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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

Myc overexpression brings out unexpected antiapoptotic effects of miR-34a

E Sotillo1, T Laver, H Mellert

  • 1Division of Cancer Pathobiology, Department of Pathology & Laboratory Medicine, The Children's Hospital of Philadelphia, PA 19104-4399, USA.

Oncogene
|February 8, 2011
PubMed

Insights

MicroRNA-34a (miR-34a) upregulation, typically promoting apoptosis, unexpectedly confers drug resistance in Myc-overexpressing B-lymphoid cancers by targeting Myc and reducing p53 levels. Inhibiting miR-34a may enhance cancer therapy.

Area of Science:

  • Molecular Biology
  • Oncology
  • Gene Regulation

Background:

  • MicroRNA-34a (miR-34a) is regulated by both Myc and p53, influencing tumorigenesis and apoptosis.
  • Myc overexpression is linked to cancer development and tumor-cell survival.
  • p53-mediated miR-34a upregulation is associated with pro-apoptotic effects.

Purpose of the Study:

  • To investigate the therapeutic potential of restoring miR-34a levels in Myc-overexpressing B-lymphoid cells.
  • To elucidate the interaction between miR-34a, Myc, and p53 in the context of cancer therapy.

Main Methods:

  • Delivery of miR-34a mimics into B-lymphoid cells with Myc overexpression.
  • Assessment of p53 protein levels and apoptosis induction.
  • Utilizing antisense RNA to inhibit miR-34a.
  • Investigating the role of the Arf-Hdm2 pathway.

Main Results:

  • Restoration of miR-34a unexpectedly decreased steady-state p53 levels in Myc-overexpressing cells.
  • miR-34a directly targeted Myc, which is crucial for maintaining p53 protein levels via the Arf-Hdm2 pathway.
  • In the presence of Myc, miR-34a inhibited p53-dependent bortezomib-induced apoptosis.
  • Inhibition of miR-34a sensitized lymphoma cells to apoptosis.

Conclusions:

  • In tumors with deregulated Myc expression, miR-34a confers resistance to apoptosis-inducing drugs.
  • miR-34a acts as a mediator of drug resistance in this context.
  • miR-34a represents a potential therapeutic target for overcoming drug resistance in Myc-driven lymphomas.

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