title: Structure-based optimization of GRP78-binding peptides that enhances efficacy in cancer imaging and therapy.
abstract: It is more challenging to design peptide drugs than small molecules through molecular docking and in silico analysis. Here, we developed a structure-based approach with various computational and analytical techniques to optimize cancer-targeting peptides for molecular imaging and therapy. We first utilized a peptide-binding protein database to identify GRP78, a specific cancer cell-surface marker, as a target protein for the lead, L-peptide. Subsequently, we used homologous modeling and molecular docking to identify a peptide-binding domain within GRP78 and optimized a series of peptides with a new protein-ligand scoring program, HotLig. Binding of these peptides to GRP78 was confirmed using an oriented immobilization technique for the Biacore system. We further examined the ability of the peptides to target cancer cells through in vitro binding studies with cell lines and clinical cancer specimens, and in vivo tumor imaging and targeted chemotherapeutic studies. MicroSPECT/CT imaging revealed significantly greater uptake of (188)Re-liposomes linked to these peptides as compared with non-targeting (188)Re-liposomes. Conjugation with these peptides also significantly increased the therapeutic efficacy of Lipo-Dox. Notably, peptide-conjugated Lipo-Dox significantly reduced stem-cell subpopulation in xenografts of breast cancer. The structure-based optimization strategy for peptides described here may be useful for developing peptide drugs for cancer imaging and therapy.
authors.affiliation: Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, and Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Sheng-Hung
authors.initials: SH
authors.lastname: Wang
authors.affiliation: Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, and Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Andy Chi-Lung
authors.initials: AC
authors.lastname: Lee
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: I-Ju
authors.initials: IJ
authors.lastname: Chen
authors.affiliation: Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, and Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Nai-Chuan
authors.initials: NC
authors.lastname: Chang
authors.affiliation: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan; Genomics Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Han-Chung
authors.initials: HC
authors.lastname: Wu
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Hui-Ming
authors.initials: HM
authors.lastname: Yu
authors.affiliation: Isotope Application Division, Institute of Nuclear Energy Research, Taiwan.
authors.forename: Ya-Jen
authors.initials: YJ
authors.lastname: Chang
authors.affiliation: Isotope Application Division, Institute of Nuclear Energy Research, Taiwan.
authors.forename: Te-Wei
authors.initials: TW
authors.lastname: Lee
authors.affiliation: General Surgery, Department of Surgery, Tri-Service General Hospital, Taipei, Taiwan.
authors.forename: Jyh-Cherng
authors.initials: JC
authors.lastname: Yu
authors.affiliation: Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, and Chang Gung University, Taoyuan 333, Taiwan; Genomics Research Center, Academia Sinica, Taipei, Taiwan; Department of Pediatrics, University of California in San Diego, USA. Electronic address: ayu@gate.sinica.edu.tw.
authors.forename: Alice L
authors.initials: AL
authors.lastname: Yu
authors.affiliation: Institute of Stem Cell and Translational Cancer Research, Chang Gung Memorial Hospital at Linkou, and Chang Gung University, Taoyuan 333, Taiwan; Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan. Electronic address: csctcr.john@cgmh.org.tw.
authors.forename: John
authors.initials: J
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D003952:Diagnostic Imaging; D004317:Doxorubicin / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D015195:Drug Design; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D016513:Mice, SCID; D008958:Models, Molecular; D009369:Neoplasms / Q000175:diagnosis* / Q000188:drug therapy*; D010455:Peptides / Q000737:chemistry / Q000627:therapeutic use*; D011092:Polyethylene Glycols / Q000494:pharmacology / Q000627:therapeutic use; D011485:Protein Binding; D013329:Structure-Activity Relationship; D023041:Xenograft Model Antitumor Assays
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; D008024:Ligands; D010455:Peptides; C506643:liposomal doxorubicin; D011092:Polyethylene Glycols; D004317:Doxorubicin
keywords: Cancer stem cells; Cancer-targeting peptide; Drug delivery; GRP78; HotLig; Tumor imaging