Related Experiment Video

Updated: Apr 17, 2026

Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library
08:40

Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library

Published on: April 6, 2012

18.1K

The regulation and function of miR-21-FOXO3a-miR-34b/c signaling in breast cancer

Xiangyan Liu1,2, Jie Feng3, Lili Tang2

  • 1Department of General Surgery, the Xiangya Hospital, Central South University, 138 Tongzipo Road, Changsha 410013, China. lilitang474@yahoo.com.

International Journal of Molecular Sciences
|February 4, 2015
PubMed

Insights

microRNA-21 (miR-21) and microRNA-34b/c (miR-34b/c) levels are altered in breast cancer (BC). This study reveals miR-21 promotes BC growth by downregulating miR-34b/c, suggesting therapeutic potential.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • Breast cancer (BC) is characterized by altered microRNA (miRNA) expression, specifically upregulation of miR-21 and downregulation of miR-34b/c.
  • The precise regulatory mechanisms and functional roles of these miRNAs in BC progression remain incompletely understood.

Purpose of the Study:

  • To elucidate the regulatory relationship between miR-21 and miR-34b/c in breast cancer.
  • To investigate the functional impact of this relationship on cancer cell signaling and tumor growth.
  • To evaluate the diagnostic and therapeutic potential of these miRNAs in BC.

Main Methods:

  • Correlation analysis of miR-21 and miR-34b/c levels in BC samples.
  • Investigation of the PTEN/PI3K/AKT signaling pathway and FOXO3a transcription factor activity.
  • Analysis of miRNA expression in serum from BC patients.
  • In vivo studies using systemic delivery of miRNAs to assess therapeutic efficacy.

Main Results:

  • A significant inverse correlation between miR-21 and miR-34b/c levels was observed in BC.
  • miR-21 upregulation leads to PTEN downregulation, activating PI3K/AKT signaling and inhibiting nuclear FOXO3a, a key regulator of miR-34b/c expression.
  • Circulating miR-21 and miR-34b/c levels in serum show potential as BC biomarkers.
  • Systemic delivery of miR-34b/c, with or without anti-miR-21, effectively inhibited breast tumor growth in vivo.

Conclusions:

  • The findings establish a novel regulatory axis where miR-21 suppresses miR-34b/c expression via the PTEN/PI3K/AKT/FOXO3a pathway in breast cancer.
  • Circulating miR-21 and miR-34b/c levels may serve as valuable biomarkers for BC diagnosis.
  • Systemic administration of miR-34b/c presents a promising therapeutic strategy for breast cancer treatment.

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

20.9K
Analysis of Combinatorial miRNA Treatments to Regulate Cell Cycle and Angiogenesis11:44

Analysis of Combinatorial miRNA Treatments to Regulate Cell Cycle and Angiogenesis

Published on: March 30, 2019

8.1K

Related Concept Videos

MicroRNAs01:22

MicroRNAs

MicroRNA (miRNA) are short, regulatory RNA transcribed from introns (non-coding regions of a gene) or intergenic regions (stretches of DNA present between genes). Several processing steps are required to form biologically active, mature miRNA. The initial transcript, called primary miRNA (pri-mRNA), base-pairs with itself, forming a stem-loop structure. Within the nucleus, an endonuclease enzyme, called Drosha, shortens the stem-loop structure into hairpin-shaped pre-miRNA. After the pre-miRNA...
4.4K
MicroRNAs01:22

MicroRNAs

MicroRNA (miRNA) are short, regulatory RNA transcribed from introns—non-coding regions of a gene—or intergenic regions—stretches of DNA present between genes. Several processing steps are required to form biologically active, mature miRNA. The initial transcript, called primary miRNA (pri-mRNA), base-pairs with itself forming a stem-loop structure. Within the nucleus, an endonuclease enzyme, called Drosha, shortens the stem-loop structure into hairpin-shaped pre-miRNA. After...
24.9K
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
5.1K
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

1.8K
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.
39.2K
Regulation of Angiogenesis and Blood Supply01:24

Regulation of Angiogenesis and Blood Supply

Rapidly dividing tumors, embryos, and wounded tissues require more oxygen than usual, lowering the oxygen concentration in the blood. At low oxygen or hypoxic conditions, an oxygen-sensitive transcription factor called the hypoxia-inducible factor 1 or HIF1 is activated. HIF1 is a dimeric protein of alpha (ɑ) and beta (β) subunits.  Under optimal oxygen conditions, HIF1β is present in the nucleus while HIF1ɑ remains in the cytosol. HIF1ɑ is hydroxylated by prolyl...
4.0K