The Role of Klotho Beta in Colorectal Cancer Tumorigenesis

摘要 结直肠癌(CRC)是美国第三大最常见和最致命的癌症。尽管最近 在治疗方面的进展，由于多种因素，包括延迟诊断， 化疗耐药性和疾病异质性。肠内分泌蛋白信号转导途径的改变 由成纤维细胞生长因子受体4及其配体成纤维细胞生长因子19组成的成分 (FGF19)和共同受体Klotho Beta(KLB)最近被认为与多种癌症有关。具体到CRC， 尽管FGF19和FGFR4有更明确的致癌功能，但KLB的作用仍然难以捉摸。一个 这项拟议研究的目的是描述KLB在结直肠癌中的作用。这项工作是以分析为基础的 来自癌症基因组图谱(TCGA)数据库的CRC RNA-seq数据一直显示出显著的 在CRC中的抑制普遍存在于所有的亚型中。总体而言，有必要进一步调查和研究 验证KLB在结直肠癌中的作用，重点研究KLB如何在较大范围内调节致癌的FGFR4-FGF19信号 上皮-间充质转化(EMT)和肿瘤发生的背景。因此，我们的总体假设是KLb 通过负向调节致癌基因，促进EMT，显示结直肠癌的肿瘤抑制特性 FGFR4-FGF19信号转导。具体目标1将通过分析详细的临床参数来验证假设 信息学评估KLB缺陷对结直肠癌预后的价值并揭示其对肿瘤动力学的影响 体外和体内。我们的初步数据显示，KLb具有肿瘤抑制因子样的特性，因为它直接表达 与治疗成功、微卫星稳定性、存活率相关，与病理分期呈负相关。 此外，KLb的下调早在腺瘤阶段就发生了，进一步得到了CRC细胞系的支持 显示与分化状态直接相关的全球KLb抑制的面板。最后，KLb表达式 在两个单独的体外CRC分化模型中增强，其转基因过表达 与CrisprCas9诱导的HT29细胞相比，HT29细胞的细胞组织化和极化程度增加 打倒在地。具体目标2将通过测试FGFR4-FGF19信号转导AS来研究KLB的作用机制 KLB影响结直肠癌的主要效应途径。为了支持这一目标，我们提出了令人信服的新 初步证据表明，KLb的表达与法尼类X受体(FXR)呈正相关。 已知的肿瘤抑制因子和FGFR4信号的靶点，在临床数据中，从而表明可能 相声。此外，FXR的化学激动剂在体外可诱导Caco 2细胞表达KLb。通过执行 通过这些研究，我们期望(I)确定KLB在结直肠癌中的临床意义，以及(Ii)证明KLB影响 结直肠癌通过调节FGFR4-FGF19信号机制发挥作用。总体而言，这项研究将建立一个试探性的 KLb在结直肠癌中的作用以及它的存在如何影响致癌的FGFR4-FGF19信号。这样做的最终目的是 建议利用KLb的表达来预测预后、治疗反应并作为潜在的 改善结直肠癌患者预后的治疗目标。

Abstract Colorectal cancer (CRC) is both the third most common and deadliest cancer in the United States. Despite recent advances in treatment, the 5-year survival rate remains poor due to multiple factors including delayed diagnosis, chemoresistance, and disease heterogeneity. Altered expression of enteroendocrine protein signaling components consisting of Fibroblast Growth Factor Receptor 4 (FGFR4), its ligand Fibroblast Growth Factor 19 (FGF19), and co-receptor Klotho Beta (KLB) recently have been implicated in various cancers. Specific to CRC, the role of KLB remains elusive, although FGF19 and FGFR4 have more established oncogenic functions. An objective of this proposed research is to delineate KLB’s function in CRC. The work is predicated on the analysis of CRC RNA-seq data from The Cancer Genome Atlas (TCGA) database consistently showing significant repression in CRC generally and across all subtypes. Collectively, it is necessary to further investigate and validate KLB’s role in CRC, focusing on how KLB modulates oncogenic FGFR4-FGF19 signaling in the larger context of epithelial-mesenchymal transition (EMT) and tumorigenesis. Thus, our overall hypothesis is that KLB demonstrates tumor suppressor properties in CRC by negatively regulating oncogenic, EMT-promoting FGFR4-FGF19 signaling. Specific Aim 1 will test the hypothesis by analyzing detailed clinical parameters via informatics to assess the prognostic value of KLB deficiency in CRC and reveal its impact on tumor dynamics in vitro and in vivo. Our preliminary data reveals tumor-suppressor-like properties of KLB as its expression is directly associated with treatment success, microsatellite stability, survivability and inversely with pathologic stage. Additionally, KLB downregulation occurs as early as the adenoma stage further supported by a CRC cell line panel showing global KLB repression which directly correlated with differentiation status. Finally, KLB expression was enhanced in two separate in vitro CRC models of differentiation and its transgenic overexpression was associated with increased cellular organization and polarization of HT29 cells compared to CrisprCas9-induced knock down. Specific Aim 2 will investigate KLB’s mechanism of action by testing FGFR4-FGF19 signaling as the major effector pathway through which KLB affects CRC. In support of this Aim, we present compelling new preliminary evidence showing that KLB expression positively correlates with Farnesoid-X-Receptor (FXR), a known tumor suppressor and target of FGFR4 signaling, within the clinical data thereby indicating possible crosstalk. Additionally, chemical agonism of FXR induces KLB expression in Caco2 cells in vitro. By performing these studies, we expect to (i) Establish KLB’s clinical implications in CRC, and (ii) Demonstrate that KLB affects CRC mechanistically through regulation of FGFR4-FGF19 signaling. Overall, this study will establish a tentative role for KLB in CRC and how its presence impacts oncogenic FGFR4-FGF19 signaling. The ultimate goal of this proposal is to utilize KLB expression to predict prognosis, treatment response and serve as a potential therapeutic target for improving CRC patient outcomes.