ER-α Transcript Levels in Normal and Atrophic Squamous Epithelium of the Uterine Cervix and the Detection of a Splicing Variant
J Hemminger, D Richardson, J Pinsonneault, A Papp, J Stephens, D Cohn, A Suarez, D O'Malley. The Ohio State University Medical Center, Columbus, OH
Background: Description of the molecular mechanisms leading to genital atrophy, a common clinical problem, will produce a better understanding of aging conditions in women. The major estrogen receptor in the female genital tract is estrogen receptor α (ER-α). Little is known about the regulation of ER-α expression and the significance of splicing variants in normal cervical squamous epithelium (NCSE) and atrophic cervical squamous epithelium (ACSE). We determined the relative ER-α transcript levels in NCSE from young women and compared it to ACSE from older women. Using primers to amplify different exons, we also investigated the ratio of full transcripts vs a splicing variant missing exon 1.
Design: Ectocervical squamous cells were exfoliated from 25 fresh hysterectomy specimens from women <45 years and >55 years without known cervical pathology. Cells from one half of the ectocervix were placed in RNAProtect and cells from the other half were placed in a liquid cytology vial (Surepath) for cytologic examination. Eight specimens showing a pure population of squamous cells were chosen for the study: four NCSE and four ACSE. Preoperatively, serum hormone levels were measured using standard clinical laboratory methods. After RNA isolation, three different regions of the ER-α transcript were studied (Exon 1, Exon 4, and 3'UTR) using reverse transcription polymerase chain reaction (PCR) followed by real-time PCR.
Results: Lower estradiol levels and much higher FSH levels in older women (ave. age 68) with ACSE compared to younger women with NCSE (ave. age 42) was confirmatory of the postmenopausal/hypoestrogenic state in the former. However, NCSE and ACSE showed similar total ER-α transcript levels (NCSE: ave. 3.45 relative abundances, std dev 1.8; ACSE: ave. 5.25 relative abundances, std dev 4.6; p value = 0.34). A splicing variant lacking Exon 1 contributed 50% of the total ER-α RNA transcripts in both NCSE and ACSE.
Conclusions: ER-α RNA levels in NCSE and ACSE are similar and appear to be unaffected by the postmenopausal hormonal milieu. An ER-α splicing variant lacking Exon 1 contributed half of the transcripts in both NCSE and ACSE. This is likely representative of a recently described variant referred in the literature as ERα46. To date, ERα46 has been reported in bone, colon and MFC7 cells, but not in cervical squamous epithelium. The role of ER-α splicing variants in the atrophic phenotype is unknown.
Category: Gynecologic & Obstetrics
Tuesday, March 23, 2010 9:30 AM
Poster Session III # 170, Tuesday Morning