Biodistribution of 99mTc-GE11 molecular probe and receptor imaging in nude mice bearing lung adenocarcinoma

Abstract

Objective To prepare a 99mTc-labled molecular probe (99mTc-GE11) targeting epidermal growth factor receptor (EGFR) on lung adenocarcinoma cells and evaluate its biodistribution and performance for EGFR imaging in nude mice bearing lung adenocarcinoma xenografts. Methods GE11 was labeled with 99mTc through oxidation and reduction of stannous chloride, and the labeling rate, specific activity, radiochemical purity and stability of 99mTc-GE11 were assessed. The biodistribution profile and receptor imaging performance of 99mTc-GE11 were evaluated in a nude mouse model bearing lung adenocarcinoma xenografts. Results The mean labeling rate of 99mTC-GE11 was (93.12±1.43)%, and its mean specific activity was 24.21±0.42 TBq/mmol. At room temperature, the radiochemical purity of 99mTC-GE11 was reduced by 2.14% at 6 h and by 3.11% at 12 h. The results of chromatography with Sephadex-G50 column showed that the binding rate of 99mTC-GE11 with plasma proteins was 4.8%. At 37 ℃, incubation of 99mTc-GE11 with different concentrations of cysteine for 1 h did not cause significant changes in the level of free 99mTc. The fat/water distribution coefficient (lgP) of 99mTC-GE11 was -1.87±0.05. In the tumor-bearing nude mice, 99mTc-GE11 was rapidly cleared in blood and kidney after intravenous injection and was selectively accumulated in the tumor; the tumor/non-tumor (T/NT) ratio reached the highest level and the clearest tumor imaging was achieved at 1 h after the injection. Conclusion 99mTc-GE11 molecular probe prepared based on a small molecular polypeptide possesses good physiochemical properties with an optimal biodistribution profile, and allows clear in vivo tumor imaging in tumor-bearing nude mice.

Keywords

• lung adenocarcinoma
• epidermal growth factor receptor
• polypeptide
• ge11
• nuclide molecular probe