Role of Gene Amplification in Breast Cancer

描述（由申请人提供）：基因组DNA扩增导致癌基因表达增加，通常有助于癌症的发展。表征这些DNA拷贝数的变化对于促进我们对癌症的理解以及癌症的诊断和治疗非常重要。本研究的目的是描述乳腺癌中复发性基因扩增的特征，了解其在肿瘤发生和进展中的作用，并研究其作为预后标志物和治疗靶点的效用。这些目标的实现依赖于三个最新的技术发展：基于阵列的比较基因组杂交（阵列CGH），组织微阵列和RNA干扰（RNAi）。在阵列CGH中，肿瘤和正常基因组DNA被差异标记并与含有数千个不同基因的微阵列共杂交。阵列上每个元素的荧光比率提供了癌症基因组中DNA拷贝数改变的高分辨率“逐基因”图谱。组织微阵列由来自单个肿瘤的数百个不同的组织活检切片组成，切片在单个显微镜载玻片上。组织微阵列上的荧光原位杂交（FISH）允许对阵列上的每个标本高度平行地检测单个基因的扩增及其与临床结果数据的相关性。最后，RNAi是由与靶基因同源的双链RNA启动的序列特异性转录后沉默。RNAi方法将允许在扩增的复发区域内鉴定癌基因，研究它们在肿瘤发生中的功能作用，并评估它们作为癌症治疗靶点的潜在效用。该提案的具体科学目标是：（1）通过阵列CGH以高分辨率识别和绘制乳腺癌中的复发性基因扩增;（2）使用组织微阵列上的FISH评估基因扩增作为预后标志物;以及（3）确定使用RNAi技术靶向乳腺癌中已识别基因扩增的功能作用和治疗潜力。

DESCRIPTION (provided by applicant): Genomic DNA amplifications, which lead to the increased expression of oncogenes, frequently contribute to the development of cancer. Characterizing these DNA copy number changes is important for advancing our understanding of cancer, as well as for its diagnosis and treatment. The objectives of this study are to characterize recurrent gene amplifications in breast cancer, to understand their role in tumor development and progression, and to investigate their utility as prognostic markers and therapeutic targets. The achievement of these goals relies on three recent technical developments: array-based comparative genomic hybridization (array CGH), tissue microarrays, and RNA interference (RNAi). In array CGH, tumor and normal genomic DNA are differentially labeled and co-hybridized to a microarray containing thousands of different genes. Fluorescence ratios at each element on the array provide a high resolution, "gene-by-gene" map of DNA copy number alteration across the cancer genome. Tissue microarrays consist of hundreds of different tissue biopsies from individual tumors sectioned onto a single microscope slide. Fluorescence in situ hybridization (FISH) on tissue microarrays permits the highly parallel detection of a single gene's amplification, and its correlation with clinical outcome data, for each of the specimens on the array. Finally, RNAi is the sequence-specific, post-transcriptional gone silencing initiated by double-stranded RNA that is homologous to the gene targeted. RNAi methods will permit the identification of oncogene(s) within recurrent regions of amplification, the investigation of their functional role in tumorigenesis, and an evaluation of their potential utility as targets for cancer therapy. The specific scientific aims of this proposal are: (1) to identify and map at high resolution recurrent gene amplifications in breast cancer by array CGH; (2) to evaluate gene amplifications as prognostic markers using FISH on tissue microarrays; and (3) to determine the functional role of, and therapeutic potential of targeting, identified gene amplifications in breast cancer using RNAi techniques.