Colorectal Cancer Prevention Through Thyroid Hormone Targets

通过甲状腺激素目标预防结直肠癌

• 批准号: 8616360
• 负责人: Adam Robert Brown
• 金额: $ 3.06万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8616360
• 关键词: Acute; Affect; Age; Aging; Alleles; Animals; Apoptosis; Cancer Etiology; Cessation of life; Clinical; Colon; Colon Adenocarcinoma; Colon Carcinoma; Colonic Adenoma; Colonic Neoplasms; Colorectal; Colorectal Cancer; Country; Data; Development; Diagnosis; Disease; Elderly; Epithelial Cells; Exhibits; Fatty-acid synthase; Genes; Goals; Hematoxylin and Eosin Staining Method; Hormonal Change; Human; Hypothyroidism; Immunohistochemistry; In Situ Nick-End Labeling; In Vitro; Incidence; Intestinal Neoplasms; Intestines; Knockout Mice; Large Intestine; Lead; Link; Malignant Neoplasms; Measures; Messenger RNA; Molecular; Monitor; Mucous Membrane; Mus; Mutate; Pathway interactions; Physiological; Play; Population; Prevention strategy; Preventive; Proteins; RNA; Rectum; Relative (related person); Role; S-Phase Fraction; Severities; Small Intestines; Staining method; Stains; Study models; Testing; Thyroid Gland; Thyroid Hormone Receptor beta 1; Thyroid Hormones; Time; Tissues; Tumor Suppression; Tumor Suppressor Proteins; Tumor Tissue; Western Blotting; Wild Type Mouse; adenoma; age effect; age related; aged; aging population; cancer prevention; cancer type; colorectal cancer prevention; hormone sensitivity; indexing; insight; novel; older patient; prevent; receptor; telomerase reverse transcriptase; therapeutic target; transcription factor; tumor; tumor growth; tumorigenesis

DESCRIPTION (provided by applicant): Colorectal cancer is the third most prevalent type of cancer and ranks second as the major cause of cancer-related deaths in the US population. The median age of diagnosis for colorectal cancer is 71, demonstrating that it is primarily a disease of old age. Studies have suggested that thyroid hormone may have a role in colon cancer prevention. Other studies have shown that many elderly patients exhibit sub-clinical hypothyroidism and decreased thyroid hormone sensitivity. Kr¿ppel-like factor 9 (KLF9) is a thyroid hormone- induced transcription factor, and a putative tumor suppressor of the human colo-rectum. The goal of this proposal is to investigate a proposed mechanism by which KLF9 prevents colorectal tumorigenesis in mice, and to evaluate the effects of aging on this relationship. My preliminary data suggest that KLF9 is a negative regulator of fatty acid synthase (FASN) in vitro, which is a gene commonly up-regulated in colon adenocarcinomas, and a potential therapeutic target for cancer. This application proposes two aims to test the hypothesis that aging, via acute reduction in circulating thyroid hormone and decreased thyroid hormone sensitivity, results in a reduction in colon mucosal expression of KLF9, which leads to increased expression of FASN. Further, we propose that KLF9 functions as a tumor suppressor of the colon, and that loss of Klf9 alleles will increase number and size of intestinal tumors in ApcMin/+ mice. Aim 1 seeks to determine if aging will, via decreased thyroid hormone sensitivity, decrease colonic expression of Klf9 and thereby increase colonic expression of Fasn in aged mice. Colons of mice at ages 6, 12, and 18 months will be collected and mucosal expression levels of Klf9 and Fasn will be evaluated at the mRNA and protein levels. Aim 2 will determine whether colonic expression of Klf9 affects intestinal tumorigenesis by crossing Klf9 knockout mice with ApcMin/+ mice and measuring tumor incidence and development. Small and large intestines will be removed from ApcMin/+ mice with two, one, or no Klf9 alleles and tumor number and sizes will be recorded. The largest adenomas will be subjected to immunohistochemistry to monitor phosphohistone H3, TUNEL, KLF9, and Tr¿1 expression. RNA and protein will be extracted from adenomas and uninvolved mucosa and expression levels of KLF9, TR¿1, FASN, and telomerase reverse transcriptase (TERT) will be evaluated by Western blot and qPCR. Finally, micro-adenomas will be quantified by H&E staining and counting. The successful completion of the study will provide insight into potential age-dependent targets that may lead to the development of new therapies to prevent or treat age-related colorectal cancer.

描述（由申请人提供）：结直肠癌是美国人口中第三大流行的癌症类型，在癌症相关死亡的主要原因中排名第二。结直肠癌的中位诊断年龄为71岁，这表明它主要是一种老年疾病。研究表明，甲状腺激素可能在预防结肠癌中起作用。其他研究表明，许多老年患者表现为亚临床甲状腺功能减退，甲状腺激素敏感性下降。KLF9是一种甲状腺激素诱导的转录因子，被认为是人类结直肠的肿瘤抑制因子。本研究的目的是研究KLF9预防小鼠结直肠肿瘤发生的机制，并评估衰老对这一关系的影响。我的初步数据表明，KLF9在体外是脂肪酸合成酶（FASN）的负调控因子，FASN是大肠癌中普遍上调的基因，是癌症的潜在治疗靶点。本申请提出了两个目的，以验证衰老通过循环甲状腺激素的急性减少和甲状腺激素敏感性的降低导致结肠粘膜KLF9表达减少，从而导致FASN表达增加的假设。此外，我们提出KLF9作为结肠肿瘤抑制因子，KLF9等位基因的缺失会增加ApcMin/+小鼠肠道肿瘤的数量和大小。Aim 1旨在确定衰老是否会通过降低甲状腺激素敏感性，降低老年小鼠结肠中Klf9的表达，从而增加结肠中Fasn的表达。收集6月龄、12月龄和18月龄小鼠结肠，从mRNA和蛋白水平评估Klf9和Fasn的粘膜表达水平。Aim 2将通过Klf9敲除小鼠与ApcMin/+小鼠杂交，测量肿瘤的发生率和发展，来确定Klf9的结肠表达是否影响肠道肿瘤的发生。将有两个、一个或没有Klf9等位基因的ApcMin/+小鼠的小肠和大肠切除，记录肿瘤的数量和大小。对最大的腺瘤进行免疫组化，监测磷酸组蛋白H3、TUNEL、KLF9和Tr¿1的表达。从腺瘤和未受损伤的粘膜中提取RNA和蛋白质，并通过Western blot和qPCR检测KLF9、TR¿1、FASN和端粒酶逆转录酶（TERT）的表达水平。最后，通过H&E染色和计数对微腺瘤进行定量。该研究的成功完成将为潜在的年龄依赖性靶点提供见解，这可能导致开发新的治疗方法来预防或治疗与年龄相关的结直肠癌。