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Phosphorylation-independent mTORC1 inhibition by the autophagy inducer Rottlerin

C Torricelli1, E Daveri1, S Salvadori1

  • 1Department of Life Sciences, University of Siena, via Aldo Moro, Siena 7-53100, Italy.

Cancer Letters
|February 10, 2015
PubMed

Insights

Rottlerin induces autophagic cell death in breast cancer cells independently of apoptosis pathways. This process involves direct interaction with mTOR, inhibiting its activity via a novel mechanism not dependent on AMPK or mTOR phosphorylation.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Death Pathways

Background:

  • Rottlerin, a natural compound, has demonstrated anti-proliferative effects in cancer cells.
  • Previous studies indicated Rottlerin induces autophagic cell death in apoptosis-resistant breast adenocarcinoma MCF-7 cells.
  • Canonical signaling pathways were excluded as mediators of Rottlerin-induced autophagy.

Purpose of the Study:

  • To investigate the role of the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) axis in Rottlerin-induced autophagy.
  • To identify upstream signaling molecules targeted by Rottlerin.
  • To elucidate the mechanism by which Rottlerin triggers autophagy in breast cancer cells.

Main Methods:

  • Utilized enzyme inhibitors and Western blotting analysis.
  • Employed mTOR siRNA (small interfering RNA) and pull-down assays.
  • Investigated phosphorylation-independent mechanisms and direct molecular interactions.

Main Results:

  • Rottlerin-triggered autophagy is mediated by the inhibition of mTOR complex 1 (mTORC1) activity.
  • This inhibition occurs through a novel mechanism independent of AMPK and mTORC1 phosphorylation.
  • Evidence suggests a direct interaction between Rottlerin and mTOR.

Conclusions:

  • Rottlerin induces autophagic cell death in breast cancer cells via a novel mTORC1-inhibitory mechanism.
  • The mechanism is independent of canonical signaling pathways, AMPK, and mTOR phosphorylation.
  • Rottlerin likely exerts its effects through direct interaction with mTOR, offering a new therapeutic target.
Keywords:
AMPKAutophagyRaptorRottlerinmTOR

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