Role of Nmi in retarding breast tumor growth.

Nmi 在延缓乳腺肿瘤生长中的作用。

• 批准号: 8038299
• 负责人: Rajeev S Samant
• 金额: $ 26.9万
• 依托单位: UNIVERSITY OF SOUTH ALABAMA
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-04 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8038299
• 关键词: Agonist; Biological; Biological Products; Breast Cancer Cell; Cancer Biology; Cancer cell line; Cell Proliferation; Cells; Chemical Agents; Colon Carcinoma; Data; Development; Developmental Biology; Disease; Event; Genetic Transcription; Interferons; Invaded; Laboratories; Laboratory Research; Malignant - descriptor; Malignant Neoplasms; Mammary Neoplasms; Mediating; Messenger RNA; Nude Mice; Pathway interactions; Patients; Pharmacologic Substance; Primary Neoplasm; Proteins; Regulation; Reporting; Research; Role; Signal Pathway; Signal Transduction; Specimen; Testing; Therapeutic; Up-Regulation; Work; Xenograft procedure; drug development; in vivo; inhibitor/antagonist; interest; malignant breast neoplasm; mimetics; neoplastic cell; public health relevance; small molecule; tumor; tumor growth; tumor progression

DESCRIPTION (provided by applicant): Research in our laboratory focuses on understanding the role of N-Myc interactor (Nmi) in cancer biology [1]. Our interest in this molecule was triggered when we saw that its expression was diminished in aggressive breast cancer cell lines. Interestingly though, Nmi expression could be induced in these cells using interferon-? (IFN-?) [1]. We found that the induced mRNA had a wild type sequence, implying that the induced Nmi protein was capable of its normal biological activities. To test its functional role, we constitutively expressed Nmi in the human breast cancer cell line, MDA-MB- 231. Functional studies of the expressors showed that Nmi reduced the ability of tumor cells to invade and grow under anchorage independent conditions. Xenograft studies in nude mice showed that Nmi expressors had reduced tumor growth in vivo [1]. Further analysis of these expressors revealed that Dickkopf-1 (Dkk1), a soluble inhibitor of the Wnt/?- catenin signaling pathway, was significantly upregulated in the Nmi expressing clones concurrent with reduced levels of the critical transcription co-factor of Wnt pathway, ?-catenin. Dkk1 has been reported to suppress primary tumor growth rates in several studies involving breast cancer [2, 3] and is a factor implicated in the anti-tumor effects elicited by IFN-? [4]. Wnt/?-catenin signaling is important in development as well as cell proliferation. While previously shown to be a critical player in colon cancer progression, the role of Wnt/?-catenin signaling in breast cancer is not clearly defined [5]. The overall objective of this proposed work is to understand the regulation of Wnt/?-catenin signaling by Nmi and to determine the role of this pathway in suppression of breast tumor growth. HYPOTHESIS Inhibition of the Wnt/?-catenin signaling pathway by upregulation of Dkk1 is critical to the role of Nmi in reducing tumor growth. Aim 1: To test the hypothesis that knockdown of Nmi expression will activate the Wnt/?-catenin signaling. Aim 2: To determine the mechanism of regulation of Dkk1 and ?-catenin by Nmi. Aim 3: To evaluate the role of Dkk1 in mediating the retardation of tumor growth by Nmi. Aim 4: To determine correlation between loss of Nmi expression and activated Wnt/?-catenin signaling in patient derived breast cancer specimens. PUBLIC HEALTH RELEVANCE: Our preliminary data demonstrates a functional role of Nmi in retarding breast tumor growth. This proposal takes the research to a next essential step in establishing the translational potential of Nmi and the downstream events that it regulates. The focus of this research is the Wnt/?-catenin pathway. Nmi up-regulates Dkk1, a secreted inhibitor of Wnt pathway, leading us to propose that Nmi down regulates Wnt/?-catenin signaling, resulting in reduced malignant activity of breast cancer.

描述（由申请人提供）：我们实验室的研究重点是了解 N-Myc 相互作用子 (Nmi) 在癌症生物学中的作用 [1]。当我们看到这种分子的表达在侵袭性乳腺癌细胞系中减少时，我们对这种分子产生了兴趣。但有趣的是，可以使用干扰素-α在这些细胞中诱导 Nmi 表达。 （干扰素-？）[1]。我们发现诱导的mRNA具有野生型序列，这意味着诱导的Nmi蛋白能够发挥其正常的生物活性。为了测试其功能作用，我们在人乳腺癌细胞系 MDA-MB-231 中组成型表达 Nmi。表达子的功能研究表明，Nmi 降低了肿瘤细胞在不依赖贴壁的条件下侵袭和生长的能力。裸鼠异种移植研究表明，Nmi 表达蛋白可减少体内肿瘤生长[1]。 对这些表达子的进一步分析表明，Wnt/β-连环蛋白信号通路的可溶性抑制剂 Dickkopf-1 (Dkk1) 在 Nmi 表达克隆中显着上调，同时 Wnt 通路关键转录辅因子 β-连环蛋白水平降低。据报道，在几项涉及乳腺癌的研究中，Dkk1 可以抑制原发性肿瘤的生长速度 [2, 3]，并且是 IFN-α 引起的抗肿瘤作用的一个因素。 [4]。 Wnt/β-连环蛋白信号传导在发育和细胞增殖中很重要。虽然之前已证明 Wnt/β-连环蛋白信号在结肠癌进展中发挥着关键作用，但其在乳腺癌中的作用尚未明确定义 [5]。 这项工作的总体目标是了解 Nmi 对 Wnt/β-连环蛋白信号传导的调节，并确定该途径在抑制乳腺肿瘤生长中的作用。 假设 通过上调 Dkk1 抑制 Wnt/β-catenin 信号通路对于 Nmi 减少肿瘤生长的作用至关重要。 目标 1：检验 Nmi 表达敲低将激活 Wnt/β-连环蛋白信号传导的假设。 目标 2：确定 Nmi 对 Dkk1 和 β-catenin 的调节机制。 目标 3：评估 Dkk1 在介导 Nmi 延缓肿瘤生长中的作用。 目标 4：确定患者来源的乳腺癌样本中 Nmi 表达缺失与激活的 Wnt/β-连环蛋白信号传导之间的相关性。 公共健康相关性：我们的初步数据证明了 Nmi 在延缓乳腺肿瘤生长方面的功能作用。该提案将研究推进到下一个重要步骤，以确定 Nmi 及其调节的下游事件的转化潜力。本研究的重点是Wnt/β-连环蛋白途径。 Nmi 上调 Dkk1（一种 Wnt 通路的分泌抑制剂），因此我们提出 Nmi 下调 Wn​​t/β-连环蛋白信号传导，从而降低乳腺癌的恶性活性。