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Hyperactivation of 4E-binding protein 1 as a mediator of biguanide-induced cytotoxicity during glucose deprivation

Junichi Matsuo1, Yoshinori Tsukumo, Sakae Saito

  • 1Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo, Japan.

Molecular Cancer Therapeutics
|March 10, 2012
PubMed

Insights

Biguanides like metformin selectively kill glucose-deprived cancer cells by hyperactivating eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), inhibiting cell survival pathways.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cellular Stress Response

Background:

  • Biguanides (metformin, buformin, phenformin) show potential as antitumor agents.
  • These drugs induce cell death under glucose deprivation, a condition prevalent in tumors.
  • Glucose deprivation is a critical factor in the tumor microenvironment influencing treatment efficacy.

Purpose of the Study:

  • To elucidate the molecular mechanisms by which biguanides induce cell death in glucose-deprived cancer cells.
  • To investigate the role of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) in biguanide-mediated cell death.
  • To explore the connection between 4E-BP1, the unfolded protein response (UPR), and the mTOR signaling pathway in cancer therapy.

Main Methods:

  • Cellular assays to assess biguanide effects on glucose-deprived cells.
  • Western blotting and molecular analysis to evaluate protein activation and signaling pathways (4E-BP1, UPR, mTOR).
  • In vivo studies using xenografted cancer models treated with biguanides.

Main Results:

  • Biguanide treatment leads to hyperactivation of 4E-binding protein 1 (4E-BP1) in glucose-deprived cells.
  • Hyperactivated 4E-BP1 inhibits the unfolded protein response (UPR), a key cell survival pathway.
  • This inhibition of UPR is mediated by the suppression of the mTOR signaling pathway.
  • Biguanide-induced 4E-BP1 hyperactivation and subsequent UPR inhibition were confirmed in vivo.

Conclusions:

  • Antitumor effects of biguanides are linked to 4E-BP1 hyperactivation.
  • This mechanism selectively eliminates glucose-deprived cancer cells by disrupting UPR.
  • Targeting the 4E-BP1/UPR/mTOR axis offers a potential therapeutic strategy for cancers experiencing glucose deprivation.

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