The role of IL8 in colitis-associated tumor initiation

描述(申请人提供)：结肠炎相关癌症的发病机制尚不清楚。填补我们知识的这一空白是一个重要的挑战，因为如果不进行干预，高达18%的慢性溃疡性结肠炎(UC)患者将发展为结直肠癌。因此，我们的长期目标是通过确定炎症促进慢性溃疡性结肠炎患者恶变的机制来开发CAC的化学预防策略。这一特殊应用的目的是确定自分泌IL8如何有助于结肠炎来源的结肠癌起始细胞(CCICs)的致瘤性。与散发性结直肠癌来源的CCICs相似，UC来源的CCICs代表了一个很好的模型，可以用体外和体内分析来剖析结肠炎向癌症转化的机制。中心假说是结肠炎向癌症的转变需要IL8信号。这项拟议研究的基本原理是，一旦我们了解了IL8促进肿瘤发生的贡献和机制，我们就能够开发出干预从良性结肠炎到恶性肿瘤进展的方法。根据我们强大的初步数据，我们将通过追求三个特定目标来检验我们的假设：1)确定IL8对结肠CCICs来源的肿瘤的体内和体外形成的影响；2)确定IL8信号的下游介质对结肠CCICs诱导的肿瘤起始的影响；以及3)描述功能获得的p53突变在IL8诱导的肿瘤形成中的作用。在目标1中，我们将在涉及增殖、侵袭、肿瘤形成、血管生成和分化的检测中检测外源性IL8如何影响结肠炎来源的CCICs的行为。我们将同时抑制IL8及其主要受体CXCR1，并确定干扰如何影响这些致瘤试验。在目标2中，我们有证据表明粘着斑激酶(FAK)是IL8功能的下游调节因子。我们将使用RNAi抑制FAK，并在相同的致瘤试验中描述变化。目的3涉及我们在每个结肠炎来源的CCIC分离株中发现的R273Hp53功能获得突变。在其他系统中，这种突变与IL8的mRNA和与IL8相关的功能的增强有关。这种方法是创新的，因为我们有独特的工具，包括结肠炎的CCICs，并且可以使用散发性结直肠癌的CCICs进行比较。这项拟议的研究意义重大，因为它将极大地扩大我们对IL8如何导致结肠炎相关癌症的理解。 公共卫生相关性：拟议的研究与公共健康相关，因为发现IL-8如何维持和促进溃疡性结肠炎患者上皮细胞的结肠癌启动细胞的致瘤性将提供创新的治疗目标和策略。因此，拟议的研究与美国国立卫生研究院的任务有关，即发展基础知识，帮助减轻人类疾病和残疾的负担。

DESCRIPTION (provided by applicant): The pathogenesis of colitis-associated cancer is unclear. Filling this gap in our knowledge is an important challenge because without intervention, up to 18% of patients with chronic ulcerative colitis (UC) will develop colorectal cancer. Thus, our long-term goal is to develop chemopreventive strategies for CAC by defining the mechanisms by which inflammation promotes malignant transformation in patients with chronic ulcerative colitis. The objective of this particular application is to determine how autocrine IL8 contributes to the tumorigenicity of colitis-derived colon cancer initiating cells (CCICs). Similar to CCICs derived from sporadic colorectal cancer, CCICs from UC represent an excellent model for dissecting out mechanisms underlying the colitis-to-cancer transition using both in vitro and in vivo assays. The central hypothesis is that IL8 signaling is required fo the colitis-to-cancer transition. The rationale for the proposed research is that once we understand the contribution and mechanisms by which IL8 promotes tumor initiation, we will be able to develop ways to interfere in the progression from benign colitis to malignant cancer. Following up on our strong preliminary data, our hypothesis will be tested by pursuing three specific aims: 1) to define the effects of IL8 on the in vivo and in vitro formation of tumors derived from CCICs isolated from colitic colon, 2) to determine the influence of downstream mediators of IL8 signaling on the initiation of tumors induced by CCICs derived from colitic colon, and, 3) to delineate the contribution of gain-of-function p53 mutations to IL8-induced potentiation of tumorigenicity. In Aim 1, we will examine how exogenous IL8 influences the behavior of colitis-derived CCICs in assays involving proliferation, invasion, tumorigenesis, angiogenesis and differentiation. We will inhibit both IL8 and its dominant receptor, CXCR1, and determine how interference affects these tumorigenic assays. In Aim 2, we have evidence that Focal Adhesion Kinase (FAK) is a downstream mediator of IL8 function. We will inhibit FAK using RNAi and delineate alterations in the same tumorigenic assays. Aim 3 involves the R273H p53 gain-of-function mutation which we found in each of our colitis-derived CCIC isolates. In other systems, this mutation has been associated with potentiation of IL8 mRNA and functions associated with IL8. The approach is innovative, because we have unique tools including the CCICs from colitis, and can use CCICs from sporadic colorectal cancer for comparison. The proposed research is significant as it will greatly expand our understanding of how IL8 contributes to colitis-associated cancer. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because the discovery of how IL8 sustains and promotes the tumorigenicity of colon cancer initiating cells from the epithelium of ulcerative colitis patients will provide innovative therapeutic targets and strategies. Thus, the proposed research is relevant to the part of the NIH's mission that pertains to developing fundamental knowledge that will help to reduce the burdens of human illness and disability.