Differential role of cathepsins B and L in autophagy-associated cell death induced by arsenic trioxide in U87 human glioblastoma cells

Biol Chem. 2010 May;391(5):519-31. doi: 10.1515/BC.2010.050.

Abstract

Arsenic trioxide (arsenite) was the first chemotherapeutic drug to be described and is now being rediscovered in cancer treatment, including glioblastoma multiforme. Arsenite toxicity triggers autophagy in cancer cells, although final stages of the process involve executive caspases, suggesting an interplay between autophagic and apoptotic pathways that awaits to be explained at a molecular level. We evaluated the contribution of the lysosomal cathepsins (Cat) L and B, which are upregulated in glioblastomas, in the mechanism of arsenite toxicity in human glioblastoma cells. Arsenite treatment induced autophagosome formation and permeabilization of mitochondria, followed by caspase 3/7-mediated apoptosis. The autophagy inhibitor 3-methyladenine protected from arsenite toxicity, whereas bafilomycin A1 did not. Furthermore, arsenite significantly decreased CatB levels and selectively inhibited its cellular and recombinant protein activity, while not affecting CatL. However, downregulation of CatL greatly enhanced apoptosis by arsenite. Our results show that arsenite toxicity involves a complex interplay between autophagy and apoptosis in human glioblastoma cells and is associated with inhibition of CatB, and that this toxicity is highly exacerbated by simultaneous CatL inhibition. The latter points to a synergy that could be used in clinical treatment to lower the therapeutic dose, thus avoiding the toxic side effects of arsenite in glioblastoma management.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Amino Acid Chloromethyl Ketones / pharmacology
  • Antineoplastic Agents / adverse effects
  • Antineoplastic Agents / therapeutic use*
  • Apoptosis / drug effects
  • Arsenic Trioxide
  • Arsenicals / adverse effects
  • Arsenicals / therapeutic use*
  • Autophagy* / drug effects
  • Caspases / metabolism
  • Cathepsin B / antagonists & inhibitors
  • Cathepsin B / physiology*
  • Cathepsin L / antagonists & inhibitors
  • Cathepsin L / physiology*
  • Cell Line, Tumor
  • Dipeptides / pharmacology
  • Down-Regulation
  • Epoxy Compounds / pharmacology
  • Glioblastoma / drug therapy*
  • Glioblastoma / metabolism
  • Humans
  • Macrolides / pharmacology
  • Oxides / adverse effects
  • Oxides / therapeutic use*
  • Pyridines / pharmacology

Substances

  • Amino Acid Chloromethyl Ketones
  • Antineoplastic Agents
  • Arsenicals
  • CA 074 methyl ester
  • CLIK 148
  • Dipeptides
  • Epoxy Compounds
  • Macrolides
  • Oxides
  • Pyridines
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • 3-methyladenine
  • bafilomycin A1
  • Caspases
  • CTSB protein, human
  • Cathepsin B
  • CTSL protein, human
  • Cathepsin L
  • Adenine
  • Arsenic Trioxide