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Updated: Apr 22, 2026
Genome-wide Screen for miRNA Targets Using the MISSION Target ID Library
Published on: April 6, 2012
Disruption of microRNA-21 by TALEN leads to diminished cell transformation and increased expression of
Buyuan Chen1,2, Xinji Chen1,2, Xiwei Wu1
1Department of Molecular and Cellular Biology, Beckman Research Institute of City of Hope, Duarte, California, USA.
Abstract:
MicroRNA-21 is dysregulated in many cancers and fibrotic diseases. Since miR-21 suppresses several tumor suppressor and anti-apoptotic genes, it is considered a cancer therapeutic target. Antisense oligonucleotides are commonly used to inhibit a miRNA; however, blocking miRNA function via an antagomir is temporary, often only achieves a partial knock-down, and may be complicated by off-target effects. Here, we used transcription activator-like effector nucleases (TALENs) to disrupt miR-21 in cancerous cells. Individual deletion clones were screened and isolated without drug selection. Sequencing and quantitative RT-PCR identified clones with no miR-21 expression. The loss of miR-21 led to subtle but global increases of mRNAs containing miR-21 target sequences. Cells without miR-21 became more sensitive to cisplatin and less transformed in culture and in mouse xenografts. In addition to the increase of PDCD4 and PTEN protein, mRNAs for COL4A1, JAG1, SERPINB5/Maspin, SMAD7, and TGFBI - all are miR-21 targets and involved in TGFβ and fibrosis regulation - were significantly upregulated in miR-21 knockout cells. Gene ontology and pathway analysis suggested that cell-environment interactions involving extracellular matrix can be an important miR-21 pathogenic mechanism. The study also demonstrates the value of using TALEN-mediated microRNA gene disruption in human pathobiological studies.
Insights
MicroRNA-21 (miR-21) was disrupted in cancer cells using TALENs, leading to reduced tumor growth and increased sensitivity to chemotherapy. This study highlights a novel gene editing approach for targeting miR-21 in cancer therapy.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- MicroRNA-21 (miR-21) is frequently dysregulated in cancers and fibrotic diseases.
- miR-21 acts as an oncomiR by suppressing tumor suppressor and anti-apoptotic genes.
- Current methods like antagomirs for miRNA inhibition have limitations including temporary effects and off-target issues.
Purpose of the Study:
- To investigate the functional consequences of miR-21 gene disruption in cancer cells using TALENs.
- To evaluate the potential of miR-21 knockout as a therapeutic strategy for cancer.
- To explore the role of miR-21 in regulating gene expression and cellular behavior.
Main Methods:
- Utilized Transcription Activator-Like Effector Nucleases (TALENs) to create miR-21 knockout in cancerous cells.
- Screened and isolated individual deletion clones without drug selection.
- Confirmed miR-21 absence using sequencing and quantitative RT-PCR.
Main Results:
- miR-21 knockout cells exhibited decreased transformation in vitro and reduced tumor growth in mouse xenografts.
- Loss of miR-21 sensitized cancer cells to cisplatin treatment.
- Upregulation of miR-21 target genes, including PDCD4, PTEN, COL4A1, JAG1, SERPINB5/Maspin, SMAD7, and TGFBI, was observed.
Conclusions:
- TALEN-mediated miR-21 gene disruption is a viable strategy for cancer therapy.
- miR-21 plays a significant role in cancer progression, cell transformation, and chemoresistance.
- Disrupting miR-21 impacts cell-environment interactions and extracellular matrix regulation, suggesting its involvement in fibrosis.
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