Differential expression of membrane-type matrix metalloproteinase and its correlation with gelatinase A activation in human malignant brain tumors in vivo and in vitro.
In this study, we investigated the expression of activated gelatinase A and membrane-type metalloproteinase (MT-MMP) induced by concanavalin A (ConA) in four highly invasive glioma cell lines (UWR2, UWR3, U251MG, and SNB-19). We also examined gelatinase A and MT-MMP expression in human brain tumor tissues in vivo. Gelatin zymography showed that all four cell lines expressed latent progelatinase A (M(r) 66,000). Activated gelatinase A (M(r) 62,000) was induced by ConA in only UWR2 or UWR3 cells. MT-MMP mRNA was present in all four cell lines prior to ConA treatment, and the relative hybridization signals were 1, 0.80, 0.25, and 0.15 in UWR2, UWR3, U251MG, and SNB-19 cells, respectively. These mRNA signals were dramatically increased (2,8-, 5.4-, and 2.2-fold in UWR2, UWR3, and U251MG cells, respectively) following ConA treatment; however, MT-MMP mRNA expression was unchanged in SNB-19 cells. MT-MMP protein was detected in various amounts in the four cell lines, but only after ConA pretreatment. The amount of MT-MMP mRNA was unchanged in SNB-19 after ConA treatment, and the MT-MMP mRNA level in ConA-treated U251MG was lower than in UWR2 and UWR3 without ConA treatment. MT-MMP protein was detected in SNB-19 and U251 cell lines only after ConA treatment. Gelatin zymography of human brain tumor tissues revealed that almost all samples examined contained a latent form of gelatinase A, whereas the activated form of gelatinase A was only seen in metastatic lung adenocarcinomas and malignant astrocytomas, and especially in glioblastomas. MT-MMP mRNA levels were significantly higher in malignant astrocytomas than in low-grade gliomas and normal brain tissues. These results were confirmed by PCR analysis, which showed that MT-MMP mRNA was absent or barely detectable in normal brain white matter but was easily detectable in malignant astrocytomas. Immunohistochemistry of MT-MMP in frozen sections showed that MT-MMP was localized in neoplastic astrocytes of malignant astrocytomas but was undetectable in normal white brain matter. The data indicate that MT-MMP is present in malignant human glial tumors and that MT-MMP expression correlates with expression and activation of gelatinase A during malignant progression in vivo. A direct correlation between the levels of MT-MMP protein and its transcripts was not found in vitro, suggesting that MT-MMP expression in glioma cell lines might be regulated either at the level of transcription message stability or at posttranscription. Altered MT-MMP expression might contribute, in part, to gelatinase A activation, which in turn facilitates invasion of these tumors.
Yamamoto
M
M
Department of Neurosurgery, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA.
Mohanam
S
S
Sawaya
R
R
Fuller
G N
GN
Seiki
M
M
Sato
H
H
Gokaslan
Z L
ZL
Liotta
L A
LA
Nicolson
G L
GL
Rao
J S
JS
D001254:Astrocytoma / Q000201:enzymology; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology; D001932:Brain Neoplasms / Q000201:enzymology* / Q000473:pathology; D003208:Concanavalin A / Q000494:pharmacology; D018450:Disease Progression; D004789:Enzyme Activation / Q000187:drug effects; D004792:Enzyme Precursors / Q000378:metabolism / Q000502:physiology; D005455:Fluorescent Antibody Technique; D018093:Gelatinases / Q000378:metabolism* / Q000502:physiology; D005910:Glioma / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D020778:Matrix Metalloproteinase 2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000096:biosynthesis* / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011506:Proteins / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000502:physiology; D012016:Reference Values; D019716:Tissue Inhibitor of Metalloproteinase-2; D014407:Tumor Cells, Cultured
D004792:Enzyme Precursors; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D003208:Concanavalin A; D019716:Tissue Inhibitor of Metalloproteinase-2; D018093:Gelatinases; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; C069860:progelatinase; D020778:Matrix Metalloproteinase 2