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E2F1-regulated microRNAs impair TGFbeta-dependent cell-cycle arrest and apoptosis in gastric cancer

Fabio Petrocca1, Rosa Visone, Mariadele Rapazzotti Onelli

  • 1Department of Molecular Virology, Immunology and Medical Genetics, Human Cancer Genetics Program, Ohio State University, 460 West 12th Avenue, Columbus, OH 43210, USA.

Cancer Cell
|March 11, 2008
PubMed

Insights

The miR-106b-25 microRNA cluster, activated by E2F1, promotes gastric cancer by creating a feedback loop that enhances E2F1 activity and blocks tumor suppression. This microRNA cluster contributes to resistance to TGFbeta signaling in gastric tumors.

Area of Science:

  • Molecular oncology
  • Gene regulation
  • Cancer biology

Background:

  • Gastric cancer is characterized by E2F1 deregulation and TGFbeta resistance.
  • MicroRNAs (miRNAs) are small noncoding RNAs often misregulated in cancers.
  • The miR-106b-25 cluster is upregulated in some gastric tumors.

Purpose of the Study:

  • To investigate the role of the miR-106b-25 cluster in gastric cancer.
  • To elucidate the regulatory relationship between E2F1, miRNAs, and the TGFbeta pathway.

Main Methods:

  • Analysis of miR-106b-25 cluster expression in gastric tumors.
  • Investigating the activation of the miR-106b-25 cluster by E2F1.
  • Studying the feedback loop between miRNAs and E2F1.
  • Assessing the impact of miRNA upregulation on the TGFbeta pathway.

Main Results:

  • The miR-106b-25 cluster is activated by E2F1 in gastric cancer.
  • miR-106b and miR-93 form a negative feedback loop regulating E2F1.
  • Upregulation of these miRNAs disrupts the TGFbeta tumor suppressor pathway.
  • Expression of CDKN1A (p21) and BCL2L11 (Bim) is impaired by the miRNAs.

Conclusions:

  • The miR-106b-25 cluster is implicated in posttranscriptional regulation of E2F1.
  • This miRNA cluster may be crucial for developing TGFbeta resistance in gastric cancer.
  • The findings highlight a novel mechanism contributing to gastric tumorigenesis.

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