Brain-enriched hyaluronan binding (BEHAB)/brevican cleavage in a glioma cell line is mediated by a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) family member

Brain-enriched hyaluronan binding (BERAB)/brevican is a brain-specific extr acellular matrix protein containing a cleavage site between Glu(395)-Ser(39 6), which bears remarkable homology to the "aggrecanase" site in the cartil age proteoglycan aggrecan. Expression of BEHAB/brevican is dramatically inc reased in human gliomas, notoriously invasive tumors. Recently, we showed t hat the rat 9L gliosarcoma cell line, which does not express BEHAB/brevican and forms non-invasive tumors when grown as intracranial grafts, can form invasive tumors when transfected with a 5' cDNA fragment of BEHAB/brevican, but not when transfected with the full-length cDNA, In marked contrast, th e highly invasive CNS-1 glioma cell line expresses and cleaves BEHAB/brevic an protein when grown as an intracranial graft. These results suggest that both synthesis and cleavage of BEHAB/brevican protein may play a role in th e invasiveness of gliomas. We report here, using an antibody developed to t he neoepitope created by BEHAB/brevican cleavage at the Glu(395)-Ser(396) s ite, that the CNS-1 cells are able to cleave the protein in vitro. We chara cterized the CNS-1 derived cleavage activity by assaying its ability to cle ave BEHAB/brevican proteoglycan, and determined that the enzyme is a consti tutively expressed, secreted activity. Using a variety of protease inhibito rs, reverse transcriptase-polymerase chain reaction, and specific antibodie s, we determined that this activity is likely to be a member of the ADAMTS family of metalloproteinases, specifically ADAMTS4. These results suggest a novel function for ADAMTS family members in BEHAB/brevican cleavage and gl ioma and indicate that inhibition of ADAMTS in glioma may provide a novel t herapeutic strategy.