Sekar Thillai V, Paulmurugan Ramasamy
Molecular Imaging Program at Stanford, Bio-X Program, Stanford University School of Medicine, 318 Campus Drive, Stanford, CA, 94305, USA.
Department of Radiology, Stanford University School of Medicine, 3155, Porter Drive, #2236, Palo Alto, CA, 94304, USA.
Methods Mol Biol. 2016;1461:241-54. doi: 10.1007/978-1-4939-3813-1_20.
Gene-directed enzyme prodrug therapy (GDEPT) is a promising therapeutic approach for treating cancers of various phenotypes. This strategy is independent of various other chemotherapeutic drugs used for treating cancers where the drugs are mainly designed to target endogenous cellular mechanisms, which are different in various cancer subtypes. In GDEPT an external enzyme, which is different from the cellular proteins, is expressed to convert the injected prodrug in to a toxic metabolite, that normally kill cancer cells express this protein. Theranostic imaging is an approach used to directly monitor the expression of these gene therapy enzymes while evaluating therapeutic effect. We recently developed a dual-GDEPT system where we combined mutant human herpes simplex thymidine kinase (HSV1sr39TK) and E. coli nitroreductase (NTR) enzyme, to improve therapeutic efficiency of cancer gene therapy by simultaneously injecting two prodrugs at a lower dose. In this approach we use two different prodrugs such as ganciclovir (GCV) and CB1954 to target two different cellular mechanisms to kill cancer cells. The developed dual GDEPT system was highly efficacious than that of either of the system used independently. In this chapter, we describe the complete protocol involved for in vitro and in vivo imaging of therapeutic cancer gene therapy evaluation.
基因导向酶前药疗法（GDEPT）是一种治疗多种表型癌症的有前景的治疗方法。该策略独立于用于治疗癌症的各种其他化疗药物，这些药物主要设计用于靶向内源性细胞机制，而这些机制在不同癌症亚型中有所不同。在GDEPT中，表达一种与细胞蛋白不同的外源酶，将注射的前药转化为有毒代谢物，通常杀死表达该蛋白的癌细胞。治疗性成像方法用于在评估治疗效果的同时直接监测这些基因治疗酶的表达。我们最近开发了一种双GDEPT系统，其中我们将突变型人单纯疱疹病毒胸苷激酶（HSV1sr39TK）和大肠杆菌硝基还原酶（NTR）酶结合起来，通过以较低剂量同时注射两种前药来提高癌症基因治疗的疗效。在这种方法中，我们使用两种不同的前药，如更昔洛韦（GCV）和CB1954，来靶向两种不同的细胞机制以杀死癌细胞。所开发的双GDEPT系统比单独使用的任何一种系统都更有效。在本章中，我们描述了用于治疗性癌症基因治疗评估的体外和体内成像的完整方案。
