Imaging expression of cytosine deaminase-herpes virus thymidine kinase fusion gene (CD/TK) expression with [124I]FIAU and PET Journal Article
| Authors: | Hackman, T.; Doubrovin, M.; Balatoni, J.; Beresten, T.; Ponomarev, V.; Beattie, B.; Finn, R.; Bornmann, W.; Blasberg, R.; Tjuvajev, J. G. |
| Article Title: | Imaging expression of cytosine deaminase-herpes virus thymidine kinase fusion gene (CD/TK) expression with [124I]FIAU and PET |
| Abstract: | Double prodrug activation gene therapy using the Escherichia coli cytosine deaminase (CD)-herpes simplex virus type 1 thymidine kinase (HSV1-tk) fusion gene (CD/TK) with 5-fluorocytosine (5FC), ganciclovir (GCV), and radiotherapy is currently under evaluation for treatment of different tumors. We assessed the efficacy of noninvasive imaging with [124I]FIAU (2′-fluoro-2′-deoxy-1-β-D-arabinofuranosyl-5-iodo-uracil) and positron emission tomography (PET) for monitoring expression of the CD/TK fusion gene. Walker-256 tumor cells were transduced with a retroviral vector bearing the CD/TK gene (W2S6CD/TK cells). The activity of HSV1-TK and CD subunits of the CD/TK gene product was assessed in different single cell-derived clones of W256CD/TK cells using the FIAU radiotracer accumulation assay in cells and a CD enzyme assay in cell homogenates, respectively. A linear relationship was observed between the levels of CD and HSV1-tk subunit expression in corresponding clones in vitro over a wide range of CD/TK expression levels. Several clones of W256CD/TK cells with significantly different levels of CD/TK expression were selected and used to produce multiple subcutaneous tumors in rats. PET imaging of HSV1-TK subunit activity with [ 124I]FIAU was performed on these animals and demonstrated that different levels of CD/TK expression in subcutaneous W256CD/TK tumors can be imaged quantitatively. CD expression in subcutaneous tumor sample homogenates was measured using a CD enzyme assay. A comparison of CD and HSV1-TK subunit enzymatic activity of the CD/TK fusion protein in vivo showed a significant correlation. Knowing this relationship, the parametric images of CD subunit activity were generated. Imaging with [124I]FIAU and PET could provide pre- and posttreatment assessments of CD/TK-based double prodrug activation in clinical gene therapy trials. |
| Keywords: | genetics; genes; enzymology; tumor cells, cultured; gene vector; genetic vectors; gene expression regulation; hybrid protein; recombinant fusion proteins; radioactive iodine; cell culture; iodine radioisotopes; medical imaging; tumors; computer assisted emission tomography; drug derivative; uracil arabinoside; arabinofuranosyluracil; fialuridine; thymidine kinase; herpesvirus 1, human; herpes simplex virus 1; enzymes; tomography, emission-computed; gene expression regulation, enzymologic; cytosine deaminase; gene expression regulation, viral; cells; viruses; deaminase; humans; human; article; nucleoside deaminases; clinical gene therapy |
| Journal Title: | Molecular Imaging |
| Volume: | 1 |
| Issue: | 1 |
| ISSN: | 1535-3508 |
| Publisher: | Sage Publications, Inc. |
| Date Published: | 2002-01-01 |
| Start Page: | 36 |
| End Page: | 42 |
| Language: | English |
| PUBMED: | 12920859 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Export Date: 14 November 2014 -- Source: Scopus |
