title: Plasminogen-induced aggregation of PANC-1 cells requires conversion to plasmin and is inhibited by endogenous plasminogen activator inhibitor-1.
abstract: PANC-1 cells express proteinase-activated receptors (PARs)-1, -2, and respond to their activation by transient elevation of cytosolic [Ca(2+)] and accelerated aggregation (Wei et al., 2006, J Cell Physiol 206:322-328). We studied the effect of plasminogen (PGN), an inactive precursor of the PAR-1-activating protease, plasmin (PN) on aggregation of pancreatic adenocarcinoma (PDAC) cells. A single dose of PGN time- and dose-dependently promoted PANC-1 cells aggregation in serum-free medium, while PN did not. PANC-1 cells express urokinase plasminogen activator (uPA), which continuously converted PGN to PN. This activity and PGN-induced aggregation were inhibited by the uPA inhibitor amiloride. PGN-induced aggregation was also inhibited by alpha-antiplasmin and by the PN inhibitor epsilon-aminocaproic acid (EACA). Direct assay of uPA activity revealed very low rate, markedly enhanced in the presence of PGN. Moreover, in PGN activator inhibitor 1-deficient PANC-1 cells, uPA activity and PGN-induced aggregation were markedly potentiated. Two additional human PDAC cell lines, MiaPaCa and Colo347, were assayed for PGN-induced aggregation. Both cell lines responded by aggregation and exhibited PGN-enhanced uPA activity. We hypothesized that the continuous conversion of PGN to PN by endogenous uPA is limited by PN's degradation and negatively controlled by endogenously produced PAI-1. Indeed, we found that PANC-1 cells inactivate PN with t1/2 of approximately 7 h, while the continuous addition of PN promoted aggregation. Our data suggest that PANC-1 cells possess intrinsic, PAI-1-sensitive mechanism for promotion of aggregation and differentiation by prolonged exposure to PGN and, possibly, additional precursors of PARs agonists.
authors: Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel.
authors: Naamit
authors: N
authors: Deshet
authors: Monica
authors: M
authors: Lupu-Meiri
authors: Ingrid
authors: I
authors: Espinoza
authors: Oded
authors: O
authors: Fili
authors: Yuval
authors: Y
authors: Shapira
authors: Ruth
authors: R
authors: Lupu
authors: Marvin C
authors: MC
authors: Gershengorn
authors: Yoram
authors: Y
authors: Oron
mesh_terms: D000230:Adenocarcinoma; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002449:Cell Aggregation; D002450:Cell Communication / Q000502:physiology; D045744:Cell Line, Tumor; D005341:Fibrinolysin / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010190:Pancreatic Neoplasms; D010958:Plasminogen / Q000235:genetics / Q000378:metabolism*; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D044463:Receptor, PAR-1; D010958:Plasminogen; D005341:Fibrinolysin; D002118:Calcium