The transcription factors Sp1, Sp3, and AP-2 are required for constitutive matrix metalloproteinase-2 gene expression in astroglioma cells.
Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that contribute to pathological conditions associated with angiogenesis and tumor invasion. MMP-2 is highly expressed in human astroglioma cells, and contributes to the invasiveness of these cells. The human MMP-2 promoter contains potential cis-acting regulatory elements including cAMP response element-binding protein, AP-1, AP-2, PEA3, C/EBP, and Sp1. Deletion and site-directed mutagenesis analysis of the MMP-2 promoter demonstrates that the Sp1 site at -91 to -84 base pairs and the AP-2 site at -61 to -53 base pairs are critical for constitutive activity of this gene in invasive astroglioma cell lines. Electrophoretic gel shift analysis demonstrates binding of specific DNA-protein complexes to the Sp1 and AP-2 sites: Sp1 and Sp3 bind to the Sp1 site, while the AP-2 transcription factor binds the AP-2 element. Co-transfection expression experiments in Drosophilia SL2 cells lacking endogenous Sp factors demonstrate that Sp1 and Sp3 function as activators of the MMP-2 promoter and synergize for enhanced MMP-2 activation. Overexpression of AP-2 in AP-2-deficient HepG2 cells enhances MMP-2 promoter activation. These findings document the functional importance of Sp1, Sp3, and AP-2 in regulating constitutive expression of MMP-2. Delineation of MMP-2 regulation may have implications for development of new therapeutic strategies to arrest glioma invasion.
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Department of Cell Biology, The University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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Benveniste
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D000818:Animals; D001254:Astrocytoma; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila; D029721:Drosophila Proteins; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000235:genetics*; D051705:Sp3 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; C493674:TfAP-2 protein, Drosophila; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D020778:Matrix Metalloproteinase 2