1. Academic Validation
  2. Glycosylation defects, offset by PEPCK-M, drive entosis in breast carcinoma cells

Glycosylation defects, offset by PEPCK-M, drive entosis in breast carcinoma cells

  • Cell Death Dis. 2022 Aug 24;13(8):730. doi: 10.1038/s41419-022-05177-x.
Petra Hyroššová 1 Marc Aragó 1 Cristina Muñoz-Pinedo 2 Francesc Viñals 1 2 Pablo M García-Rovés 1 Carmen Escolano 3 Andrés Méndez-Lucas 1 2 Jose C Perales 4 5
Affiliations

Affiliations

  • 1 Department of Physiological Sciences, School of Medicine, University of Barcelona-IDIBELL, L'Hospitalet de Llobregat, Spain.
  • 2 Programs of Molecular Mechanisms and Experimental Therapeutics in Oncology (Oncobell), and Cancer Therapeutics Resistance (ProCURE), Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Spain.
  • 3 Laboratory of Medicinal Chemistry (Associated Unit to CSIC), Faculty of Pharmacy and Food Sciences, and Institute of Biomedicine (IBUB), University of Barcelona, Barcelona, Spain.
  • 4 Department of Physiological Sciences, School of Medicine, University of Barcelona-IDIBELL, L'Hospitalet de Llobregat, Spain. jperales@ub.edu.
  • 5 Programs of Molecular Mechanisms and Experimental Therapeutics in Oncology (Oncobell), and Cancer Therapeutics Resistance (ProCURE), Catalan Institute of Oncology, Bellvitge Institute for Biomedical Research (IDIBELL), L'Hospitalet del Llobregat, Spain. jperales@ub.edu.
Abstract

On glucose restriction, epithelial cells can undergo entosis, a cell-in-cell cannibalistic process, to allow considerable withstanding to this metabolic stress. Thus, we hypothesized that reduced protein glycosylation might participate in the activation of this cell survival pathway. Glucose deprivation promoted entosis in an MCF7 breast carcinoma model, as evaluated by direct inspection under the microscope, or revealed by a shift to Apoptosis + necrosis in cells undergoing entosis treated with a Rho-GTPase kinase inhibitor (ROCKi). In this context, curbing protein glycosylation defects with N-acetyl-glucosamine partially rescued entosis, whereas limiting glycosylation in the presence of glucose with tunicamycin or NGI-1, but not with other unrelated ER-stress inducers such as thapsigargin or amino-acid limitation, stimulated entosis. Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M; PCK2) is upregulated by glucose deprivation, thereby enhancing cell survival. Therefore, we presumed that PEPCK-M could play a role in this process by offsetting key metabolites into glycosyl moieties using alternative substrates. PEPCK-M inhibition using iPEPCK-2 promoted entosis in the absence of glucose, whereas its overexpression inhibited entosis. PEPCK-M inhibition had a direct role on total protein glycosylation as determined by Concanavalin A binding, and the specific ratio of fully glycosylated LAMP1 or E-cadherin. The content of metabolites, and the fluxes from 13C-glutamine label into glycolytic intermediates up to glucose-6-phosphate, and ribose- and ribulose-5-phosphate, was dependent on PEPCK-M content as measured by GC/MS. All in all, we demonstrate for the first time that protein glycosylation defects precede and initiate the entosis process and implicates PEPCK-M in this survival program to dampen the consequences of glucose deprivation. These results have broad implications to our understanding of tumor metabolism and treatment strategies.

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