title: Galectin-8 promotes migration and proliferation and prevents apoptosis in U87 glioblastoma cells.
abstract: BACKGROUND
  Glioblastoma is one of the most aggressive cancers of the brain. Malignant traits of glioblastoma cells include elevated migration, proliferation and survival capabilities. Galectins are unconventionally secreted glycan-binding proteins that modulate processes of cell adhesion, migration, proliferation and apoptosis by interacting with beta-galactosides of cell surface glycoproteins and the extracellular matrix. Galectin-8 is one of the galectins highly expressed in glioblastoma cells. It has a unique selectivity for terminally sialylated glycans recently found enhanced in these highly malignant cells. A previous study in glioblastoma cell lines reported that Gal-8 coating a plastic surface stimulates two-dimensional motility. Because in other cells Gal-8 arrests proliferation and induces apoptosis, here we extend its study by analyzing all of these processes in a U87 glioblastoma cell model.
  
  
  METHODS
  We used immunoblot and RT-PCR for Gal-8 expression analysis, recombinant Gal-8 produced in a bacteria system for Gal-8 treatment of the cells, and shRNA in lentivirus transduction for Gal-8 silencing. Cell migration as assessed in transwell filters. Cell proliferation, cell cycle and apoptosis were analyzed by FACS.
  
  
  RESULTS
  Gal-8 as a soluble stimulus triggered chemotactic migration of U87 cells across the polycarbonate filter of transwell chambers, almost as intensively as fetal bovine serum. Unexpectedly, Gal-8 also enhanced U87 cell growth. Co-incubation of Gal-8 with lactose, which blocks galectin-glycan interactions, abrogated both effects. Immunoblot showed Gal-8 in conditioned media reflecting its secretion. U87 cells transduced with silencing shRNA in a lentiviral vector expressed and secreted 30-40 % of their normal Gal-8 levels. These cells maintained their migratory capabilities, but decreased their proliferation rate and underwent higher levels of apoptosis, as revealed by flow cytometry analysis of cell cycle, CFSE and activated caspase-3 staining. Proliferation seemed to be more sensitive than migration to Gal-8 expression levels.
  
  
  CONCLUSIONS
  Gal-8, either secreted or exogenously enriched in the media, and acting through extracellular glycan interactions, constitutes a strong stimulus of directional migration in glioblastoma U87 cells and for the first time emerges as a factor that promotes proliferation and prevents apoptosis in cancerous cells. These properties could potentially contribute to the exaggerated malignancy of glioblastoma cells.
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Metz
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Remziye
authors.initials: R
authors.lastname: Döger
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Riquelme
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Cortés
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Christopher
authors.initials: C
authors.lastname: Holmes
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Ronan
authors.initials: R
authors.lastname: Shaughnessy
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Fundación Ciencia y Vida, Av. Zañartu 1482, 77803444, Santiago, Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Oyanadel
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Catalina
authors.initials: C
authors.lastname: Grabowski
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile.
authors.forename: Alfonso
authors.initials: A
authors.lastname: González
authors.affiliation: Departamento de Inmunología Clínica y Reumatología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile. amsoza@med.puc.cl.|Centro de Envejecimiento y Regeneración, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, 8331010, Santiago, Chile. amsoza@med.puc.cl.
authors.forename: Andrea
authors.initials: A
authors.lastname: Soza
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001932:Brain Neoplasms / Q000235:genetics / Q000473:pathology*; D002417:Cattle; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D005434:Flow Cytometry / Q000379:methods; D037483:Galectin 1 / Q000032:analysis / Q000502:physiology; D037502:Galectin 3 / Q000032:analysis / Q000502:physiology; D037161:Galectins / Q000032:analysis / Q000494:pharmacology / Q000502:physiology*; D005909:Glioblastoma / Q000235:genetics / Q000473:pathology*; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D037483:Galectin 1; D037502:Galectin 3; D037161:Galectins; C091991:LGALS8 protein, human
keywords: Apoptosis; Cancer; Cell cycle; Galectin-8; Glioblastoma; Migration; Proliferation