Related Experiment Video

Updated: Aug 29, 2026

An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation
08:48

An In Vitro Dormancy Model of Estrogen-sensitive Breast Cancer in the Bone Marrow: A Tool for Molecular Mechanism Studies and Hypothesis Generation

Published on: June 30, 2015

Estrogen receptor beta inhibits human breast cancer cell proliferation and tumor formation by causing a G2 cell cycle

Sreenivasan Paruthiyil1, Hema Parmar, Vaishali Kerekatte

  • 1Department of Obstetrics, University of California, San Francisco, CA 94143-0556, USA.

Cancer Research
|January 20, 2004
PubMed

Insights

Estrogen receptor beta (ERbeta) inhibits breast cancer cell proliferation and tumor formation, unlike estrogen receptor alpha (ERalpha). ERbeta may offer a new strategy for breast cancer chemoprevention.

Area of Science:

  • Oncology
  • Molecular Biology
  • Endocrinology

Background:

  • Estrogen receptor alpha (ERalpha) promotes breast cancer, but the role of estrogen receptor beta (ERbeta) remains unclear.
  • Many human breast tumors co-express both ERalpha and ERbeta, necessitating an understanding of their distinct roles.
  • Estrogens are known to promote breast cancer, primarily through ERalpha signaling.

Purpose of the Study:

  • To elucidate the role of ERbeta in breast cancer pathogenesis.
  • To investigate the contrasting effects of ERalpha and ERbeta on breast cancer cell behavior.
  • To assess the potential of ERbeta as a therapeutic target or chemopreventive agent.

Main Methods:

  • Adenovirus-mediated gene transfer to express ERbeta in ERalpha-positive MCF-7 breast cancer cells.
  • In vitro proliferation assays to evaluate cell growth.
  • In vivo mouse xenograft models to assess tumor formation.
  • Analysis of cell cycle regulatory gene expression (c-myc, cyclin D1, cyclin A, p21(Cip1), p27(Kip1)).

Main Results:

  • ERalpha expression in MCF-7 cells led to increased proliferation and tumor formation upon estradiol treatment.
  • Introduction of ERbeta into MCF-7 cells inhibited proliferation in vitro and prevented tumor formation in vivo.
  • ERbeta mediated its inhibitory effects by repressing oncogenic gene transcription (c-myc, cyclin D1, cyclin A) and upregulating cell cycle inhibitors (p21(Cip1), p27(Kip1)), inducing G2 cell cycle arrest.

Conclusions:

  • ERalpha and ERbeta exert opposing effects on breast cancer cell proliferation and tumorigenesis.
  • ERbeta acts as a tumor suppressor in this context, contrasting with ERalpha's proliferative role.
  • ERbeta-selective estrogens may be beneficial for breast cancer chemoprevention due to their lack of tumor-promoting properties.

More Related Videos

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells16:24

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells

Published on: February 21, 2014

Related Concept Videos

Mitogens and the Cell Cycle02:38

Mitogens and the Cell Cycle

Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Inhibition of CDK Activity02:34

Inhibition of CDK Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Negative Regulator Molecules01:23

Negative Regulator Molecules

Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
The Retinoblastoma Gene01:20

The Retinoblastoma Gene

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
Molecular Factors Affecting Cell Division01:27

Molecular Factors Affecting Cell Division

Several external and internal factors influence the initiation and inhibition of cell division. For instance, the death of nearby cells or the release of human growth hormone (hGH) promotes cell division. In contrast, lack of hGH or crowding of cells can inhibit cell division.
Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...