Oestrogen receptor (ER)-alpha and ER-beta isoforms in normal endometrial and endometriosis-derived stromal cells.
Several investigators have noted that hormone-dependent development of endometriosis implants lags behind that of simultaneously analysed eutopic endometrium. With the recent discovery of the oestrogen receptor-beta (ER-beta) isoform, the aim of this study was to investigate whether differences in the expression of ER-alpha and ER-beta might explain this observation. mRNA transcripts from endometrial stromal cells isolated from normal endometrium (NE) and from endometriomas (EI) were analysed using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. RT-PCR and Southern blot analyses of the two ER isoforms indicated that NE and EI stromal cells predominantly express ER-alpha mRNA, however the relative concentrations of ER isoform mRNA transcripts differed between the two cell types. Steady-state ER-alpha:ER-beta mRNA ratios were 15.5 +/- 2.8 and 5.2 +/- 0.9 respectively for NE and EI cells (P = 0.02). NE and EI stromal cells expressed ER proteins with similar Kd ( approximately 0.9 nM) and densities ( approximately 24 500 binding sites/cell) respectively. Functional ER expression was indicated by an increase in progesterone receptor concentrations of approximately 60% (P = 0.03) after incubation with 10 nM oestradiol. We postulate that differential transcript processing, ligand specificity and biological actions of the ER-alpha and -beta isoforms may influence differential growth responses in normal and ectopic endometrium.
Brandenberger
A W
AW
Reproductive Endocrinology Center, Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, CA 94143, USA.
Lebovic
D I
DI
Tee
M K
MK
Ryan
I P
IP
Tseng
J F
JF
Jaffe
R B
RB
Taylor
R N
RN
D004715:Endometriosis / Q000378:metabolism* / Q000473:pathology; D004717:Endometrium / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D005260:Female; D006801:Humans; D020033:Protein Isoforms / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D011960:Receptors, Estrogen / Q000235:genetics*; D011980:Receptors, Progesterone / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000187:drug effects
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D020033:Protein Isoforms; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D004958:Estradiol