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Updated: Jun 22, 2026

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death
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Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Published on: December 27, 2016

Enhancing the apoptotic potential of insulin-like growth factor-binding protein-3 in prostate cancer by modulation of

Laura J Cobb1, Hemal Mehta, Pinchas Cohen

  • 1Division of Pediatric Endocrinology, Mattel Children's Hospital at University of California, Los Angeles, California, USA.

Molecular Endocrinology (Baltimore, Md.)
|June 27, 2009
PubMed

Insights

Insulin-like growth factor-binding protein 3 (IGFBP-3) phosphorylation by casein kinase 2 (CK2) regulates its ability to induce apoptosis in prostate cancer cells. Inhibiting CK2 enhances IGFBP-3

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Biochemistry

Background:

  • Insulin-like growth factor-binding protein 3 (IGFBP-3) is a key regulator of apoptosis, acting through both IGF-dependent and -independent pathways.
  • Previous research established that phosphorylation of IGFBP-3 at serine 156 (S156) by DNA-dependent protein kinase (DNA-PK) is crucial for its nuclear localization and interaction with retinoid X receptor-alpha (RXRα), thereby inducing apoptosis in prostate cancer cells.

Purpose of the Study:

  • To investigate the role of casein kinase 2 (CK2) in regulating the apoptotic function of IGFBP-3.
  • To identify specific CK2 phosphorylation sites on IGFBP-3 and elucidate their impact on apoptosis induction.

Main Methods:

  • Utilized specific chemical inhibitors and small interfering RNA (siRNA) to modulate CK2 activity.
  • Employed site-directed mutagenesis to create IGFBP-3 mutants (S167A, S175A) and assessed their apoptotic potential.
  • Investigated the effects of IGFBP-3 siRNA and exogenous IGFBP-3 on CK2 inhibitor-induced apoptosis in 22RV1 prostate cancer cells.

Main Results:

  • Inhibition of CK2 activation significantly enhanced the apoptotic potential of IGFBP-3.
  • Identified serine 167 (S167) and serine 175 (S175) as potential CK2 phosphorylation sites on IGFBP-3.
  • The IGFBP-3-S167A mutant exhibited significantly enhanced apoptosis induction compared to wild-type IGFBP-3, indicating that CK2 phosphorylation at S167 negatively regulates apoptosis.
  • IGFBP-3 siRNA reduced the efficacy of CK2 inhibitors in inducing apoptosis, suggesting a reciprocal regulatory relationship between IGFBP-3 and CK2.

Conclusions:

  • Multisite phosphorylation of IGFBP-3 by CK2 plays a critical role in both positively and negatively regulating its apoptotic activity.
  • Understanding the intricate regulation of IGFBP-3 by CK2 phosphorylation offers potential therapeutic strategies for prostate cancer treatment.

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