title: Human lactoferricin derived di-peptides deploying loop structures induce apoptosis specifically in cancer cells through targeting membranous phosphatidylserine.
abstract: Host defense-derived peptides have emerged as a novel strategy for the development of alternative anticancer therapies. In this study we report on characteristic features of human lactoferricin (hLFcin) derivatives which facilitate specific killing of cancer cells of melanoma, glioblastoma and rhabdomyosarcoma compared with non-specific derivatives and the synthetic peptide RW-AH. Changes in amino acid sequence of hLFcin providing 9-11 amino acids stretched derivatives LF11-316, -318 and -322 only yielded low antitumor activity. However, the addition of the repeat (di-peptide) and the retro-repeat (di-retro-peptide) sequences highly improved cancer cell toxicity up to 100% at 20 μM peptide concentration. Compared to the complete parent sequence hLFcin the derivatives showed toxicity on the melanoma cell line A375 increased by 10-fold and on the glioblastoma cell line U-87mg by 2-3-fold. Reduced killing velocity, apoptotic blebbing, activation of caspase 3/7 and formation of apoptotic DNA fragments proved that the active and cancer selective peptides, e.g. R-DIM-P-LF11-322, trigger apoptosis, whereas highly active, though non-selective peptides, such as DIM-LF11-318 and RW-AH seem to kill rapidly via necrosis inducing membrane lyses. Structural studies revealed specific toxicity on cancer cells by peptide derivatives with loop structures, whereas non-specific peptides comprised α-helical structures without loop. Model studies with the cancer membrane mimic phosphatidylserine (PS) gave strong evidence that PS only exposed by cancer cells is an important target for specific hLFcin derivatives. Other negatively charged membrane exposed molecules as sialic acid, heparan and chondroitin sulfate were shown to have minor impact on peptide activity.
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Humboldtstraße 50/III, A-8010 Graz, Austria. Electronic address: sabrina.riedl@uni-graz.at.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Riedl
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Humboldtstraße 50/III, A-8010 Graz, Austria.
authors.forename: Regina
authors.initials: R
authors.lastname: Leber
authors.affiliation: Center for Medical Research, Medical University of Graz, Stiftingtalstraße 24, A-8010 Graz, Austria.
authors.forename: Beate
authors.initials: B
authors.lastname: Rinner
authors.affiliation: Cancer Biology Unit, Department of Dermatology, Medical University of Graz, Auenbruggerplatz 8, A-8036 Graz, Austria; Dermatology Research Centre, Translational Research Institute, School of Medicine, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Helmut
authors.initials: H
authors.lastname: Schaider
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Humboldtstraße 50/III, A-8010 Graz, Austria; BioTechMed-Graz, Austria.
authors.forename: Karl
authors.initials: K
authors.lastname: Lohner
authors.affiliation: Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Humboldtstraße 50/III, A-8010 Graz, Austria. Electronic address: dagmar.zweytick@uni-graz.at.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Zweytick
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects*; D002152:Calorimetry, Differential Scanning; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002942:Circular Dichroism; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry / Q000494:pharmacology*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008563:Membrane Lipids / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010718:Phosphatidylserines / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D013997:Time Factors
chemical_list: D004151:Dipeptides; D008051:Lipid Bilayers; D008563:Membrane Lipids; D010718:Phosphatidylserines; C082171:lactoferricin B; D007781:Lactoferrin
keywords: Antitumor peptides; Apoptosis; Glioblastoma; Melanoma; Phosphatidylserine; Targeted therapy