Related Experiment Video

Updated: Jun 25, 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-205 regulates HER3 in human breast cancer

Marilena V Iorio1, Patrizia Casalini, Claudia Piovan

  • 1Molecular Biology Unit, Department of Experimental Oncology, Fondazione Istituto Di Ricovero e Cura a Carattere Scientifico, Istituto Nazionale Tumori, Milano, Italy.

Cancer Research
|March 12, 2009
PubMed

Insights

MicroRNA-205 (miR-205) acts as a tumor suppressor in breast cancer by targeting the HER3 receptor and inhibiting the Akt pathway. Restoring miR-205 enhances sensitivity to cancer therapies.

Area of Science:

  • Molecular Biology
  • Oncology
  • Genetics

Background:

  • MicroRNAs play critical roles in breast cancer, acting as oncogenes or tumor suppressors.
  • HER2-overexpressing breast tumors are aggressive and rely on HER family interactions, particularly HER3, for PI3K/Akt pathway activation.

Purpose of the Study:

  • To investigate the role of miR-205 in breast cancer.
  • To determine if miR-205 targets the HER3 receptor and affects downstream signaling.
  • To assess the therapeutic potential of miR-205 in breast cancer treatment.

Main Methods:

  • Quantitative analysis of miR-205 expression in breast tumors versus normal tissue.
  • Direct targeting of HER3 receptor by miR-205 was confirmed.
  • Assessment of Akt pathway activation and cell proliferation (clonogenic potential) in response to miR-205 modulation.
  • Evaluation of drug sensitivity to Gefitinib and Lapatinib upon miR-205 reintroduction.

Main Results:

  • miR-205 is downregulated in breast tumors compared to normal tissue.
  • miR-205 directly targets and downregulates the HER3 receptor, inhibiting Akt activation.
  • Reintroduction of miR-205 into SKBr3 cells reduced clonogenic potential and restored sensitivity to tyrosine-kinase inhibitors.
  • miR-205 abrogated HER3-mediated resistance and promoted apoptosis.

Conclusions:

  • miR-205 functions as a tumor suppressor gene in breast cancer.
  • miR-205 interferes with the HER receptor family-mediated proliferative pathway.
  • miR-205 holds potential for improving patient response to specific anticancer therapies.

More Related Videos

Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization06:01

Clinicopathological Analysis of miRNA Expression in Breast Cancer Tissues by Using miRNA In Situ Hybridization

Published on: June 7, 2016

Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library08:40

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

Published on: April 6, 2012

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...
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 ends...
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 ends...
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...
Receptor Downregulation in MVBs01:15

Receptor Downregulation in MVBs

Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that  lead to cell proliferation, migration, and differentiation. Overexpression of EGFR  stimulates cells to proliferate. Excessive  EGFR activation may...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...