Cystic Fibrosis (CF) is caused by a number of mutations in the gene coding for a cAMP-regulated anion channel, the cystic fibrosis transmembrane regulator (CFTR) protein. The most common mutation is a deletion of Phe 508 (delta F508). A major complication of CF is extensive inflammation of the airways. Alterations in fatty acid metabolism have been suggested to be part of the biochemical makeup of CF patients with or without pancreatic insufficiency. It has been suggested that the regulation of phospholipase A2 (PLA2)-catalyzed arachidonic acid release may be defective in CF lymphocytes and fibroblasts. PLA2s catalyze the hydrolysis of membrane phospholipids, releasing free fatty acids. We have studied calcium ionophore A23187- induced arachidonic acid release in the following cell lines: T84 cells, a colon carcinoma line which expresses high level of normal CFTR; CFPAC- 1 cells, a pancreatic carcinoma line from a delta F508 CF patient and clones derived from CFPAC-1 cells after transfection with a retroviral vector containing the normal CFTR gene (CFPAC-PLJ-CFTR) or with vector only (CFPAC-PLJ). Our data indicate that those lines containing a mutant CFTR and showing defective c-AMP-induced C1- efflux have a 5-10 fold higher arachidonic release that in the controls. This increased release is dependent upon extracellular calcium and is further enhanced by phorbol-12-myristate, 13-acetate (PMA, stimulator of PKC) but not by the inactive derivative 4alpha phorbol, 12, 13 didecanoate and is inhibited by staurosporine (a PKC inhibitor). An inhibitor of PLA2, quinacrine (200 micros), abolishes arachidonate release in these cells. These data suggest that calcium and pKC-stimulated arachidonate release, possibly catalyzed by PLA2, is disregulated in cells carrying the delta F508 CFTR mutation in CF. Should this be the case in respiratory epithelial cells, a chronically increased production of pro-inflammatory and chemotactic eicosanoids might contribute to the pathogenesis of the severe inflammation commonly found in the respiratory tracts of CF patients.
