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Updated: Jun 7, 2026

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells
16:24

Profiling of Estrogen-regulated MicroRNAs in Breast Cancer Cells

Published on: February 21, 2014

MicroRNA-101-mediated Akt activation and estrogen-independent growth

M Sachdeva1, H Wu, P Ru

  • 1Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine, Springfield, IL, USA.

Oncogene
|October 20, 2010
PubMed

Insights

MicroRNAs regulate genes post-transcriptionally. This study reveals microRNA-101 promotes estrogen-independent growth in ER-positive tumors by upregulating phosphorylated Akt (pAkt) via MAGI-2 suppression, contributing to tamoxifen resistance.

Area of Science:

  • Molecular Biology
  • Genetics
  • Oncology

Background:

  • MicroRNAs (miRNAs) are key post-transcriptional gene regulators.
  • Dysregulated miRNA expression is linked to human cancers and anti-hormone therapy resistance.
  • The role of miRNAs in estrogen-independent growth and tamoxifen resistance remains unclear.

Purpose of the Study:

  • To investigate the role of microRNAs in estrogen-independent growth and tamoxifen resistance in estrogen receptor (ER)-positive breast cancer.
  • To identify specific microRNAs involved in promoting growth in the absence of estrogen.
  • To elucidate the molecular mechanisms underlying microRNA-mediated tamoxifen resistance.

Main Methods:

  • Utilized an in vivo selection system with a microRNA library against the MCF-7 cell line model.
  • Assessed the impact of miR-101 on estrogen-independent growth and phosphorylated Akt (pAkt) levels.
  • Investigated miR-101's effect on ER activity and expression.
  • Performed experiments in both estradiol (E2)-containing and E2-free media.
  • Identified MAGI-2 (membrane-associated guanylate kinase) as a direct target of miR-101.
  • Examined the effect of miR-101 on PTEN (phosphatase and tensin homolog) activity and subsequent Akt activation.

Main Results:

  • Demonstrated that miR-101 promotes estrogen-independent growth in ER-positive breast cancer cells.
  • Showed miR-101 upregulates phosphorylated Akt (pAkt) without affecting ER level or activity.
  • Observed that miR-101 suppresses cell growth in normal E2-containing medium but promotes growth in E2-free medium.
  • Found that estrogen deprivation significantly enhances miR-101-mediated Akt activation.
  • Identified MAGI-2 as a direct target of miR-101, with miR-101-mediated suppression of MAGI-2 leading to reduced PTEN activity and subsequent Akt activation.

Conclusions:

  • Establishes a significant role for miR-101 in driving estrogen-independent signaling pathways in ER-positive breast cancer.
  • Provides a novel mechanistic link between miR-101, MAGI-2 suppression, PTEN inhibition, and Akt activation.
  • Suggests miR-101 as a potential therapeutic target for overcoming tamoxifen resistance in breast cancer.

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