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Updated: Jul 30, 2026
Isolation of Intact, Whole Mouse Mammary Glands for Analysis of Extracellular Matrix Expression and Gland Morphology
Published on: October 30, 2017
Trichostatin A inhibits beta-casein expression in mammary epithelial cells
P Pujuguet1, D Radisky, D Levy
1Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Insights
The extracellular matrix (ECM) and prolactin (Prl) regulate mammary cell beta-casein expression. While trichostatin A (TSA) activates an ECM-responsive element, it inhibits the endogenous beta-casein gene, revealing differential chromatin regulation.
Area of Science:
- Cell Biology
- Molecular Biology
- Epigenetics
Background:
- Cellular behavior is influenced by extracellular matrix (ECM) and cell membrane receptor interactions.
- Mammary epithelial cells express beta-casein in response to ECM and prolactin (Prl).
- A previously identified ECM- and Prl-responsive enhancer element (BCE-1) requires stable chromatin integration for activity and is activated by trichostatin A (TSA).
Purpose of the Study:
- To investigate the differential response of the endogenous beta-casein gene and the BCE-1 enhancer element to TSA.
- To elucidate the mechanisms underlying TSA's distinct effects on beta-casein gene regulation.
- To explore the role of chromatin structure in ECM-mediated gene expression.
Main Methods:
- Culturing mammary epithelial cells in the presence of ECM and Prl.
- Treating cells with TSA to assess its effect on gene expression.
- Analyzing chromatin structure and histone modifications.
- Comparing the regulation of the endogenous beta-casein gene and the BCE-1 enhancer element.
Main Results:
- The endogenous beta-casein gene, similar to BCE-1, is activated by ECM and Prl.
- TSA inhibits the expression of the endogenous beta-casein gene, contrasting with its activation of the BCE-1 enhancer.
- ECM was found to mediate rapid histone deacetylation in mammary epithelial cells.
- The differing responses are not due to unusual TSA effects, secondary gene expression, or BCE-1 construct properties.
Conclusions:
- The regulation of the endogenous beta-casein gene by ECM and Prl involves distinct epigenetic mechanisms compared to the BCE-1 enhancer element.
- TSA exhibits differential effects on gene differentiation, activating some cancer cells while inhibiting others.
- These findings highlight the complex interplay between extracellular signals, chromatin modifications, and gene expression in mammary epithelial cells.
Abstract:
Many aspects of cellular behavior are defined by the content of information provided by association of the extracellular matrix (ECM) and with cell membrane receptors. When cultured in the presence of laminin-containing ECM and prolactin (Prl), normal mammary epithelial cells express the milk protein beta-casein. We have previously found that the minimal ECM- and Prl-responsive enhancer element BCE-1 was only active when stably integrated into chromatin, and that trichostatin A (TSA), a reagent that leads to alterations in chromatin structure, was able to activate the integrated enhancer element. We now show that endogenous beta-casein gene, which is controlled by a genetic assembly that is highly similar to that of BCE-1 and which is also activated by incubation in ECM and Prl, is instead inhibited by TSA. We provide evidence that the differing response of beta-casein and BCE-1 to TSA is neither due to an unusual effect of TSA on mammary epithelial cells, nor to secondary consequences from the expression of a separate gene, nor to a particular property of the BCE-1 construct. As a component of this investigation, we also showed that ECM mediated rapid histone deacetylation in mammary epithelial cells. These results are discussed in combination with previous work showing that TSA mediates the differentiation of many types of cancer cells but inhibits differentiation of some nonmalignant cell types.
