Evaluating the utility of human glucagon-like peptide 1 receptor gene as a novel radionuclide reporter gene: a promising molecular imaging tool
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Radiolabelled ligands of glucagon-like peptide 1 receptor (GLP-1R) have been used to image the GLP-1R-expressing tissues (e.g., islets and insulinoma). Here, we introduced human glucagon-like peptide 1 receptor (hglp-1r) gene as a novel radionuclide reporter gene to broaden its applications in molecular imaging in vivo. Transient and stable baculoviral vectors (BV) were re-constructed and used to transfer the hglp-1r gene or enhanced green fluorescent protein (egfp) reporter gene into the stem cells or tumor cells. Cell proliferation assay and flow cytometry analysis demonstrated that BV-mediated reporter gene transferring and expression was biosafe and highly efficient. The BV-mediated exogenous hGLP-1R in target cells showed same ligand-receptor binding characteristics compared with its counterpart in insulinoma cells. Furthermore, the ligand-receptor binding assay showed a high affinity (IC50 = 0.3708 nM) and robust correlation (R2 = 0.9264) between the fluorescein-tagged or radiolabeled ligand probes and exogenous hGLP-1R in target cells. The target cells transferred with BV-mediated hGLP-1R could be clearly visualized in nude mice by micro-PET, which was capable of the purposes of short-term tracking transplanted stem cells or long-term monitoring tumor formation. Then, the image-based analysis and bio-distribution analysis quantitatively confirmed high target-to-background ratio of hGLP-1R-expressing cells. This study also investigated the endogenous GLP-1R-expressing organs/tissues in nude mice in the hGLP-1R radionuclide reporter gene imaging. Summarily, we evaluated the utility of hglp-1r gene as a novel radionuclide reporter gene, and demonstrated that it was a favorable and promising candidate of molecular imaging tool, which would expand the spectrum of radionuclide reporter gene imaging systems.
KeywordsHuman glucagon-like peptide 1 receptor Exendin-4 Molecular imaging Reporter gene imaging Baculovirus Stem cells
We would like to thank Prof. Dehua Yang for providing the hglp-1r-containing plasmid and the research group led by Prof. Ningli Li for the help in the flow cytometry analysis.
YP, MY, and YZ designed and coordinated the study; YP, JL, YX, and LZ performed the in vitro experiments; YP, JL, DP, and QZ performed the in vivo experiments; DP radiolabeled the probes; YP and JL wrote the initial manuscript; YP, HJ, and JZ did the data statistics and made the graphs and charts; YP and YZ contributed to the final manuscript. All authors read and approved the final manuscript.
This study was sponsored by the National Natural Science Foundation of China (81471688, 81671720, and 81801726), the Shanghai Sailing Program (18YF1414300), and the Jiangsu Province Science and Technology Foundation (BE2014609 and BE2016632).
Compliance with ethical standards
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
This study was approved by the ethic board of Ruijin Hospital. All animal experiments were approved by the Institutional Animal Care and Use Committee of Ruijin Hospital, and were performed according to the Animal Care and Use Guideline. The isolation procedure of hUC-MSCs was approved by the Tongji University Institutional Review Board, and performed with informed consent.
- Christ E, Wild D, Ederer S, Béhé M, Nicolas G, Caplin M, Brändle M, Clerici T, Fischli S, Stettler C, Ell P, Seufert J, Gloor B, Perren A, Reubi J, Forrer F (2013) Glucagon-like peptide-1 receptor imaging for the localisation of insulinomas: a prospective multicentre imaging study. Lancet Diabetes Endocrinol 1(2):115–122PubMedCrossRefGoogle Scholar
- Mikkola K, Yim C-B, Fagerholm V, Ishizu T, Elomaa V-V, Rajander J, Jurttila J, Saanijoki T, Tolvanen T, Tirri M, Gourni E, Behe M, Gotthardt M, Reubi JC, Macke H, Roivainen A, Solin O, Nuutila P (2014) 64Cu- and 68Ga-labelled [Nle14,Lys40(Ahx-NODAGA)NH2] -exendin-4 for pancreatic beta cell imaging in rats. Mol Imaging Biol 16(2):255–263PubMedCrossRefGoogle Scholar
- Pyke C, Heller RS, Kirk RK, Orskov C, Reedtz-Runge S, Kaastrup P, Hvelplund A, Bardram L, Calatayud D, Knudsen LB (2014) GLP-1 receptor localization in monkey and human tissue: novel distribution revealed with extensively validated monoclonal antibody. Endocrinology 155(4):1280–1290PubMedCrossRefGoogle Scholar