ESTROGEN RECEPTOR 1 ISOFORM, ESR1-36, IS PRESENT IN PC-3 PROSTATE CANCER CELLS

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 355-388-Sex Hormone Receptor Action & Reaction
Basic/Translational
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-381
Raisa Pisolato1, Thais F G Lucas1, Maria Fatima Magalhaes Lazari1, ZhaoYi Wang2 and Catarina Segreti Porto*1
1Universidade Federal de Sao Paulo, Sao Paulo, Brazil, 2Creighton Univ, Omaha, NE
Androgen, estrogen and stromal-epithelial interactions are involved in the development of prostate cancer (Mol Cell Endocrinol 288:30, 2008; Steroids 73:233, 2008). Although androgen deprivation is initially effective, it may lead to an androgen-independent prostate cancer (also known as castration resistant prostate cancer), which presents a poor prognosis and no effective therapy.  The estrogen, acting through its receptors, may play an important role in this progress. Recently it was identified and cloned, in breast cancer cells, a novel 36 kDa isoform of the full-length ESR1, designated  ESR1-36 (Biochem. Biophys. Res. Commun. 336:1023, 2005). This receptor is primarily localized in the cytoplasm and the plasma membrane, responds to membrane-initiated estrogen and antiestrogen signaling pathways and its expression may be regulated by the G protein–coupled estrogen receptor (GPER) (Proc. Natl. Acad. Sci. 103:9063, 2006; Mol. Endocrinol.  24:709, 2010). The presence of ESR1-36 in the prostate or in the prostate cancer has not been reported yet. Thus, this study was performed to identify and characterize the expression and the cellular localization of ESR1-36 in the androgen-independent prostate cancer cell line PC-3. PC-3 cells were grown in RPMI 1640 medium without phenol red, supplemented with 10% of fetal bovine serum, HEPES (5.95 mg/ml) and gentamicin (0.02 mg/ml), at 37ºC, in a humidified atmosphere with 5% CO2, for 48 hours. After that, the medium was replaced by another without serum and the cells were grown for 24 hours. Conventional RT-PCR was performed for detection of ESR1-36, using specific primers (forward 5’-CAA GTG GTT TCC TCG TGT CTA AAG-3’; reverse 5’-TGT TGA GTG TTG GTT GCC AGG-3’). MCF-7 cells were used as positive control. Product of the expected size (290 bp) was detected in PC-3 cells and its identity was confirmed by direct nucleotide sequencing. Western blot and immunofluorescence assays were performed, using rabbit polyclonal antibody raised against a synthetic peptide antigen corresponding to the unique C-terminal 20 aa of hESR1-36. Specific band of 36 kDa (ESR1-36) was detected in PC-3 cells. ESR1-36 immunostaining was found in the cytoplasm and/or plasma membrane. In conclusion, the identification of this novel isoform of ESR1 in PC-3 cells may help us understand the estrogen-mediated functions in the prostate cancer and the possible role of this hormone in the progress of the disease to an androgen-independent phenotype.

Nothing to Disclose: RP, TFGL, MFML, ZW, CSP

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: FAPESP