title: Mammalian orthoreovirus T3D infects U-118 MG cell spheroids independent of junction adhesion molecule-A.
abstract: In the canonical pathway, infection of cells by the wild-type mammalian orthoreovirus Type 3 Dearing (T3D) is dependent on the interaction of the viral spike protein σ1 with the high-affinity cellular receptor junction adhesion molecule-A (JAM-A). We previously demonstrated that the human glioblastoma cell line U-118 MG does not express JAM-A and resists reovirus T3D infection in standard cell culture conditions (SCCC). Heterologous JAM-A expression sensitises U-118 MG cells to reovirus T3D. Here we studied reovirus infection in U-118 MG cells grown in spheroid cultures with the premise that cells in such cultures resemble cells in tumours more than those grown under standard adherent cell culture conditions on a plastic surface. Although the U-118 MG cells in spheroids do not express JAM-A, they are susceptible to reovirus T3D infection. We show that this can be attributed to factors secreted by cells in the spheroids. The concentration of active extracellular proteases cathepsin B and L in the medium of spheroid cultures was increased 19- and 24-fold, respectively, as compared with SCCC. These enzymes can convert the reovirus particles into a form that can infect the U-118 MG cells independent of JAM-A. Taken together, these data demonstrate that infection of tumour cells by wild-type reovirus T3D is not strictly dependent on the expression of JAM-A on the cell surface.
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: I J C
authors.initials: IJ
authors.lastname: Dautzenberg
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: D J M
authors.initials: DJ
authors.lastname: van den Wollenberg
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: S K
authors.initials: SK
authors.lastname: van den Hengel
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: R W A
authors.initials: RW
authors.lastname: Limpens
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Bárcena
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: Koster
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: R C
authors.initials: RC
authors.lastname: Hoeben
mesh_terms: D002401:Cathepsin B / Q000378:metabolism; D056668:Cathepsin L / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D005909:Glioblastoma / Q000473:pathology* / Q000821:virology*; D006801:Humans; D012089:Mammalian orthoreovirus 3 / Q000472:pathogenicity*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000821:virology*
chemical_list: D015815:Cell Adhesion Molecules; C407243:F11R protein, human; D011956:Receptors, Cell Surface; C533912:CTSB protein, human; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L