Purpose: To demonstrate the efficacy of repeated, non-invasive optical imaging of reporter gene expression in monitoring the ability of bi-specific recombinant molecules (i) to "transductionally untarget" adenovirus from Coxsackie and Adenovirus Receptor (CAR)-dependent infection of normal tissue and (ii) to "transductionally retarget" infection to specific target cells. Procedures: sCAR-EGF is a recombinant, bi-specific molecule conta ining the soluble portion of CAR fused to Epidermal Growth Factor. The sCAR moiety binds to the virus and blocks CAR-dependent adenovirus infection. The EGF moity binds to cellular EGF receptors. We used non-invasive optical imaging of firefly luciferase to repeatedly monitor, in living animals, the ability of sCAR-EGF (i) to "transductionally untarget" systemically administered Ad.CMVfLuc, an adenovirus that constitutively expresses luciferase, from normal tissues and (ii) to "transductionally redirect" adenovirus infection in mice to xenograft tumors that express elevated epidermal growth factor (EGF) receptor levels. Results: Systemic injection of sCAR-EGF "coated" adenovirus expressing firefly luciferase from the CMV early promoter, reduces expression of the reporter gene in the liver and facilitates expression of the reporter gene in tumor xenografts expressing high levels of the EGF-receptor. Conclusion: Both liver "untargeting" and tumor "retargeting" of adenovirus by recombinant sCAR-EGF can be imaged non-invasively using a luciferase reporter gene.
Bibliographical noteFunding Information:
These studies were supported by the In vivo Molecular and Cellular Imaging Center award P50 CA86306 from the National cancer institute and by Grant RO1 CA84572 from the National Cancer Institute (HH), by grants DK063615-01 and DAMD17-03-1-0104 (MY) and CRAD (R01 CA94084) and DOD W81XWH-04-1-0025 (DC). We thank Arthur Catapang, Raymond Basconcillo, Julie Nguyen, and Yusuke Inoue for help with several of the experiments, and the members of the Herschman research group and the UCLA Molecular Imaging community for helpful discussions.
- Gene therapy
- Molecular imaging
- Noninvasive imaging
- Optical imaging
- Transcriptional restriction