Tumor cell contact mediated transcriptional activation of the fibroblast matrix metalloproteinase-9 gene: involvement of multiple transcription factors including Ets and an alternating purine-pyrimidine repeat.
The 92-kDa type IV collagenase (MMP-9) is a metalloproteinase frequently localized in both tumor stroma and in tumor cells, particularly at the tumor invasion front. To explore the factors regulating transcriptional activation of MMP-9 in stromal cells, we used a model system in which fibroblast MMP-9 expression can be upregulated by cell-cell contact with metastatic transformed rat embryo cells. Using transient transfection of reporter gene constructs containing 5'-deleted or mutated MMP-9 promoter fragments, as well as electrophoretic mobility shift assays, the upstream NFkappaB, SP-1, and Ets sites and the downstream AP-1 site and retinoblastoma binding element were shown to be necessary for basal transcriptional activity of fibroblast MMP-9. In contrast only Ets or SP-1 appeared to be involved in contact-mediated induction of MMP-9. Mutation of the upstream AP-1 site increased both basal and contact-stimulated promoter activation. Deletion of the alternating purine-pyrimidine repeat in the downstream promoter decreased transcriptional activity. Together these findings suggest that Ets and SP-1 are the central transcriptional activators of MMP-9 gene expression in fibroblasts specifically responding to tumor cell contact, and that promoter conformation may regulate MMP-9 expression.
Himelstein
B P
BP
Division of Oncology, The Children's Hospital of Philadelphia, PA 19104, USA. Himelstein@kermit.oncol.chop.edu
Lee
E J
EJ
Sato
H
H
Seiki
M
M
Muschel
R J
RJ
D000818:Animals; D002450:Cell Communication; D002461:Cell Line, Transformed; D017364:Collagenases / Q000235:genetics*; D005347:Fibroblasts / Q000201:enzymology; D015972:Gene Expression Regulation, Neoplastic; D020780:Matrix Metalloproteinase 9; D009154:Mutation; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D051381:Rats; D014157:Transcription Factors / Q000502:physiology*
D014157:Transcription Factors; D017364:Collagenases; D020780:Matrix Metalloproteinase 9