The Development Of Integrin αvβ3 Specific Peptide Ligands And Their Cancer Theranostic Applications

Integrins are a family of cell adhesion factors,and are closely associated with cell physiological activities by regulating the recognition and adhesion between cells and cells,or cells and the extracellular matrix.In particular,integrin αvβ3 is overexpressed on tumor cells and active endothelial cells of tumor neovasculature,and regulates tumor associated biological events such as tumor growth,invasion and angiogenesis.Therefore,integrin αvβ3 is regarded as an ideal target for tumor diagnosis and treatment.Integrin αvβ3 can selectively recognize arginine-glycine-aspartic acid(RGD)sequence,and therefore,a number of RGD peptide mimics have been developed to target integrin αvβ3.However,the application of RGD and its analogs is limited by their low affinity.Therefore,it is of great significance to develop novel integrin αvβ3 target peptides with high affinity and good specificity.In this study,integrin αvβ3 target peptides were designed and screened by computer-aided drug design method and in vitro and in vivo drug screening strategy.One of peptides,composed of Arg-Trp-(D-Arg)-Asn-Arg(RWr NR),was identified as a potent integrin αvβ3 targeting peptide with high affinity and specificity.In addition,we investigate the potential of RWr NR in tumor diagnosis and therapy.First,we have developed a novel tumor diagnostic agent cooperatively targeting integrin αvβ3 and ROS,which provided a fast and accurate tumor diagnosis.Next,a multivalent RWr NR(Octopus-R)functionalized with 8-arm PEG have been prepared to inhibit tumor growth.Octopus-R exhibited enhanced binding affinity to integrin αvβ3 and improved tumor ability,and consequently effectively inhibit tumor growth with minimal adverse effects.Therefore,Octopus-R represents a promising anti-cancer agent.The detailed information of this study is shown as follow.In the first part,integrin αvβ3 target peptides have been designed based on computer-aided drug design method and screened by in vitro and in vivo drug screening strategy.One of peptides,composed of Arg-Trp-(D-Arg)-Asn-Arg(RWr NR),was identified as a potent integrin αvβ3 targeting peptide.In vitro assays showed that RWr NR could target integrin αvβ3 with high binding affinity and specificity,which is better than c-RGDy K.In addition,in vivo study indicated that RWr NR could target tumor effectively,which may broad application in tumor diagnosis and treatment.In the second part,an integrin αvβ3 and ROS-targeted tumor diagnostic agent have been developed.We conjugated ROS responsive fluorescent probe Hydro-Cy5 with integrin αvβ3 target peptide RWr NR to achieve a fast and accurate tumor diagnosis.Hydro-Cy5-RWr NR showed good sensitivity and specificity to ROS,and can recognize and target glioblastoma cells in vitro.Furthermore,Hydro-Cy5-RWr NR could target glioblastoma specificity with effectively discriminating between glioblastoma and inflammatory tissues.Therefore,Hydro-Cy5-RWr NR is a novel tumor diagnostic agent with high sensitivity and specificity,which provide a powerful tool for the diagnosis of tumor.In the third part,we have developed an anti-tumor target peptide based on multivalent effect to inhibit tumor growth.In order to enhance the target ability of RWr NR and improve its long systemic circulation in vivo,we prepared a PEGylation target peptide Octopus-R with multivalent effect,and researched its tumor targeting ability and anti-tumor effect.In vivo study showed that Octopus-R has good affinity,good biostability and long circulation time.More importantly,Octopus-R could significantly reduce tumor cell proliferation,angiogenesis and prevent tumor cell migration,realizing an effective and safe tumor diagnosis and treatment.Therefore,Octopus-R is a novel antitumor agent,which provide a novel method for tumor therapy.In this article,we screened an integrin αvβ3 target peptide RWr NR with high specificity and affinity,developed a tumor diagnostic agent Hydro-Cy5-RWr NR with cooperatively targeting integrin αvβ3 and ROS,and an anti-tumor agent Octopus-R with multivalent effect.This research not only provide a novel method for tumor theranostic,but also provide a new research idea for diseases about integrin αvβ3.