DEVELOPMENT OF AN IN VIVO MODEL OF GENOMIC INSTABILITY (LACI--P53(+/-)MICE)

工作总结：p53蛋白对细胞功能至关重要， 维持基因组的完整性以应对环境变化 压力，包括化学和物理致癌物。 还原型p53 剂量（杂合p53缺陷小鼠）本身不足以 诱导基因组不稳定性并导致癌症。 然而，我们和其他人， 已经证明，暴露于化学物质和 物理致癌物迅速发展成癌症。 获得洞察力， 了解器官/组织诱导的机制基础 使用模型致癌物的特定癌症对于开发 致癌物识别和最大限度减少接触的方法， 制定干预和预防的公共卫生战略。的 致癌物质，对克瑞西定，苯，和酚酞每迅速 诱导部位特异性肿瘤（膀胱、组织细胞肉瘤或胸腺 在杂合p53（+/-）缺陷型C57 BL/6小鼠中， (het p53 def）。研究结果与假设一致， 涉及trp 53基因座的失活突变或洛缺失在 啮齿动物和人类的癌症。每一种致癌物都能诱发肿瘤， 显示了不同水平的野生型p53等位基因丢失 （酚酞>苯>对克立西定）。 与 高频（苯）或完全（酚酞）损失 野生型等位基因（Southern分析）p53无失活突变 然而，在芳香胺诱导的情况下， 膀胱肿瘤，我们未能观察到失活突变的p53外显子 5-9通过p53免疫组织化学、冷SSCP分析或有限的 PCR扩增的外显子5-8的测序。虽然，用同样的老鼠 携带lacI中性报告基因的菌株，我们能够 证明膀胱被诱变了 这些数据证明 致癌物和组织特异性p53等位基因显著差异 损失 因此，我们建立了模型来研究这种关系 p53基因剂量，失活突变， 染色体不稳定的机制。

Summary of Work: The p53 protein is critical for cell function and maintaining the integrity of the genome in response to environmental stresses, including chemical and physical carcinogens. Reduced p53 gene dosage (heterozygous p53 deficient mice)by itself is insufficient to induce genomic instability and to cause cancer. However, we, and others, have demonstrated that p53 deficient mice exposed to chemical and physical carcinogens rapidly develop cancer. Gaining insight and understanding the mechanistic basis for induction of organ/tissue specific cancer using model carcinogens is important to developing methods for carcinogen identification and minimizing exposure as well as developing public health strategies for intervention and prevention. The carcinogens, p-cresidine, benzene, and phenolphthalein each rapidly induce site specific tumors (bladder, histiocytic sarcoma, or thymic lymphoma, respectively) in heterozygous p53 (+/-) deficient C57BL/6 mice (het p53 def). The findings are consistent with the hypothesis that inactivating mutations or LOH involving the trp53 locus are critical in rodent as well as human cancers. Each carcinogen induced tumors that demonstrated different levels of wild type p53 allele loss (phenolphthalein > benzene > p-cresidine) in the het p53 def mice. With either high frequency (benzene) or complete (phenolphthalein) loss of the wild type allele (Southern analysis) no inactivating mutations in p53 could be found. However, in the case of the aromatic amine induced bladder tumors, we failed to observe inactivating mutations in p53 exons 5-9 by either p53 immunohistochemistry, cold SSCP analysis, or limited sequencing of PCR amplified exon 5-8. Although, using mice of the same strain carrying the lacI neutral reporter gene we were able to demonstrate that the bladder was mutagenized. These data demonstrates the dramatic difference in carcinogen and tissue specific p53 allele loss. Thus, we have established models to investigate the relationship between p53 gene dosage, inactivating mutations, and the potential mechanism of chromosomal instability.