title: Proteolysis during tumor cell extravasation in vitro: metalloproteinase involvement across tumor cell types.
abstract: To test if proteolysis is involved in tumor cell extravasation, we developed an in vitro model where tumor cells cross an endothelial monolayer cultured on a basement membrane. Using this model we classified the ability of the cells to transmigrate through the endothelial cell barrier onto the underlying matrix, and scored this invasion according to the stage of passage through the endothelium. Metalloproteinase inhibitors reduced tumor cell extravasation by at least 35%. Visualization of protease and cell adhesion molecules by confocal microscopy demonstrated the cell surface localization of MMP-2, MMP-9, MT1-MMP, furin, CD44 and αvβ3, during the process of transendothelial migration. By the addition of inhibitors and bio-modulators we assessed the functional requirement of the aforementioned molecules for efficient migration. Proteolytic digestion occurred at the cell-matrix interface and was most evident during the migratory stage. All of the inhibitors and biomodulators affected the transition of the tumor cells into the migratory stage, highlighting the most prevalent use of proteolysis at this particular step of tumor cell extravasation. These data suggest that a proteolytic interface operates at the tumor cell surface within the tumor-endothelial cell microenvironment.
authors.affiliation: Ontario Cancer Institute, Princess Margaret Hospital, Toronto, Ontario, Canada ; Department of Biology, Dominican College, Orangeburg, New York, United States of America.
authors.forename: Evelyn B
authors.initials: EB
authors.lastname: Voura
authors.forename: Jane L
authors.initials: JL
authors.lastname: English
authors.forename: Hoi-Ying E
authors.initials: HY
authors.lastname: Yu
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Ho
authors.forename: Patrick
authors.initials: P
authors.lastname: Subarsky
authors.forename: Richard P
authors.initials: RP
authors.lastname: Hill
authors.forename: Carlo V
authors.initials: CV
authors.lastname: Hojilla
authors.forename: Rama
authors.initials: R
authors.lastname: Khokha
mesh_terms: D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D045726:Metalloproteases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018613:Microscopy, Confocal; D059748:Proteolysis; D057705:Transendothelial and Transepithelial Migration / Q000502:physiology*; D014407:Tumor Cells, Cultured / Q000502:physiology*; D059016:Tumor Microenvironment / Q000502:physiology*
chemical_list: D015815:Cell Adhesion Molecules; D045726:Metalloproteases