p21在大肠肿瘤细胞凋亡中的作用

目的 探讨细胞内基本p21水平和被应急反应诱导的p21,在大肠肿瘤细胞DLD1对化学治疗、放射治疗和基因治疗所诱发的细胞凋亡中的作用和机制。方法 建立受IPTG控制表达p21大肠肿瘤细胞系DLD1－p21,用阿霉素、X射线和暂时性转染p53基因的方法处理表达和不表达p21的两种DLD1细胞,观察其细胞形态、DNA片段化和测定细胞的生存率;并用放射性同位素标记进入S期细胞来显示细胞周期和凋亡间的关系。结果 （1）p21不仅能以p53依赖性方式产生,而且还能以p53非依赖性方式产生。（2）细胞内基本的p21在抗细胞凋亡中发挥着主要作用,而相反,应急产生的p21几乎不在抗细胞凋亡中发挥作用。凋亡细胞数分别为9％对55％、12％对65％和7％对59％。结论 在抗细胞凋亡作用中,基本的p21比应急产生的p21起着更为重要作用。

The role of p21 (wafl/cip1) in human colorectal carcinoma cell apoptosis

OBJECTIVE: To investigate the role of basal expression p21 and stress-stimulated p21 in preventing apoptosis of human colorectal carcinoma cells DLD1 after treatment of adriamycin, roentgenotherapy and gene therapy of p53. METHODS: A human colorectal carcinoma cell line DLD1 whose p21 expression can be controlled by isopropyl-beta-D-thiogalactoside (IPTG) was established. The morphology, DNA fragmentation and survival rates of two kinds of DLD1 cells expressing or not expressing p21 were observed after treatment with adriamycin, X-ray and transient transfection of p53. The cells in S stage were incubated with [3H] thymidine so as to examine the relationship between apoptosis and cell cycle. RESULTS: (1) p21 may be one of the most important stress-stimulated proteins in the cells, which can be induced by the p53-dependent pathway and the p53-independent pathway as well. (2) Basal expression of p21 plays an important antiapoptosis role in carcinoma cells after stress-treatment. In contrast, stress-stimulated p21 plays a minor role in preventing apoptosis. CONCLUSION: Basal expression of p21 plays a more important antiapoptosis role than stress-stimulated p21 in carcinoma cells. Apoptosis;