, Volume 22, Issue 9, pp 1471-1479

99mTc-EC-Guanine: Synthesis, Biodistribution, and Tumor Imaging in Animals

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DNA markers are useful in assessing cell proliferation. The purpose of this study was to synthesize 99mTc-ethylenedicysteine-guanine (EC-Guan) for evaluation of cell proliferation.


Tumor cells were incubated with 99mTc-EC-Guan for cell cycle analysis. Prostate tumor cells that were overexpressing the HSV thymidine kinase gene, or various tumor cells were incubated with 99mTc-EC-Guan at 0.5–2 h. Thymidine incorporation assays were performed in lung cancer cells incubated with EC-Guan at 0.1–1 mg/well. Tissue distribution, autoradiography, and planar scintigraphy of 99mTc-EC-Guan and 99mTc-EC (control) were determined in tumor-bearing rodents at 0.5–4 h.


Cell culture assays indicated that EC-Guan was incorporated in DNA, and there was no significant uptake difference between HSVTK overexpressed and normal groups. Biodistribution and scintigraphic imaging studies of 99mTc-EC-Guan showed increased tumor/tissue count density ratios as a function of time.


Our results indicate that 99mTc-EC-Guan may be useful as a tumor proliferation imaging agent.