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Updated: Aug 19, 2026
In Vitro Assays to Evaluate the Migration, Invasion, and Proliferation of Immortalized Human First-trimester Trophoblast Cell Lines
Published on: March 5, 2019
A quantitative comparison of dual control of a hormone response element by progestins and glucocorticoids in the same
S K Nordeen1, B Kühnel, J Lawler-Heavner
1Department of Pathology, University of Colorado Health Sciences Center, Denver 80262.
Abstract:
Progesterone receptor-containing T47D human breast cancer cells are responsive to progestins but fail to respond to other steroid hormones, in particular dexamethasone, because they have no measurable levels of receptors for estrogens, androgens, or glucocorticoids. To quantitatively study dual responsiveness of the mouse mammary tumor virus (MMTV) promoter to progestins and glucocorticoids, we have stably transfected T47D cells with a glucocorticoid receptor (GR) expression vector. A cloned derivative (A1-2) was isolated that expresses a normal, full length GR, as assessed by steroid binding and Western immunoblot with a monoclonal anti-GR antibody. Moreover, GR is expressed at levels (80,000-100,000 molecules per cell) comparable to the high levels of endogenous progesterone receptor (200,000 molecules per cell). In A1-2 cells transiently transfected with an MMTV-chloramphenicol acetyl transferase reporter gene, induction by glucocorticoid was substantially greater (5-fold) than induction mediated by progestins. These results suggest that glucocorticoids may be the primary regulator of MMTV.
Insights
This study investigated how breast cancer cells respond to different steroid hormones. Glucocorticoid receptor expression in T47D cells revealed glucocorticoids are a stronger regulator of the mouse mammary tumor virus promoter than progestins.
Area of Science:
- Endocrinology
- Molecular Biology
- Cancer Research
Background:
- T47D human breast cancer cells express progesterone receptors but lack receptors for other steroid hormones like glucocorticoids.
- This lack of glucocorticoid receptors prevents T47D cells from responding to dexamethasone.
Purpose of the Study:
- To quantitatively assess the dual responsiveness of the mouse mammary tumor virus (MMTV) promoter to both progestins and glucocorticoids.
- To investigate the role of glucocorticoid receptor (GR) in mediating MMTV promoter activity in T47D cells.
Main Methods:
- Stable transfection of T47D cells with a glucocorticoid receptor (GR) expression vector to create the A1-2 cell line.
- Assessment of full-length GR expression using steroid binding assays and Western immunoblotting.
- Transient transfection of A1-2 cells with an MMTV-chloramphenicol acetyl transferase reporter gene to measure promoter activity.
Main Results:
- The A1-2 cell line expressed functional, full-length GR at levels comparable to endogenous progesterone receptors.
- Glucocorticoid treatment induced significantly greater MMTV promoter activity (5-fold induction) compared to progestin treatment.
- These findings indicate a differential regulatory role for glucocorticoids and progestins on the MMTV promoter.
Conclusions:
- Glucocorticoids may serve as the primary regulators of the mouse mammary tumor virus (MMTV) promoter.
- Restoring glucocorticoid receptor expression enables T47D cells to respond to glucocorticoids, highlighting the importance of receptor availability in hormone signaling.
