Estrogen receptor alpha/beta isoforms, but not betacx, modulate unique patterns of gene expression and cell...

Area of Science:

• Endocrinology
• Molecular Biology
• Cancer Research

Background:

• Estrogen receptor-alpha (ERalpha) is a primary target for treating estrogen receptor-positive (ER+) breast cancer (BC).
• ERbeta and its splice variants, like ERbetacx, are also present in BC and may influence treatment response.
• Understanding the distinct roles of different estrogen receptor (ER) isoforms is crucial for developing effective BC therapies.

Purpose of the Study:

• To investigate the specific functions of ERalpha, ERbeta, and ERbetacx in BC cells.
• To compare the gene expression patterns and cellular proliferation changes induced by different ER isoforms and ligands.
• To establish a cellular model for studying ER actions in BC.

Main Methods:

• Stable expression of ERalpha, ERbeta, or ERbetacx in Hs578T BC cells under doxycycline control.
• Microarray analysis to assess gene expression changes following treatment with 17beta-estradiol (E2) or 4OH-tamoxifen (4HT).
• Cellular proliferation assays and flow cytometry to evaluate cell-cycle effects.

Main Results:

• ERalpha and ERbeta mediated distinct, ligand-dependent gene expression patterns.
• E2 stimulation of ERbeta-expressing cells decreased proliferation by 27% and reduced S-phase entry by 50%.
• ERbetacx expression did not significantly alter gene expression or proliferation, and 4HT had limited effects on ERalpha and ERbeta cells.

Conclusions:

• ERalpha and ERbeta regulate unique gene expression profiles in BC cells.
• ERbeta activation by E2 influences cell proliferation and cell-cycle progression, suggesting isoform-specific therapeutic potential.
• The developed Hs578T ER-expressing cell lines offer a valuable model for comparative ER isoform studies in breast cancer.