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Updated: Aug 15, 2026
Primary Culture of Rat Adrenocortical Cells and Assays of Steroidogenic Functions
Published on: March 12, 2019
Antiestrogens upregulate estrogen receptor beta expression and inhibit adrenocortical H295R cell proliferation
D Montanaro1, M Maggiolini, A G Recchia
1Department of Pharmaco-Biology, University of Calabria, 87036 Arcavacata di Rende (CS), Italy.
Abstract:
The molecular mechanisms involved in adrenocortical tumorigenesis are still not completely understood. In this study, using the H295R cell line as a model system, we investigated the role of estrogens and estrogen receptor (ER) alpha and ER beta in the growth regulation of adrenocortical tumors. We demonstrated that H295R cells are able to convert androgens to estrogens by a constitutive expression of active cytochrome P450 aromatase protein and express ER beta to a greater extent than ER alpha. Moreover, physiological concentrations of 17beta-estradiol (E2) determined an increase of thymidine incorporation, suggesting the presence of an autocrine mechanism in maintaining H295R cell proliferation. Evaluating the response to ER antagonists like 4-hydroxytamoxifen (OHT) and ICI 182 780 (ICI), we observed an up-regulation of ER beta and a dose-dependent inhibition of H295R cell proliferation. Whereas ICI determined the growth arrest of H295R cells, OHT induced morphological changes that were characteristic of apoptosis. According to the above-mentioned observations, OHT but not ICI clearly induced a marked expression of FasL and the cleavage of both caspase-8 and caspase-3. Interestingly, the apoptotic effects of OHT in H295R cells may be consequent to the enhanced levels of ER beta which stimulate the expression of FasL interacting with activating protein (AP)-1 sites located within its promoter sequence. In conclusion, we have demonstrated that H295R cells are able to transform androgens to estrogens that activate an autocrine mechanism, mediated by their own receptors, and contribute to regulate the proliferation of these cells. Moreover, this study points towards a role for ER beta as an important mediator of the repressive effects exerted by antiestrogens on H295R cells; however, further studies are needed to clarify its role in the control of adrenocortical cell proliferation and on the potential benefits of antiestrogens for treatment of adrenocortical cancer.
Insights
Estrogens and estrogen receptors (ERs) play a role in adrenocortical tumor growth. Antiestrogens like OHT and ICI inhibit proliferation, with ER beta mediating OHT
Area of Science:
- Endocrinology
- Molecular Biology
- Oncology
Background:
- Adrenocortical tumorigenesis mechanisms remain unclear.
- Estrogen signaling and its receptors (ER alpha, ER beta) are investigated for their role in tumor growth regulation.
Purpose of the Study:
- To investigate the role of estrogens and estrogen receptors (ER alpha and ER beta) in adrenocortical tumor growth regulation using the H295R cell line.
- To explore the autocrine mechanisms and the effects of antiestrogens on H295R cell proliferation.
Main Methods:
- Utilized the H295R cell line as a model for adrenocortical tumors.
- Assessed estrogen and androgen conversion, ER expression, and response to 17beta-estradiol (E2).
- Evaluated the effects of antiestrogens 4-hydroxytamoxifen (OHT) and ICI 182 780 (ICI) on cell proliferation, apoptosis, and specific molecular markers (FasL, caspases).
Main Results:
- H295R cells constitutively express aromatase, converting androgens to estrogens, and predominantly express ER beta.
- Physiological 17beta-estradiol (E2) concentrations increased thymidine incorporation, suggesting an autocrine proliferation mechanism.
- Antiestrogens OHT and ICI inhibited H295R cell proliferation, with ICI causing growth arrest and OHT inducing apoptosis via FasL and caspase activation.
- OHT-induced apoptosis correlated with increased ER beta levels, suggesting ER beta mediates antiestrogen effects.
Conclusions:
- H295R cells utilize an autocrine estrogen mechanism for proliferation, involving androgen conversion and ER signaling.
- ER beta is identified as a key mediator of antiestrogen-induced apoptosis in these cells.
- Further research is needed to clarify ER beta's role in adrenocortical cell proliferation and the therapeutic potential of antiestrogens in adrenocortical cancer.
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