<atl>Trypsin is produced by and activates protease-activated receptor-2 in human cancer colon cells: Evidence for new autocrine loop

In this work, we showed that human colon cancer cell lines produce trypsin which can activate a receptor for trypsin, the protease-activated receptor-2 (PAR-2), in these cells. RT-PCR experiments showed that trypsinogen transcripts were present in four colon cancer cell lines : T84, Caco-2, HT-29 and Cl.19A. By Western blot analysis we found a 25 kDa immunoreactive band identified as trypsinogen I in cell lysates and in the corresponding culture media. Concentrations of trypsin in cell media were found in nanomolar range, thus compatible with activation of protease-activated receptor 2 (PAR-2). This was further demonstrated in a colon cancer cell line (H-29) Ca2+i assay since increases in Ca2+i were observed in response to media from T84, Caco-2 or Cl.19A cells that were similar to that observed with 2–5 nM trypsin and were abolished by trypsin inhibitor. Altogether, these data show that colon cancer cell lines produce and secrete trypsin at concentrations compatible with activation of PAR-2. They support possible autocrine/paracrine regulation of PAR-2 activity by trypsin in colon cancer cells. [Copyright &y& Elsevier]