A cancer-derived truncating mutation in disease penetrance and progression of MSI CRC

项目摘要 结直肠癌（CRC）是癌症死亡的第二大常见原因。几乎所有 Lynch综合征患者以及15-20%的散发性早期CRC患者 由于DNA错配修复（MMR）缺陷而具有微卫星不稳定性（MSI）。值得注意的是， 有缺陷的MMR本身不足以驱动细胞转化和肿瘤发生， 有限数量的靶基因中的微卫星突变可能会被积极选择， 肿瘤发展，潜在的MSI相关发病机制。不幸的是， 已知MSI靶基因的分子基础及其在 MSI相关疾病的发病率。这个项目将填补这一空白，利用我们最近的 发现MSI表型与复发性移码（FS）之间存在强相关性 自噬肿瘤抑制基因UVRAG突变。FS突变的蛋白产物 在CRC中作为癌基因和中心体扩增（CA）的真正触发剂发挥作用。我们 现在，我们将CRC遗传学和分子生物学领域的领导者合作纳入该提案 沿着与临床医生和病理学家了解CA的分子机制， 增强了MMR突变的表达能力，有助于人类结肠癌的发生。到 为了实现这一目标，我们提出了三个具体目标，包括（1）鉴定分子 与UVRAGFS表达相关的MSI CRC中CA的机制;（2）检查 CA对MSI患者来源的结肠类器官的分化和转移能力的影响; 以及（3）研究MSI衍生的UVRAGFS在疾病转移和癌症中的体内作用 使用靶向突变小鼠模型的进展。这些目标将通过 多学科的创新方法，整合了最先进的遗传，生物化学，活的， 细胞成像和细胞中的生理学测定以及基因中具有靶向突变的小鼠 与MMR缺陷和中心体失调有关。我们有机会接触到合适的 患者和我们使用患者来源的结肠类器官将最大限度地提高我们的相关性， 最终转化为临床上的癌症患者。我们共同期待， 研究将描绘一种新的机制，潜在的MSI相关疾病的发病率， 提供了令人信服的CA作为一种新的预后和预测生物标志物的体内验证， 用于MSI CRC（包括Lynch综合征）的个性化治疗的治疗靶点。

Project Summary Colorectal cancer (CRC) ranks as the 2nd most common cause of cancer mortality. Nearly all patients suffering from Lynch Syndrome as well as 15-20% of patients with sporadic early CRC have microsatellite instability (MSI) due to DNA mismatch repair (MMR) deficiency. Notably, defective MMR by itself is not sufficient to drive cell transformation and tumorigenesis, but microsatellite mutations in a limited number of target genes might be positively selected during tumor development, underlying MSI-associated pathogenesis. Unfortunately, relatively little is known about the molecular underpinnings of MSI target genes and their mechanism of action in MSI-associated disease penetrance. This project will fill this gap, capitalizing on our recent discovery of a strong correlation between the MSI phenotype and recurrent frameshift (FS) mutation in the autophagy tumor suppressor UVRAG. The protein product of this FS mutation functions as an oncogene and a bona fide trigger of centrosome amplification (CA) in CRC. We now bring within this proposal a collaboration of leaders in CRC genetics and molecular biology along with clinicians and pathologists to understand the molecular mechanism by which CA augments the expressivity of MMR mutations, contributing to human colonic carcinogenesis. To achieve this goal, we propose three Specific Aims, including (1) identifying the molecular mechanism of CA in MSI CRC associated with UVRAGFS expression; (2) examining the impact of CA on the differentiation and metastatic capacity of MSI patient-derived colonic organoids; and (3) investigating the in vivo role of MSI-derived UVRAGFS in disease penetrance and cancer progression using targeted mutant mouse models. These aims will be addressed using multidisciplinary innovative approaches that integrate state-of-the-art genetic, biochemistry, live- cell imaging, and physiological assays in cells and in mice with targeted mutations in genes related to MMR deficiency and centrosome deregulation. We have access to the right cohort of patients and our use of patient-derived colonic organoids will maximize the relevance of our findings for eventual translation to cancer patients in the clinic. Together, we anticipate that our studies will delineate a novel mechanism underlying MSI-associated disease penetrance and provide compelling in vivo validation of CA as a novel prognostic and predictive biomarker and a therapeutic target for personalized treatment of MSI CRC including Lynch Syndrome.