Tc‑99m Ser‑Asp‑Val‑Glu‑Cys‑Gly: A novel Tc‑99m labeled hexapeptide for molecular and non‑invasive tumor imaging

In a ProteoChip‑based screening system and subsequent studies, serine‑aspartic acid‑valine (SDV) was demonstrated to specifically bind to integrin αvβ3. An SDV‑containing peptide could target the tumor vessel and it may be an effective replacement for molecular imaging of the tumor. In the present study, a hexapeptide, SDV‑glutamic acid‑cysteine‑glycine (ECG), was developed and evaluated its diagnostic performance as a tumor imaging agent in tumor‑bearing mice. The hexapeptide SDV‑ECG was synthesized using Fmoc solid‑phase peptide synthesis. Following radiolabeling procedures with technetium‑99m, the Tc‑99m SDV‑ECG complexes were prepared at high yields (>97%). The uptake of Tc‑99m SDV‑ECG within HT‑1080 tumor cells (integrin αvβ3‑positive) was confirmed by in vitro studies. γ‑camera imaging revealed substantial uptake of Tc‑99m SDV‑ECG in the HT‑1080 cell line tumor murine model. With the co‑injection of excess SDV, tumoral uptake was blocked. Furthermore, HT‑29 tumor cells (integrin αvβ3‑negative) and inflammatory lesions demonstrated minimal uptake of Tc‑99m SDV‑ECG. In the present study, Tc‑99m SDV‑ECG was developed as a novel Tc‑99m agent for tumor imaging. The current in vitro and in vivo studies demonstrated specific functions of Tc‑99m SDV‑ECG in tumor imaging.