De Novo Computational Design for Development of a Peptide Ligand Oriented to VEGFR-3 with High Affinity and Long Circulation.

The overexpression of VEGFR-3 is correlated with a worse prognosis in lung cancer and has been regarded as a rational target for specific drug delivery. Here, VEGFR-3 homing peptide library was efficiently established by computational design. Strong fluorescent signals of selected peptides were observed in A549 cells, but much weaker in other cells. The positive immunostaining overlapped with VEGFR-3 confirmed high affinity and selectivity of one novel peptide (CP-7). In addition, cell uptake of FITC-CP-7 peptide was significantly blocked by coinjection of excess CP-7 peptide. After labeled with 131 I, the profile of pharmacology and biodistribution could be traced in vivo. The 131 I-radiolabeled CP-7 peptide conjugates were >85% stable in serum over 4 h and exhibited a specific uptake of 18.04 ± 2.04% ID/g at 0.5 h after injection to high VEGFR-3 expressing A549 tumor mice. More importantly, lower uptake concentration in heart (1.06 ± 0.15% ID/g) after 2 h demonstrated the safety of peptide in vivo. The high uptake in the kidneys revealed that renal clearance was the main route of 131 I-CP-7 peptide elimination from the body. Lower accumulation of 131 I-CP-7 peptide in VEGFR-3 negative HeLa tumor mice further indicated that CP-7 peptide exhibited a higher tumor-homing efficiency. These studies provided a straightforward analytical access to design and screen bioactive peptide based on protein structure and revealed that CP-7 peptide represented a promising homing peptide of VEGFR-3-positive cancer in vitro and in vivo which could be used as a novel target molecule to achieve efficient drug delivery.