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Gossypol inhibits phosphorylation of Bcl-2 in human leukemia HL-60 cells

Li-heng Huang1, Jia-qi Hu, Wei-qun Tao

  • 1Department of Biochemistry, School of Medicine, Shantou University, China.

European Journal of Pharmacology
|July 17, 2010
PubMed

Insights

Gossypol induces apoptosis in leukemia cells by reducing Bcl-2 phosphorylation at serine 70. This finding suggests gossypol as a potential therapeutic for leukemia, particularly in patients with phosphorylated Bcl-2.

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Gossypol is recognized as a potential anti-tumor agent that induces apoptosis.
  • The precise molecular mechanisms of gossypol-induced apoptosis in cancer cells require further elucidation.
  • Understanding the role of Bcl-2 family proteins in gossypol's anti-leukemic effects is crucial.

Purpose of the Study:

  • To investigate the effects of gossypol on apoptosis-related protein levels and phosphorylation in human leukemia HL-60 cells.
  • To elucidate the specific alterations in Bcl-2, Bcl-xL, and Mcl-1 protein expression and Bcl-2 phosphorylation.
  • To determine the role of protein kinase C (PKC) in gossypol-mediated apoptosis.

Main Methods:

  • Treatment of human leukemia HL-60 cells with varying doses and durations of gossypol.
  • Analysis of Bcl-2, Bcl-xL, and Mcl-1 protein levels via Western blotting.
  • Assessment of Bcl-2 phosphorylation at specific sites (Serine 70 and Threonine 56).
  • Investigation of the effects of phorbol 12,13-dibutyrate (PDBu), a PKC activator, on gossypol-induced changes.

Main Results:

  • Gossypol inhibited HL-60 cell growth and induced apoptosis.
  • Slight reductions in Bcl-2, Bcl-xL, and Mcl-1 protein levels were observed.
  • Gossypol significantly down-regulated Bcl-2 phosphorylation at serine 70 (phospho S70) in a dose- and time-dependent manner.
  • Phorbol 12,13-dibutyrate (PDBu) treatment blocked the reduction in Bcl-2 phospho S70 and partially inhibited gossypol-induced apoptosis.

Conclusions:

  • Gossypol induces apoptosis in leukemia HL-60 cells, partly by reducing Bcl-2 phosphorylation at serine 70.
  • The modulation of Bcl-2 phosphorylation by gossypol is influenced by protein kinase C (PKC) activity.
  • Gossypol demonstrates potential as a therapeutic agent for leukemia, especially in patients with elevated phosphorylated Bcl-2 at Ser70.

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