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Luteolin induces carcinoma cell apoptosis through binding Hsp90 to suppress constitutive activation of STAT3

Jin Fu1, Dan Chen, Bo Zhao

  • 1Jiangsu Province Key Laboratory for Molecular and Medicine Biotechnology, College of Life Science, Nanjing Normal University, Nanjing, People's Republic of China.

Plos One
|November 13, 2012
PubMed
Abstract

Insights

Luteolin triggers cancer cell apoptosis by degrading STAT3, a protein stabilized by Hsp90. This study reveals luteolin

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Signal transducer and activator of transcription 3 (STAT3) hyperactivity is linked to human cancers.
  • Heat shock protein 90 (Hsp90) stabilizes STAT3, crucial for cell growth and oncogenesis.
  • Luteolin exhibits anticancer properties by degrading Tyr(705)-phosphorylated STAT3.

Purpose of the Study:

  • To investigate the mechanism by which luteolin induces STAT3 degradation.
  • To explore the interaction between luteolin, Hsp90, and STAT3.
  • To determine if luteolin can serve as an Hsp90 inhibitor for cancer therapy.

Main Methods:

  • Co-immunoprecipitation and immunoblot analysis to assess protein interactions and degradation.
  • Molecular modeling with CHARMm-Discovery Studio 2.1 for binding pocket analysis.
  • Surface Plasmon Resonance (SPR) and ATP-sepharose binding assays to confirm luteolin-Hsp90 interaction and inhibition.

Main Results:

  • Overexpression of Hsp90 impeded luteolin-induced STAT3 degradation.
  • Luteolin disrupted the Hsp90-STAT3 association, leading to proteasomal degradation of phosphorylated STAT3 (Tyr705 and Ser727).
  • Luteolin binds to Hsp90's ATP-binding pocket, inhibiting Hsp90-ATP interaction.

Conclusions:

  • Luteolin promotes STAT3 degradation by interacting with Hsp90, inducing cancer cell apoptosis.
  • Luteolin acts as a functional Hsp90 inhibitor, suggesting potential in antitumor strategies.

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