Demonstration of Tightly Radiation-Controlled Molecular Switch Based on CArG Repeats by In Vivo Molecular Imaging.

Autor: Hsieh, Ya-Ju, Hwu, Luen, Ke, Chien-Chih, Huang, Ai-Lin, Chen, Fu-Du, Wu, Shyh-Jong, Chen, Sharon, Zhao, Yong-Hua, Liu, Ren-Shyan, Chen, Sharon Chia-Ju
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Zdroj: Molecular Imaging & Biology; Dec2015, Vol. 17 Issue 6, p802-810, 9p
Abstrakt: Purpose: Promoters developed for radiogene therapy always show non-negligible transcriptional activities, even when cells are not irradiated. This study developed a tightly radiation-controlled molecular switch based on radiation responsive element (CArG) repeats for in vivo molecular imaging using the Cre/loxP system.Procedures: Different numbers of CArG repeats were cloned as a basal promoter directly, and its pre- and postirradiation transcriptional activities were analyzed by luciferase assay. Nine CArG repeats (E9) were chosen for use as a radiation-controlled molecular switch for the Cre/loxP system, and the feasibility of the switch in vitro and in vivo was demonstrated by luciferase assay and bioluminescence imaging, respectively.Results: The E9 promoter, which exhibits extremely low transcriptional activity, showed a 1.8-fold enhancement after irradiation with a clinical dose of 2 Gy. Both in vitro and in vivo results indicated that E9 is relatively inert but sufficient to trigger the Cre/loxP system. The luciferase activity of stable H1299/pSTOP-FLuc cells transfected with pE9-NLSCre and exposed to 2-Gy radiation can reach 44 % of that of the same cells transfected with pCMV-NLSCre and not subjected to irradiation. By contrast, no appreciable difference was observed in reporter gene expression in both H1299/pSTOPFluc cells and tumors transfected with pE4Pcmv-NLSCre before and after irradiation, because the strong basal transcriptional activity of the CMV promoter, which acts as a copartner of E4, masked the response of E4 to radiation.Conclusions: Our results provide detailed insight into CArG elements as a radiation-controlled molecular switch that can facilitate the development of radiogene therapy. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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