Plasminogen-induced aggregation of PANC-1 cells requires conversion to plasmin and is inhibited by endogenous plasminogen activator inhibitor-1
✍ Scribed by Naamit Deshet; Monica Lupu-Meiri; Ingrid Espinoza; Oded Fili; Yuval Shapira; Ruth Lupu; Marvin C. Gershengorn; Yoram Oron
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 392 KB
- Volume
- 216
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
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 α‐antiplasmin and by the PN inhibitor ε‐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. J. Cell. Physiol. 216: 632–639, 2008, © 2008 Wiley‐Liss, Inc.