title: Resveratrol augments ER stress and the cytotoxic effects of glycolytic inhibition in neuroblastoma by downregulating Akt in a mechanism independent of SIRT1.
abstract: Cancer cells typically display increased rates of aerobic glycolysis that are correlated with tumor aggressiveness and a poor prognosis. Targeting the glycolytic pathway has emerged as an attractive therapeutic route mainly because it should spare normal cells. Here, we evaluate the effects of combining the inhibition of glycolysis with application of the polyphenolic compound resveratrol (RSV) in neuroblastoma (NB) cancer cell lines. Inhibiting glycolysis with 2-deoxy-D-glucose (2-DG) significantly reduced NB cell viability and was associated with increased endoplasmic reticulum (ER) stress and Akt activity. Administration of 2-DG increased the expression of the ER molecular chaperones GRP78 and GRP94, the prodeath protein C/EBP homology protein (CHOP) and the phosphorylation of Akt at S473, T450 and T308. Combined treatment with both RSV and 2-DG reduced GRP78, GRP94 and Akt phosphorylation but increased CHOP and NB cell death when compared with the administration of 2-DG alone. The selective inhibition of Akt activity also decreased 2-DG-induced GRP78 and GRP94 expression and increased CHOP expression, suggesting that Akt can modulate ER stress. Protein phosphatase 1α (PP1α) was activated by RSV, as indicated by a reduction in PP1α phosphorylation at T320. Pretreatment of cells with tautomycin, a selective PP1α inhibitor, prevented the RSV-mediated decrease in Akt phosphorylation, suggesting that RSV enhances 2-DG-induced cell death by activating PP1 and downregulating Akt. The RSV-mediated inhibition of Akt in the presence of 2-DG was not prevented by the selective inhibition of SIRT1, a known target of RSV, indicating that the effects of RSV on this pathway are independent of SIRT1. We propose that RSV inhibits Akt activity by increasing PP1α activity, thereby potentiating 2-DG-induced ER stress and NB cell death.
authors.affiliation: Department of Neurological Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.
authors.forename: Regina M
authors.identifier: http://orcid.org/0000-0003-0103-2971
authors.initials: RM
authors.lastname: Graham
authors.affiliation: Miami Children's Hospital, Miami, FL, USA.
authors.forename: Fiorela
authors.initials: F
authors.lastname: Hernandez
authors.affiliation: Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA.
authors.forename: Nataly
authors.initials: N
authors.lastname: Puerta
authors.affiliation: Miami Children's Hospital, Miami, FL, USA.
authors.forename: Guillermo
authors.initials: G
authors.lastname: De Angulo
authors.affiliation: Department of Molecular and Cellular Pharmacology, Miller School of Medicine, University of Miami, Miami, FL, USA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Webster
authors.affiliation: Department of Neurological Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Vanni
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003847:Deoxyglucose / Q000494:pharmacology; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects*; D006019:Glycolysis; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D054645:Protein Phosphatase 1 / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D000077185:Resveratrol; D015398:Signal Transduction / Q000187:drug effects; D056564:Sirtuin 1 / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D003847:Deoxyglucose; D000091342:Endoplasmic Reticulum Chaperone BiP; D055504:Insulin Receptor Substrate Proteins; D019869:Phosphatidylinositol 3-Kinases; D054645:Protein Phosphatase 1; D051057:Proto-Oncogene Proteins c-akt; D000077185:Resveratrol; D056564:Sirtuin 1; D013267:Stilbenes; C000717247:HSPA5 protein, human; C526292:IRS1 protein, human