title: Inhibition of alanine aminotransferase in silico and in vivo promotes mitochondrial metabolism to impair malignant growth.
abstract: Cancer cells commonly exhibit increased nonoxidative D-glucose metabolism whereas induction of mitochondrial metabolism may impair malignant growth. We have first used an in silico method called elementary mode analysis to identify inhibition of ALAT (L-alanine aminotransferase) as a putative target to promote mitochondrial metabolism. We then experimentally show that two competitive inhibitors of ALAT, L-cycloserine and β-chloro-L-alanine, inhibit L-alanine production and impair D-glucose uptake of LLC1 Lewis lung carcinoma cells. The latter inhibition is linked to an initial energy deficit, as quantified by decreased ATP content, which is then followed by an activation of AMP-activated protein kinase and subsequently increased respiration rates and mitochondrial production of reactive oxygen species, culminating in ATP replenishment in ALAT-inhibited LLC1 cells. Moreover, we observe altered phosphorylation of p38 MAPK (mitogen-activated protein kinase 14), ERK (extracellular signal-regulated kinase 1/2), and Rb1 (retinoblastoma 1) proteins, as well as decreased expression of Cdc25a (cell decision cycle 25 homolog A) and Cdk4 (cyclin-dependent kinase 4). Importantly, these sequelae of ALAT inhibition culminate in similarly reduced anchorage-dependent and anchorage-independent growth rates of LLC1 cells, together suggesting that inhibition of ALAT efficiently impairs cancer growth by counteracting the Warburg effect due to compensatory activation of mitochondrial metabolism.
authors.affiliation: Department of Human Nutrition, Institute of Nutrition, University of Jena, Jena D-07743, Germany.
authors.forename: Gregor
authors.initials: G
authors.lastname: Beuster
authors.forename: Kim
authors.initials: K
authors.lastname: Zarse
authors.forename: Christoph
authors.initials: C
authors.lastname: Kaleta
authors.forename: René
authors.initials: R
authors.lastname: Thierbach
authors.forename: Michael
authors.initials: M
authors.lastname: Kiehntopf
authors.forename: Pablo
authors.initials: P
authors.lastname: Steinberg
authors.forename: Stefan
authors.initials: S
authors.lastname: Schuster
authors.forename: Michael
authors.initials: M
authors.lastname: Ristow
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000263:Adenylate Kinase / Q000378:metabolism; D000409:Alanine / Q000096:biosynthesis; D000410:Alanine Transaminase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019069:Cell Respiration / Q000187:drug effects; D019295:Computational Biology; D004734:Energy Metabolism / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D005973:Glutamine; D000255:Adenosine Triphosphate; D000410:Alanine Transaminase; D000263:Adenylate Kinase; D005947:Glucose; D000409:Alanine