Reduction of human recombinant type II phospholipase A(2) and prostaglandin F-2 alpha release by microtubule depolymerizing agents

1. The present study examines the effects of the microtubule depolarizing a gent colchicine on secretary type II phospholipase A(2) (PLA(2)) function i n Chinese hamster ovary (CHO) cells that specifically overexpress human typ e II PLA(2) and the effect of both colchicine and tubulazole on the release of type II PLA(2) and prostaglandin (PG) F-2 alpha from human placental ex plants. 2. Significant suppression by colchicine (0.01-10 mu mol/L) of PLA(2) activ ity (P < 0.00001), immunoreactive type II PLA(2) (irPLA(2); P < 0.00001) an d PGF(2 alpha) release (P < 0.01) was observed in medium from overexpressin g CHO cells. These effects were significantly reduced (P < 0.0001) in the p resence of 10 mu mol/L taxol, an agent that prevents depolymerization of mi crotubules, The addition of 30 mu mol/L arachidonic acid significantly redu ced (P < 0.0001) the inhibition of PGF(2 alpha) production in CHO cell line s, 3. The addition of 1 mu mol/L colchicine to human placental explants for 24 h significantly reduced irPLA(2) (P < 0.00001) and PGF(2 alpha) production (P < 0.00001). Similarly, 1 mu mol/L tubulazole significantly blocked irPL A(2) (P < 0.001) and PGF(2 alpha) (P < 0.0001). 4. At 10 mu mol/L, taxol significantly reduced irPLA(2) inhibition by colch icine (n = 8; P < 0.05) and tubulazole (n = 8; P < 0.05). Similarly, taxol significantly reduced the reduction in PGF(2 alpha) production caused by co lchicine (P < 0.001) and by tubulazole (P < 0.001). 5. These results suggest that integrity of the microtubule system is requir ed for PLA(2) function and the subsequent production of pro-inflammatory me diators.