Related Experiment Video

Updated: Jun 1, 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

Loss of the miR-21 allele elevates the expression of its target genes and reduces tumorigenesis

Xiaodong Ma1, Munish Kumar, Saibyasachi N Choudhury

  • 1Department of Biochemistry and Molecular Biology, School of Medicine, University of Louisville, 319 Abraham Flexner Way, Louisville, KY 40202, USA.

Proceedings of the National Academy of Sciences of the United States of America
|June 8, 2011
PubMed

Insights

MicroRNA 21 (miR-21) drives cancer development. Deleting the miR-21 gene in mice significantly reduced skin tumors by increasing cell death and decreasing cell growth, confirming its oncogenic role.

Area of Science:

  • Oncology
  • Molecular Biology
  • Genetics

Background:

  • MicroRNA 21 (miR-21) is frequently overexpressed in various cancers, suggesting a role in tumorigenesis.
  • Its specific function in promoting tumor development in vivo remains to be fully elucidated.

Purpose of the Study:

  • To investigate the in vivo role of miR-21 in chemical-induced skin carcinogenesis.
  • To determine if miR-21 promotes tumor development by regulating target genes involved in cell proliferation and apoptosis.

Main Methods:

  • Generation of miR-21-null mice by gene knockout.
  • Application of the 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate skin carcinogenesis protocol.
  • Analysis of papilloma formation, cellular apoptosis, cell proliferation, and expression of miR-21 target genes and signaling pathways (ERK, AKT, JNK).

Main Results:

  • miR-21-null mice exhibited significantly reduced papilloma formation compared to wild-type mice.
  • Absence of miR-21 led to increased cellular apoptosis and decreased cell proliferation in the skin.
  • Key miR-21 target genes (Spry1, Pten, Pdcd4) were upregulated in miR-21-null keratinocytes, correlating with reduced phosphorylation of ERK, AKT, and JNK signaling pathways.

Conclusions:

  • These findings provide in vivo evidence that miR-21 promotes skin carcinogenesis.
  • miR-21 exerts its oncogenic function by negatively regulating its target genes, impacting critical signaling pathways involved in cell growth and survival.

More Related Videos

Utilizing Murine Inducible Telomerase Alleles in the Studies of Tissue Degeneration/Regeneration and Cancer08:34

Utilizing Murine Inducible Telomerase Alleles in the Studies of Tissue Degeneration/Regeneration and Cancer

Published on: April 13, 2015

Related Concept Videos

Loss of Tumor Suppressor Gene Functions01:12

Loss of Tumor Suppressor Gene Functions

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
Loss of Tumor Suppressor Gene Functions01:12

Loss of Tumor Suppressor Gene Functions

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
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...
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...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...