Therapeutic potential of FANCM for BRCA1-linked cancer

项目摘要/摘要 乳腺癌和卵巢癌是全世界女性最常见的癌症之一。 显示出治疗BRCA相关癌症的潜力，通过一种合成致死机制利用 人力资源缺陷。然而，肿瘤往往对这些药物和其他药物产生抗药性。因此，有一个迫在眉睫的 需要找到新的、有针对性的治疗BRCA相关癌症的方法。基因组不稳定是癌细胞的一个标志 也是肿瘤发生的潜在来源。基因组不稳定的一个主要原因是复制分叉在站点停滞不前 DNA损伤或DNA结构异常。研究哺乳动物失速的叉子修复的一个局限性是 缺乏工具来分析这一过程的分子细节。Scully实验室通过以下方式解决了这个问题 调整大肠杆菌Tus/Ter复制叉屏障(RFB)诱导位点特异性复制叉 停滞在哺乳动物的染色体上。 在缺乏BRCA1的原代细胞中，串联复制(TDS)是由TUS/Ter区块特异性地诱导的，但不是 通过传统的双链断裂(DSB)，表明停滞的叉状反应的特异性。有趣的是， 缺乏BRCA1的乳腺癌和卵巢癌同样会获得大量的小(~10kb)TD，我们 已将其称为“第1组”TD。因此，TUS/Ter系统概括了BRCA1特定于 组1在人乳腺癌和卵巢癌中观察到TD形成。我发现失速的叉子马达 蛋白-FANCM(Fanconi贫血[FA]Group M基因的产物)与BRCA1协同作用 抑制TUS/Ter诱导的TDS。此外，我发现了BRCA1之间一种新的合成致命相互作用 以及小鼠胚胎干细胞以及乳腺和卵巢癌细胞中的Fancm丢失。这些发现 提示FANCM可能是BRCA1相关乳腺癌和卵巢癌的一个有前途的治疗靶点。 我在这项提案中的目标是描绘癌细胞中新颖的FANCM-BRCA1合成致死相互作用 并确定合成致死机制(Aim1)。此外，我还将探索染色质环境 和蛋白质动力学，并将研究这些过程中的变化如何有助于 FANCM-BRCA1合成致死相互作用(AIM2)。我观察到Fancm及其下游的上位作用 以TUS/Ter的FANCD2为目标，促进无错误修复和抑制容易出错的修复。这是 Fancm和FANCD2在失速分叉的修复途径选择中增加了它们可能共享相似的可能性 与BRCA1的遗传互作。将确定FANCD2的各个结构域如何在修复途径中发挥作用 失速叉子的选择及其与BRCA1的遗传交互作用(目标3)。这种全面的方法将提供一个完整的 FANCM-BRCA1合成致死相互作用的机制图，并可能在FANCD2中识别一个新的 癌症治疗的合成致命靶点。 我

Project Summary/Abstract Breast and ovarian cancer are among the most common cancers in women worldwide.PARP inhibitors have shown potential for the treatment of BRCA-linked cancer, via a synthetic lethality mechanism that exploits the HR defect. However, tumors often develop resistance to these and other drugs. Therefore, there is a pressing need to find new, targeted treatments for BRCA-linked cancer. Genomic instability is a hallmark of cancer cells and a potential source of tumorigenesis. A major cause of genomic instability is replication fork stalling at sites of DNA damage or abnormal DNA structure. A limitation in the study of mammalian stalled fork repair has been a dearth of tools with which to analyze this process in molecular detail. The Scully lab solved this problem by adapting the Escherichia coli Tus/Ter replication fork barrier (RFB) to induce site-specific replication fork stalling on a mammalian chromosome. Tandem duplications (TDs) in primary cells lacking BRCA1 are induced specifically by a Tus/Ter block but not by a conventional double strand break (DSB), indicating specificity for the stalled fork response. Intriguingly, breast and ovarian cancers lacking BRCA1 similarly acquire large numbers of small (~10 kb) TDs, which we have termed “Group 1” TD. Thus, the Tus/Ter system recapitulates the BRCA1-specific regulation of Group 1 TD formation observed in human breast and ovarian cancer. I found that the stalled fork motor protein—FANCM (product of the Fanconi anemia [FA] group M gene) acts synergistically with BRCA1 to suppress Tus/Ter-induced TDs. Further, I discovered a novel synthetic lethal interaction between Brca1 and Fancm loss in mouse embryonic stem (ES) cells and in breast and ovarian cancer cells. These findings suggest that FANCM may be a promising therapeutic target in BRCA1-linked breast and ovarian cancer. My goals in this proposal are to delineate the novel FANCM-BRCA1 synthetic lethal interaction in cancer cells and to determine the mechanism of synthetic lethality (Aim1). Further, I will explore the chromatin environment and protein dynamics at the stalled fork and will study how alterations in these processes contribute to the FANCM-BRCA1 synthetic lethal interaction (Aim2). I observe an epistatic role of Fancm and its downstream target Fancd2 at Tus/Ter in promoting error free repair and suppressing error-prone repair.This critical role of Fancm and Fancd2 in repair pathway choice at stalled forks raises the possibility that they might share similar genetic interactions with Brca1. will identify how individual domains of FANCD2 function in repair pathway choice at stalled forks and their genetic interaction with Brca1 (Aim 3). This holistic approach will provide a full picture of the mechanism of FANCM-BRCA1 synthetic lethal interactions and might identify in FANCD2 a new synthetic lethal target for cancer therapy. I