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Downregulation of myc promoter-binding protein 1 (MBP-1) in growth-arrested malignant B cells

D Tvrdík1, P Dundr, C Povýsil

  • 1Institute of Pathology, Charles University in Prague, 1st Faculty of Medicine and General Teaching Hospital, Prague, Czech Republic. Daniel.Tvrdik@vfn.cz

Folia Biologica
|December 12, 2007
PubMed

Insights

Transforming growth factor-beta1 (TGF-beta1) inhibits malignant B lymphoma cell growth by downregulating myc-binding protein-1 (MBP-1). This leads to c-Myc overexpression via MBP-1 binding to the myc gene promoter.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Cancer Research

Background:

  • Normal B lymphocytes are sensitive to TGF-beta1 growth inhibition, but malignant B lymphoma cells often exhibit resistance.
  • Previous studies demonstrated TGF-beta1's significant growth inhibition of the DoHH2 cell line.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying TGF-beta1-induced growth arrest in malignant B cells.
  • To elucidate the role of myc-binding protein-1 (MBP-1) and c-Myc in TGF-beta1's effects on B lymphoma cells.

Main Methods:

  • Treatment of DoHH2 malignant B cells with TGF-beta1.
  • Analysis of MBP-1 expression levels following TGF-beta1 treatment.
  • Investigation of the binding of MBP-1 to the myc gene promoter region.

Main Results:

  • TGF-beta1 treatment led to significant growth arrest in DoHH2 cells.
  • TGF-beta1-induced growth arrest was correlated with a notable downregulation of MBP-1.
  • c-Myc overexpression in arrested cells was mediated by MBP-1 acting as a transcription repressor, binding to the (+118/+153) element of the myc promoter.

Conclusions:

  • MBP-1 downregulation is a key event in TGF-beta1-induced growth arrest of malignant B cells.
  • MBP-1 plays a critical role in regulating c-Myc expression in response to TGF-beta1.
  • The interaction between MBP-1 and the myc promoter offers a potential therapeutic target for B cell lymphomas.

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