Defining the genetic requirements for maintenance of colorectal cancer

确定维持结直肠癌的遗传要求

• 批准号: 8916057
• 负责人: LUKAS Edward DOW
• 金额: $ 19.47万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8916057
• 关键词: APC gene; Address; Adenomatous Polyposis Coli; Adult; Affect; Apoptosis; Award; Benign; Biological Models; Biology; Cancer Etiology; Candidate Disease Gene; Cessation of life; Colon; Colon Carcinoma; Colorectal Cancer; Complex; Cytotoxic Chemotherapy; Data; Dependence; Dependency; Development; Diagnostic Neoplasm Staging; Disease; Disease Progression; Disseminated Malignant Neoplasm; Doxycycline; Drug Targeting; Epigenetic Process; Event; Foundations; Future; Genes; Genetic; Goals; Growth; Health; In Vitro; Intestines; Knowledge; Lesion; Maintenance; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of gastrointestinal tract; Mediating; Molecular; Mouse Strains; Mus; Mutate; Mutation; Nature; Oncogenic; Pathway interactions; Patients; Population; Prevalence; Protein p53; Publications; Reagent; Recurrence; Relapse; Research; Resistance; Role; Signal Pathway; Signal Transduction; Staging; System; Therapeutic; Therapeutic Intervention; Tissues; Transgenic Mice; Transgenic Organisms; Tumor Suppressor Genes; Tumor Suppressor Proteins; Tumor stage; Vision; Withdrawal; Work; adenoma; advanced disease; base; cancer cell; cancer therapy; carcinogenesis; cell behavior; clinical application; combinatorial; drug development; effective therapy; flexibility; genetic approach; genetic technology; in vivo; in vivo Model; inhibitor/antagonist; innovation; insight; malignant phenotype; member; metastatic colorectal; mouse model; mutant; neoplastic cell; novel; post-doctoral training; programs; research study; response; restoration; senescence; small hairpin RNA; standard of care; targeted treatment; therapeutic target; tool; treatment strategy; tumor; tumor progression; tumorigenesis

DESCRIPTION (provided by applicant): Colorectal cancer (CRC) is an extremely prevalent and difficult to treat cancer. In the advanced stage of disease there are virtually no effective treatment options rendering it the second-leading cause of cancer- related deaths in the developed world. Unlike a number of other cancer treatment strategies, which have benefited from the development of targeted agents, the standard of care for CRC remains a combination of cytotoxic chemotherapies. There is an urgent need for more targeted, less toxic, treatments. Defining the tumor-specific requirements for cancer growth and progression offers one potential avenue for drug target discovery. This proposal integrates new genetic technologies and ex vivo cultures systems to characterize the genetic requirements for CRC maintenance and progression, with the goal of identifying tumor-specific weaknesses that could be exploited for cancer therapy. Mutational inactivation of the Adenomatous Polyposis Coli (APC) tumor suppressor is thought to be the initiating event in most familial and sporadic colon cancers. APC disruption results in uncontrolled activation of the Wnt pathway and because of this there is currently significant effort to develop selective Wnt signalling inhibitors for treatment of CRC. However, progression from benign adenoma to CRC involves many additional genetic and epigenetic alterations, most commonly, loss of the p53 tumor suppressor (60%) and/or oncogenic activation of Kras (45%). Given the complex nature of the disease it is unclear if CRCs remain dependent on APC loss and Wnt hyperactivation for growth and survival, and thus whether Wnt- targeted therapies will be effective in treating advanced malignancies. Here I will address this outstanding, but important question, using a unique transgenic mouse model I developed that allows temporal, spatial and reversible control of APC expression. The approach described combines existing and novel mouse strains to enable doxycycline-inducible shRNA-mediated APC silencing specifically in the intestine and colon of adult mice. Most importantly, APC loss can be reversed simply by withdrawal of doxycycline, restoring the endogenous tumor suppressor network. In Aim 1 I will define the requirement for sustained APC loss in the maintenance of benign and dysplastic lesions, which represent the initiation of carcinogenesis in the colon and mirror the early stage tumors that develop in patients with Familial Adenomatous Polyposis (FAP). In addition, I will use the same transgenic mouse model to develop and characterize and surrogate ex vivo culture system to examine the molecular consequences of APC restoration in early stage disease. Aim 2 expands on the systems developed in Aim 1 to investigate how recurrent genetic alterations acquired during progression to invasive and metastatic CRC (oncogenic Kras mutation and loss of p53) affect the response to Wnt inhibition. As Kras and/or p53 mutations are observed in ~80% of APC mutant tumors, understanding how these events contribute to Wnt- dependency is critical for future clinical applications of Wnt-targeted therapy. Finally, through characterisation of the tumor response to APC restoration and detailed analysis of resistant or relapsed, Wnt-independent disease, I aim to identify candidate genes/pathways that mediate resistance to Wnt inhibition with the vision that they will represent attractive targeted for combinatorial therapeutic approaches. The work outlined in this proposal will provide key insights into the role of commonly mutated genes in CRC and define factors that are essential for the growth and survival of CRC cells, representing potential targets for rational drug development. The reagents, tools and knowledge developed through this work will form the foundation of a flexible and innovative research program that has the potential to contribute significantly to the understanding and treatment of many forms of cancer.

