摘要
目的:检测辐射诱发的胸腺瘤组织中第10染色体PTEN的表达,观察外源PTEN基因导入辐射诱发小鼠胸腺瘤细胞体外增殖能力及体内成瘤作用的影响,探讨PTEN与辐射诱发肿瘤的可能作用机制。方法:采用SP免疫组织化学法和Western印迹比较辐射诱发的小鼠胸腺瘤组织和正常小鼠胸腺组织中PTEN、γ-H2AX和Rad51蛋白的表达。RT-PCR技术检测胸腺瘤组织和正常胸腺组织中PTEN基因的缺失情况。利用基因转染技术将外源性PTEN转入小鼠胸腺瘤细胞中,观察其对小鼠胸腺瘤组织细胞体外增殖能力和体内成瘤作用的影响。结果:辐射诱发的小鼠胸腺瘤组织中PTEN蛋白表达阳性率为22.73%(5/22),显著低于正常胸腺瘤组织的阳性率(P<0.01);Western印迹结果显示胸腺瘤组织中PTEN表达水平明显低于正常组织(P<0.01);RT-PCR检测发现在肿瘤组织中存在高频率PTEN缺失。外源性PTEN表达后胸腺瘤细胞生长速度显著降低,而且细胞致瘤能力明显下降(P<0.01)。辐射诱发的胸腺瘤细胞γ-H2AX水平明显高于正常组织,而Rad51蛋白水平明显低于正常组织(P<0.01)。结论:PTEN表达缺失可能通过影响Rad51途径的DNA断裂修复通路,导致辐射诱发胸腺瘤的发生;外源PTEN的导入可以抑制胸腺瘤细胞的体外增殖能力及体内成瘤作用,有望成为辐射诱发肿瘤防治的新靶点。
Objective： To investigate the expression of tumor suppressor gene PTEN in the radiation-induced mouse thymoma cells,and to observe the inhibitory effect of exogenous PTEN transfection on the in vitro proliferation and in vivo tumor forming ability of radiation-induced thymoma. Methods： Immunohistochemistry SP and Western blotting assay were used to examine the expression of PTEN, γ-H2AX, and Rad51 protein in radiation-induced mice thymoma and normal thymus tissues. RT-PCR assay was conducted to examine the PTEN gene loss. Exogenous PTEN gene was transferred into mouse thymoma cells and its inhibitory effects on cell proliferation and tumor-forming ability were observed. Results： The positive rate of PTEN protein expression was 22. 73%（5/22） in radiation-induced thymoma tissue, significantly lower than that in the normal thymus tissue （P〈 0. 01 ）. Western blotting assay showed that the expression of PTEN protein in thymoma was markedly lower than that in the normal thymus tissue （P〈0.01）. RT-PCR found that in tumor tissue there was high-frequency of PTEN gene loss. Exogenous PTEN expression in thymoma significantly inhibited the cell proliferation and the tumor-forming ability （P〈0.01）. The expression of γ-H2AX protein in the thymoma tissue was significantly higher than that in the normal thymus tissue; the expression of Rad51 protein was significantly lower than that in the normal tissue. Conclusion： Loss of PTEN gene may contribute to radiation-induced thymoma via influencing the Rad51-mediated DNA repair pathway. Exogenous PTEN gene transfer can inhibit the in vitro proliferation of thymoma cells, which may contribute to the treatment and prevention of radiation-induced tumor.
出处
《第二军医大学学报》
CAS
CSCD
北大核心
2008年第8期888-891,共4页
Academic Journal of Second Military Medical University
