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Related Concept Videos

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...
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...
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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...
Negative Regulator Molecules01:23

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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.
Mitogens and the Cell Cycle02:38

Mitogens and the Cell Cycle

Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...
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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.
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Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library
08:40

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Published on: April 6, 2012

MicroRNA-21 promotes cell transformation by targeting the programmed cell death 4 gene.

Z Lu1, M Liu, V Stribinskis

  • 1Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, KY 40202, USA.

Oncogene
|April 1, 2008
PubMed
Summary

MicroRNA-21 (miR-21) is overexpressed in many cancers. This study shows miR-21 promotes cell transformation by downregulating the tumor suppressor Pdcd4 protein, acting as an oncogene.

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Area of Science:

  • Molecular Biology
  • Oncology
  • Gene Regulation

Background:

  • MicroRNAs (miRNAs) are small noncoding RNAs regulating gene expression.
  • microRNA-21 (miR-21) is frequently overexpressed in various solid tumors.
  • The role of miR-21 in cancer progression is under investigation.

Purpose of the Study:

  • To identify miR-21 target genes.
  • To investigate the mechanism by which miR-21 influences cell transformation.
  • To determine if miR-21 functions as an oncogene.

Main Methods:

  • Reporter assays to identify miR-21 targets in the PDCD4 3'-UTR.
  • Western blotting and quantitative real-time PCR to assess protein and mRNA levels.
  • Cell transformation assays (soft agar colony formation) in cancer and mouse cells.

Main Results:

  • miR-21 directly targets the programmed cell death 4 (PDCD4) gene's 3'-UTR.
  • miR-21 downregulates PDCD4 protein levels, with minimal effect on mRNA.
  • Overexpression of miR-21 promotes cell transformation by inhibiting PDCD4.

Conclusions:

  • miR-21 acts as an oncogene by translationally repressing the tumor suppressor PDCD4.
  • miR-21's role in promoting cell transformation is mediated through PDCD4 downregulation.
  • These findings highlight miR-21 as a potential therapeutic target in cancer.