title: Synthesis, characterization, and biological activity of poly(arginine)-derived cancer-targeting peptides in HepG2 liver cancer cells.
abstract: The solid-phase synthesis, structural characterization, and biological evaluation of a small library of cancer-targeting peptides have been determined in HepG2 hepatoblastoma cells. These peptides are based on the highly specific Pep42 motif, which has been shown to target the glucose-regulated protein 78 receptors overexpressed and exclusively localized on the cell surface of tumors. In this study, Pep42 was designed to contain varying lengths (3-12) of poly(arginine) sequences to assess their influence on peptide structure and biology. Peptides were effectively synthesized by 9-fluorenylmethoxycarbonyl-based solid-phase peptide synthesis, in which the use of a poly(ethylene glycol) resin provided good yields (14-46%) and crude purities >95% as analyzed by liquid chromatography-mass spectrometry. Peptide structure and biophysical properties were investigated using circular dichroism spectroscopy. Interestingly, peptides displayed secondary structures that were contingent on solvent and length of the poly(arginine) sequences. Peptides exhibited helical and turn conformations, while retaining significant thermal stability. Structure-activity relationship studies conducted by flow cytometry and confocal microscopy revealed that the poly(arginine) derived Pep42 sequences maintained glucose-regulated protein 78 binding on HepG2 cells while exhibiting cell translocation activity that was contingent on the length of the poly(arginine) strand. In single dose (0.15 mM) and dose-response (0-1.5 mM) cell viability assays, peptides were found to be nontoxic in human HepG2 liver cancer cells, illustrating their potential as safe cancer-targeting delivery agents.
authors.affiliation: Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ, 07079, USA.
authors.forename: Stesha C
authors.initials: SC
authors.lastname: Joseph
authors.forename: Brittany A
authors.initials: BA
authors.lastname: Blackman
authors.forename: Megan L
authors.initials: ML
authors.lastname: Kelly
authors.forename: Mariana
authors.initials: M
authors.lastname: Phillips
authors.forename: Michael W
authors.initials: MW
authors.lastname: Beaury
authors.forename: Ivonne
authors.initials: I
authors.lastname: Martinez
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Parronchi
authors.forename: Constantine
authors.initials: C
authors.lastname: Bitsaktsis
authors.forename: Allan D
authors.initials: AD
authors.lastname: Blake
authors.forename: David
authors.initials: D
authors.lastname: Sabatino
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D057846:Cell-Penetrating Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D016503:Drug Delivery Systems / Q000379:methods*; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D009363:Neoplasm Proteins / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D013329:Structure-Activity Relationship
chemical_list: D057846:Cell-Penetrating Peptides; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D009363:Neoplasm Proteins; D010455:Peptides; C015462:polyarginine
keywords: GRP78; HepG2 liver cancer cell cytotoxicity; cancer-targeting peptides; poly(arginine) peptides; solid-phase peptide synthesis