IMMUNOFLUORESCENCE-STUDIES AND BIOCHEMICAL-STUDIES OF THE TYPE-VI COLLAGEN EXPRESSION BY HUMAN GLIOBLASTOMA CELLS IN-VITRO

The human glioblastoma cell line U-87 MG was found to express a 140 kD polypeptide which was recognized on immunoblot analysis by a monoclon al antibody to type VI collagen. This polypeptide was digestible by a highly purified bacterial collagenase. After treatment of U-87 MC cell s by pepsin, the protein profile revealed the two major pepsin-resista nt fragments identical in Mr to those of collagen VI extracted from hu man placenta. The respective peptide maps from V8 protease one-dimensi onal gels of these two fragments were identical to those obtained with human collagen VI. Immunofluorescent staining by antibodies to type V I collagen was observed in the extracellular matrix. Moreover, U-87 MC cells were found to be positive for A(2)B(5) a cell surface marker sp ecific for O-2A type glial precursor cells. These data indicate that t he human glioblastoma cell line U-87 MC exhibits the properties of gli al precursor cells and expresses collagen type VI in vitro. This cell line therefore may prove valuable for comparative investigations of th e regulation of type VI collagen synthesis, and may be useful as a mod el to study the function and pathological importance of type VI collag en in human brain tumours, both in vitro and in vivo.