In-vivo PET imaging of inducible D2R reporter transgene expression using [11C]FLB 457 as reporter probe in living rats.
BACKGROUND
Increasing interest is being shown in a variety of methods for the in-vivo monitoring of gene expression. Of these, the reporter assay using positron emission tomography (PET) has been studied most extensively.


METHODS
We evaluated tetracycline-induced gene expression using a PET reporter method employing the dopamine type 2 receptor (D2R) gene as a reporter gene and [(11)C]FLB 457 as a reporter probe. We constructed a plasmid containing the D2R gene, whose expression was under the control of the tetracycline-responsive element, and transfected it into HeLa-Tet-On cells. D2R messenger RNA (mRNA) expression was measured by reverse transcription-polymerase chain reaction (RT-PCR) and D2R binding in the cultured cells was measured by a binding assay using methoxy-[(3)H]raclopride as a ligand. The tetracycline analogue, doxycycline, was used to regulate D2R expression.


RESULTS
Doxycycline dose- and exposure time-dependent D2R transgene expression was observed in the mRNA measurements and receptor binding in the cells. The stably transfected cells were inoculated into nude rats and D2R expression in xenograft tumours was monitored by in-vivo receptor binding using PET. Doxycycline-dependent D2R expression was also observed in this in-vivo system. The correlation between the magnitude of the [(11)C]FLB 457 PET signal and the D2R-expressing cell fraction in the tumours showed the usefulness of the D2R-FLB 457 reporter gene-reporter probe system with PET for the quantitative evaluation of inducible in-vivo gene expression.


CONCLUSIONS
The D2R-FLB 457 reporter gene-reporter probe system should be considered as a useful technique for measuring inducible in-vivo gene expression.
Aung
Winn
W
Redox Regulation Research Group, National Institute of Radiological Sciences, Chiba 263-8555, Japan.
Okauchi
Takashi
T
Sato
Masaaki
M
Saito
Toshiyuki
T
Nakagawa
Hidehiko
H
Ishihara
Hiroshi
H
Ikota
Nobuo
N
Suhara
Tetsuya
T
Anzai
Kazunori
K
D000818:Animals; D030801:Animals, Genetically Modified / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D049268:Positron-Emission Tomography / Q000379:methods*; D011759:Pyrrolidines / Q000493:pharmacokinetics*; D051381:Rats; D011923:Rats, Nude; D017448:Receptors, Dopamine D2 / Q000235:genetics* / Q000378:metabolism*; D012457:Salicylamides / Q000493:pharmacokinetics*; D014162:Transfection / Q000379:methods; D019076:Transgenes / Q000235:genetics
D002250:Carbon Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C065065:FLB 457