title: C1q-tumour necrosis factor-related protein 8 (CTRP8) is a novel interaction partner of relaxin receptor RXFP1 in human brain cancer cells.
abstract: We report a novel ligand-receptor system composed of the leucine-rich G-protein-coupled relaxin receptor, RXFP1, and the C1q-tumour necrosis factor-related protein 8 (CTRP8) in human primary brain cancer, a tumour entity devoid of the classical RXFP1 ligands, RLN1-3. In structural homology studies and computational docking experiments we delineated the N-terminal region of the globular C1q region of CTRP8 and the leucine-rich repeat units 7 and 8 of RXFP1 to mediate this new ligand-receptor interaction. CTRP8 secreted from HEK293T cells, recombinant human (rh) CTRP8, and short synthetic peptides derived from the C1q globular domain of human CTRP8 caused the activation of RXFP1 as determined by elevated intracellular cAMP levels and the induction of a marked pro-migratory phenotype in established glioblastoma (GB) cell lines and primary cells from GB patients. Employing a small competitor peptide, we were able to disrupt the CTRP8-RXFP1-induced increased GB motility. The CTRP8-RXFP1-mediated migration in GB cells involves the activation of PI3K and specific protein kinase C pathways and the increased production/secretion of the potent lysosomal protease cathepsin B (cathB), a known prognostic marker of GB. Specific inhibition of CTRP8-induced cathB activity effectively blocked the ability of primary GB to invade laminin matrices. Finally, co-immunoprecipitation studies revealed the direct interaction of human CTRP8 with RXFP1. Our results support a therapeutic approach in GB aimed at targeting multiple steps of the CTRP8-RXFP1 signalling pathway by a combined inhibitor and peptide-based strategy to block GB dissemination within the brain.
authors.affiliation: Department of Human Anatomy and Cell Science, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Glogowska
authors.forename: Usakorn
authors.initials: U
authors.lastname: Kunanuvat
authors.forename: Jörg
authors.initials: J
authors.lastname: Stetefeld
authors.forename: Trushar R
authors.initials: TR
authors.lastname: Patel
authors.forename: Thatchawan
authors.initials: T
authors.lastname: Thanasupawat
authors.forename: Jerry
authors.initials: J
authors.lastname: Krcek
authors.forename: Ekkehard
authors.initials: E
authors.lastname: Weber
authors.forename: G William
authors.initials: GW
authors.lastname: Wong
authors.forename: Marc R
authors.initials: MR
authors.lastname: Del Bigio
authors.forename: Cuong
authors.initials: C
authors.lastname: Hoang-Vu
authors.forename: Sabine
authors.initials: S
authors.lastname: Hombach-Klonisch
authors.forename: Thomas
authors.initials: T
authors.lastname: Klonisch
mesh_terms: D052242:Adiponectin / Q000378:metabolism* / Q000494:pharmacology; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000378:metabolism; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002401:Cathepsin B / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D009361:Neoplasm Invasiveness / Q000503:physiopathology; D009363:Neoplasm Proteins / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D018000:Receptors, Peptide / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D052242:Adiponectin; D014408:Biomarkers, Tumor; C543616:C1QTNF8 protein, human; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; C417543:RXFP1 protein, human; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; D011994:Recombinant Proteins; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D002401:Cathepsin B
keywords: CTRP8; RXFP1; brain cancer; cathepsin; relaxin receptor