Progression, response, and resistance of RSPO fusion colorectal cancer

项目摘要 结直肠癌（CRC）是西方世界癌症相关死亡的第二大原因， 对于晚期疾病患者没有有效的治疗方法。大的染色体重排， WNT途径共激动剂的RSPO家族的两个成员最近在5-10%的人 CRC，并提供了一个潜在的目标，以治疗这一子集的患者。然而，我们仍然不完全理解 特异性RSPO融合蛋白（例如PTPRK-RSPO 3）有助于肿瘤发生，以及是否靶向该融合蛋白， 基因组改变将提供有意义的治疗反应和改善的患者结果。开始 为了描述RSPO融合的后果，我们开发了基因工程动物模型， 内源性染色体重排可以使用诱导型CRISPR/Cas9基因在肠中产生， 我们开创的平台使用这种方法，我们提供了Ptprk-Rspo 3染色体的第一个证据， 重排足以引发肠道中的肿瘤发展。此外，来自 内源性染色体改变产生的表型与已发表的诱导异位妊娠的模型不同， Rspo 3cDNA的过表达。因此，定义特定融合事件的分子后果是 这对于理解这种重排对肿瘤生物学的真正影响可能至关重要。另外我们 显示在天然肠粘膜内生长的Ptprk-Rspo 3融合病变对 药物阻断WNT分泌，但遗传变异的积累可以影响药物反应。 基于这项工作，我们将测试Ptprk-Rspo 3融合蛋白提供WNT依赖性细胞的假设， 内生性增长优势源于内生性融合事件，而协同性积累 致癌损伤促进WNT独立性和耐药性。 使用离体类器官模型系统，Aim 1将确定特异性RSPO的分子后果 融合，并描述特定的融合事件和融合伴侣（PTB）的丢失如何促进细胞 转型在目标2中，通过在类器官和原位肿瘤模型中进行基于CRISPR的连续编辑， 我们将定义与治疗失败和获得性药物相关的遗传景观和分子机制， 阻力总之，这项工作将有助于从分子水平上了解RSPO基因组是如何 重排影响致癌WNT信号传导，并有可能使一个直接的和重要的 临床贡献，通过定义影响肿瘤进展和治疗抗性的机制。 我们希望我们的研究将揭示如何更有效地识别患者人群， 治疗和/或预测用于治疗难治性肿瘤的组合和二线疗法。因此，结果 这将是朝着安全有效的靶向治疗的总体目标迈出的重要一步。 CRC，改善患者结局。

PROJECT SUMMARY Colorectal cancer (CRC) is the second leading cause of cancer-related death in the Western world, and there are no effective therapies for patients with advanced disease. Large chromosome rearrangements involving two members of the RSPO family of WNT pathway co-agonists were recently described in 5-10% of human CRC, and offer a potential target to treat this subset of patients. However, we still do not fully understand how specific RSPO fusion proteins (e.g. PTPRK-RSPO3) contribute to tumorigenesis, and whether targeting this genomic change will provide meaningful therapeutic responses and improved patient outcomes. To begin to delineate the consequences of RSPO fusions, we developed genetically engineered animal models in which endogenous chromosome rearrangements can be generated in the intestine using an inducible CRISPR/Cas9 platform we pioneered. Using this approach, we provided the first evidence that Ptprk-Rspo3 chromosome rearrangements are sufficient to initiate tumor development in the gut. Moreover, tumors derived from endogenous chromosome alterations produce phenotypes distinct from published models that induce ectopic overexpression of an Rspo3 cDNA. Thus, defining the molecular consequences of specific fusion events is likely critical for understanding the true impact of such rearrangements on tumor biology. In addition, we showed that Ptprk-Rspo3 fusion lesions growing within the native intestinal mucosa are exquisitely sensitive to drugs that block WNT secretion, but that the accumulation of genetic alterations can influence drug response. Based on this work, we will test the hypothesis that Ptprk-Rspo3 fusion proteins provide a WNT-dependent cell intrinsic growth advantage due to the endogenous fusion event, but that the accumulation of cooperating oncogenic insults promotes WNT independence and drug resistance. Using ex vivo organoid model systems, Aim 1 will determine the molecular consequences of specific RSPO fusions and delineate how specific fusion events and loss of the fusion partner (PTPRK) promote cell transformation. In Aim 2, through sequential CRISPR-based editing in organoids and orthotopic tumor models, we will define genetic landscape and molecular mechanisms linked to therapy failure and acquired drug resistance. Together, this work will contribute significantly to a molecular understanding of how RSPO genomic rearrangements impact oncogenic WNT signaling, and has the potential to make an immediate and significant clinical contribution, by defining the mechanisms that influence tumor progression and therapy resistance. We expect our studies will reveal ways to more effectively identify patient populations that would respond to treatment and/or predict combination and second line therapies for treatment refractory tumors. Thus, results from this study will be a significant step toward the overall goal of safe and effective targeted therapies for CRC, and improved patient outcomes.