描述（由申请人提供）：结直肠癌（CRC）非常普遍且难以治疗癌症。在疾病的晚期阶段，几乎没有有效的治疗方案，它使其成为发达国家与癌症相关死亡的第二大原因。与许多其他癌症治疗策略从靶向药物的发展中受益不同，CRC的护理标准仍然是细胞毒性化学疗法的结合。迫切需要更多针对性，毒性较小的治疗方法。定义针对癌症生长和进展的肿瘤特异性需求为药物靶标的发现提供了一个潜在的途径。该提案整合了新的遗传技术和离体培养系统，以表征CRC维持和进展的遗传需求，目的是鉴定可用于癌症治疗的肿瘤特异性弱点。腺瘤性息肉病（APC）肿瘤抑制剂的突变失活被认为是大多数家族性和零星结肠癌的起始事件。 APC破坏导致WNT途径的不受控制激活，因此，目前有重大的努力来开发选择性Wnt信号抑制剂以治疗CRC。然而，从良性腺瘤到CRC的进展涉及许多额外的遗传和表观遗传改变，最常见的是p53肿瘤抑制剂的丧失（60％）和/或KRAS的致癌激活（45％）。鉴于该疾病的复杂性质尚不清楚CRC是否仍取决于APC损失和Wnt过度激活的生长和生存，因此CRC是否会有效地治疗晚期恶性肿瘤。在这里，我将使用我开发的独特的转基因鼠标模型来解决这个出色但重要的问题，该模型允许对APC表达式进行时间，空间和可逆控制。该方法描述的方法结合了现有的和新型的小鼠菌株，使多西环素诱导的shRNA介导的APC沉默专门在成年小鼠的肠道和结肠中。最重要的是，APC损失可以通过撤回强力霉素来逆转，从而恢复内源性肿瘤抑制器网络。在AIM 1中，我将定义对维持良性和发育不良病变维持持续APC损失的要求，这代表了结肠中致癌作用的发生，并反映了家族性腺瘤性溶质膜（FAP）患者中发生的早期阶段肿瘤。此外，我将使用相同的转基因小鼠模型来开发和表征和替代体内培养系统，以检查早期疾病中APC恢复的分子后果。 AIM 2扩展了AIM 1中开发的系统，以研究在进展为侵入性和转移性CRC期间获得的复发遗传改变（致癌性KRAS突变和p53的损失）如何影响对WNT抑制的反应。由于在〜80％的APC突变肿瘤中观察到KRAS和/或p53突变，因此了解这些事件如何促进WNT依赖性对于WNT靶向疗法的未来临床应用至关重要。最后，通过表征肿瘤对APC恢复的反应以及对抗性或复发性，无关疾病的详细分析，我旨在鉴定候选基因/途径，这些基因/途径介导了对Wnt抑制的抑制性，即它们将代表针对组合治疗方法的有吸引力的视力。该提案中概述的工作将为CRC中普遍突变基因的作用提供关键见解，并定义了CRC细胞生长和存活至关重要的因素，代表了有理性的潜在目标。 药物开发。通过这项工作开发的试剂，工具和知识将构成灵活和创新的研究计划的基础，该计划有可能为多种形式的癌症的理解和治疗做出重大贡献。