title: Autophagy-dependent metabolic reprogramming sensitizes TSC2-deficient cells to the antimetabolite 6-aminonicotinamide.
abstract: The mammalian target of rapamycin complex 1 (mTORC1) is hyperactive in many human cancers and in tuberous sclerosis complex (TSC). Autophagy, a key mTORC1-targeted process, is a critical determinant of metabolic homeostasis. Metabolomic profiling was performed to elucidate the cellular consequences of autophagy dysregulation under conditions of hyperactive mTORC1. It was discovered that TSC2-null cells have distinctive autophagy-dependent pentose phosphate pathway (PPP) alterations. This was accompanied by enhanced glucose uptake and utilization, decreased mitochondrial oxygen consumption, and increased mitochondrial reactive oxygen species (ROS) production. Importantly, these findings revealed that the PPP is a key autophagy-dependent compensatory metabolic mechanism. Furthermore, PPP inhibition with 6-aminonicotinamide (6-AN) in combination with autophagy inhibition suppressed proliferation and prompted the activation of NF-κB and CASP1 in TSC2-deficient, but not TSC2-proficient cells. These data demonstrate that TSC2-deficient cells can be therapeutically targeted, without mTORC1 inhibitors, by focusing on their metabolic vulnerabilities.
  
  
  CONCLUSIONS
  This study provides proof-of-concept that therapeutic targeting of diseases with hyperactive mTORC1 can be achieved without the application of mTORC1 inhibitors.
authors.affiliation: Brigham and Women's Hospital, Harvard Medical School, 1 Blackfan Circle, Boston, MA 02115. cpriolo@partners.org.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Parkhitko
authors.forename: Carmen
authors.initials: C
authors.lastname: Priolo
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Coloff
authors.forename: Jihye
authors.initials: J
authors.lastname: Yun
authors.forename: Julia J
authors.initials: JJ
authors.lastname: Wu
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizumura
authors.forename: Wenping
authors.initials: W
authors.lastname: Xu
authors.forename: Izabela A
authors.initials: IA
authors.lastname: Malinowska
authors.forename: Jane
authors.initials: J
authors.lastname: Yu
authors.forename: David J
authors.initials: DJ
authors.lastname: Kwiatkowski
authors.forename: Jason W
authors.initials: JW
authors.lastname: Locasale
authors.forename: John M
authors.initials: JM
authors.lastname: Asara
authors.forename: Augustine M K
authors.initials: AM
authors.lastname: Choi
authors.forename: Toren
authors.initials: T
authors.lastname: Finkel
authors.forename: Elizabeth P
authors.initials: EP
authors.lastname: Henske
mesh_terms: D015120:6-Aminonicotinamide / Q000494:pharmacology*; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; D020170:Caspase 1 / Q000096:biosynthesis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D065150:Cellular Reprogramming; D002738:Chloroquine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006886:Hydroxychloroquine / Q000494:pharmacology; D052119:Lysosomal-Associated Membrane Protein 2 / Q000235:genetics; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008805:Mice, Inbred A; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism; D046912:Multiprotein Complexes / Q000096:biosynthesis / Q000378:metabolism*; D016328:NF-kappa B / Q000096:biosynthesis; D010101:Oxygen Consumption / Q000235:genetics; D010427:Pentose Phosphate Pathway / Q000187:drug effects / Q000235:genetics*; D034622:RNA Interference; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000096:biosynthesis / Q000378:metabolism*; D013723:Teratogens / Q000494:pharmacology; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D051017:Apoptosis Regulatory Proteins; C495773:Atg5 protein, mouse; D000071187:Autophagy-Related Protein 5; D000071186:Beclin-1; C115010:Becn1 protein, mouse; D004791:Enzyme Inhibitors; D052119:Lysosomal-Associated Membrane Protein 2; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; D016328:NF-kappa B; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C000624653:TSC2 protein, human; D013723:Teratogens; C000624654:Tsc2 protein, mouse; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; D015120:6-Aminonicotinamide; D006886:Hydroxychloroquine; D002738:Chloroquine; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020170:Caspase 1; D005947:Glucose