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Transcriptional activation of Skp2 by BCR-ABL in K562 chronic myeloid leukemia cells

Jing-Yi Chen1, Ming-Chung Wang, Wen-Chun Hung

  • 1Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, Taiwan.

Leukemia Research
|March 31, 2009
PubMed

Insights

The BCR-ABL oncoprotein boosts Skp2 expression through the PI3K/AKT/Sp1 pathway. Inhibiting this pathway reduces Skp2 levels, offering potential therapeutic targets for BCR-ABL-driven cancers.

Area of Science:

  • Molecular Biology
  • Oncology
  • Biochemistry

Background:

  • The BCR-ABL oncoprotein is a key driver in chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL).
  • Skp2 (S-phase kinase-associated protein 2) is an oncogenic protein involved in cell cycle progression and cancer development.
  • Understanding the regulation of Skp2 by BCR-ABL is crucial for developing targeted therapies.

Purpose of the Study:

  • To elucidate the molecular mechanism by which the BCR-ABL oncoprotein regulates Skp2 expression.
  • To investigate the role of the PI3K/AKT signaling pathway and Sp1 transcription factor in this regulation.

Main Methods:

  • Utilized K562 cells (BCR-ABL-positive human leukemia cell line).
  • Administered Imatinib (BCR-ABL inhibitor) and LY294002 (PI3K inhibitor).
  • Performed small hairpin RNA (shRNA) knockdown of AKT and Sp1.
  • Analyzed Skp2 mRNA levels and promoter activity.
  • Conducted chromatin immunoprecipitation (ChIP) assays to assess protein-DNA interactions.

Main Results:

  • Imatinib and LY294002 treatments significantly reduced Skp2 mRNA levels in K562 cells.
  • Knockdown of AKT using shRNA also led to decreased Skp2 expression.
  • The Sp1 binding site (-386/-380) on the Skp2 promoter was essential for BCR-ABL-induced promoter activity.
  • Imatinib treatment inhibited the recruitment of p300 to the Sp1 site of the Skp2 promoter.
  • Knockdown of Sp1 effectively reduced Skp2 expression in K562 cells.

Conclusions:

  • BCR-ABL oncoprotein up-regulates Skp2 expression via the PI3K/AKT/Sp1 signaling pathway.
  • Sp1 acts as a critical transcription factor mediating BCR-ABL's effect on Skp2.
  • Targeting the PI3K/AKT/Sp1 pathway could be a therapeutic strategy to control Skp2 levels in BCR-ABL-positive malignancies.

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