TY - JOUR
T1 - A human-derived reporter gene for noninvasive imaging in humans
T2 - Mitochondrial thymidine kinase type 2
AU - Ponomarev, Vladimir
AU - Doubrovin, Michael
AU - Shavrin, Aleksander
AU - Serganova, Inna
AU - Beresten, Tatiana
AU - Ageyeva, Ludmila
AU - Cai, Changde
AU - Balatoni, Julius
AU - Alauddin, Mian
AU - Gelovani, Juri
PY - 2007/5/1
Y1 - 2007/5/1
N2 - A human-derived intrinsically nonimmunogenic reporter gene was tested for PET imaging of different molecular-genetic processes for potential clinical use. Methods: The human mitochondrial thymidine kinase type 2 (hTK2) reporter gene truncated at the N terminus (ΔhTK2), alone or fused with green fluorescent protein (GFP), was used for preclinical evaluation in a mouse model. The levels of enzymatic activity of ΔhTK2 and ΔhTK2 GFP proteins were assessed using radiotracer accumulation and prodrug activation assays in vitro and in subcutaneous tumors grown from the corresponding cell lines in nude mice. Kinetic analyses of 124I-2′-fluoro-2′-deoxy-1-β-D- β-arabinofuranosyl-5-iodouracil (FIAU), 18F-2′-fluoro- 2′-deoxy-1-β-D-β-arabinofuranosyl-5-ethyluracil (FEAU), or 18F-9-(4-18F-fluoro-3-hydroxymethylbutyl)guanine (FHBG) uptake in tumors and biodistribution studieswere performed. Results: ΔhTK2 was successfully expressed in the cytoplasm of transduced cells. A new anti-hTK2 monoclonal antibody 8G2 was developed. The levels of FIAU and FEAU accumulation in cells expressing ΔhTK2 and ΔhTK2 GFP were at least 10-fold higher than in wild-type cells in vitro and about 6 times higher in vivo. We determined that FEAU is a more specific reporter substrate for ΔhTK2 than FIAU, whereas FHBG is not phosphorylated by this enzyme. In addition, we showed that ΔhTK2 transduced cells can be eliminated by treatment with D-arabinofuranosyl-cytosine. Conclusion: We have tested a human-derived reporter gene that is likely to be non-immunogenic and potentially allows for long-term monitoring of different molecular-genetic processes by nuclear imaging techniques in humans. Using 124I-FIAU, 18F-FIAU, or 18F-FEAU, it should be possible to image ΔhTK2 reporter gene expression with PET in preclinical and clinical studies.
AB - A human-derived intrinsically nonimmunogenic reporter gene was tested for PET imaging of different molecular-genetic processes for potential clinical use. Methods: The human mitochondrial thymidine kinase type 2 (hTK2) reporter gene truncated at the N terminus (ΔhTK2), alone or fused with green fluorescent protein (GFP), was used for preclinical evaluation in a mouse model. The levels of enzymatic activity of ΔhTK2 and ΔhTK2 GFP proteins were assessed using radiotracer accumulation and prodrug activation assays in vitro and in subcutaneous tumors grown from the corresponding cell lines in nude mice. Kinetic analyses of 124I-2′-fluoro-2′-deoxy-1-β-D- β-arabinofuranosyl-5-iodouracil (FIAU), 18F-2′-fluoro- 2′-deoxy-1-β-D-β-arabinofuranosyl-5-ethyluracil (FEAU), or 18F-9-(4-18F-fluoro-3-hydroxymethylbutyl)guanine (FHBG) uptake in tumors and biodistribution studieswere performed. Results: ΔhTK2 was successfully expressed in the cytoplasm of transduced cells. A new anti-hTK2 monoclonal antibody 8G2 was developed. The levels of FIAU and FEAU accumulation in cells expressing ΔhTK2 and ΔhTK2 GFP were at least 10-fold higher than in wild-type cells in vitro and about 6 times higher in vivo. We determined that FEAU is a more specific reporter substrate for ΔhTK2 than FIAU, whereas FHBG is not phosphorylated by this enzyme. In addition, we showed that ΔhTK2 transduced cells can be eliminated by treatment with D-arabinofuranosyl-cytosine. Conclusion: We have tested a human-derived reporter gene that is likely to be non-immunogenic and potentially allows for long-term monitoring of different molecular-genetic processes by nuclear imaging techniques in humans. Using 124I-FIAU, 18F-FIAU, or 18F-FEAU, it should be possible to image ΔhTK2 reporter gene expression with PET in preclinical and clinical studies.
KW - FEAU
KW - FIAU
KW - Human mitochondrial thymidine kinase
KW - Molecular imaging
KW - PET
UR - http://www.scopus.com/inward/record.url?scp=34250672869&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34250672869&partnerID=8YFLogxK
U2 - 10.2967/jnumed.106.036962
DO - 10.2967/jnumed.106.036962
M3 - Article
C2 - 17468435
AN - SCOPUS:34250672869
SN - 0161-5505
VL - 48
SP - 819
EP - 826
JO - Journal of Nuclear Medicine
JF - Journal of Nuclear Medicine
IS - 5
ER -