The first reporter systems were developed in the early 1980s and were based on measuring the activity of an enzyme—as a surrogate measure of promoter-driven transcriptional activity—which is now known as a reporter gene system. The initial objective and application of reporter techniques was to analyze the activity of a specific promoter (namely, the expression of a gene that is under the regulation of the specific promoter that is linked to the reporter gene). This system allows visualization of specific promoter activity with great sensitivity. In general, there are 2 classes of reporter systems: constitutively expressed (always-on) reporter constructs used for cell tracking, and inducible reporter systems sensitive to endogenous signaling molecules and transcription factors that characterize specific tissues, tumors, or signaling pathways.

This review traces the development of different reporter systems, using fluorescent and bioluminescent proteins as well as radionuclide-based reporter systems. The development and application of radionuclide-based reporter systems is the focus of this review. The question at the end of the review is whether the “promise” of reporter gene imaging has been realized. What is required for moving forward with radionuclide-based reporter systems, and what is required for successful translation to clinical applications?

第一个报告系统是在1980年代初期开发的，其基础是测量酶的活性（作为启动子驱动的转录活性的替代指标），现在被称为报告基因系统。报告基因技术的最初目的和应用是分析特定启动子的活性（即，在与报告基因相连的特定启动子的调控下的基因表达）。该系统可以高度敏感地可视化特定启动子的活性。通常，有两类报告系统：用于细胞跟踪的组成型表达（始终在线）报告构建体，以及对表征特定组织，肿瘤或信号通路的内源信号分子和转录因子敏感的诱导型报告系统。

这篇综述追踪了使用荧光和生物发光蛋白以及基于放射性核素的报道系统的不同报道系统的发展。基于放射性核素的报告系统的开发和应用是本综述的重点。审查结束时的问题是报告基因成像的“承诺”是否已实现。基于放射性核素的报告系统向前发展需要什么？将其成功翻译成临床应用又需要什么？