Modulation, bioinformatic screening, and assessment of small molecular peptides targeting the vascular endothelial growth factor receptor.

Shibin Feng,Lei Zheng,Dingde Huang,Lingyun Zou,Hongmin Li,Qianwei Li,Laiping Xie,Xiang Zhang,Qingshan Ni

doi:10.1007/s12013-014-0151-x

Shibin Feng, Lei Zheng + Show 7 more

Open Access

https://doi.org/10.1007/s12013-014-0151-x

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Abstract

Vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) are important factors in tumor growth and metastasis. Molecular probes or drugs designed to target VEGF/VEGFR interactions are crucial in tumor molecular imaging and targeted therapy. Bioinformatic methods enable molecular design based on the structure of bio-macromolecules and their interactions. This study was aimed to identify tumor-targeting small-molecule peptides with high affinity for VEGFR using bioinformatics screening. The VEGFR extracellular immunoglobulin-like modules Ig1–Ig3 were used as the target to systematically alter the primary peptide sequence of VEGF125–136. Molecular docking and surface functional group interaction methods were combined in an in silico screen for polypeptides, which in theory, would have higher affinities for VEGFR. In vitro receptor competition binding assays were used to assess the affinity of the putative VEGFR-binding polypeptides. Rhodamine-conjugated peptides were used to label and visualize peptide-binding sites on A549 cells. Using bioinformatic screening, we identified 20 polypeptides with potentially higher affinity for VEGFR. The polypeptides were capable of inhibiting the binding of 125I-VEGF to VEGFR in a dose-dependent manner. The IC50 values of QKRKRKKSRKKH and RKRKRKKSRYIVLS (80 and 185 nmol/L, respectively) were significantly lower than that of VEGF125–136 (464 nmol/L); thus, the affinity of these peptides for VEGFR was 6- and 2.5-fold higher, respectively, than that of VEGF125–136. Rhodamine labeling of A549 cells revealed peptide binding mainly on the plasma membrane and in the cytoplasm. Bioinformatic approaches hold promise for the development of molecular imaging probes. Using this approach, we designed two peptides that showed higher affinity toward VEGFR. These polypeptides may be used as molecular probes or drugs targeting VEGFR, which can be utilized in molecular imaging and targeted therapy of certain tumors.

Highlights

In tumor diagnosis and therapy, the discovery of diseaserelevant molecular targets and the construction of molecular probes or targeted drugs with high specificity for these targets are crucial [1, 2]
We designed two peptides that showed higher affinity toward VEGF receptor (VEGFR). These polypeptides may be used as molecular probes or drugs targeting VEGFR, which can be utilized in molecular imaging and targeted therapy of certain tumors
Molecular probes or targeted drugs based on Vascular endothelial growth factor (VEGF) or VEGFR can be widely applied in tumor-targeted molecular imaging or therapy [11,12,13,14,15,16,17]

Summary

Introduction

In tumor diagnosis and therapy, the discovery of diseaserelevant molecular targets and the construction of molecular probes or targeted drugs with high specificity for these targets are crucial [1, 2]. Certain molecules, including vascular endothelial growth factor receptor (VEGFR), integrin avb3 [3, 4], somatostatin receptor [5], vasoactive intestinal peptide receptor [6], matrix metalloproteinases [7], E-selectin [8], and CD105 [9], are expressed at higher levels in tumor cells and in newly formed vascular endothelial cells. These molecules are often used as targets in tumor-targeted radionuclide imaging or therapy [10]. Molecular probes and tumor-targeting drugs need to possess high binding affinity as well as a long half-life in the tumor tissues; we aimed to modify VEGF125–136 to improve its affinity for VEGFR

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