Aromatase expression in uterine leiomyomata is regulated primarily by proximal promoters I.3/II.
BACKGROUND
Uterine leiomyomata are common tumors that cause irregular uterine bleeding and pregnancy loss and depend on estrogen for growth. Aromatase catalyzes the conversion of androgens to estrogens. Aromatase expression is regulated via alternatively used promoters in the placenta (I.1 and I.2a), fat (I.4, I.3, and II), bone (I.6), and gonads (II). A prostaglandin E(2)/cAMP-dependent pathway regulates coordinately the proximal promoters I.3/II, whereas glucocorticoids and cytokines regulate the distal promoter I.4. Use of each promoter gives rise to a population of aromatase mRNA species with unique 5'-untranslated regions (5'-UTRs). Uterine leiomyoma tissue, but not normal myometrium, overexpresses aromatase leading to estrogen-stimulated cell proliferation. Aromatase inhibitor treatment shrank uterine leiomyomata in a few women.


OBJECTIVE
Promoter I.4 was reported to regulate aromatase expression in uterine leiomyomata from a group of Japanese women. Here, we used two independent techniques to identify the promoters that regulate aromatase expression in uterine leiomyomata (n = 30) from 23 African-American, Hispanic, and white women.


RESULTS
Rapid amplification of 5'-cDNA ends of aromatase mRNA species revealed the following distribution of promoter usage in leiomyomata: promoters I.3/II, 61.5%; I.2a, 15.4%; I.6, 15.4%; and I.4, 7.7%. Real-time PCR, which quantifies mRNA species with promoter-specific 5'-UTRs, revealed the following distribution for each 5'-UTR as a fraction of total aromatase mRNA: I.3/II, 69.6%; I.4, 7.3%; and other promoters, 23.1%.


CONCLUSIONS
The primary in vivo aromatase promoter in leiomyoma tissues in non-Asian U.S. women is the prostaglandin E(2)/cAMP-responsive I.3/II region. Alternative signals may stimulate aromatase expression that is a common biological phenotype in uterine leiomyomata.
Imir
Ayse Gonca
AG
Department of Obstetrics and Gynecology, Northwestern University, 303 East Superior Street, Suite 4-123, Chicago, IL 60611, USA.
Lin
Zhihong
Z
Yin
Ping
P
Deb
Santanu
S
Yilmaz
Bertan
B
Cetin
Meral
M
Cetin
Ali
A
Bulun
Serdar E
SE
D020121:5' Untranslated Regions / Q000235:genetics; D000328:Adult; D001141:Aromatase / Q000096:biosynthesis* / Q000235:genetics*; D005260:Female; D005784:Gene Amplification; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D007889:Leiomyoma / Q000201:enzymology* / Q000235:genetics*; D008875:Middle Aged; D011401:Promoter Regions, Genetic / Q000235:genetics*; D018075:RNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014594:Uterine Neoplasms / Q000201:enzymology* / Q000235:genetics*
D020121:5' Untranslated Regions; D018075:RNA, Complementary; D012333:RNA, Messenger; D001141:Aromatase