Elucidating the Role of SMAD4 in Colorectal Cancer

项目概要/摘要 结肠癌是美国癌症相关死亡的第二大原因，也是最好的癌症之一。 根据其常见的基因突变来表征实体瘤。然而，知识差距存在于 基本了解这些癌症的遗传特征下游。例如，肿瘤抑制因子 SMAD 4基因在大约57%的结肠肿瘤中发生突变，并且与结肠癌的预后不良相关。 患者，但仍然很少了解其在结肠癌中的分子机制。此外，本发明还 虽然约70%的结肠癌遵循典型的WNT驱动的腺瘤到癌的途径， 20%遵循“锯齿状肿瘤途径”-通常由功能获得性BRAF突变驱动， 结肠癌的预后。该提案的主要目标将侧重于阐明 结肠癌中的肿瘤抑制因子SMAD 4。假设SMAD 4在转录调控中起关键作用， 在调节WNT途径中具有调节作用，并且是锯齿状肿瘤途径中的关键调节剂。的 基本原理是基于初步研究，这些研究揭示：1）SMAD 4与基因组的调节区域结合 也被β-连环蛋白结合，β-连环蛋白是最常见的突变信号通路的转录效应子， 结肠癌，WNT通路; 2）SMAD 4丢失，当与BRAF激活结合时，可以触发 锯齿状肿瘤的形成在小鼠中快达1个月。Aim 1将使用表观基因组方法来绘制 SMAD 4与β-连环蛋白在DNA结合水平上的相互作用-详细描述了这些相互作用的第一个交叉点。 结肠癌基因组上的通路。Aim 2将使用新的小鼠模型来确定SMAD 4 抑制锯齿状癌从增生性病变向发育不良的转变。目标3将使用国家的- 本发明的肿瘤类器官模型系统以确定SMAD 4如何抑制锯齿状癌转移。目标 SMAD 4通过重定向β-连环蛋白直接调节WNT信号通路 与RUNX 3协调作用于肿瘤抑制基因靶点，从而影响癌症发展，以及2） SMAD 4抑制锯齿状肿瘤进展所需的关键信号通路， 转移拟议的研究意义重大，因为它们将确定一种常见的 突变的肿瘤抑制基因，并提出了一个新的角度对研究不足，但更致命的，结肠 癌症肿瘤类型这些研究将在癌症研究领域产生广泛的影响，并将揭示新的 以识别和治疗锯齿状肿瘤患者。在Michael Verzi博士和 罗纳德哈特，这个建议的训练计划将为我过渡到独立做好准备，1）继续 提高我的表观基因组学技能，2）开发新的模型系统来解决结肠中的关键问题 癌症领域，和3）加强所需的技能，建立和维护我自己的独立研究计划。 罗格斯大学遗传学系一直是我博士后的杰出机构 培训，我将大大受益于环境，因为我过渡到独立。

Project Summary/Abstract Colon cancer is the 2nd-leading cause of cancer-related deaths in the United States and is one of the best- characterized solid tumors in terms of its common genetic mutations. However, knowledge gaps exist in the basic understanding of these cancers downstream of their genetic profile. For instance, the tumor-suppressor gene SMAD4 is mutated in approximately 57% of all colon tumors, and is associated with poor prognosis in patients, yet there is still little understanding of its molecular mechanisms in colon cancer. Additionally, while ~70% of colon cancers follow the typical WNT-driven adenoma-to-carcinoma pathway, approximately 20% follow the “serrated tumor pathway”- often driven by gain-of-function BRAF mutations and have the worst prognosis of colon cancers. The proposal’s main objective will focus on elucidating the mechanistic role of the tumor suppressor SMAD4 in colon cancers. The hypothesis is that SMAD4 plays a critical transcriptional regulatory role in regulating the WNT pathway and is a key regulator in the serrated tumor pathway. The rationale is based on preliminary studies that reveal: 1) that SMAD4 binds to regulatory regions of the genome also bound by ß-catenin – the transcriptional effector of the most commonly mutated signaling pathway in colon cancer, the WNT pathway; and 2) SMAD4 loss, when combined with activation of BRAF, can trigger serrated tumor formation as rapidly as 1 month in mice. Aim 1 will use epigenomic approaches to map the interaction of SMAD4 with ß-catenin at the level of DNA-binding - detailing the first intersection of these pathways on the colon cancer genome. Aim 2 will use new mouse models to determine how SMAD4 suppresses the serrated cancer transition from hyperplastic lesions to dysplasias. Aim 3 will use state-of-the- art tumor organoid model systems to determine how SMAD4 suppresses serrated cancer metastasis. The goal is to test the hypotheses that 1) SMAD4 directly regulates the WNT-signaling pathway by redirecting ß-catenin to tumor-suppressive gene targets in coordination with RUNX3, thus impacting cancer development, and 2) that SMAD4 suppresses key signaling pathways that are required for serrated tumor progression and metastasis. The proposed studies are significant in that they will identify the regulatory targets of a commonly mutated tumor-suppressor gene and present a new perspective on an understudied, but more deadly, colon cancer tumor type. These studies would have broad impacts in the cancer research field, and will reveal new targets to identify and treat patients with serrated tumors. With the co-mentorship of Drs. Michael Verzi and Ronald Hart, this proposal's training plan will prepare me for a transition to independence by 1) continuing to enhance my epigenomics skillset, 2) develop novel model systems to address critical questions in the colon cancer field, and 3) fortify the skills required to establish and maintain my own independent research program. The Department of Genetics at Rutgers University has been an outstanding institution for my postdoctoral training, and I will benefit greatly from the environment as I transition towards independence.