title: Targeting glutamine metabolism sensitizes pancreatic cancer to PARP-driven metabolic catastrophe induced by ß-lapachone.
abstract: BACKGROUND
  Pancreatic ductal adenocarcinomas (PDA) activate a glutamine-dependent pathway of cytosolic nicotinamide adenine dinucleotide phosphate (NADPH) production to maintain redox homeostasis and support proliferation. Enzymes involved in this pathway (GLS1 (mitochondrial glutaminase 1), GOT1 (cytoplasmic glutamate oxaloacetate transaminase 1), and GOT2 (mitochondrial glutamate oxaloacetate transaminase 2)) are highly upregulated in PDA, and among these, inhibitors of GLS1 were recently deployed in clinical trials to target anabolic glutamine metabolism. However, single-agent inhibition of this pathway is cytostatic and unlikely to provide durable benefit in controlling advanced disease.
  
  
  RESULTS
  Here, we report that reducing NADPH pools by genetically or pharmacologically (bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES) or CB-839) inhibiting glutamine metabolism in mutant Kirsten rat sarcoma viral oncogene homolog (KRAS) PDA sensitizes cell lines and tumors to ß-lapachone (ß-lap, clinical form ARQ761). ß-Lap is an NADPH:quinone oxidoreductase (NQO1)-bioactivatable drug that leads to NADPH depletion through high levels of reactive oxygen species (ROS) from the futile redox cycling of the drug and subsequently nicotinamide adenine dinucleotide (NAD)+ depletion through poly(ADP ribose) polymerase (PARP) hyperactivation. NQO1 expression is highly activated by mutant KRAS signaling. As such, ß-lap treatment concurrent with inhibition of glutamine metabolism in mutant KRAS, NQO1 overexpressing PDA leads to massive redox imbalance, extensive DNA damage, rapid PARP-mediated NAD+ consumption, and PDA cell death-features not observed in NQO1-low, wild-type KRAS expressing cells.
  
  
  CONCLUSIONS
  This treatment strategy illustrates proof of principle that simultaneously decreasing glutamine metabolism-dependent tumor anti-oxidant defenses and inducing supra-physiological ROS formation are tumoricidal and that this rationally designed combination strategy lowers the required doses of both agents in vitro and in vivo. The non-overlapping specificities of GLS1 inhibitors and ß-lap for PDA tumors afford high tumor selectivity, while sparing normal tissue.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Drive, Dallas, 75390-8807 TX USA ; Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Gaurab
authors.initials: G
authors.lastname: Chakrabarti
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Drive, Dallas, 75390-8807 TX USA ; Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Zachary R
authors.initials: ZR
authors.lastname: Moore
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Drive, Dallas, 75390-8807 TX USA ; Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Xiuquan
authors.initials: X
authors.lastname: Luo
authors.affiliation: Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Mariya
authors.initials: M
authors.lastname: Ilcheva
authors.affiliation: Touchstone Diabetes Center, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Aktar
authors.initials: A
authors.lastname: Ali
authors.affiliation: Department of Internal Medicine, Weill Cornell Medical College, 413 East 69th Street, BB-1362, New York, NY 10021 USA.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Padanad
authors.affiliation: Department of Bioinformatics and Biostatistics, Clinical Sciences, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390 USA.
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Bioinformatics and Biostatistics, Clinical Sciences, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390 USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Burma
authors.affiliation: Department of Internal Medicine, Weill Cornell Medical College, 413 East 69th Street, BB-1362, New York, NY 10021 USA.
authors.forename: Pier P
authors.initials: PP
authors.lastname: Scaglioni
authors.affiliation: Department of Medicine, Weill Cornell Medical College, 413 East 69th Street, BB-1362, New York, NY 10021 USA.
authors.forename: Lewis C
authors.initials: LC
authors.lastname: Cantley
authors.affiliation: Children's Medical Center Research Institute, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390 USA.
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: DeBerardinis
authors.affiliation: Department of Radiation Oncology, Division of Genomic Stability and DNA Repair, Dana-Farber Cancer Institute, Boston, MA 02215 USA.
authors.forename: Alec C
authors.initials: AC
authors.lastname: Kimmelman
authors.affiliation: Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109 USA ; Internal Medicine, Division of Gastroenterology, University of Michigan, Ann Arbor, MI 48109 USA.
authors.forename: Costas A
authors.initials: CA
authors.lastname: Lyssiotis
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Drive, Dallas, 75390-8807 TX USA ; Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Boothman
keywords: Glutamine metabolism; Metabolic cancer therapy; NQO1-bioactivated drugs; Transamination