KLF4 Genetic and Epigenetic Changes in Human Pancreatic Cancer

描述(申请人提供)：我们最近的研究表明，KLF4蛋白表达增加抑制了人胰腺癌的生长，而KLF4表达下调则相反。此外，我们还在人胰腺癌细胞中鉴定了三个KLF4选择性剪接变异体和一个点突变KLF4。其中一种剪接变体KLF41的实验强制表达促进了肿瘤的生长。然而，KLF4表达和功能改变在胰腺癌发病机制中的作用机制尚不清楚。我们推测KLF4的遗传和表观遗传学改变影响其肿瘤抑制功能，并参与胰腺癌的发病。为了验证我们的假设，我们提出了以下三个具体目标。具体目标1将检验这样一个假设，即遗传和表观遗传改变导致KLF4表达和功能改变，并影响胰腺癌的临床结果。KLF4基因(突变和LOH)和表观遗传学(启动子高甲基化和选择性剪接)的变化及其在胰腺癌发病机制中的临床意义将被确定。特定目标2将检验KLF4异常表达和功能促进肿瘤生长和转移的假设。KLF4表达和功能的改变对恶性表型的影响将通过体外和动物模型来确定，重点是人胰腺癌细胞的血管生成表型。具体目标3将验证以下假设：改变KLF4的表达和功能会导致Sp1表达失调，而Sp1和KLF4的表达和功能不平衡会导致Sp1主要调控的促血管生成因子的表达增加。KLF4的表达和功能改变对人胰腺癌细胞中Sp1及其下游分子的表达和功能的影响将被确定。这三个具体目标得到了我们各自的初步数据的支持，可以利用我们独特的研究资源进行独立测试，但它们高度相关，相互支持。我们预测，这些研究的完成将为胰腺癌发病的分子遗传学基础和识别分子靶点以设计有效的治疗策略提供有洞察力的信息。从长远来看，我们的研究还可以进一步研究KLF4表达和功能失控的分子机制。公共卫生相关性：KLF4是一种新发现的在胃肠道癌症中可能的肿瘤抑制因子。然而，KLF4信号在人类肿瘤尤其是胰腺癌的发生和发展中的关键作用尚不清楚。

DESCRIPTION (provided by applicant): Our recent studies have shown that increased KLF4 protein expression suppressed the growth of human pancreatic cancer, whereas knockdown of KLF4 expression did the opposite. Moreover, we have identified three KLF4 alternative splice variants and a point-mutant KLF4 in human pancreatic cancer cells. Experimentally enforced expression of one of the splice variant, KLF41, promoted tumor growth. However, the underlying mechanisms for the impact of altered KLF4 expression and function on pancreatic cancer pathogenesis are unclear. We postulate that genetic and epigenetic changes of KLF4 impact its tumor suppressor function and contribute to pancreatic cancer pathogenesis. To test our hypothesis, we propose the following three specific aims. Specific Aim 1 will test the hypothesis that genetic and epigenetic alterations lead to altered KLF4 expression and function and affect pancreatic cancer clinical outcome. Genetic (mutation and LOH) and epigenetic (promoter hypermethylation and alternative splicing) changes of KLF4 and their clinical significance in pancreatic cancer pathogenesis will be determined. Specific aim 2 will test the hypothesis that aberrant KLF4 expression and function promotes tumor growth and metastasis. Impacts of altered KLF4 expression and function on the malignant phenotype with a focus on angiogenic phenotype of human pancreatic cancer cells will be determine using in vitro and animal models. Specific Aim 3 will test the hypothesis that altered KLF4 expression and function results in dysregulated Sp1 expression and the imbalanced expression and function of Sp1 and KLF4 leads to an increased expression of pro-angiogenic factors that are predominantly regulated by Sp1. Impacts of altered expression and function of KLF4 on the expression and function of Sp1 and its downstream molecules in human pancreatic cancer cells will be determined. These three specific aims are supported by our respective preliminary data and can be tested independently using our unique research resources, yet they are highly interrelated and support one another. We predict that completion of these studies will provide insightful information for the molecular genetic basis of pancreatic cancer pathogenesis and for identification of molecular targets to design effective therapeutic strategies. In the long term, our study also can lead to further investigation of the molecular mechanisms mediating disregulated KLF4 expression and function. PUBLIC HEALTH RELEVANCE: KLF4 is a newly identified putative tumor suppressor in gastrointestinal cancers. However, the critical role of KLF4 signaling in human cancer development and progression in general and human pancreatic cancer in particular is unclear.