Studies of amplification in rhabdomyosarcoma

高级研究员在2011财年转移到国家癌症研究所，并在剩下的时间里建立了实验室。因此，2011财年未对该项目进行任何研究。然而，在宾夕法尼亚大学以前的研究中，高级研究员做出了以下观察。基于先前的研究表明融合基因在这些癌症的一个子集中扩增，我们对这些扩增事件进行了全面的分子和临床研究。利用寡核苷酸阵列对扩增子进行定位，我们发现最小的1p36扩增子面积为0.13 Mb，仅包含PAX7，而最小的13q14扩增子面积为0.53 Mb，包含FOXO1和特征不明显的LOC646982基因。对100多例融合阳性病例进行荧光原位杂交分析发现，93%的pax7 - fox01阳性病例和9%的pax3 - fox01阳性病例扩增出融合基因。在pax7 - foxo1阳性扩增的病例中，大多数细胞含有该扩增子，而在PAX3-FOXO1阳性扩增的病例中，只有一小部分细胞含有该扩增子。表达研究表明，在扩增病例中，融合转录物的表达水平普遍较高，并且PAX7-FOXO1融合转录物的表达水平高于PAX3-FOXO1融合转录物。最后，融合基因扩增和PAX7-FOXO1融合状态均与预后显著改善相关；多变量分析表明，该预测值与其他标准预后参数无关。因此，这些发现为融合阳性横纹肌肉瘤新的良好预后亚群提供了进一步的证据。

The Senior Investigator moved to the National Cancer Institute during FY2011 and has been setting up the laboratory during the remaining time. Therefore no research studies were performed on this project during FY2011. However, in previous studies at the University of Pennsylvania, the Senior Investigator made the following observations. Based on previous studies indicating that the fusion genes are amplified in a subset of these cancers, we conducted a comprehensive molecular and clinical investigation of these amplification events. Using oligonucleotide arrays to localize amplicons, we found that the minimal 1p36 amplicon measured 0.13 Mb and only contained PAX7 whereas the minimal 13q14 amplicon measured 0.53 Mb region and contained FOXO1 and the poorly characterized LOC646982 gene. Application of a fluorescence in situ hybridization assay to over 100 fusion-positive cases revealed that the fusion gene is amplified in 93% of PAX7-FOXO1-positive and 9% of PAX3-FOXO1-positive cases. While most cells in amplified PAX7-FOXO1-positive cases contained the amplicon, only a fraction of cells in the amplified PAX3-FOXO1- positive cases contained the amplicon. Expression studies demonstrated that the fusion transcripts were generally expressed at higher levels in amplified cases, and that the PAX7-FOXO1 fusion transcript was expressed at higher levels than the PAX3-FOXO1 fusion transcript. Finally, fusion gene amplification and PAX7-FOXO1 fusion status were each associated with significantly improved outcome; a multivariate analysis demonstrated that this predictive value was independent of other standard prognostic parameters. These findings therefore provide further evidence for a novel good prognosis subset of fusion-positive rhabdomyosarcoma.