PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers Journal Article
| Authors: | Likar, Y.; Dobrenkov, K.; Olszewska, M.; Shenker, L.; Cai, S.; Hricak, H.; Ponomarev, V. |
| Article Title: | PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers |
| Abstract: | Purpose: The aim of this study was to create an alternative mutant of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene with reduced phosphorylation capacity for acycloguanosine derivatives, but not pyrimidine-based compounds that will allow for successful PET imaging. Methods: A new mutant of HSV1-tk reporter gene, suitable for PET imaging using pyrimidine-based radiotracers, was developed. The HSV1-tk mutant contains an arginine-to-glutamine substitution at position 176 (HSV1-R176Qtk) of the nucleoside binding region of the enzyme. Results: The mutant-gene product showed favorable enzymatic characteristics toward pyrimidine-based nucleosides, while exhibiting reduced activity with acycloguanosine derivatives. In order to enhance HSV1-R176Qtk reporter activity with pyrimidine-based radiotracers, we introduced the R176Q substitution into the more active HSV1-sr39tk mutant. U87 human glioma cells transduced with the HSV1-R176Qsr39tk double mutant reporter gene showed high <sup>3</sup>H-FEAU pyrimidine nucleoside and low <sup>3</sup>H-penciclovir acycloguanosine analog uptake in vitro. PET imaging also demonstrated high <sup>18</sup>F-FEAU and low <sup>18</sup>F-FHBG accumulation in HSV1-R176Qsr39tk+ xenografts. The feasibility of imaging two independent nucleoside-specific HSV1-tk mutants in the same animal with PET was demonstrated. Two opposite xenografts expressing the HSV1-R176Qsr39tk reporter gene and the previously described acycloguanosine-specific mutant of HSV1-tk, HSV1-A167Ysr39tk reporter gene, were imaged using a short-lived pyrimidine-based <sup>18</sup>F-FEAU and an acycloguanosine-based <sup>18</sup>F-FHBG radiotracer, respectively, administered on 2 consecutive days. Conclusion: We conclude that in combination with acycloguanosine-specific HSV1-A167Ysr39tk reporter gene, a HSV1-tk mutant containing the R176Q substitution could be used for PET imaging of two different cell populations or concurrent molecular biological processes in the same living subject. © 2009 Springer-Verlag. |
| Keywords: | controlled study; unclassified drug; gene mutation; genetics; mutation; nonhuman; positron emission tomography; neoplasm; neoplasms; mouse; animal; metabolism; animals; mice; animal tissue; amino acid substitution; animal experiment; animal model; gene product; aciclovir; in vitro study; tumor xenograft; enzymology; molecular imaging; cell line, tumor; pyrimidines; phosphorylation; physiology; genetic transduction; gene expression regulation; gene expression regulation, neoplastic; chemistry; diagnostic agent; glioma cell; substrate specificity; tumor cell line; positron-emission tomography; retrovirus vector; radiopharmaceutical agent; scintiscanning; reporter gene; binding site; thymidine kinase; genes, reporter; herpesvirus 1, human; radioactive tracers; tracer; pyrimidine derivative; enzyme specificity; pet; herpes simplex virus 1; glutamine; arginine; feau; fhbg; hsv1-tk; 2' fluoro 2' deoxy 1 beta dextro arabinofuranosyl 5 ethyluracil f 18; 9 [4 fluoro 3 (hydroxymethyl)butyl]guanine f 18; aciclovir derivative; nucleoside; pyrimidine; virus mutant; antiviral resistance; acyclovir; drug resistance, viral |
| Journal Title: | European Journal of Nuclear Medicine and Molecular Imaging |
| Volume: | 36 |
| Issue: | 8 |
| ISSN: | 1619-7070 |
| Publisher: | Springer |
| Date Published: | 2009-08-01 |
| Start Page: | 1273 |
| End Page: | 1282 |
| Language: | English |
| DOI: | 10.1007/s00259-009-1089-x |
| PUBMED: | 19259663 |
| PROVIDER: | scopus |
| PMCID: | PMC4416642 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 3" - "Export Date: 30 November 2010" - "CODEN: EJNMA" - "Source: Scopus" |
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