Constitutive Activation of p62/Sequestosome-1-Mediated Proteaphagy Regulates Proteolysis and Impairs Cell Death in Bortezomib-Resistant Mantle Cell Lymphoma

Grégoire Quinet, Wendy Xolalpa, Diana Reyes-Garau, Núria Profitós-Pelejà, Mikel Azkargorta, Laurie Ceccato, Maria Gonzalez-Santamarta, Maria Marsal, Jordi Andilla, Fabienne Aillet, Francesc Bosch, Felix Elortza, Pablo Loza-Alvarez, Brigitte Sola, Olivier Coux, Rune Matthiesen, Gaël Roué, Manuel S. Rodriguez

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Abstract

Protein ubiquitylation coordinates crucial cellular events in physiological and pathological conditions. A comparative analysis of the ubiquitin proteome from bortezomib (BTZ)-sensitive and BTZ-resistant mantle cell lymphoma (MCL) revealed an enrichment of the autophagy-lysosome system (ALS) in BTZ-resistant cells. Pharmacological inhibition of autophagy at the level of lysosome-fusion revealed a constitutive activation of proteaphagy and accumulation of proteasome subunits within autophagosomes in different MCL cell lines with acquired or natural resistance to BTZ. Inhibition of the autophagy receptor p62/SQSTM1 upon verteporfin (VTP) treatment disrupted proteaphagosome assembly, reduced co-localization of proteasome subunits with autophagy markers and negatively impacted proteasome activity. Finally, the silencing or pharmacological inhibition of p62 restored the apoptosis threshold at physiological levels in BTZ-resistant cells both in vitro and in vivo. In total, these results demonstrate for the first time a proteolytic switch from the ubiquitin-proteasome system (UPS) to ALS in B-cell lymphoma refractory to proteasome inhibition, pointing out a crucial role for proteaphagy in this phenomenon and paving the way for the design of alternative therapeutic venues in treatment-resistant tumors.

Original languageEnglish
Article number923
JournalCancers
Volume14
Issue number4
DOIs
Publication statusPublished - 1 Feb 2022

Keywords

  • Apoptosis
  • Autophagy
  • Proteasome inhibitor
  • TUBEs
  • Ubiquitin proteome
  • Verteporfin

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