title: Two functional epitopes of pigment epithelial-derived factor block angiogenesis and induce differentiation in prostate cancer.
abstract: Pigment epithelial-derived factor (PEDF), an angiogenesis inhibitor with neurotrophic properties, balances angiogenesis in the eye and blocks tumor progression. Its neurotrophic function and the ability to block vascular leakage is replicated by the PEDF 44-mer peptide (residues 58-101). We analyzed PEDFs' three-dimensional structure and identified a potential receptor-binding surface. Seeking PEDF-based antiangiogenic agents we generated and tested peptides representing the middle and lower regions of this surface. We identified previously unknown antiangiogenic epitopes consisting of the 34-mer (residues 24-57) and a shorter proximal peptide (TGA, residues 16-26) with the critical stretch L19VEEED24 and a fragment within the 44-mer (ERT, residues 78-94), which retained neurotrophic activity. The 34-mer and TGA, but not the 44-mer reproduced PEDF angioinhibitory signals hinged on c-jun-NH2-kinase-dependent nuclear factor of activated T cell deactivation and caused apoptosis. Conversely, the ERT, but not the 34-mer/TGA induced neuronal differentiation. For the 44-mer/ERT, we showed a novel ability to cause neuroendocrine differentiation in prostate cancer cells. PEDF and the peptides bound endothelial and PC-3 prostate cancer cells. Bound peptides were displaced by PEDF, but not by each other, suggesting multiple receptors. PEDF and its active fragments blocked tumor formation when conditionally expressed by PC-3 cells. The 34- and 44-mer used distinct mechanisms: the 34-mer acted on endothelial cells, blocked angiogenesis, and induced apoptosis whereas 44-mer prompted neuroendocrine differentiation in cancer cells. Our results map active regions for the two PEDF functions, signaling via distinct receptors, identify candidate peptides, and provide their mechanism of action for future development of PEDF-based tumor therapies.
authors.affiliation: Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Filleur
authors.forename: Karl
authors.initials: K
authors.lastname: Volz
authors.forename: Thomas
authors.initials: T
authors.lastname: Nelius
authors.forename: Yelena
authors.initials: Y
authors.lastname: Mirochnik
authors.forename: Hanhua
authors.initials: H
authors.lastname: Huang
authors.forename: Tetiana A
authors.initials: TA
authors.lastname: Zaichuk
authors.forename: Maria S
authors.initials: MS
authors.lastname: Aymerich
authors.forename: Sofia P
authors.initials: SP
authors.lastname: Becerra
authors.forename: Ronald
authors.initials: R
authors.lastname: Yap
authors.forename: Dorina
authors.initials: D
authors.lastname: Veliceasa
authors.forename: Emelyn H
authors.initials: EH
authors.lastname: Shroff
authors.forename: Olga V
authors.initials: OV
authors.lastname: Volpert
mesh_terms: D000595:Amino Acid Sequence; D020533:Angiogenesis Inhibitors / Q000276:immunology / Q000494:pharmacology; D000818:Animals; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D002454:Cell Differentiation / Q000276:immunology; D045744:Cell Line, Tumor; D016510:Corneal Neovascularization; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D042783:Endothelial Cells / Q000166:cytology / Q000276:immunology; D018604:Epitope Mapping; D000939:Epitopes / Q000502:physiology*; D005136:Eye Proteins / Q000276:immunology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D050778:NFATC Transcription Factors; D009389:Neovascularization, Pathologic / Q000276:immunology / Q000517:prevention & control*; D009414:Nerve Growth Factors / Q000276:immunology*; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000502:physiology; D010446:Peptide Fragments / Q000276:immunology / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000098:blood supply* / Q000276:immunology / Q000473:pathology*; D015843:Serpins / Q000276:immunology*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000502:physiology; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D020533:Angiogenesis Inhibitors; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D004268:DNA-Binding Proteins; D000939:Epitopes; D005136:Eye Proteins; D047908:Intracellular Signaling Peptides and Proteins; D050778:NFATC Transcription Factors; D009414:Nerve Growth Factors; D009687:Nuclear Proteins; D010446:Peptide Fragments; D015843:Serpins; D014157:Transcription Factors; D000099174:Pigment Epithelium-Derived Factor; C506386:CFLAR protein, human; C506387:Cflar protein, mouse