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Transcriptional downregulation of stromelysin by tetracycline

We investigated the role of tetracycline in the transcriptional regulation of matrix metalloproteinases. Using interleukin‐1β (IL‐1) induced stromelysin as a model system, we describe the repression of the endogenous stromelysin RNA accumulation, as well as the transcriptional inhibition of various stromelysin promoter/chloramphenicol‐acetyltransferase constructs in transient transfection assays. The inhibition occurred in a dose‐dependent fashion, with an IC50 of about 1 μM. Our results suggest that the transcriptional inhibition by tetracycline is not due to a block of activity of the activating protein complex 1 (AP‐1) but is mediated by sequences upstream of the AP‐1 binding site. © 1996 Wiley‐Liss, Inc.