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Expression and tissue localization of membrane-type 1, 2, and 3 matrix metalloproteinases in human astrocytic tumors
M Nakada1, H Nakamura, E Ikeda
1Department of Molecular Immunology and Pathology, Cancer Research Institute, School of Medicine, Kanazawa University, Japan.
Abstract:
Three different membrane-type matrix metalloproteinases (MT1-, MT2-, and MT3-MMPs) are known to activate in vitro the zymogen of MMP-2 (pro-MMP-2, progelatinase A), which is one of the key MMPs in invasion and metastasis of various cancers. In the present study, we have examined production and activation of pro-MMP-2, expression of MT1-, MT2-, and MT3-MMPs and their correlation with pro-MMP-2 activation, and localization of MMP-2, MT1-MMP, and MT2-MMP in human astrocytic tumors. The sandwich enzyme immunoassay demonstrates that the production levels of pro-MMP-2 in the anaplastic astrocytomas and glioblastomas are significantly higher than that in the low-grade astrocytomas (P<0.05 and P<0.01, respectively), metastatic brain tumors (P<0.05), or normal brains (P<0.01). Gelatin zymography indicates that the pro-MMP-2 activation ratio is significantly higher in the glioblastomas than in other astrocytic tumors (P<0.01), metastatic brain tumors (P<0.01), and normal brains (P<0.01). The quantitative reverse transcription polymerase chain reaction analyses demonstrate that MT1-MMP and MT2-MMP are expressed predominantly in glioblastoma tissues (17/17 and 12/17 cases, respectively), and their expression levels increase significantly as tumor grade increases. MT3-MMP is detectable in both astrocytic tumor and normal brain tissues, but the mean expression level is approximately 50-fold lower compared with that of MT1-MMP and MT2-MMP in the glioblastomas. The activation ratio of pro-MMP-2 correlates directly with the expression levels of MT1-MMP and MT2-MMP but not MT3-MMP. In situ hybridization indicates that neoplastic astrocytes express MT1-MMP and MT2-MMP in the glioblastoma tissues (5/5 cases and 5/5 cases, respectively). Immunohistochemically, MT1-MMP and MT2-MMP are localized to the neoplastic astrocytes in glioblastoma samples (17/17 cases and 12/17 cases, respectively), which are also positive for MMP-2. In situ zymography shows gelatinolytic activity in the glioblastoma tissues but not in the normal brain tissues. These results suggest that both MT1-MMP and MT2-MMP play a key role in the activation of pro-MMP-2 in the human malignant astrocytic tumors and that the gelatinolytic activity is involved in the astrocytic tumor invasion.
Insights
Matrix metalloproteinases (MMPs) are key in cancer invasion. This study shows MT1-MMP and MT2-MMP activate MMP-2 in malignant astrocytic tumors, contributing to invasion.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Matrix metalloproteinases (MMPs) are crucial in cancer invasion and metastasis.
- MMP-2 (progelatinase A) is a key MMP implicated in tumor progression.
- Membrane-type MMPs (MT1-, MT2-, and MT3-MMPs) activate pro-MMP-2 in vitro.
Purpose of the Study:
- To investigate the production and activation of pro-MMP-2 in human astrocytic tumors.
- To examine the expression and localization of MT1-, MT2-, and MT3-MMPs in these tumors.
- To correlate MMP expression with pro-MMP-2 activation and tumor grade.
Main Methods:
- Sandwich enzyme immunoassay for pro-MMP-2 production.
- Gelatin zymography for pro-MMP-2 activation ratio.
- Quantitative reverse transcription polymerase chain reaction (RT-PCR) for MMP gene expression.
- In situ hybridization and immunohistochemistry for MMP localization.
- In situ zymography for gelatinolytic activity.
Main Results:
- Pro-MMP-2 production and activation ratios were significantly higher in glioblastomas and anaplastic astrocytomas compared to low-grade tumors and normal brain.
- MT1-MMP and MT2-MMP were predominantly expressed in glioblastomas, with expression levels increasing with tumor grade.
- Pro-MMP-2 activation correlated with MT1-MMP and MT2-MMP expression, but not MT3-MMP.
- MT1-MMP and MT2-MMP were localized to neoplastic astrocytes in glioblastomas, co-localizing with MMP-2.
- Gelatinolytic activity was detected in glioblastoma tissues.
Conclusions:
- MT1-MMP and MT2-MMP play a significant role in pro-MMP-2 activation within human malignant astrocytic tumors.
- The observed gelatinolytic activity is likely involved in astrocytic tumor invasion.
- Targeting MT1-MMP and MT2-MMP may offer therapeutic strategies for astrocytic tumors.