PROSTAGLANDIN ENDOPEROXIDE SYNTHASE-1 AND SYNTHASE-2 EXPRESSION IN DIFFERENTIATING HUMAN MONOCYTIC CELLS

Upon treatment with the phorbol ester TPA human myeloid leukemia U-937 cells acquire a macrophage-like phenotype including the capacity to metabolize arachidonate to prostanoids. We investigated the differentiation-associated expression of the key enzyme of prostanoid synthesis from arachidonate, prostaglandin endoperoxide synthase (PGHS). Our results of Western and Northern blot analyses indicate that the previously found 5-10-fold induction of PGHS activity during differentiation is due to enhanced expression of both currently known PGHS isoforms. In this system PGHS-2 differs from PGHS-1 in its time course of induction, its sensitivity to glucocorticoid suppression and its more extensive and heterogeneous glycosylation.