Caspase-8 deficiency induces a switch from TLR3 induced apoptosis to lysosomal cell death in neuroblastoma

Sci Rep. 2021 May 19;11(1):10609. doi: 10.1038/s41598-021-89793-1.

Abstract

In cancer cells only, TLR3 acquires death receptor properties by efficiently triggering the extrinsic pathway of apoptosis with Caspase-8 as apical protease. Here, we demonstrate that in the absence of Caspase-8, activation of TLR3 can trigger a form of programmed cell death, which is distinct from classical apoptosis. When TLR3 was activated in the Caspase-8 negative neuroblastoma cell line SH-SY5Y, cell death was accompanied by lysosomal permeabilization. Despite caspases being activated, lysosomal permeabilization as well as cell death were not affected by blocking caspase-activity, positioning lysosomal membrane permeabilization (LMP) upstream of caspase activation. Taken together, our data suggest that LMP with its deadly consequences represents a "default" death mechanism in cancer cells, when Caspase-8 is absent and apoptosis cannot be induced.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis* / drug effects
  • Caspase 8 / metabolism*
  • Cell Line, Tumor
  • Enzyme Activation / drug effects
  • Humans
  • Interferon Type I / pharmacology
  • Intracellular Membranes / drug effects
  • Intracellular Membranes / metabolism
  • Lysosomes / drug effects
  • Lysosomes / metabolism
  • Necroptosis / drug effects
  • Neuroblastoma / metabolism*
  • Neuroblastoma / pathology*
  • Permeability / drug effects
  • Poly I-C / pharmacology
  • Toll-Like Receptor 3 / metabolism*

Substances

  • Interferon Type I
  • Toll-Like Receptor 3
  • Caspase 8
  • Poly I-C