Novel noncanonical actions of CAR in human Liver

CAR 在人类肝脏中的新的非常规作用

• 批准号: 10275448
• 负责人: Hongbing Wang
• 金额: $ 39.06万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-06 至 2026-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10275448
• 关键词: Affect; Agar; Amino Acids; Apoptosis; Apoptotic; Carcinogens; Cell Line; Cell Proliferation; Clinical; DNA biosynthesis; Data; Development; Diagnosis; Disease; Down-Regulation; Ectopic Expression; Environment; Erythropoietin; Erythropoietin Receptor; Event; Exhibits; Gene Cluster; Genes; Genetic Transcription; Growth; Growth Factor; Hepatic; Hepatocarcinogenesis; Hepatocyte; Homeostasis; Human; Human Activities; In Vitro; Incidence; Knowledge; Lead; Liver; Liver neoplasms; Malignant neoplasm of liver; Mediating; Modeling; Molecular; Mus; Nuclear; Nude Mice; Oncogenes; Oncogenic; Outcome; Patient-Focused Outcomes; Pharmacology; Phenobarbital; Physiological; Play; Primary carcinoma of the liver cells; Prognosis; Protein Isoforms; Proteins; RNA Splicing; Rattus; Receptor Signaling; Repression; Rodent; Role; Sampling; Signal Transduction; Testing; Therapeutic; Tissues; Transgenic Mice; Transgenic Organisms; Tumor Promoters; Tumor Suppressor Proteins; Variant; Xenobiotics; Xenograft procedure; anti-cancer; base; constitutive androstane receptor; design; drug clearance; drug metabolism; epidemiology study; genetic approach; hepatoma cell; in vivo; insight; liver cell proliferation; migration; novel; novel marker; novel strategies; novel therapeutics; overexpression; response; sensor; transcriptome; transcriptome sequencing; tumor; tumor growth; tumor progression; tumor xenograft; tumorigenesis

Project Summary The constitutive androstane receptor (CAR; NR1i3) is a well-established xenobiotic sensor that regulates the expression of numerous genes encoding proteins important for drug metabolism and clearance. Accumulating evidence suggests that CAR also plays noncanonical roles in coordinating diverse physiological and pathophysiological responses associated with energy homeostasis and cell proliferation. Studies in rodents have established activation of CAR as a key event promoting liver tumor formation. In contrast, CAR activation- induced replicative DNA synthesis and hepatocyte proliferation in rodents were not observed in either cultured human liver cells in vitro or in chimeric mice with humanized liver in vivo. Moreover, epidemiological studies have shown that even after long-term clinical use, phenobarbital, a prototypical CAR activator, does not increase the incidence of liver tumors in humans. Yet, the role of human CAR (hCAR) in hepatoma cell proliferation and liver cancer development remains poorly understood. The overall objective of this application is to delineate the role of hCAR in liver tumor progression and to develop a comprehensive understanding of the molecular mechanisms underlying the effects of hCAR on hepatoma cell proliferation. To this end, we have shown that 1) expression of hCAR was significantly lower in hepatocellular carcinoma (HCC) compared to normal liver and, importantly, hCAR expression is inversely correlated with HCC outcomes; 2) ectopic expression of the reference hCAR but not a splicing variant isoform (hCAR3) in hepatoma cells markedly repressed cell proliferation, soft agar colony formation, and the growth of hepatoma xenografts in nude mice; 3) RNA-seq analyses revealed that hCAR alters the expression of a cluster of tumor suppressors and oncogenes including the downregulation of erythropoietin (EPO), a pleiotropic growth factor that exhibits cell proliferation and anti-apoptosis functions; and 4) activation of human and mouse CAR differentially alters the expression of cell proliferation genes in vivo. Based on these exciting preliminary findings, we hypothesize that in stark contrast to its rodent counterparts, hCAR exhibits anticancer functions that repress the progression of HCC by downregulating EPO. This central hypothesis will be tested in two Specific Aims: Aim 1. Define the role of hCAR isoforms in hepatoma cell proliferation and HCC progression; and Aim 2. Delineate the mechanisms by which hCAR represses HCC progression. Our findings are expected to determine the role of hCAR in HCC development and provide novel mechanistic insights into hCAR-mediated suppression of HCC progression that will open the door to novel biomarkers and therapeutics.

项目摘要 组成型雄甾烷受体（CAR; NR 113）是一种公认的外源性生物素传感器，其调节 许多编码对药物代谢和清除重要的蛋白质的基因的表达。积累 有证据表明，CAR在协调多种生理和 与能量稳态和细胞增殖相关的病理生理反应。在啮齿类动物中的研究 建立了CAR激活作为促进肝肿瘤形成的关键事件。相反，CAR激活- 在啮齿类动物中，在两种培养物中均未观察到诱导的复制DNA合成和肝细胞增殖。 体外人肝细胞中或体内具有人源化肝的嵌合小鼠中。此外，流行病学研究表明， 表明即使在长期临床使用后，苯巴比妥（一种典型的CAR激活剂）也不会增加 人类肝脏肿瘤的发病率。然而，人CAR（hCAR）在肝癌细胞增殖和肝细胞凋亡中的作用尚不清楚。 癌症的发展仍然知之甚少。本申请的总体目标是描述 hCAR在肝肿瘤进展中的作用，并全面了解其分子机制 hCAR对肝癌细胞增殖的影响。为此，我们已经表明，1）表达 与正常肝脏相比，hCAR在肝细胞癌（HCC）中显著降低，重要的是， hCAR表达与HCC结果呈负相关; 2）参考hCAR的异位表达， 肝癌细胞中的非剪接变体同种型（hCAR 3）显著抑制细胞增殖，软琼脂集落 3）RNA-seq分析显示hCAR改变了hCAR在裸鼠中的表达， 一组肿瘤抑制因子和癌基因的表达，包括促红细胞生成素的下调 (EPO)，一种显示细胞增殖和抗凋亡功能的多效性生长因子;和4）激活 人和小鼠CAR在体内差异性地改变细胞增殖基因的表达。基于这些 令人兴奋的初步发现，我们假设，在鲜明的对比，其啮齿类动物的对应物，hCAR表现出 通过下调EPO抑制HCC进展的抗癌功能。这一核心假设将 在两个具体目标中进行测试：目标1。确定hCAR亚型在肝癌细胞增殖和HCC中的作用 目标2;目标2。描述hCAR抑制HCC进展的机制。我们的研究结果 预计将确定hCAR在HCC发展中的作用，并提供新的机制见解， hCAR介导的HCC进展抑制将为新型生物标志物和治疗方法打开大门。