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The Ripoptosome, a signaling platform that assembles in response to genotoxic stress and loss of IAPs

Tencho Tenev1, Katiuscia Bianchi, Maurice Darding

  • 1The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK. tencho.tenev@icr.ac.uk

Molecular Cell
|July 9, 2011
PubMed

Insights

Scientists discovered the Ripoptosome, a large cell death platform crucial for anticancer drug efficacy. This complex forms under genotoxic stress, independent of known death pathways, and promotes cancer cell death.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Drug Discovery

Background:

  • Understanding anticancer drug mechanisms is vital for improving combination therapies.
  • Genotoxic stress is a key mechanism by which chemotherapeutics induce cancer cell death.
  • The precise molecular platforms mediating stress-induced cell death remain incompletely defined.

Purpose of the Study:

  • To identify and characterize novel cell death platforms involved in anticancer drug action.
  • To elucidate the molecular composition and assembly requirements of the Ripoptosome.
  • To investigate the role of the Ripoptosome in mediating cancer cell death upon genotoxic stress.

Main Methods:

  • Cellular assays to detect and analyze large protein complexes.
  • Biochemical analyses including immunoprecipitation and Western blotting.
  • Studies involving genotoxic agents (e.g., etoposide) and Smac-mimetics.

Main Results:

  • Discovery of a ~2MDa cell death-inducing platform, the Ripoptosome, containing RIP1, FADD, and caspase-8.
  • Ripoptosome assembly is triggered by genotoxic stress-induced depletion of IAPs (XIAP, cIAP1, cIAP2).
  • Formation occurs independently of TNF, death receptors, and mitochondrial pathways, and requires RIP1 kinase activity.
  • The Ripoptosome mediates both apoptosis and necrosis and is negatively regulated by FLIP and IAPs.
  • Etoposide-induced Ripoptosome formation converts inflammatory signals into pro-death signals.

Conclusions:

  • The Ripoptosome represents a novel, fundamental cell death platform assembled under genotoxic stress.
  • Its assembly and function provide new insights into how chemotherapeutics kill cancer cells.
  • Targeting the Ripoptosome or its regulators could offer new strategies for cancer therapy.

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