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摘要
Introduction: Visualization of tumor angiogenesis using radionuclide targeting provides important diagnostic information. In previous study, we proved that an arginine-arginine-leucine (RRL) peptide should be a tumor endothelial cell specific binding sequence. The overall aim of this study was to evaluate whether Tc-99m-radiolabeled RRL could be noninvasively used for imaging of malignant tumors in vivo, and act as a new molecular probe targeting tumor angiogenesis. Methods: The RRL peptide was designed and radiosynthesized with Tc-99m by a one-step method. The radiolabeling efficiency and radiochemical purity were then characterized in vitro. Tc-99m-RRL was injected intravenously in HepG2 xenograft-bearing BALB/c nude mice. Biodistribution and in vivo imaging were performed periodically. The relationship between tumor size and %ID uptake of Tc-99m-RRL was also explored. Results: The labeling efficiencies of Tc-99m-RRL reached 76.9%+/- 64.5% (n = 6) within 30-60 min at room temperature, and the radiochemical purity exceeded 96% after purification. In vitro stability experiment revealed the radiolabeled peptide was stable. Biodistribution data showed that Tc-99m-RRL rapidly cleared from the blood and predominantly accumulated in the kidneys and tumor. The specific uptake of Tc-99m-RRL in tumor was significantly higher than that of unlabeled RRL blocking and free pertechnetate control test after injection (p<0.05). The ratio of the tumor-to-muscle exceeded 6.5, tumor-to-liver reached 1.98 and tumor-to-blood reached 1.95. In planar gamma imaging study, the tumors were imaged clearly at 2-6 h after injection of Tc-99m-RRL, whereas the tumor was not imaged clearly in blocking group. The tumor-to-muscle ratio of images with Tc-99m-RRL was comparable with that of F-18-FDG PET images. Immunohistochemical analysis verified the excessive vasculature of tumor. There was a linear relationship between the tumor size and uptake of Tc-99m-RRL with R-2 = 0.821. Conclusion: Tc-99m-RRL can be used as a potential candidate for visualization of tumor angiogenesis in malignant carcinomas.
- 出版日期2013-4-3
- 单位北京大学
