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PTEN suppresses the oncogenic function of AIB1 through decreasing its protein stability via mechanism involving Fbw7

Chunhua Yang1, Shujing Li, Miao Wang

  • 1School of Life Science and Biotechnology, Dalian University of Technology, 2 Ling Gong Road, Dalian 116024, China.

Molecular Cancer
|March 22, 2013
PubMed
Abstract

Insights

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) negatively regulates Amplified in breast cancer 1 (AIB1) by promoting its degradation. This interaction, involving F-box and WD repeat domain-containing 7 alpha (Fbw7α), downregulates AIB1

Area of Science:

  • Oncology
  • Molecular Biology
  • Biochemistry

Background:

  • Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) antagonizes the PI3K/AKT pathway and regulates transcription factors.
  • Amplified in breast cancer 1 (AIB1) is a transcriptional coactivator overexpressed in human carcinomas.
  • The study explores the regulatory relationship between PTEN and AIB1 in cancer.

Purpose of the Study:

  • To investigate the mechanism by which PTEN regulates the transcriptional coactivator AIB1.
  • To understand the role of PTEN-mediated regulation of AIB1 in cancer progression.

Main Methods:

  • Investigated protein-protein interactions between PTEN and AIB1.
  • Assessed the role of PTEN's phosphatase activity in AIB1 regulation.
  • Utilized knockdown experiments in MCF-7 cells to evaluate the functional consequences of PTEN and AIB1 interactions.

Main Results:

  • PTEN interacts with AIB1 via its phosphatase domain, enhancing AIB1 ubiquitination and degradation.
  • PTEN interacts with the E3 ubiquitin ligase Fbw7α via its C2 domain, bridging PTEN and AIB1 for degradation.
  • PTEN's regulation of AIB1 degradation does not require PTEN's phosphatase activity.
  • Knockdown of PTEN in MCF-7 cells increased proliferation, which was abolished by simultaneous AIB1 knockdown.

Conclusions:

  • PTEN acts as a negative regulator of AIB1, downregulating its transcriptional activity.
  • The association of PTEN with AIB1 and Fbw7α leads to AIB1 degradation and reduced oncogenic function.
  • PTEN's regulation of AIB1 is a critical mechanism for controlling cell proliferation in breast cancer.

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