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Bim-dependent apoptosis follows IGFBP-5 down-regulation in neuroblastoma cells

Barbara Tanno1, Roberta Vitali, Davide De Arcangelis

  • 1ENEA, Research Center Casaccia, Section of Toxicology and Biomedical Sciences, Rome, Italy.

Biochemical and Biophysical Research Communications
|October 28, 2006
PubMed

Insights

Silencing insulin-like growth factor binding protein-5 (IGFBP-5) in neuroblastoma cells triggers mitochondrial apoptosis. This process involves Bim upregulation and Erk1/Erk2 inhibition, highlighting IGFBP-5 as a potential therapeutic target.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • The insulin-like growth factor (IGF) axis is often activated in neuroblastoma (NB), a common pediatric cancer.
  • IGF Binding Protein-5 (IGFBP-5) plays a role in the IGF axis and cancer progression.

Purpose of the Study:

  • To investigate the functional role of endogenous IGFBP-5 in neuroblastoma cells.
  • To determine the molecular mechanisms by which IGFBP-5 influences neuroblastoma cell death.

Main Methods:

  • Silencing of IGFBP-5 using microRNA and small interfering RNA (siRNA) in neuroblastoma cell lines.
  • Assessment of apoptosis through cytochrome c release, caspase 9 activation, and pro-apoptotic protein expression (Bim, Bax).
  • Analysis of Erk1 and Erk2 signaling pathway activity.

Main Results:

  • Silencing IGFBP-5 induced mitochondrial apoptosis, evidenced by cytochrome c release and caspase 9 activation.
  • IGFBP-5 inhibition led to Erk1 and Erk2 signaling pathway suppression.
  • Pro-apoptotic proteins Bim and Bax were upregulated, with Bim stabilization potentially linked to Erk inhibition.
  • Knockdown of Bim partially rescued apoptosis in IGFBP-5-silenced cells.

Conclusions:

  • Endogenous IGFBP-5 inhibition triggers Bim-dependent apoptosis in neuroblastoma cells.
  • The Erk1/Erk2 pathway and Bim protein stabilization are involved in IGFBP-5-mediated apoptosis.
  • Targeting IGFBP-5 represents a potential therapeutic strategy for neuroblastoma.

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