title: Tumor cell invasion of collagen matrices requires coordinate lipid agonist-induced G-protein and membrane-type matrix metalloproteinase-1-dependent signaling.
abstract: BACKGROUND
  Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are bioactive lipid signaling molecules implicated in tumor dissemination. Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a membrane-tethered collagenase thought to be involved in tumor invasion via extracellular matrix degradation. In this study, we investigated the molecular requirements for LPA- and S1P-regulated tumor cell migration in two dimensions (2D) and invasion of three-dimensional (3D) collagen matrices and, in particular, evaluated the role of MT1-MMP in this process.
  
  
  RESULTS
  LPA stimulated while S1P inhibited migration of most tumor lines in Boyden chamber assays. Conversely, HT1080 fibrosarcoma cells migrated in response to both lipids. HT1080 cells also markedly invaded 3D collagen matrices (approximatly 700 microm over 48 hours) in response to either lipid. siRNA targeting of LPA1 and Rac1, or S1P1, Rac1, and Cdc42 specifically inhibited LPA- or S1P-induced HT1080 invasion, respectively. Analysis of LPA-induced HT1080 motility on 2D substrates vs. 3D matrices revealed that synthetic MMP inhibitors markedly reduced the distance (approximately 125 microm vs. approximately 45 microm) and velocity of invasion (approximately 0.09 microm/min vs. approximately 0.03 microm/min) only when cells navigated 3D matrices signifying a role for MMPs exclusively in invasion. Additionally, tissue inhibitors of metalloproteinases (TIMPs)-2, -3, and -4, but not TIMP-1, blocked lipid agonist-induced invasion indicating a role for membrane-type (MT)-MMPs. Furthermore, MT1-MMP expression in several tumor lines directly correlated with LPA-induced invasion. HEK293s, which neither express MT1-MMP nor invade in the presence of LPA, were transfected with MT1-MMP cDNA, and subsequently invaded in response to LPA. When HT1080 cells were seeded on top of or within collagen matrices, siRNA targeting of MT1-MMP, but not other MMPs, inhibited lipid agonist-induced invasion establishing a requisite role for MT1-MMP in this process.
  
  
  CONCLUSIONS
  LPA is a fundamental regulator of MT1-MMP-dependent tumor cell invasion of 3D collagen matrices. In contrast, S1P appears to act as an inhibitory stimulus in most cases, while stimulating only select tumor lines. MT1-MMP is required only when tumor cells navigate 3D barriers and not when cells migrate on 2D substrata. We demonstrate that tumor cells require coordinate regulation of LPA/S1P receptors and Rho GTPases to migrate, and additionally, require MT1-MMP in order to invade collagen matrices during neoplastic progression.
authors.affiliation: Department of Pathology and Laboratory Medicine, Texas A&M University System Health Science Center, College Station, TX 77843, USA. kefgfd@mizzou.edu
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Fisher
authors.forename: Andreia
authors.initials: A
authors.lastname: Pop
authors.forename: Wonshill
authors.initials: W
authors.lastname: Koh
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Anthis
authors.forename: W Brian
authors.initials: WB
authors.lastname: Saunders
authors.forename: George E
authors.initials: GE
authors.lastname: Davis
mesh_terms: D002465:Cell Movement / Q000187:drug effects; D003094:Collagen / Q000378:metabolism / Q000502:physiology; D005109:Extracellular Matrix / Q000473:pathology*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D008055:Lipids / Q000819:agonists / Q000502:physiology*; D008246:Lysophospholipids / Q000494:pharmacology / Q000502:physiology; D053511:Matrix Metalloproteinase 14 / Q000502:physiology*; D020782:Matrix Metalloproteinases / Q000502:physiology; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D009369:Neoplasms / Q000473:pathology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D049368:Receptors, Lysophosphatidic Acid / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D008055:Lipids; D008246:Lysophospholipids; D034741:RNA, Small Interfering; D049368:Receptors, Lysophosphatidic Acid; D049349:Receptors, Lysosphingolipid; C060506:sphingosine 1-phosphate; D003094:Collagen; D020782:Matrix Metalloproteinases; D053511:Matrix Metalloproteinase 14; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D013110:Sphingosine; C032881:lysophosphatidic acid