Sodium lodide Symporter as an Imaging Reporter Gene

描述(由申请人提供)： Na+/I-转运体(NIS)是一种固有的膜糖蛋白，介导甲状腺滤泡细胞摄取活性碘。我们和其他人已经证明，NIS基因转移可以诱导多种细胞摄取碘，并且表达外源NIS的异种移植可以在体内成像。这些数据表明，基于NIS摄取放射性碘的能力，可以在体内定量测量NIS的表达和功能。因此，NIS可能作为一个成像报告基因(“lmagene”)来优化载体传递，监测治疗性基因的表达，并在体内定位再生的祖细胞的组织/器官位置。拟议的项目旨在解决对NIS作为成像仪的有用性至关重要的两个参数：可接受的信噪比以及基因表达与测量的信号水平之间存在线性关系的条件。我们假设，这两个参数将根据靶细胞和体内宿主环境而变化。我们将确定不同信噪比组织中NIS表达水平的相对重要性以及体内成像所需的NIS表达细胞的数量。目的1.确定与培养细胞中放射性碘蓄积相关的NIS表达水平的范围；目的2.确定异种皮下移植体内成像所需的NIS表达水平和细胞数；目的3.研究不同信噪比下体内成像所需的不同NIS表达水平；以及目的4.评价NIS作为影像报告基因在临床前动物模型中监测治疗性基因表达的可行性。拟议研究的成功将使我们能够使用NIS作为成像剂进行人类临床试验，以确保有针对性和有效的基因转移，并跟踪体内重新繁殖的祖细胞。

DESCRIPTION (provided by applicant): Na+/I- symporter (NIS) is an intrinsic membrane glycoprotein that mediates active iodide uptake into thyroid follicular cells. We and others have shown that NIS gene transfer can induce iodide uptake into a variety of cells and that xenografts expressing exogenous NIS could be imaged in vivo. These data suggest that NIS expression and function could be measured quantitatively in vivo based on NIS' ability to uptake radioiodide. Thus, NIS may serve as an imaging reporter gene ("lmagene") to optimize vector delivery, to monitor therapeutic gene expression, and to map the tissue/organ sites of repopulated progenitor cells in vivo. The proposed project aims to address the two parameters that are vital to the usefulness of NIS as an Imagene: acceptable signal-to-noise ratio and conditions in which a linear relationship exists between gene expression and measured signal levels. We hypothesize that these two parameters will vary, based upon target cells and in vivo host environment. We will determine the relative importance of NIS expression levels and the number of NIS expressing cells required for in vivo imaging in tissues of different signal to noise ratios. Four specific aims are identified: Aim 1. Determine the range of NIS expression levels that correlate with radioiodide accumulation in cultured cells; Aim 2. Determine the NIS expression levels and the number of NIS expressing cells required for in vivo imaging in subcutaneous xenografts; Aim 3. Investigate the different NIS expression levels required for in vivo imaging in internal organs with different signal to noise ratios; and Aim 4. Evaluate the feasibility of NIS as an imaging reporter gene to monitor therapeutic gene expression in a preclinical animal model. The success of the proposed studies will allow us to proceed to human clinical trials using NIS as an Imagene to ensure targeted and effective gene transfer and to track repopulated progenitor cells in vivo.