Basic and Clinical Research of p53 Gene Therapy for Human Cancer

血管生成是恶性肿瘤生长和发展所必需的。最近的研究表明，基因改变可能伴随着血管生成表型的获得。肿瘤抑制基因p53是人类癌症中最常发生突变的基因，也是多种基因的转录调节因子。在这里，我们研究了野生型p53基因在人非小细胞肺癌细胞系上的抗血管生成作用。利用重组腺病毒载体（Ad5CMVp53）将表达p53突变体的H226Br NSCLC细胞转染野生型p53基因，并应用半定量逆转录聚合酶链反应检测血管生成和/或抗血管生成因子mRNA表达变化。然后采用膜扩散室系统皮下移植于nu/nu小鼠，进行ad5cmvp53感染细胞的体内新生血管实验。我们还通过将ad5cmvp53感染的H226Br细胞皮下接种于nu/nu小鼠，观察其对体内非转导肿瘤细胞的影响。Ad5CMVp53感染显著抑制血管生成因子血管内皮生长因子（VEGF）的表达，增加新型抗血管生成因子脑特异性血管生成抑制剂1 （BAI1）的表达，导致体内新生血管减少。混合实验表明，转染野生型p53基因的肿瘤细胞抑制了邻近未转染的肿瘤细胞的体内肿瘤生长。我们的数据表明，表达野生型p53基因的重组腺病毒具有抗血管生成作用，这可能部分解释了野生型p53基因转移对邻近肿瘤细胞诱导的旁观者效应的机制。

Angiogenesis is required for the growth and progression of malignancies. Recent studies have demonstrated that genetic alterations may accompany acquisition of the angiogenic phenotype. The tumor suppressor p53 gene is most frequently mutated in human cancers and is also known to be a transcriptional regulator of a variety of genes. Here we investigated the antiangiogenic effect of the wild-type p53 gene transfer on a human non-small-cell lung cancer cell line. Mutant p53-expressing H226Br NSCLC cells were transduced with the wild-type p53 gene using a recombinant adenoviral vector (Ad5CMVp53) and applied to semi-quantitative reverse transcription-polymerase chain reactions to detect altered mRNA expression of angiogenic and/or antiangiogenic factors. In vivo neovascularization assay of Ad5CMVp53-infected cells was then performed using a membrane-diffusion chamber system subcutaneously transplanted in nu/nu mice. We also evaluated the effect of Ad5CMVp53-infected H226Br cells on nontransduced tumor cells in vivo by subcutaneously inoculating mixture of cells into nu/nu mice. Ad5CMVp53 infection markedly inhibited the expression of an angiogenic factor, vascular endothelial growth factor (VEGF), and increased the expression of a novel antiangiogenic factor, brain-specific angiogenesis inhibitor 1 (BAI1), resulting in the reduced neovascularization in vivo. Mixing experiments showed that tumor cells transduced with the wild-type p53 gene inhibited the in vivo tumor growth of adjacent nontransduced cells. Our data suggest that a recombinant adenovirus expressing the wild-type p53 gene is antiangiogenic, which may explain in part the mechanism of the bystander effect induced by the wild-type p53 gene transfer on adjacent tumor cells.