The importance of angiogenesis in tumor growth and metastasis has led to develop new imaging tracers to understand angiogenic
vasculature. Based on the previous study, we further focused on the tumor molecular imaging application of the novel peptide
Arginine-Arginine-Leucine (Tyr-Cys-Gly-Gly-Arg-Arg-Leu-Gly-Gly-Cys, tRRL) in this study. The cytotoxicity of raioiodinated
tRRL (131I-tRRL) in HepG2 cells was assessed by tested cell viability using kit. tRRL was conjugated with fluorescein FITC to observe
its binding with tumor cells and human aortic endothelial cells (HAEC) in vitro. Whole body SPECT imaging of varied tumors
xenograftes was performed after intravenous injection of 131I-tRRL for 24 h in BALB/c nude mice. Compared with negative control PBS, small peptide tRRL was of non-cytotoxicity. 131I-tRRL could lead to significant cytotoxicity on HepG2 cells when the radioactivity was greater than 370 kBq. In vitro binding
experiment and cellular uptake results revealed that tRRL could adhere to tumor cells besides tumor derived endothelial cells.
In vivo SPECT imaging, 131I-tRRL mainly accumulated in various tumor tissues, including melanoma, liver cancer and lung cancer bearing mice. In breast
cancer xenografte imaging, the tumor has no significant radionuclide accumulation at 24 h after injected of 131I-tRRL. Radioiodinated tRRL offers a noninvasive nuclear imaging method for functional molecular imaging of tumors, and may
be a promising candidate carrier for tumor targeted therapy.