Aberrant Expression and Activation of the Thrombin Receptor Protease-Activated receptor-1 Induces Cell Proliferation and Motility in Human Colon Cancer Cells

Am J Pathol. 2003 May;162(5):1503-13. doi: 10.1016/S0002-9440(10)64283-6.

Abstract

The traditional view on the role of serine proteases in tumor biology has changed with the recent discovery of a family of protease-activated receptors (PARs). In this study we explored the expression and functional role of the thrombin receptor PAR-1 in human colon cancer cells. Reverse transcriptase-polymerase chain reaction analysis showed that PAR-1 mRNAs are present in 11 of 14 human colon cancer cell lines tested but not in normal human colonic epithelial cells. This is in line with the immunolocalization of PAR-1 in human colon tumors and its absence in normal human colonic mucosa. The functional significance of the aberrant expression of PAR-1 in colon cancer cells was then investigated. We found that 1) a prompt increase in intracellular calcium concentration was observed on thrombin (10 nmol/L) or PAR-1 agonist AP1 (100 micro mol/L) challenge of HT29 cells; 2) HT29 quiescent cells treated with thrombin (0.01 to 20 nmol/L) or AP1 (1 to 300 micro mol/L) exhibited dramatic mitogenic responses (3.5-fold increase in cell number). Proliferative effects of thrombin or AP1 were also observed in other colon cancer cell lines expressing PAR-1. This effect was reversed by the MEK inhibitor PD98059 in consonance with the ability of thrombin or AP1 to induce phosphorylation of p42/p44 extracellular-regulated protein kinases. 3) PAR-1 activation by thrombin or AP1 led to a two-fold increase in cell motility of wounded HT29-D4. Our results demonstrate for the first time the aberrant expression of the functional thrombin receptor PAR-1 in colon cancers and its important involvement in cell proliferation and motility. Thrombin should now be considered as a growth factor for human colon cancer.

MeSH terms

  • Calcium / analysis
  • Cell Division
  • Cell Movement
  • Colonic Neoplasms / genetics
  • Colonic Neoplasms / pathology*
  • Colonic Neoplasms / physiopathology*
  • Enzyme Inhibitors / pharmacology
  • Flavonoids / pharmacology
  • Gene Expression Regulation, Neoplastic*
  • Hirudins / pharmacology
  • Humans
  • Kinetics
  • Receptor, PAR-1
  • Receptors, Thrombin / drug effects
  • Receptors, Thrombin / genetics*
  • Receptors, Thrombin / physiology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Thrombin / pharmacology
  • Tumor Cells, Cultured

Substances

  • Enzyme Inhibitors
  • Flavonoids
  • Hirudins
  • Receptor, PAR-1
  • Receptors, Thrombin
  • Thrombin
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
  • Calcium