We compared the expression profiles of the mRNAs of both estrogen receptors, ER-alpha and the recently cloned ER-beta, in the midgestational human fetus by semiquantitative RT-PCR. ER-alpha was most abundant in the uterus, and smaller quantities were detected in the ovary, testis, skin and gut. High amounts of ER-beta mRNA were present in fetal ovaries, testes, adrenals and spleen. In these tissues, the levels of ER-beta mRNA were higher than ER-alpha. In the uterus, however, ER-alpha mRNA was more abundant, and ER-beta mRNA was expressed only moderately. ER-beta mRNA was present at moderate to low levels in the thymus, pituitary gland, skin, lung, kidney and brain cortex. In the course of our work, using the ER-beta primers on genomic DNA, an intron of 2468 bp in length, located between nt 222 and 223 in the A/B domain of ER-beta cDNA, was detected, cloned and sequenced. The study shows that the expression profile of the two ERs is different, and ER-beta is expressed in a variety of tissues during human fetal development, suggesting different, organ-specific roles for the two receptors.

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-β (ER-β) isoform, the aim of this study was to investigate whether differences in the expression of ER-α and ER-β 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-α mRNA, however the relative concentrations of ER isoform mRNA transcripts differed between the two cell types. Steady-state ER-α:ER-β 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 K d (~0.9 nM) and densities (~24 500 binding sites/cell) respectively. Functional ER expression was indicated by an increase in progesterone receptor concentrations of~60% (P ⍧ 0.03) after incubation with 10 nM oestradiol. We postulate that differential transcript processing, ligand specificity and biological actions of the ER-α and -β isoforms may influence differential growth responses in normal and ectopic endometrium.

The prognosis in ovarian carcinoma, the most lethal of the gynecologic neoplasms, is poor and has changed little in the last three decades. Only a small number respond to antiestrogen therapy, although the classic estrogen receptor, ER-alpha, has been identified in ovarian surface epithelium, from which approximately 90% of ovarian cancers originate. We have previously shown that ER-beta mRNA is most abundant in human fetal ovaries, suggesting that it might play an important role in ovarian development. Therefore, we investigated the mRNA levels of both ERs in normal ovaries, ovarian serous cystadenocarcinomas, granulosa cells from patients undergoing in vitro fertilization (IVF), the ovarian surface epithelium cell line IOSE-Van, and the ovarian cancer cell lines SKOV3, HEY and OCC1. Northern blots of normal and neoplastic ovaries were hybridized with an ER-beta riboprobe that spans the A/B domain. We detected two major hybridizing bands at approximately 8 and 10 kb. An RNase protection assay using the same probe revealed a single band of the expected size. Hybridizing the same blot with an ER-alpha riboprobe showed a strong hybridizing band at approximately 6.5 kb. In ovarian cancer samples, ER-beta mRNA level was decreased when compared to normal ovaries. Using 25 cycles of RT-PCR followed by Southern blotting, we found equal amounts of ER-alpha and -beta mRNAs in normal ovaries in all age groups from 33 to 75 years; however, in ovarian cancer tissue, the level of ER-alpha mRNA was similar or slightly higher, comparable to 10(3) to 10(4) copies of plasmid DNA, but ER-beta mRNA levels were markedly decreased. Granulosa cells from IVF patients expressed high levels of ER-beta mRNA. The OSE cell line expressed a low level of ER-alpha, detectable after 40 cycles of RT-PCR and no ER-beta mRNA. SKOV3 showed a low level of ER-alpha and -beta mRNAs, whereas OCC1 showed a low level of ER-beta and a relatively high level of ER-alpha. HEY did not contain detectable amounts of either ER after 40 cycles of RT-PCR. We found no evidence of differential splicing or major deletions in almost the entire coding region of ER-beta in either normal ovaries or tumor samples.

We compared the expression profiles of the mRNAs of both estrogen receptors, ER-alpha and the recently cloned ER-beta, in the midgestational human fetus by semiquantitative RT-PCR. ER-alpha was most abundant in the uterus, and smaller quantities were detected in the ovary, testis, skin and gut. High amounts of ER-beta mRNA were present in fetal ovaries, testes, adrenals and spleen. In these tissues, the levels of ER-beta mRNA were higher than ER-alpha. In the uterus, however, ER-alpha mRNA was more abundant, and ER-beta mRNA was expressed only moderately. ER-beta mRNA was present at moderate to low levels in the thymus, pituitary gland, skin, lung, kidney and brain cortex. In the course of our work, using the ER-beta primers on genomic DNA, an intron of 2468 bp in length, located between nt 222 and 223 in the A/B domain of ER-beta cDNA, was detected, cloned and sequenced. The study shows that the expression profile of the two ERs is different, and ER-beta is expressed in a variety of tissues during human fetal development, suggesting different, organ-specific roles for the two receptors.

The prognosis in ovarian carcinoma, the most lethal of the gynecologic neoplasms, is poor and has changed little in the last three decades. Only a small number respond to antiestrogen therapy, although the classic estrogen receptor, ER-alpha, has been identified in ovarian surface epithelium, from which approximately 90% of ovarian cancers originate. We have previously shown that ER-beta mRNA is most abundant in human fetal ovaries, suggesting that it might play an important role in ovarian development. Therefore, we investigated the mRNA levels of both ERs in normal ovaries, ovarian serous cystadenocarcinomas, granulosa cells from patients undergoing in vitro fertilization (IVF), the ovarian surface epithelium cell line IOSE-Van, and the ovarian cancer cell lines SKOV3, HEY and OCC1. Northern blots of normal and neoplastic ovaries were hybridized with an ER-beta riboprobe that spans the A/B domain. We detected two major hybridizing bands at approximately 8 and 10 kb. An RNase protection assay using the same probe revealed a single band of the expected size. Hybridizing the same blot with an ER-alpha riboprobe showed a strong hybridizing band at approximately 6.5 kb. In ovarian cancer samples, ER-beta mRNA level was decreased when compared to normal ovaries. Using 25 cycles of RT-PCR followed by Southern blotting, we found equal amounts of ER-alpha and -beta mRNAs in normal ovaries in all age groups from 33 to 75 years; however, in ovarian cancer tissue, the level of ER-alpha mRNA was similar or slightly higher, comparable to 10(3) to 10(4) copies of plasmid DNA, but ER-beta mRNA levels were markedly decreased. Granulosa cells from IVF patients expressed high levels of ER-beta mRNA. The OSE cell line expressed a low level of ER-alpha, detectable after 40 cycles of RT-PCR and no ER-beta mRNA. SKOV3 showed a low level of ER-alpha and -beta mRNAs, whereas OCC1 showed a low level of ER-beta and a relatively high level of ER-alpha. HEY did not contain detectable amounts of either ER after 40 cycles of RT-PCR. We found no evidence of differential splicing or major deletions in almost the entire coding region of ER-beta in either normal ovaries or tumor samples.