METHODS: Analyses performed using sandwich
enzyme immunoassays demonstrated that the production levels of
pro-MMP-2 and
TIMP-1, but not
TIMP-2, are significantly higher in
glioblastomas multiforme than in other grades of astrocytic
tumors. Quantitative reverse transcription-polymerase chain reaction indicated that
MT1-MMP is expressed predominantly in
glioblastoma tissues, and its expression levels are significantly enhanced as
tumor grade increases. In addition, the expression levels and
proMMP-2 activation ratio were remarkably higher in
glioblastomas associated with cerebrospinal fluid (CSF) dissemination than in those not associated with CSF dissemination. In contrast, an examination of
TIMP-2 levels showed a reverse correlation. Like
MT1-MMP,
TIMP-1 and
TIMP-2 were immunolocalized to neoplastic cells in
glioblastoma samples. To study the roles of these molecules in the invasion of astrocytic
tumors more fully, stable transfectants expressing the
MT1-MMP gene were developed in a U251 human
glioblastoma cell line. The
MT1-MMP transfectants displayed prominent activation of
proMMP-2 and invasive growth in three-dimensional
collagen gel; however, mock transfectants and parental cells displayed noninvasive growth without the activation. The invasion and gelatinolytic activity of the transfectants were completely inhibited by addition of recombinant
TIMP-2, but not recombinant
TIMP-1.
CONCLUSIONS: