title: Cathepsin K cleavage of SDF-1α inhibits its chemotactic activity towards glioblastoma stem-like cells.
abstract: Glioblastoma (GBM) is the most aggressive primary brain tumor with poor patient survival that is at least partly caused by malignant and therapy-resistant glioma stem-like cells (GSLCs) that are protected in GSLC niches. Previously, we have shown that the chemo-attractant stromal-derived factor-1α (SDF-1α), its C-X-C receptor type 4 (CXCR4) and the cysteine protease cathepsin K (CatK) are localized in GSLC niches in glioblastoma. Here, we investigated whether SDF-1α is a niche factor that through its interactions with CXCR4 and/or its second receptor CXCR7 on GSLCs facilitates their homing to niches. Furthermore, we aimed to prove that SDF-1α cleavage by CatK inactivates SDF-1α and inhibits the invasion of GSLCs. We performed mass spectrometric analysis of cleavage products of SDF-1α after proteolysis by CatK. We demonstrated that CatK cleaves SDF-1α at 3 sites in the N-terminus, which is the region of SDF-1α that binds to its receptors. Confocal imaging of human GBM tissue sections confirmed co-localization of SDF-1α and CatK in GSLC niches. In accordance, 2D and 3D invasion experiments using CXCR4/CXCR7-expressing GSLCs and GBM cells showed that SDF-1α had chemotactic activity whereas CatK cleavage products of SDF-1α did not. Besides, CXCR4 inhibitor plerixafor inhibited invasion of CXCR4/CXCR7-expressing GSLCs. In conclusion, CatK can cleave and inactivate SDF-1α. This implies that CatK activity facilitates migration of GSLCs out of niches. We propose that activation of CatK may be a promising strategy to prevent homing of GSLCs in niches and thus render these cells sensitive to chemotherapy and radiation.
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands; Division of Neurobiology, Barrow Brain Tumor Research Center, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA. Electronic address: v.v.hira@amc.uva.nl.
authors.forename: Vashendriya V V
authors.initials: VV
authors.lastname: Hira
authors.affiliation: Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia.
authors.forename: Urška
authors.initials: U
authors.lastname: Verbovšek
authors.affiliation: Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia; Jozef Stefan International Postgraduate School, Jamova 39, 1000 Ljubljana, Slovenia.
authors.forename: Barbara
authors.initials: B
authors.lastname: Breznik
authors.affiliation: Department of Biochemistry, Faculty of Chemistry and Chemical Engineering, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Matic
authors.initials: M
authors.lastname: Srdič
authors.affiliation: Department of Biochemistry, Faculty of Chemistry and Chemical Engineering, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Novinec
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Hala
authors.initials: H
authors.lastname: Kakar
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Jill
authors.initials: J
authors.lastname: Wormer
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Britt Van
authors.initials: BV
authors.lastname: der Swaan
authors.affiliation: Department of Biochemistry, Faculty of Chemistry and Chemical Engineering, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Brigita
authors.initials: B
authors.lastname: Lenarčič
authors.affiliation: Department of Biophysics, Medical School, Federal University of Sao Paolo, Brazil.
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.affiliation: Division of Neurobiology, Barrow Brain Tumor Research Center, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA.
authors.forename: Shwetal
authors.initials: S
authors.lastname: Mehta
authors.affiliation: Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
authors.forename: Cornelis J F
authors.initials: CJ
authors.lastname: Van Noorden
authors.affiliation: Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Večna pot 111, 1000 Ljubljana, Slovenia; Jozef Stefan International Postgraduate School, Jamova 39, 1000 Ljubljana, Slovenia; Department of Biochemistry, Faculty of Chemistry and Chemical Engineering, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia.
authors.forename: Tamara T
authors.initials: TT
authors.lastname: Lah
mesh_terms: D000595:Amino Acid Sequence; D001596:Benzylamines; D056657:Cathepsin K / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D054377:Chemokine CXCL12 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002633:Chemotaxis; D000080027:Cyclams; D015870:Gene Expression; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D009457:Neuroglia / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D059748:Proteolysis; D054387:Receptors, CXCR / Q000235:genetics / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D055153:Stem Cell Niche / Q000235:genetics
chemical_list: C501896:ACKR3 protein, human; D001596:Benzylamines; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D000080027:Cyclams; D006571:Heterocyclic Compounds; D054387:Receptors, CXCR; D019718:Receptors, CXCR4; C534130:CTSK protein, human; D056657:Cathepsin K; C088327:plerixafor
keywords: Cathepsin K; Glioma stem-like cells; Niche; Stromal-derived factor-1α