The role of Dclk1 in the initiation of colorectal cancer

结直肠癌（CRC）是美国癌症死亡的第三大原因， 为晚期疾病患者研发更好的药物CRC肿瘤干细胞（TSC）的特异性标志物具有 多年来一直难以捉摸，但最近出现了强有力的数据来支持最初提出的TSC角色 双皮质素样激酶1（DCLK 1）在APC突变型CRC中的作用。具体来说，Dclk 1+簇细胞启动 ApcMin/+模型中的谱系追踪证实了肿瘤发生对Apc突变的响应。 肠瘤形成以及炎症诱导的结肠癌模型中。值得注意的是，在ApcMin/+ 在一个模型中，白喉毒素诱导的Dclk 1+细胞缺失导致肿瘤完全崩溃， 明显的负面影响。 而APC被认为是结直肠肿瘤发生的守门人，34-70%的人存在失活突变。 在CRC肿瘤中，KRAS突变也异常常见（30-60%），并与 总生存率显著降低，特别是在转移性疾病中。除了限制治疗 对于CRC患者的选择，KRAS突变伴随APC丢失强烈增加肿瘤发生， 转移和TSC特性。DCLK 1+细胞现在强烈暗示为KRAS-1的起源细胞。 最近的蛋白质组学研究表明，KRASG 12/G13突变的敲入 进入CRC细胞导致特异性DCLK 1上调20。此外，DCLK 1在CRC中高表达， 转移并预测患者的生存率显著降低。我们建议解开DCLK 1在 KRAS突变型CRC进展并评估具有以下特定目的的DCLK 1靶向治疗： 目的1：确定DCLK 1和DCLK 1+簇细胞在KRAS突变的发生和发展中的作用 结肠直肠癌 目的2：剖析DCLK 1在KRASG 12 D下游的CRC中的机制作用和APC的背景 损失 目的3：证明在KRAS突变型患者来源的CRC模型中靶向DCLK 1作为靶向治疗的可行性。 主要治疗和克服对EGFR靶向西妥昔单抗和吉非替尼的耐药性。 这些研究将利用新的模型来提供对DCLK 1功能的第一个明确的评估。 在KRAS驱动的CRC中的重要性及其作为主要治疗靶点和辅助治疗的潜力， 逆转KRAS介导的EGFR抑制剂耐药性。我们将以一种高度多元的方式进行这些研究- 学科专家团队包括：Courtney Houchen和Dongfeng Qu（DCLK 1/胃肠道肿瘤）， Timothy Wang（DCLK 1小鼠模型），Channing Der（KRAS），Robert Langer（生物工程），Hans Clevers (CRC类器官）、Min Li（小鼠手术模型）和Magdalena Bieniasz（患者来源的异种移植物）。 这些研究可能为晚期CRC患者带来新的有效治疗方法。

Colorectal cancer (CRC) is the 3rd leading cause of cancer death in the U.S, and it is a necessity to develop better drugs for those with advanced disease. Specific markers of CRC tumor stem cells (TSCs) have been elusive for many years, but recently strong data has emerged to support the TSC-role originally proposed by our lab for doublecortin-like kinase 1 (DCLK1) in APC mutant CRC. Specifically, Dclk1+ tuft cells initiate tumorigenesis in response to Apc mutation as demonstrated by lineage tracing in the ApcMin/+ model of intestinal neoplasia as well as in a model of inflammation-induced colon cancer. Strikingly, in the ApcMin/+ model, diphtheria toxin-inducible deletion of Dclk1+ cells results in a complete collapse of tumors with no apparent negative effects. While, APC is considered a gatekeeper in colorectal tumorigenesis and inactivating mutations exist in 34-70% of CRC tumors, KRAS mutations are also exceptionally common (30-60%) and associated with significantly decreased overall survival, particularly in metastatic disease. In addition to limiting therapeutic options for CRC patients, KRAS mutations accompanied by APC loss strongly increase tumorigenesis, metastasis, and TSC properties. The DCLK1+ cell is now strongly implicated as a cell-of-origin for KRAS- driven pancreatic cancer, and recent proteomic studies demonstrate that knock-in of KRASG12/G13 mutations into CRC cells results in specific DCLK1 upregulation20. Moreover, DCLK1 is highly expressed in CRC metastases and predicts significantly decreased survival in patients. We propose to unravel DCLK1's role in KRAS-mutant CRC progression and assess DCLK1-targeted therapies with the following Specific Aims: Aim 1: Determine the role of DCLK1 and the DCLK1+ tuft cell in the initiation and progression of KRAS-mutant colorectal cancer. Aim 2: Dissect DCLK1's mechanistic role in CRC downstream of KRASG12D and in the background of APC loss. Aim 3: Demonstrate the feasibility of targeting DCLK1 in KRAS-mutant patient-derived CRC models as a primary therapy and to overcome resistance to EGFR-targeted cetuximab and gefitinib. These studies will utilize novel models to provide the first definitive assessment of the DCLK1's functional significance in KRAS-driven CRC and its potential as both a primary therapeutic target and an adjuvant to reverse KRAS-mediated resistance to EGFR inhibitors. We will pursue these studies with a highly multi- disciplinary team of experts including: Courtney Houchen and Dongfeng Qu (DCLK1/gastrointestinal cancers), Timothy Wang (DCLK1 mouse model), Channing Der (KRAS), Robert Langer (bioengineering), Hans Clevers (CRC organoids), Min Li (mouse surgery models), and Magdalena Bieniasz (patient-derived xenografts). These studies may lead to novel and effective therapies for patients with advanced CRC.