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Oncogene-mediated downregulation of RECK, a novel transformation suppressor gene
R M Sasahara1, C Takahashi, M C Sogayar
1Instituto de Química, Universidade de São Paulo, Brasil. sasahar@quim.iq.usp.br
Abstract:
The RECK gene was initially isolated as a transformation suppressor gene encoding a novel membrane-anchored glycoprotein and later found to suppress tumor invasion and metastasis by regulating matrix metalloproteinase-9. Its expression is ubiquitous in normal tissues, but undetectable in many tumor cell lines and in fibroblastic lines transformed by various oncogenes. The RECK gene promoter has been cloned and characterized. One of the elements responsible for the oncogene-mediated downregulation of mouse RECK gene is the Sp1 site, where the Sp1 and Sp3 factors bind. Sp1 transcription factor family is involved in the basal level of promoter activity of many genes, as well as in dynamic regulation of gene expression; in a majority of cases as a positive regulator, or, as exemplified by the oncogene-mediated suppression of RECK gene expression, as a negative transcription regulator. The molecular mechanisms of the down-regulation of mouse RECK gene and other tumor suppressor genes are just beginning to be uncovered. Understanding the regulation of these genes may help to develop strategies to restore their expression in tumor cells and, hence, suppress the cells' malignant behavior.
Insights
The RECK gene suppresses tumor invasion and metastasis. Oncogenes downregulate RECK expression via Sp1 transcription factors, offering potential therapeutic targets for cancer.
Area of Science:
- Molecular Biology
- Cancer Research
- Gene Regulation
Background:
- The RECK gene encodes a glycoprotein that suppresses tumor invasion and metastasis.
- RECK expression is widespread in normal tissues but absent in many cancer cell lines.
- Oncogene activation leads to RECK downregulation, suggesting its role as a tumor suppressor.
Purpose of the Study:
- To investigate the molecular mechanisms of RECK gene downregulation by oncogenes.
- To identify transcription factors involved in regulating RECK gene expression.
- To explore therapeutic strategies for restoring RECK expression in tumors.
Main Methods:
- Cloning and characterization of the RECK gene promoter.
- Analysis of transcription factor binding sites within the RECK promoter.
- Investigating the role of Sp1 and Sp3 in RECK gene regulation.
Main Results:
- The Sp1 binding site in the RECK promoter is crucial for oncogene-mediated downregulation.
- Sp1 and Sp3 transcription factors bind to this site.
- RECK acts as a negative regulator in this context, contributing to tumor progression.
Conclusions:
- Oncogene-induced downregulation of the RECK gene is mediated by Sp1/Sp3 transcription factors binding to its promoter.
- Understanding these regulatory mechanisms is key to developing strategies to restore RECK expression and suppress cancer cell malignancy.