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Inhibition of matrix metalloproteinase 9 expression by a ribozyme blocks metastasis in a rat sarcoma model system
1Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Abstract:
Matrix metalloproteinases (MMPs) have been implicated in tumor progression, but the exact roles that each member of this family may play in contributing to the behavior of malignant tumors are only beginning to be understood. MMP-9 (gelatinase B or the 92-kDa gelatinase/type IV collagenase) expression has been associated with metastasis in a variety of model systems including that of rat sarcomas generated by transformation of rat embryo cells with rasH and myc. To determine the effect that expression of MMP-9 has in this system, we inhibited the expression of MMP-9 using a hammerhead ribozyme. Introduction of an expression vector for a ribozyme directed against the rat MMP-9 mRNA sequence into a metastatic rat embryo cell line transformed by rasH and myc (2.10.10) that constitutively secretes MMP-9 resulted in the absence of detectable MMP-9 mRNA and loss of released 92-kDa gelatinase activity. These cells were no longer metastatic in a lung colonization assay but retained tumorigenicity. Introduction of an expression vector for a control hammerhead ribozyme had no effect. These data document the requirement for MMP-9 expression in metastasis in this system.
Insights
Matrix metalloproteinase-9 (MMP-9) is crucial for cancer metastasis. Inhibiting MMP-9 expression in rat sarcoma cells stopped metastasis while retaining tumor formation, confirming MMP-9
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Matrix metalloproteinases (MMPs) are implicated in tumor progression.
- MMP-9 (gelatinase B) expression is linked to metastasis in various models.
- The specific role of MMP-9 in malignant tumor behavior requires further elucidation.
Purpose of the Study:
- To determine the effect of MMP-9 expression on tumor metastasis.
- To investigate the necessity of MMP-9 for metastasis in a specific rat sarcoma model.
Main Methods:
- Utilized a hammerhead ribozyme to inhibit rat MMP-9 mRNA expression.
- Introduced the ribozyme into a metastatic rat embryo cell line (2.10.10) expressing MMP-9.
- Assessed MMP-9 mRNA levels, gelatinase activity, tumorigenicity, and metastatic potential (lung colonization assay).
Main Results:
- Ribozyme introduction led to undetectable MMP-9 mRNA and loss of gelatinase activity.
- Cells with inhibited MMP-9 expression showed no metastasis in the lung colonization assay.
- Tumorigenicity was retained in the absence of detectable MMP-9.
- A control ribozyme had no effect on these parameters.
Conclusions:
- MMP-9 expression is required for metastasis in this rat sarcoma model.
- Targeting MMP-9 could be a strategy to inhibit cancer spread.
- This study provides direct evidence for MMP-9's role in the metastatic cascade.