Mitotic failure in Fanconi anemia: mechanisms and role in carcinogenesis

摘要 FA/BRCA基因的双等位基因突变导致范可尼贫血（FA），一种骨髓衰竭综合征 与基因组不稳定性和癌症有关。患有FA的个体患有广泛的临床症状， 表现，包括白血病和其他恶性肿瘤的高风险，导致主要的终身发病率， mortality.此外，获得性FA基因突变发生在急性白血病和其他癌症的非FA 这表明FA基因可以保护普通人群免受癌症的侵害。因此，对FA的理解 基因组持家功能对公众健康非常重要。在间期，检测 DNA损伤促进多蛋白FA复合物的形成，该复合物协调遗传损伤的修复。 病变我们以前的工作表明，FA信号确保高保真有丝分裂染色体分离 通过调节纺锤体组装检查点（SAC）和维持中心体的结构和功能 （Nalepa等人，JCI 2013）。这些发现，加上其他人的工作，表明基因组的维护， FA/BRCA通路的作用超越了间期，以预防癌症。然而，它不是机械地 清楚FA基因的破坏如何损害SAC和有丝分裂的其他阶段。此外，虽然我们 已经证明，最常见的FA基因FANCA的缺失，增强了间期和有丝分裂错误 在人类造血过程中（Abdul-Sater et al，Exp Hem 2015），尚不清楚FA-1的错误分裂是否存在。 缺陷细胞直接导致恶性转化。在初步研究中，我们进行了 在FANCA-/-患者来源原代细胞中筛选合成的致死性激酶组范围的shRNA， 在有丝分裂过程中与FA信号传导功能相互作用的新的候选途径。在此，我们建议 机械地剖析这些新发现的离体和体内途径。此外，我们还创建了一个新的 遗传修饰的FA小鼠模型，以直接确定错误的有丝分裂是否促进 在FA缺乏背景下通过SAC的进一步遗传损伤的白血病发生。我们一起， 这项工作将提供对基因组不稳定性和由损失引起的恶性转化的机理性见解 FA信号传导，评估缺陷细胞分裂作为FA-/-白血病的致病因素，并建立临床前 在未来的研究中测试针对FA-/-癌症的个性化治疗策略。

Abstract Biallelic mutations in the FA/BRCA genes cause Fanconi anemia (FA), a bone marrow failure syndrome associated with genomic instability and cancer. Individuals with FA suffer from a wide range of clinical manifestations, including high risk of leukemia and other malignancies that cause major lifelong morbidity and mortality. Furthermore, acquired mutations of FA genes occur in acute leukemia and other cancers in non-FA patients, indicating that FA genes protect the general population from cancer. Thus, understanding of the FA genome-housekeeping function is highly significant for health of the general public. In interphase, detection of the DNA damage promotes formation of the multiprotein FA complex that orchestrates the repair of genetic lesions. Our previous work revealed that FA signaling ensures high-fidelity mitotic chromosome segregation through regulating the spindle assembly checkpoint (SAC) and maintaining centrosome structure and function (Nalepa et al, JCI 2013). These findings, together with the work of others, suggest that the genome maintenance role of the FA/BRCA pathway extends beyond interphase to prevent cancer. However, it is not mechanistically clear how disruption of the FA genes impairs the SAC and other stages of mitosis. Furthermore, although we have demonstrated that loss of the most common FA gene, FANCA, enhances both interphase and mitotic errors during human hematopoiesis (Abdul-Sater et al, Exp Hem 2015), it is not known whether faulty division of FA- deficient cells directly contributes to malignant transformation. In preliminary studies, we have conducted a synthetic lethal kinome-wide shRNA screen in FANCA-/- patient-derived primary cells and have identified strong novel candidate pathways that functionally interact with FA signaling during mitosis. Here, we propose to mechanistically dissect these newly found pathways ex vivo and in vivo. Further, we have generated a new genetically modified mouse model of FA to directly determine whether erroneous mitosis promotes leukemogenesis in the FA-deficient background through further genetic impairment of the SAC. Together, our work will provide mechanistic insights into genomic instability and malignant transformation resulting from loss of FA signaling, evaluate defective cell division as a causative factor in FA-/- leukemia, and create a preclinical platform to test personalized therapeutic strategies against FA-/- cancers in future studies.