Functional role of STRAP in colorectal cancer metastasis and in chemoresistance

项目总结/摘要 尽管结肠直肠癌（CRC）治疗后复发率高， 癌症干细胞样细胞在实体瘤中的研究进展缓慢，但由于对肿瘤干细胞的认识有限， 结直肠癌上皮干细胞的层次结构和疾病的复杂异质性。最近的证据表明， 结直肠肿瘤包含一小部分的癌干细胞样细胞，其接种肿瘤块，并且可以是 负责转移、对治疗的抗性和肿瘤复发。其他（Buess等人，（2004）我们 （Halder等，2006）已经表明，STRAP（丝氨酸苏氨酸激酶受体相关蛋白）是一种与人的细胞增殖相关的蛋白。 在结直肠癌（包括转移）中显著上调，在CRC中上调STRAP 化疗患者的生存率更差，这表明其对化疗的潜在贡献。 侵袭性疾病和化学抗性。因此，理解STRAP在CRC中的功能作用 转移、维持癌症干细胞样细胞和化学抗性是非常关键的。 我们发现了一种新的WD结构域蛋白，称为STRAP，它与TGF-β 1和TGF-β 2都结合， 受体复合物和Smad7，并抑制TGF-β信号传导。我们已经证明，STRAP在 几种癌症，诱导上皮向间充质（EMT）转化（Kashikar et al，2010），并促进细胞增殖。 在体外以TGF-β 1非依赖性方式抑制肿瘤生长和致瘤性（Halder等，2006）。我们的初步数据 表明STRAP调节MMPs的表达以及Wnt/β-catenin和Notch信号传导。以确定 关于STRAP在体内的作用，我们最近已经产生了Strap基因敲除小鼠，其在9.5 民主党。当使用氧化偶氮甲烷治疗Strap杂合子小鼠时， 与野生型小鼠相比。为了研究STRAP在器官特异性方面的作用，我们还 使用Cre-lox方法产生条件性敲除小鼠。因此，对TGF-β的了解很少， STRAP在肠癌转移和化疗耐药中独立作用。基于背景 根据这些信息和我们的初步结果，我们提出了以下假设： 在结直肠癌转移中起着积极的作用，它与Wnt/β-连环蛋白和 Notch通路参与结肠癌干细胞样细胞的自我更新和化疗耐药。以下 具体的目的是为了验证这些假设：目的1：确定如何STRAP的机制 有助于结直肠癌转移。目的2：确定STRAP在维护和自我管理中的作用。 结肠癌干细胞样细胞的更新。目的3：确定STRAP在调节化疗耐药性中的作用。 结肠直肠癌 影响：尽管治疗方案的发展，转移仍然是最关键的 生存的决定因素，因为转移性结直肠癌患者的中位生存期为5个月， 老兵此外，耐药性和癌症复发是影响生存率的另外两个关键因素 CRC的因素。完成所提出的目标将揭示新的功能，STRAP在CRC 转移、干细胞样细胞自我更新和耐药性。该项目的成果将提供强有力的 通过靶向STRAP来开发治疗这种非靶向侵袭性疾病的治疗剂的翻译潜力。 这项基础和临床前生物医学研究将包括两个特别感兴趣的优先研究领域， BLR & D，与吸烟和女性健康相关的危险行为（RFA #BX-16 - 001）。

Project Summary/Abstract Despite the high rate of recurrence following therapy in colorectal cancer (CRC) and relatively rapid pace of cancer stem-like cell research in solid tumors, researches are impeded due to limited knowledge of the CRC epithelial stem cell hierarchy and complex heterogeneity of the disease. Recent evidences suggest that colorectal tumors comprise a small fraction of cancer stem-like cells that seed the tumor bulk and may be responsible for metastasis, resistance to therapy, and tumor recurrence. Others (Buess et al., 2004) and we (Halder et al, 2006) have shown that STRAP (Serine Threonine Kinase Receptor Associated Protein) is significantly upregulated in colorectal carcinomas including metastases, and upregulation of STRAP in CRC patients contributes to worse survival with chemotherapy, suggesting its potential contribution to the aggressive disease and chemoresistance. Therefore, understanding the functional role of STRAP in CRC metastasis, in the maintenance of cancer stem-like cells, and in chemoresistance is very crucial. We identified the novel WD-domain containing protein called STRAP that binds with both TGF-ß receptor complex and Smad7, and inhibits TGF-ß signaling. We have shown that STRAP is upregulated in several cancers, induces epithelial-to-mesenchymal (EMT) transition (Kashikar et al, 2010), and promotes cell growth and tumorigenicity in vitro in a TGF-ß-independent manner (Halder et al, 2006). Our preliminary data suggest that STRAP regulates the expression of MMPs, and Wnt/ß-catenin and Notch signaling. To determine the role of STRAP in vivo, we have recently generated Strap knock out mice, which is embryonic lethal at 9.5 dpc. Azoxymethane treatment of the Strap heterozygous mice produces fewer and smaller tumors when compared with wild type mice. To study the effect of STRAP in an organ specific manner, we have also generated conditional knock out mice using the Cre-lox approach. Therefore, little is known about the TGF-ß- independent role of STRAP in intestinal cancer metastasis and chemoresistance. Based on the background information and our preliminary results, we have formulated the following hypotheses: Upregulation of STRAP in colorectal cancer plays an active role in metastasis and its functional interaction with Wnt/ß-catenin and Notch pathway is involved in colon cancer stem-like cell self-renewal and chemoresistance. The following Specific Aims are proposed to test these hypotheses: Aim 1: Determine the mechanism of how STRAP contributes to colorectal cancer metastasis. Aim 2: Determine the role of STRAP in the maintenance and self- renewal of colon cancer stem-like cells. Aim 3: Determine the role of STRAP in regulating chemoresistance of colorectal cancer. Impact: Despite the development of treatment regimens, metastasis remains the most critical determinant of survival, as median survival for patients with metastatic colorectal cancer is 5 months among veterans. Moreover, drug resistance and relapse of cancers are the other two critical survival-influencing factors of CRC. Completion of the proposed aims will uncover the novel function of STRAP in CRC metastasis, stem-like cell self-renewal, and drug resistance. The outcome of this project will provide strong translational potential to develop therapeutics by targeting STRAP for this un-targetable aggressive disease. This basic and preclinical biomedical research will include two priority research areas of specific interest to BLR&D, risky behavior related to smoking and women's health (RFA# BX-16-001).