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Homotypic gap junctional communication associated with metastasis suppression increases with PKA activity and is

Thomas M Bodenstine1, Kedar S Vaidya, Aimen Ismail

  • 1Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA.

Cancer Research
|November 25, 2010
PubMed

Insights

Loss of gap junctional intercellular communication (GJIC) is reversed by PI3K inhibitors LY294002 and LY303511, independent of PI3K/AKT. This restoration involves protein kinase A (PKA) activation and connexin 43 relocalization, offering potential antimetastatic therapies.

Area of Science:

  • Oncology
  • Cell Biology
  • Molecular Biology

Background:

  • Loss of gap junctional intercellular communication (GJIC) is a hallmark of cancer progression.
  • Breast cancer metastasis suppressor 1 (BRMS1) links GJIC and phosphoinositide-3-kinase (PI3K) signaling.
  • Connexin regulation involves protein phosphorylation, affecting trafficking and degradation.

Purpose of the Study:

  • To investigate the link between PI3K signaling and GJIC in cancer cells.
  • To determine if PI3K inhibitors can restore GJIC.
  • To elucidate the molecular mechanisms underlying GJIC restoration.

Main Methods:

  • Treatment of cancer cell lines with PI3K inhibitors LY294002 and LY303511.
  • Assessment of GJIC using established assays.
  • Analysis of connexin 43 (CX43) protein levels and localization.
  • Measurement of protein kinase A (PKA) activity.
  • Inhibition of PKA using H89 to assess its role.

Main Results:

  • LY294002 and LY303511 increased GJIC in a PI3K/AKT-independent manner.
  • GJIC restoration occurred without altering connexin gene expression.
  • Connexin 43 relocalized from the cytosol to the plasma membrane.
  • Both LY294002 and LY303511 enhanced PKA activity.
  • PKA inhibition blocked the GJIC-restoring effects of LY294002/LY303511.

Conclusions:

  • PI3K-independent activation of PKA mediates GJIC restoration by LY294002 and LY303511.
  • Connexin 43 relocalization is a key event in GJIC recovery.
  • Targeting PKA and related pathways may offer novel antimetastatic strategies.

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