DETECTION OF P53 MUTATIONS IN SOLID PEDIATRIC TUMORS

在许多肿瘤中都检测到了p53突变，并将其解释为晚期 肿瘤发生中的事件，可能与肿瘤的进展有关，而不是 肿瘤的发展。最近的研究表明， 一些Li-Fraumeni家系中的胚系P53突变及其作用 人类癌症遗传易感性中的p53突变。 横纹肌肉瘤是一种常见的软组织肉瘤，在有 Li-Fraumeni综合征，被发现有P53突变。然而， 这种突变在儿科肿瘤中的频率仍不清楚。我们有 最近建立了一种非放射性同位素方法来检测突变。这 该方法是基于可变DNA异源双链的形成 突变检测增强(MDE)凝胶中的运动性。突变可以因此 即使从石蜡包埋的DNA中也能检测到PCR扩增的DNA 纸巾。利用这种方法，我们研究了跨越外显子的pcr片段。 13例横纹肌肉瘤(RMS)中P53基因的4、5、6、7和8(大多数 石蜡块)。所研究的肿瘤中有很高比例(46%)显示 P53突变，更常见的是外显子7，其次是外显子8和5。 在某些情况下，用标准的单一基因证实了突变的存在 链式构象多态(SSCP)方法和直接 不对称聚合酶链式反应获得的单链DNA测序方法。我们 目前已将这项研究扩大到包括更多的RMS，如 以及其他儿童实体肿瘤，如神经母细胞瘤和外周肿瘤 和中央PNET/尤因肉瘤病例。慢性阻塞性肺疾病患者的生存 突变和非突变肿瘤将进行比较，以探索一种潜在的 P53突变在这类肿瘤中的预后作用。

p53 mutations have been detected in many tumors and interpreted as a late event in tumorigenesis, probably involved in tumor progression rather than tumor development. Recent studies have demonstrated the presence of germline p53 mutations in some Li-Fraumeni pedigrees and hence a role of p53 mutations in hereditary susceptibility to human cancer. Rhabdomyosarcoma, a common soft tissue sarcoma in the families with the Li-Fraumeni syndrome, was found to have p53 mutations. However, the frequency of such mutations in pediatric tumors remains unknown. We have recently established a non-radioisotopic method to detect mutations. This method is based on the formation of DNA hetero-duplexes with variable motility in mutation detection enhancement (MDE) gels. Mutations can thus be detected in PCR-amplified DNA extracted even from paraffin embedded tissues. Using this method, we have studied PCR fragments spanning exons 4, 5, 6, 7, and 8 of the p53 gene from 13 rhabdomyosarcomas (RMS) (mostly paraffin blocks). A high percentage of the studied tumors (46%) exhibited p53 mutations, more often in exon 7, followed by exons 8 and 5. The presence of mutations was confirmed in some cases with the standard single stranded conformational polymorphism (SSCP) method and with a direct sequencing method of single stranded DNA obtained by asymmetric PCR. We have currently expanded the study to include a larger number of RMS, as well as other solid pediatric tumors, such as neuroblastoma and peripheral and central PNET/Ewing's sarcoma cases. The survival of patients with mutated and non-mutated tumors will be compared to explore a potential prognostic role of p53 mutations in this group of tumors.