Regulation of urokinase-type plasminogen activator expression by an ERK1-dependent signaling pathway in a squamous cell carcinoma cell line

J Cell Biochem. 1996 Jun 1;61(3):430-43. doi: 10.1002/(sici)1097-4644(19960601)61:3<430::aid-jcb10>3.0.co;2-n.

Abstract

The urokinase-type plasminogen activator contributes to tissue remodeling by controlling the synthesis of the extracellular matrix-degrading plasmin. We undertook a study to determine the role of the extracellular signal-regulated kinases (ERKs) in the regulation of urokinase-type plasminogen activator expression in a squamous cell carcinoma cell line (UM-SCC-1) that contains a transcriptionally activated urokinase-type plasminogen activator gene. Transient transfection studies using a CAT reporter driven by the urokinase-type plasminogen activator promoter, which had progressive 5' deletions or which had been point-mutated, indicated the requirement of binding sites for AP-1 (-1967) and PEA3 (-1973) for its maximal activation. Expression of a mutant jun protein, which lacks the transactivation domain, caused a dose-dependent repression of a CAT reporter driven by either the urokinase-type plasminogen activator promoter or three tandem AP-1 repeats upstream of a thymidine kinase minimal promoter indicating the importance of AP-1-binding transcription factor(s) in the regulation of urokinase-type plasminogen activator synthesis. Mobility shift assays with UM-SCC-1 nuclear extract revealed binding of fos and junD proteins to an oligonucleotide spanning the AP-1 site at -1967. In-gel kinase assays indicated the constitutive activation of ERK1, which regulates fos synthesis via phosphorylation of p62TCF, but not ERK2, in UM-SCC-1 cells. Moreover, the expression of a dominant-negative ERK1, but not ERK2, repressed urokinase-type plasminogen activator promoter activity. Similarly, interfering with the function of the c-raf serine-threonine kinase, which lies upstream of ERK1, by the expression of a kinase-inactive c-raf repressed the activity of a CAT reporter driven by either the urokinase-type plasminogen activator promotor or tandem AP-1 repeats. These data suggest that urokinase-type plasminogen activator expression in UM-SCC-1 cells is regulated partly by an ERK1, but not ERK2, -dependent signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blotting, Western
  • Calcium-Calmodulin-Dependent Protein Kinases / physiology*
  • Gene Expression Regulation, Neoplastic*
  • Genes, jun
  • Humans
  • Mutagenesis
  • Oncogene Proteins v-fos / metabolism
  • Promoter Regions, Genetic
  • Protein-Serine-Threonine Kinases / genetics
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins c-jun / metabolism
  • Proto-Oncogene Proteins c-raf
  • Signal Transduction
  • Transcription Factor AP-1 / physiology
  • Transcription Factors / physiology
  • Transcription, Genetic
  • Transfection
  • Tumor Cells, Cultured
  • Urokinase-Type Plasminogen Activator / genetics*
  • Urokinase-Type Plasminogen Activator / metabolism

Substances

  • Oncogene Proteins v-fos
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-jun
  • Transcription Factor AP-1
  • Transcription Factors
  • transcription factor PEA3
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-raf
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Urokinase-Type Plasminogen Activator