Role of an RNA-Binding Protein in Mammary Carcinogenesis

该提案研究了RNA结合癌蛋白在乳腺肿瘤发生中的作用。这 蛋白质位于细胞质中，与胰岛素样生长因子-11、p-肌动蛋白、c-myc等结合。 MRNAs。我们称其为c-myc编码区不稳定决定簇结合蛋白或CRD-BP。因为它 与c-myc mRNA编码区的一个不稳定决定簇结合。CRD-BP影响RNA翻译， 稳定性和局部化，取决于它与之结合的RNA。它在胎儿组织中大量表达。 但在出生后不久就被压抑了。因此，它可能在胎儿生活中具有特殊的作用。还有三个发现 CRD-BP与乳腺癌的关系：(A)CRD-BP在正常乳腺组织中检测不到，但在乳腺癌中存在 -60%的人类乳房肿瘤，(B)CRD-BP基因在-30%的人类乳房肿瘤中扩增，(C) CRD-BP诱导雌性转基因小鼠乳腺癌的研究三个目标使用转基因小鼠 目的：探讨该RNA结合癌蛋白诱发乳腺肿瘤的途径。 目的I.确定是否需要持续表达CRD-BP来维持现有的乳房 肿瘤。转基因小鼠的乳腺肿瘤继续表达CRD-BP，因此可能是CRD-BP- 依赖于他们的生存。为了研究这个想法，Aim I利用了一个小鼠模型，在这个模型中，乳房- 四环素类似物多西环素(DOX)可诱导CRD-BP的特异性表达。乳腺肿瘤是 预计会出现在接受DOX治疗的小鼠身上。我接着问：这些肿瘤在服用DOX后是否停止生长或消退？ 被撤回了吗？我们的工作假设是，当CRD-BP的表达被抑制时，肿瘤会退化。 目的II.应用微阵列分析比较正常乳腺组织中的基因表达谱 在表达或不表达CRD-BP的小鼠的组织和纯化的乳腺上皮细胞中。一些慢性阻塞性肺疾病- BP调控的RNAs可能在乳腺肿瘤的诱导和维持中发挥中心作用。 目的III.确定遗传和环境因素如何在年内促进乳腺肿瘤的发生 表达CRD-BP的小鼠。目标是评估肿瘤抑制因子Ape和这种化学物质是如何 致癌物N-乙基-N-亚硝脲(ENU)影响CRD-BP介导的肿瘤形成。我们预测心尖缺乏症 ENU治疗将与CRD-BP协同作用，增加肿瘤发生率和恶性肿瘤。 许多研究得很好的癌蛋白是转录因子或蛋白激酶。CRD-BP是一种 不同寻常的癌蛋白，因为它驻留在细胞质中并与RNA结合。通过调查致癌因素 CRD-BP的性质，它在体内影响的RNA，以及它与诱发肿瘤的遗传和 环境因素，我们希望揭示新的肿瘤发生途径。

This proposal investigates the role of an RNA-binding oncoprotein in mammary tumorigenesis. This protein is located in the cytoplasm and binds to insulin-like growth factor-ll, p-actin, c-myc, and other mRNAs. We call it the c-myc Coding Region instability Determinant-binding Protein or CRD-BP. because it binds to an instability determinant in the c-myc mRNA coding region. The CRD-BP affects RNA translation, stability, and localization, depending on the RNA to which it binds. It is expressed abundantly in fetaltissues but is repressed shortly after birth. Therefore, it probably has a special role in fetal life. Three findings also link the CRD-BP to breast cancer: (a) The CRD-BP is undetectable in normal breast tissue but is present in -60% of human breast tumors, (b) The CRD-BP gene is amplified in -30% of human breast tumors, (c) The CRD-BP induces mammary adenocarcinomas in female transgenic mice. Three aims use transgenic mice to investigate the pathways of mammary tumor induction by this RNA-binding oncoprotein. Aim I. Determine if CRD-BP expression is required continuously to maintain an existing mammary tumor. Mammary tumors in transgenic mice continue to express the CRD-BP and thus might be CRD-BP- dependent for their survival. To investigate this idea, Aim I exploits a mouse model in which mammary- specific CRD-BP expression is induced by doxycycline (dox), a tetracycline analog. Mammary tumors are expected to arise in dox-treated mice. Aim I then asks: Do these tumors stop growing or regress when dox is withdrawn? Our working hypothesis is that tumors will regress when CRD-BP expression is repressed. Aim II. Use microarray analysis to compare gene expression profiles in nori-neoplastic mammary tissues and in purified mammary epithelial cells of mice that do or do not express the CRD-BP. Some CRD- BP-regulated RNAs could play central roles in the induction and maintenance of mammary tumors. Aim III. Determine how genetic and environmental factors contribute to mammary tumorigenesis in CRD-BP-expressing mice. The goal is to assess how the tumor suppressor Ape and the chemical carcinogen N-ethyl-N-nitrosurea (ENU) affect CRD-BP-mediated tumor formation. We predict Apedeficiency and ENU treatment will synergize with the CRD-BP to increase tumor incidence and malignancy. Many of the well-studied oncoproteins are transcription factors or protein kinases. The CRD-BP is an unusual oncoprotein, because it resides in the cytoplasm and binds to RNA. By investigating the oncogenic properties of the CRD-BP, the RNAs it affects in vivo, and its interactions with tumor-inducing genetic and environmental factors, we hope to uncover novel tumorigenesis pathways.