Absence of aromatase protein and mRNA expression in endometriosis.
BACKGROUND
Aromatase has been reported to be involved in estrogen biosynthesis and expressed in eutopic and ectopic endometrium of endometriosis patients. The objective of the present study was to investigate its expression and localization in three distinct types of endometriosis.


METHODS
Human peritoneal, ovarian and rectovaginal endometriotic lesions and matched eutopic endometrium were collected from patients during laparoscopy. Aromatase protein localization (immunohistochemistry, n = 63) and mRNA expression [quantitative polymerase chain reaction (Q-PCR), n = 64] were assessed.


RESULTS
No aromatase protein was detected by immunohistochemistry in either the glandular or stromal compartment of endometriotic lesions or eutopic endometrium, while it was strong in placental syncytiotrophoblasts, granulosa and internal theca cells from pre-ovulatory follicles, and luteal cells from corpus luteum. By Q-PCR, low but discernible levels of aromatase expression were found in endometriomas, probably due to follicular expression. Transcripts for aromatase were barely detectable in only a few peritoneal and rectovaginal endometriotic lesions, and a few eutopic endometrium samples, probably due to contaminating surrounding tissues (adipose tissue, intact peritoneum).


CONCLUSIONS
Unlike previous studies, we observed no aromatase protein in any of the endometriosis types, and barely detectable aromatase mRNA expression, suggesting that locally produced aromatase (within endometriotic lesions) may be less implicated in endometriosis development than previously postulated. Potential factors responsible for these discrepancies are discussed.
Colette
S
S
Université Catholique de Louvain, Faculty of Medicine, Gynecology Unit, 1200 Brussels, Belgium.
Lousse
J C
JC
Defrère
S
S
Curaba
M
M
Heilier
J F
JF
Van Langendonckt
A
A
Mestdagt
M
M
Foidart
J M
JM
Loumaye
E
E
Donnez
J
J
D000328:Adult; D001141:Aromatase / Q000235:genetics*; D004715:Endometriosis / Q000378:metabolism*; D004717:Endometrium / Q000201:enzymology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism*
D012333:RNA, Messenger; D001141:Aromatase