Human Copper Transporter 1 as Reporter Gene for Imaging

描述（由申请人提供）：监测转基因表达对人类基因治疗的有效性和安全性至关重要。利用报告基因来监测基因在靶组织中的传递和表达是一种创新的分子成像技术。报告基因与治疗基因同时传递后，来自报告基因的成像信号间接反映了治疗基因在体内的分布和表达。由于目前可用的报告基因存在一些局限性，因此有必要寻找新的报告基因，以便在其他报告基因的使用受到限制时使用。人类铜转运蛋白1 （hCtrl）基因编码一个高亲和力的铜转运蛋白。内源性hCtrl在肝脏中高表达，在肝外组织中表达较低。在这里，我们假设hCtrl可能被用作PET在体内成像基因传递的报告基因。我们将针对两个具体目标进行探索性实验。目的1：以人宫颈癌异种移植小鼠为实验动物模型，探讨Cu-64 PET能否对肿瘤组织中hCtrl过表达进行无创定量成像。目的2：以人神经母细胞瘤异种移植小鼠为动物模型，评价利用hCtrl作为报告基因，通过Cu-64 PET成像转录靶向hCtrl表达至肿瘤过表达N-MYC癌蛋白的可行性。与其他报告基因相比，这种新的报告基因可能具有独特的特点：1)hCtrl不会刺激人体免疫反应，有望用于无创和定量的转基因表达纵向监测；2) hCtrl报告基因在前列腺癌基因治疗中，由于其在膀胱中的背景活性很小，因此有望在靶向基因传递成像中发挥特别重要的作用；3) hCtrl有潜力作为一种治疗基因，基于其药物顺铂细胞摄取的能力。这项初步研究的数据将帮助我们确定hCtrl作为报告基因用于成像是否可行。该新hCtrl报告基因的成功开发有望通过提供一个多功能报告基因，通过PET成像无创和定量地纵向监测转基因在体内的表达，从而为人类基因治疗的发展做出重大贡献。

DESCRIPTION (provided by applicant): It is essential to monitor transgene expression for efficacy and safety of human gene therapy. Use of a reporter gene to monitor gene delivery and expression in targeted tissue represents an innovative molecular imaging technique. After simultaneous delivery of a reporter gene with a therapeutic gene, imaging signals from a reporter gene indirectly reflect the distribution and expression of a therapeutic gene in vivo. Because there are some limitations associated with the reporter genes currently available, it is necessary to search for new reporter genes which may be used when use of other reporter genes is limited. Human copper transporter 1 (hCtrl) gene encodes a high affinity copper transporter. Endogenous hCtrl is highly expressed in liver, with much lower expression in extra-hepatic tissues. Here, we hypothesize that hCtrl may be used as a reporter gene for imaging gene delivery in vivo by PET. We will perform exploratory experiments with two specific aims. AIM 1: To determine whether over-expression of hCtrl in tumor tissue can be imaged non-invasively and quantitatively by Cu-64 PET, using human cervical carcinoma xenograft in mice as an experimental animal model. AIM 2: To evaluate feasibility using hCtrl as a reporter gene for imaging transcriptional targeting of hCtrl expression to tumor over-expressing N-MYC oncoprotein by Cu-64 PET, using human neuroblastoma xenograft in mice as an animal model. This new reporter gene may have unique desirable features in comparison to other reporter genes: 1) hCtrl will not stimulate immunological reaction in humans and is expected to be very useful for longitudinal monitoring of transgene expression non-invasively and quantitatively; 2) the hCtrl reporter gene is expected to be especially useful for imaging targeted gene delivery in prostate cancer gene therapy because there is little background activity in the urinary bladder; 3) hCtrl holds potential as a therapeutic gene based on its capability to medicate cellular uptake of cisplatin. The data from this pilot study will help us to determine whether it is feasible to use hCtrl as a reporter gene for imaging. Successful development of this new hCtrl reporter gene is expected to contribute to advance of human gene therapy significantly by providing a versatile reporter gene for longitudinal monitor of transgene expression in vivo non-invasively and qunatitatively by PET imaging.