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 治疗的进步，5年生存率仍然很低，由于多种因素，包括延迟诊断， 化学抗性和疾病异质性。肠内分泌蛋白信号传导的表达改变 由成纤维细胞生长因子受体4（FGFR 4）、其配体成纤维细胞生长因子19 最近，FGF 19和共受体Klotho Beta（KLB）已经涉及各种癌症。具体到CRC， 尽管FGF 19和FGFR 4具有更确定的致癌功能，但KLB的作用仍然难以捉摸。一个 本研究的目的是阐明KLB在CRC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数据一致显示， 在CRC中普遍存在抑制，并跨越所有亚型。总的来说，有必要进一步调查， 验证KLB在CRC中的作用，重点是KLB如何调节较大肿瘤细胞中的致癌FGFR 4-FGF 19信号传导。 上皮-间质转化（EMT）和肿瘤发生的背景。因此，我们的总体假设是，KLB 在CRC中通过负调节致癌、EMT促进 FGFR 4-FGF 19信号传导。具体目标1将通过分析详细的临床参数来检验假设， 信息学评估KLB缺陷在CRC中的预后价值，并揭示其对肿瘤动力学的影响。 体外和体内。我们的初步数据揭示了KLB的肿瘤抑制样特性，因为它的表达是直接的。 与治疗成功率、微卫星稳定性、生存率相关，与病理分期呈负相关。 此外，KLB下调早在腺瘤阶段就发生，进一步得到CRC细胞系的支持 显示与分化状态直接相关的整体KLB抑制的图。最后，KLB表达式 在两种不同的体外大肠癌分化模型中， 与CrisprCas 9诱导的HT 29细胞相比， 打倒。具体目标2将通过测试FGFR 4-FGF 19信号传导来研究KLB的作用机制， KLB影响CRC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 初步证据显示KLB表达与法尼醇X受体（FXR）正相关， 已知的肿瘤抑制因子和FGFR 4信号传导的靶点，在临床数据中，从而表明可能的 串话此外，FXR的化学激动剂在体外诱导Caco 2细胞中的KLB表达。通过执行 这些研究，我们希望（i）建立KLB在CRC中的临床意义，（ii）证明KLB影响 CRC通过调节FGFR 4-FGF 19信号传导机制。总体而言，本研究将建立一个初步的 KLB在CRC中的作用及其存在如何影响致癌FGFR 4-FGF 19信号传导。这个项目的最终目标 建议利用KLB表达来预测预后、治疗反应并作为潜在的 用于改善CRC患者结局的治疗目标。

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.