Initiation of human colon cancer cell proliferation by trypsin acting at protease-activated receptor-2

Abstract

SummaryThe protease-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is cleaved and activated by trypsin. We investigated the expression of PAR-2 and the role of trypsin in cell proliferation in human colon cancer cell lines. A total of 10 cell lines were tested for expression of PAR-2 mRNA by Northern blot and RT-PCR. PAR-2 protein was detected by immunofluorescence. Trypsin and the peptide agonist SLIGKV (AP2) were tested for their ability to induce calcium mobilization and to promote cell proliferation on serum-deprived cells. PAR-2 mRNA was detected by Northern blot analysis in 6 out of 10 cell lines Cl.19A, SW480,. Other cell lines expressed low levels of transcripts, which were detected only by RT-PCR. Further results were obtained with HT-29 cells: (1) PAR-2 protein is expressed at the cell surface; (2) an increase in intracellular calcium concentration was observed upon trypsin (1-100 nM) or AP2 (10-100 µM) challenges; (3) cells grown in serum-deprived media supplemented with trypsin (0.1-1 nM) or AP2 (1-300 µM) exhibited important mitogenic responses (3-fold increase of cell number). Proliferative effects of trypsin or AP2 were also observed in other cell lines expressing PAR-2. These data show that subnanomolar concentrations of trypsin, acting at PAR-2, promoted the proliferation of human colon cancer cells. The results of this study indicate that trypsin could be considered as a growth factor and unravel a new mechanism whereby serine proteases control colon tumours.

Protease-activated Receptor 2 in Colon Cancer

“…In addition, overexpression of exogenous trypsinogen cDNA in human gastric cancer cells increases their tumorigenicity in nude mice (7). Recently, it has been shown that down-regulation of trypsin (11) or serine protease inhibitors suppresses carcinogenesis in many different in vivo and in vitro assay systems (12,13).We have demonstrated that trypsin acting at PAR2 is a very robust growth factor for human colon cancer cells (14). These data support the idea that some serine proteases should now be considered as crucial contributors to the development of human colon cancer.…”

Epithelial effects of proteinase-activated receptors in the gastrointestinal tract

“…In the colon, activation of PAR-2 leads to proliferation of several colonic epithelial cancer cell lines (Darmoul et al 2001), which in the case of the DLD-1 colonic carcinoma cell line is mediated by a MEK-MAP kinase signal transduction pathway (Jikuhara et al 2003). Likewise, PAR-2 has been implicated in cell proliferation, invasion and fibrosis in pancreatic cancer (Ikeda et al 2003, Ohta et al 2003, Shimamoto et al 2004).…”

Down-regulation of Protease-activated Receptor 4 in Lung Adenocarcinoma is Associated with a More Aggressive Phenotype

“…The chromosomal location of the PAR4 gene (19p12) is different from that of the PAR1 and PAR2 genes (5q13) (Kahn et al, 1996). Recently, several studies have suggested that PARs, especially PAR1 and PAR2, might exert a dual role in tumorigenesis (Vergnolle et al, 2001;Elste et al, 2010), as they were found to be overexpressed in several malignant tumors and implicated in tumor growth and cancer metastasis (Darmoul et al, 2001;Darmoul et al, 2003;DorsamGutkind 2007). However, other studies showed an opposite effect of PARs in breast, prostate and gastric cancers (Ahmad et al, 2000;Huang et al, 2000;Zhang et al, 2011).…”