Testican 2 abrogates inhibition of membrane-type matrix metalloproteinases by other testican family proteins.
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.
Mesh Terms:
Astrocytoma, Brain Neoplasms, Cell Line, Cell Movement, Collagen, Disease Progression, Enzyme Activation, Gene Expression Regulation, Neoplastic, Glioma, Humans, Kidney, Matrix Metalloproteinase 16, Matrix Metalloproteinase 2, Matrix Metalloproteinases, Matrix Metalloproteinases, Membrane-Associated, Metalloendopeptidases, Neoplasm Invasiveness, Nerve Tissue Proteins, Protein Interaction Mapping, Protein Structure, Tertiary, Proteoglycans, RNA, Messenger, RNA, Neoplasm, Recombinant Fusion Proteins, Reverse Transcriptase Polymerase Chain Reaction, Sequence Deletion, Tissue Inhibitor of Metalloproteinase-2, Tumor Cells, Cultured
Astrocytoma, Brain Neoplasms, Cell Line, Cell Movement, Collagen, Disease Progression, Enzyme Activation, Gene Expression Regulation, Neoplastic, Glioma, Humans, Kidney, Matrix Metalloproteinase 16, Matrix Metalloproteinase 2, Matrix Metalloproteinases, Matrix Metalloproteinases, Membrane-Associated, Metalloendopeptidases, Neoplasm Invasiveness, Nerve Tissue Proteins, Protein Interaction Mapping, Protein Structure, Tertiary, Proteoglycans, RNA, Messenger, RNA, Neoplasm, Recombinant Fusion Proteins, Reverse Transcriptase Polymerase Chain Reaction, Sequence Deletion, Tissue Inhibitor of Metalloproteinase-2, Tumor Cells, Cultured
Cancer Res.
Date: Jun. 15, 2003
PubMed ID: 12810672
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