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。几乎所有人 患有Lynch综合征的患者以及15%-20%的散发性早期CRC患者 由于DNA错配修复(MMR)缺陷而导致微卫星不稳定性(MSI)。值得注意的是， MMR缺陷本身不足以驱动细胞转化和肿瘤形成，但 有限数量的靶基因中的微卫星突变可能在 肿瘤的发展，潜在的MSI相关的发病机制。不幸的是，相对较少的是 已知MSI靶基因的分子基础及其作用机制 MSI相关疾病的外显性。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)密切相关 自噬肿瘤抑制基因UVRAG的突变。这种FS突变的蛋白质产物 在结直肠癌中起癌基因和中心体扩增(CA)的真正触发作用。我们 现在，将CRC遗传学和分子生物学领域的领先者们的合作纳入这个提案中 与临床医生和病理学家一起了解CA的分子机制 增加MMR突变的表达能力，促进人类结肠癌的发生。至 为了实现这一目标，我们提出了三个具体的目标，包括(1)鉴定分子 MSI CRC中CA与UVRAGFS表达相关的机制；(2)检测其影响 CA对MSI患者来源的结肠器官分化和转移能力的影响； 以及(3)研究MSI来源的UVRAGFS在疾病外显和癌症中的体内作用 使用靶向突变小鼠模型的进展。这些目标将通过以下方式实现 多学科的创新方法，将最先进的遗传学、生物化学、活体- 细胞成像，细胞和基因靶向突变小鼠的生理分析 与MMR缺乏症和中心体失控有关。我们有权接触到合适的 患者和我们使用患者衍生的结肠有机化合物将最大限度地提高我们的 最终将发现翻译给临床上的癌症患者。我们共同期待我们的 研究将描绘一种新的机制，在MSI相关的疾病外显和 提供令人信服的体内验证CA作为一种新的预后和预测生物标志物和 包括Lynch综合征在内的MSI CRC个体化治疗的治疗目标。

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.