目的:探讨外源性p53AIP1（p53regulated apoptosisinducing protein 1）基因抗肿瘤效应及其作用机制，以评估p53AIP1基因在肿瘤基因治疗中应用的可行性。方法：构建携带p53AIP1基因的重组复制缺陷型腺病毒Adp53AIP1，感染人肝癌细胞HepG2，应用MTT比色法、Western blotting、流式细胞术、罗丹明染色以及电镜等观察外源性p53AIP1基因表达对肿瘤细胞的作用及其相关机制。小鼠皮下接种感染Adp53AIP1的小鼠乳腺癌4T1细胞，观察Adp53AIP1对肿瘤细胞体内成瘤性的影响;建立4T1细胞皮下移植瘤小鼠模型, 直接瘤内多点注射重组腺病毒，观察Adp53AIP1的抗肿瘤疗效。结果：感染Adp53AIP1的HepG2细胞能够高效表达P53AIP1蛋白。MTT检测显示Adp53AIP1对人肝癌细胞HepG2的生长抑制率达50％以上；流式细胞术分析证实p53AIP1使肿瘤细胞周期阻滞于G2/M期；罗丹明染色、电镜观察以及凋亡相关蛋白PARP表达的检测均证实p53AIP1 能诱导肿瘤细胞发生明显凋亡。感染Adp53AIP1的肿瘤细胞体内成瘤受到非常明显的抑制（P<001）, Adp53AIP1瘤体注射对移植瘤生长也有明显的抑制作用（P<0.05）。Western blotting以及RTPCR检测证实Adp53AIP1对p53mRNA表达无影响，能下调mdm2 基因的表达；p53AIP1能上调P53蛋白的表达、下调MDM2蛋白的表达水平，同时还影响P21等细胞周期相关蛋白和凋亡相关蛋白的表达。结论：p53AIP1有明显的体内外抗肿瘤作用，其作用机制与其反向调控P53蛋白、调控多种细胞周期和细胞凋亡相关蛋白、诱导细胞周期阻滞和细胞凋亡有关，该基因在肿瘤基因治疗中具有潜在的应用前景。

Objective:To investigate the antitumor effect of exogenous p53regulated apoptosisinducing protein 1（p53AIP1）and the related mechanism, so as to assess the feasibility of using p53AIP1 in tumor gene therapy. Methods: The recombinant replicationdefective adenovirus Adp53AIP1 containing p53AIP1 gene was constructed and transfected into human hepatocellular carcinoma HepG2 cell line. The effects and the relevant mechanisms of exogenous p53AIP1 gene on cell growth were examined by MTT, Western blotting, flow cytometry, rhodamine staining and electron microscopy. Nude mice were subcutaneously inoculated with Adp53AIP1infected mouse breast cancer cell line 4T1 to observe the effect of Adp53AIP1 on tumorigenesis of tumor cells. 4T1 breast cancer xenograft models were established in mice and intratumoral injections of Adp53AIP1 were given to observe the antitumor effect of Adp53AIP1. Results: Overexpression of p53AIP1 protein was confirmed in HepG2 cells infected with Adp53AIP1. Cell growth of HepG2 cells which contain wildtype p53 gene was inhibited by over 50% after infection. Flow cytometry showed transfection with p53AIP1 gene resulted in cell cycle arrest at G2/M. Results of PARP protein examination, rhodamine staining and electron microscopic observation demonstrated that p53AIP1induced obvious apoptosis in tumor cells. Moreover, the infection with Adp53AIP1 significantly inhibited the tumorigenesis of 4T1 cells in vivo （P<0.01）and the growth of tumors in vivo after intratumorial injection（P<0.05）. Furthermore, Western blotting and RTPCR confirmed that Adp53AIP1 had no influence on p53 mRNA expression and downregulated mdm2gene and protein; it also upregulated P53 protein expression. In addition, Adp53AIP1 could regulate cell cyclerelated proteins and apoptosisrelated proteins such as P21. Conclusions: Adp53AIP1 possess obvious tumor inhibitory effect in vitro and in vivo; the mechanism is related to its regulation of P53 protein, cell cycle and apoptosisrelated proteins. p53AIP1 might have a future in tumor gene therapy.

国家重点基础研究发展规划(973)资助项目（No.2002CB513105）。