酸化（p-p53增加，P < 0.05），处理8 h后观察到PARP的剪切增加（P < 0.05），而p53和NF-90蛋白表达未发现明显改变。结论：MDA-MB-231细胞通过p21-PARP途径发生死亡，而磷酸化p53的增加则可以促进细胞存活，从而抑制DNA损伤引起的细胞死亡。

Involvement of p53 in regulation of DNA damage-induced cell death in MDA-MB-231

OBJECTIVE:To investigate protective effect against cell death in DNA damage-induced breast 2 cancer cell line MDA-MB-231. METHODS:MDA-MB-231 cells were irradiated with 5 J/m² UVC and were used to establish our DNA damage cell model. Western blot was used to detect DNA damage marker phospho-H2AX;cell death related proteins:p53, p21, and PARP; and nuclear factor NF-90 which regulates p53 and p21 expression. 2 RESULTS:At 0.5 h after 5 J/m² UVC irradiation of MDA-MB-231 cells,phospho-H2AX expression was induced (P < 0.05),p21 was degraded (P < 0.05),and phosphor-p53 (p-p53) was induced (P < 0.05). At 8 hours after irradiation, PARP was cleaved (P < 0.05). There were not any significant changes on p53 and NF-90. CONCLUSION:From our cell model of DNA damage in MDA-MB-231 cell line,p21-PARP pathway was involved in induction of cell death,but phosphor-p53 was resistant. These imply that phosphor-p53 showed a protective role on this model.