title: Testican 2 abrogates inhibition of membrane-type matrix metalloproteinases by other testican family proteins.
abstract: Testican family proteins are putative extracellular heparan/chondroitin sulfate proteoglycans of unknown function. We identified recently N-Tes, which is a product of testican 3 splicing variant gene, as an inhibitor of membrane-type matrix metalloproteinases (MT-MMPs). The inhibitory function is common among testican family members except for testican 2, which was shown to uniquely abolish inhibition of MT1-MMP- or MT3-MMP-mediated pro-MMP-2 activation by other testican family members. Testican 2 inactivates N-Tes by binding to the COOH-terminal extracellular calcium-binding domain of N-Tes through its NH(2)-terminal unique domain as demonstrated by coimmunoprecipitation analysis, and, thus, testican 2 was unable to inactivate a N-Tes deletion mutant lacking the extracellular calcium-binding domain (N-Tes-Delta 122). Migration of U251 cells on collagen, which was dependent on MT1-MMP activity under serum-free condition, was inhibited by N-Tes or N-Tes-Delta 122 deposited on collagen. Testican 2 was not incorporated into collagen by itself, and was deposited only in the presence of N-Tes, suggesting that testican 2 binds to N-Tes deposited on collagen. Binding of testican 2 to N-Tes deposited on collagen allowed migration of cells expressing MT1-MMP. Unlike wild-type N-Tes, N-Tes-Delta 122 did not bind to testican 2, and, thus, expression of testican 2 did not recover cell migration blocked by N-Tes-Delta 122. In situ hybridization showed that neurons are a major source of all of the testican family members in the normal brain. The quantitative reverse transcription-PCR analysis demonstrated that all of the testican family members are expressed prominently in normal brain, and their expression levels decrease as tumor grade increases. The expression level of testican 2 was the highest among testican family members regardless of histological grade of astrocytic tumors. These results suggest that abundant distribution of testican 2 may contribute to glioma invasion by inactivating other testican family members including N-Tes, which all inhibit MT-MMPs. We propose that N-Tes-Delta 122, which is resistant to testican 2, may have therapeutic potential as a barrier against glioma invasion.
authors.affiliation: Department of Molecular Virology and Oncology, Kanazawa University, Ishikawa 920-0934, Japan.
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Nakada
authors.forename: Hisashi
authors.initials: H
authors.lastname: Miyamori
authors.forename: Junkoh
authors.initials: J
authors.lastname: Yamashita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
mesh_terms: D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002465:Cell Movement; D003094:Collagen; D018450:Disease Progression; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007668:Kidney; D053513:Matrix Metalloproteinase 16; D020778:Matrix Metalloproteinase 2 / Q000235:genetics; D061965:Matrix Metalloproteinase Inhibitors; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors* / Q000235:genetics; D009361:Neoplasm Invasiveness; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D011509:Proteoglycans / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000502:physiology; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: C507102:MMP16 protein, human; D061965:Matrix Metalloproteinase Inhibitors; D009419:Nerve Tissue Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011993:Recombinant Fusion Proteins; C504404:SPOCK2 protein, human; C504409:SPOCK3 protein, human; D019716:Tissue Inhibitor of Metalloproteinase-2; D003094:Collagen; D053513:Matrix Metalloproteinase 16; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2