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Published on: May 29, 2014
Ishikawa cells exhibit differential gene expression profiles in response to oestradiol or 4-hydroxytamoxifen
Suzanne M Johnson1, Manijeh Maleki-Dizaji, Jerry A Styles
1MRC Molecular Endocrinology Group, Reproductive Sciences Section, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester LE2 7LX, UK. smj4@le.ac.uk
Abstract:
In this study, the oestrogen agonist/antagonist action of 4-hydroxytamoxifen (OHT; 1 x 10(-6) M) and 17beta-oestradiol (E(2); 1 x 10(-8) M) were assessed on the oestrogen receptor (ER)-positive epithelial cell line (Ishikawa) with respect to cell proliferation, and to gene and protein expression. qRT-PCR and western blotting confirmed that Ishikawa cells expressed both ER isoforms and that there was no change in transcript levels in response to either ligand. Gene expression profiles, using oligonucleotide arrays representing approxiamtely 19,000 human genes, showed that the expression of 716 and 534 genes were changed differentially by treatment with either OHT or E(2) respectively, at the 24-h time point, with modulation of 46 genes common to both ligands, whereas 335 (OHT) and 240 (E(2)) genes showed expression changes unique to ligand, with 13 common alterations at 48 h. Both OHT and E(2) had demonstrable oestrogen agonist actions on Ishikawa cells, exemplified by increased proliferation and expression of known oestrogen-responsive genes, such as creatine kinase B and by the induction of alkaline phosphatase activity. Additionally, the data indicate that the two oestrogen agonists generated not only common gene expression changes but also unique ligand-specific profiles, raising the intriguing possibility that tamoxifen has E(2)-independent effects on the uterine epithelium.
Insights
4-hydroxytamoxifen (OHT) and 17beta-oestradiol (E2) exhibit estrogen agonist actions on Ishikawa cells, influencing proliferation and gene expression. Tamoxifen may exert effects independent of estrogen signaling.
Area of Science:
- Endocrinology
- Molecular Biology
- Genomics
Background:
- The Ishikawa cell line, derived from human endometrial adenocarcinoma, expresses estrogen receptor (ER) isoforms.
- Understanding the differential effects of estrogenic compounds is crucial for hormone-related research.
Purpose of the Study:
- To compare the estrogen agonist/antagonist actions of 4-hydroxytamoxifen (OHT) and 17beta-oestradiol (E2) on ER-positive Ishikawa cells.
- To investigate the impact of these ligands on cell proliferation, gene expression, and protein expression.
Main Methods:
- Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting were used to confirm ER expression.
- Oligonucleotide arrays were employed to analyze gene expression profiles at 24 and 48 hours.
- Cell proliferation assays and alkaline phosphatase activity measurements assessed functional responses.
Main Results:
- Both OHT and E2 demonstrated estrogen agonist activity, increasing cell proliferation and alkaline phosphatase activity.
- Gene expression analysis revealed differential modulation of thousands of genes by OHT and E2, with common and unique profiles.
- Specific estrogen-responsive genes, such as creatine kinase B, were upregulated by both ligands.
Conclusions:
- OHT and E2 induce common and ligand-specific gene expression changes in Ishikawa cells.
- The findings suggest that tamoxifen may have estrogen-independent effects on the uterine epithelium.
- Further research is warranted to elucidate the mechanisms of tamoxifen's unique actions.
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