Different mechanisms of regulation of the human stromelysin and collagenase genes. Analysis by a reverse-transcription-coupled-PCR assay.

Tissue-remodeling processes are largely controlled by matrix metalloproteinases that degrade the extracellular components of connective tissues. In this study, gene regulation of two human matrix metalloproteinases, stromelysin and collagenase, was investigated by a reverse-transcription-coupled (RT)-PCR assay. Here, signals from both the heterogenous nuclear RNA (hnRNA) and mRNA are amplified, allowing the regulation of gene expression to be divided between transcriptional and/or post-transcriptional control. In confluent human lung fibroblast cultures, tumor-necrosis factor-alpha and 12-O-tetradecanoyl-phorbol 13-acetate induce stromelysin and collagenase genes transcriptionally. Interleukin-1 beta (IL-1 beta) induces stromelysin gene transcription but has little, if any, effect on the collagenase gene transcription in cells cultured in the presence of 10% serum. By a competitive RT-PCR assay, the IL-1 beta-reated cultures contain an average of 60 molecules of stromelysin mRNA/cell and the untreated cultures about 1.9 molecules/cell. In serum-starved cells, both IL-1 beta and serum induce transcription of the collagenase gene. Also, in serum-starved cells type II collagen can induce collagenase mRNA but not stromelysin mRNA. Inhibition of protein synthesis with cycloheximide induces stromelysin gene transcription but has no effect on the collagenase gene. These data indicate different mechanisms of regulation of the human stromelysin and collagenase genes in cultured cells.