The induction of cyclooxygenase-2 by 17beta-estradiol in endothelial cells is mediated through protein kinase C.
OBJECTIVE
We investigated whether estrogen affected COX isoform expressed in human umbilical vein endothelial cells (HUVEC).


METHODS
HUVEC were grown to confluence and replaced with fresh medium containing 17beta-estradiol (0.001, 0.01, 0.1 and 1 nM) or 17beta-estradiol (1 nM) plus staurosporine (0.1, 1 and 10 ng/ml) for 24 h, after which the supernatant medium was collected to measure 6-keto-PGF1alpha using enzyme immunoassay. To measure COX activity via exogenous substrates, the remaining cells were replaced with fresh medium containing arachidonic acid (10 microM for 10 min), and then the medium was removed to measure 6-keto-PGF1alpha. The COX isoform expressed in cells was detected by immunoblotting using specific antibody.


RESULTS
17beta-estradiol (0.001 to 1 nM) increased the production of 6-keto-PGF1alpha via either endogenous or exogenous substrate in a dose dependent manner. These increases were significantly inhibited when cells were coincubated with staurosporine. Interestingly, only COX-2 protein, but not COX-1 protein, was induced in 17beta-estradiol treated HUVEC and was also inhibited by staurosporine.


CONCLUSIONS
Our data showed that 17beta-estradiol increased the release of PGI2 from HUVEC via the induction of COX-2 which was mediated through protein kinase C. The results suggested that COX-2 might have a role in the cardiovascular protective effect of estrogen.
Akarasereenont
P
P
Department of Pharmacology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Techatraisak
K
K
Thaworn
A
A
Chotewuttakorn
S
S
D015121:6-Ketoprostaglandin F1 alpha / Q000096:biosynthesis; D002478:Cells, Cultured; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D004730:Endothelium, Vascular / Q000201:enzymology*; D004790:Enzyme Induction / Q000187:drug effects; D011464:Epoprostenol / Q000096:biosynthesis; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000502:physiology*
D007527:Isoenzymes; D008565:Membrane Proteins; D004958:Estradiol; D015121:6-Ketoprostaglandin F1 alpha; D011464:Epoprostenol; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D011493:Protein Kinase C