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Updated: Sep 19, 2025

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
Published on: February 21, 2014
Isoform-Specific Gene Regulation by Progesterone Receptors Drives Divergent Phenotypes in Breast Cancer Cells
Noelle E Gillis1, Thu H Truong1,2, Caroline H Diep1
1University of Minnesota, Masonic Cancer Center, Minneapolis, MN 55455, USA.
Progesterone receptor (PR) isoforms PR-A and PR-B have distinct roles in estrogen receptor-positive breast cancer. PR-A drives cell cycle progression and predicts poor outcomes, while PR-B influences metabolism and signaling.
Area of Science:
- Endocrinology
- Molecular Biology
- Cancer Research
Background:
- Progesterone receptor (PR) polymorphisms are linked to breast cancer risk.
- Two PR isoforms, PR-A and PR-B, are crucial in breast tissue physiology and cancer.
- An elevated PR-A to PR-B ratio is common in breast cancer, correlating with tamoxifen resistance and endocrine resistance.
Purpose of the Study:
- To investigate the distinct molecular and epigenetic mechanisms of PR-A and PR-B in estrogen receptor-positive (ER+) breast cancers.
- To understand how PR isoforms influence cell fate, gene expression, and clinical outcomes.
- To identify isoform-specific genomic binding patterns and target genes.
Main Methods:
- Utilized T47D cell lines expressing exclusively PR-A or PR-B.
- Compared gene expression profiles in adherent (2D) and mammosphere (3D) cultures.
- Performed CUT&RUN assays to map PR isoform genomic binding sites.
- Analyzed the METABRIC dataset to correlate gene signatures with clinical outcomes.
Main Results:
- PR-A and PR-B isoforms regulate distinct cellular phenotypes: PR-B promotes proliferation, while PR-A enhances mammosphere formation.
- Differential gene regulation by PR-A and PR-B was observed under 2D and 3D conditions.
- A PR-A-driven gene signature from 3D cultures predicted poor clinical outcome in ER+ breast cancer patients.
- CUT&RUN identified unique genomic binding patterns for PR-A (cell cycle regulation) and PR-B (metabolism and signaling).
Conclusions:
- PR isoforms exhibit novel, isoform-specific functions in gene regulation within ER+ breast cancer.
- PR-A's role in cell cycle regulation and its association with poor prognosis highlight its significance.
- PR-B's involvement in metabolism and signaling offers further insights into breast cancer progression.
- This research provides a foundation for developing targeted therapeutic strategies for ER+ breast cancer based on PR isoform activity.
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