Discovery of Homologous Recombination DNA Repair Deficiency in Lung Tumor

描述(由申请人提供)：Fanconi贫血(FA)途径是同源重组DNA修复的主要机制，以应对遗传毒性侮辱。FA缺乏的细胞对DNA损伤剂如顺铂和丝裂霉素C(MMC)敏感。在DNA损伤诱导后，或在细胞周期的S阶段，BRCA基因与同一修复途径(FA途径)中的其他基因协作，形成染色质上的DNA修复中心。鉴于该途径涉及大量基因，我们假设相当大比例的肺癌患者存在体细胞遗传或表观遗传学改变，导致FA同源重组修复缺陷。这些患者更有可能从链间DNA交联剂中受益。为了识别这些患者，有必要进行一种测试，这种测试可以检查整个通路的功能，并且可以实际应用于大规模筛查。我们最近报道了一项FA三染免疫荧光(FATSI)测试，以评估FANCD2病灶的存在或不存在，并产生了包括肺癌在内的几个器官部位的患者肿瘤中这一途径的体细胞缺陷的初步数据。然而，在这些散发性肿瘤中，导致FA途径失活的具体遗传和表观遗传学改变仍不清楚。为了为临床治疗提供足够的分子证据支持这种选择，并了解导致肺癌FA途径缺陷的遗传和表观遗传学变化，我们建议完成以下目标：(1)通过分析100例人肺癌和100例匹配的非肿瘤标本来鉴定肺癌患者的FANCD2灶缺陷肿瘤；(2)通过分析与FA途径相关的RNA转录组，利用下一代测序(RNAseq)技术，对目标1中发现的FANCD2灶缺陷肿瘤进行功能基因组分析。以及(3)研究AIM 1中发现的FANCD2病灶缺陷性肿瘤中FA基因启动子甲基化情况。 验证了基于免疫荧光的三重染色试验可用于肺癌患者后续临床治疗的合理性。

DESCRIPTION (provided by applicant): The Fanconi Anemia (FA) pathway is a major mechanism of homologous recombination DNA repair in response to genotoxic insults. Cells with FA deficiency are hypersensitive to DNA damage agents such as cisplatin and mitomycin C (MMC). BRCA genes collaborate with other genes in the same repair pathway, the FA pathway, to form foci of DNA repair on chromatin following DNA damage induction, or during the S phase of cell cycle. Given the large number of genes involved in this pathway, we hypothesize that a substantial proportion of patients with lung cancer harbor somatic genetic or epigenetic alterations resulting in defective FA homologous recombination repair. These patients are more likely to derive benefit from interstrand DNA crosslink agents. A test that could examine the functionality of this pathway as a whole and that could be practically applied for large-scale screening would be necessary to identify these patients. We have recently reported a FA triple-staining immunofluorescence (FATSI) test to evaluate the presence or absence of FANCD2 foci, and have generated preliminary data for somatic deficiency of this pathway in patients' tumors across several organ sites that include lung cancers. However, the specific genetic and epigenetic alterations that lead to inactivation of FA pathway in these sporadic tumors are still unknown. In order to provide sufficient molecular evidence to support such selection for clinical treatment and to understand the genetic and epigenetic changes that lead to FA pathway deficiency in lung cancers, we propose to accomplish following aims: (1) to identify FANCD2 foci defective tumor in lung cancer patients by analyzing 100 human lung tumor and 100 matching non-tumor samples, and (2) to perform a functional genomics analysis of FANCD2 foci defective tumors identified in aim 1 through analysis of the RNA transcriptome associated with the FA pathway in the tumor and adjacent non-tumor tissues, using next generation sequencing (RNAseq), and (3) to investigate promoter methylation of FA genes in FANCD2 foci defective tumors identified in aim 1. The information obtained from this project is expected to be useful for validating the immunofluorescence based triple staining test which can be used for justifying subsequent clinical therapeutic treatment for the patient with lung cancer.