Regulation of catechol-O-methyltransferase expression in human myometrial cells.
OBJECTIVE
The catechol-O-methyltransferase enzyme catalyzes the methylation of the catechol estrogens, 2- or 4-hydroxyestrogen, to 2- or 4-methoxyestrogen. Both the hydroxy estrogens and methoxy estrogens were shown to modulate the effects of estrogen. Because catechol-O-methyltransferase activity controls levels of these metabolites, it may help regulate the cellular estrogenic milieu. In this study, we examined the regulation of catechol-O-methyltransferase expression in human myometrial cells.


METHODS
Catechol-O-methyltransferase expression was assessed by reverse transcription-polymerase chain reaction, Western blot, and luciferase assays in human myometrial cells after treatment with estrogen or progesterone. Catechol-O-methyltransferase expression was measured in cells after treatment with tumor necrosis factor alpha (TNFalpha) alone or with lactacystin, a proteasome inhibitor. Luciferase assays were also conducted using human myometrial cells containing an estrogen response element-luciferase reporter gene to measure levels of estrogen-mediated transactivation after treatment with estrogen and increasing concentrations of 2-hydroxestrogen.


RESULTS
Catechol-O-methyltransferase expression was down-regulated by progesterone or estrogen. Tumor necrosis factor alpha upregulated catechol-O-methyltransferase expression, whereas cotreatment with lactacystin attenuated this response, suggesting that TNFalpha activated nuclear factor kappa B to induce catechol-O-methyltransferase expression. Increased concentrations of 2-hydroxyestrogen attenuated estrogen-mediated transcription in the myometrial cells.


CONCLUSIONS
Catechol-O-methyltransferase expression may be regulated in the myometrium to control the local action of estrogen. Low levels of catechol-O-methyltransferase in the myometrium would result in an accumulation of 2-hydroxyestrogen and may antagonize the local effect of estrogen. High levels of catechol-O-methyltransferase in the myometrium would result in lower levels of 2-hydroxyestrogen and may increase sensitivity to estrogen.
Wentz
Melissa J
MJ
Department of Obstetrics & Gynecology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
Jamaluddin
Mohammad
M
Garfield
Robert E
RE
Al-Hendy
Ayman
A
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D015153:Blotting, Western; D002394:Catechol O-Methyltransferase / Q000032:analysis*; D002478:Cells, Cultured; D015536:Down-Regulation; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D017930:Genes, Reporter; D006801:Humans; D006894:Hydroxyestrones / Q000032:analysis; D008156:Luciferases / Q000032:analysis; D009215:Myometrium / Q000166:cytology / Q000201:enzymology*; D011374:Progesterone / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation
D004967:Estrogens; D006894:Hydroxyestrones; D014409:Tumor Necrosis Factor-alpha; C067713:lactacystin; D011374:Progesterone; D008156:Luciferases; D002394:Catechol O-Methyltransferase; D000111:Acetylcysteine