title: Mitochondrial ADP/ATP exchange inhibition: a novel off-target mechanism underlying ibipinabant-induced myotoxicity.
abstract: Cannabinoid receptor 1 (CB1R) antagonists appear to be promising drugs for the treatment of obesity, however, serious side effects have hampered their clinical application. Rimonabant, the first in class CB1R antagonist, was withdrawn from the market because of psychiatric side effects. This has led to the search for more peripherally restricted CB1R antagonists, one of which is ibipinabant. However, this 3,4-diarylpyrazoline derivative showed muscle toxicity in a pre-clinical dog study with mitochondrial dysfunction. Here, we studied the molecular mechanism by which ibipinabant induces mitochondrial toxicity. We observed a strong cytotoxic potency of ibipinabant in C2C12 myoblasts. Functional characterization of mitochondria revealed increased cellular reactive oxygen species generation and a decreased ATP production capacity, without effects on the catalytic activities of mitochondrial enzyme complexes I-V or the complex specific-driven oxygen consumption. Using in silico off-target prediction modelling, combined with in vitro validation in isolated mitochondria and mitoplasts, we identified adenine nucleotide translocase (ANT)-dependent mitochondrial ADP/ATP exchange as a novel molecular mechanism underlying ibipinabant-induced toxicity. Minor structural modification of ibipinabant could abolish ANT inhibition leading to a decreased cytotoxic potency, as observed with the ibipinabant derivative CB23. Our results will be instrumental in the development of new types of safer CB1R antagonists.
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.|Center for Systems Biology and Bioenergetics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Tom J J
authors.initials: TJ
authors.lastname: Schirris
authors.affiliation: Computational Discovery and Design Group, Center for Molecular and Biomolecular Informatics (CMBI), Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Tina
authors.initials: T
authors.lastname: Ritschel
authors.affiliation: Center for Systems Biology and Bioenergetics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.|Department of Pediatrics, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: G
authors.initials: G
authors.lastname: Herma Renkema
authors.affiliation: Center for Systems Biology and Bioenergetics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.|Department of Biochemistry, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Peter H G M
authors.initials: PH
authors.lastname: Willems
authors.affiliation: Center for Systems Biology and Bioenergetics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.|Department of Pediatrics, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Jan A M
authors.initials: JA
authors.lastname: Smeitink
authors.affiliation: Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.|Center for Systems Biology and Bioenergetics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical Center, Nijmegen, 6500 HB, The Netherlands.
authors.forename: Frans G M
authors.initials: FG
authors.lastname: Russel
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000578:Amidines / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D000818:Animals; D019440:Anti-Obesity Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D063387:Cannabinoid Receptor Antagonists / Q000138:chemical synthesis / Q000737:chemistry* / Q000633:toxicity; D002460:Cell Line; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D045222:Electron Transport Chain Complex Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D000226:Mitochondrial ADP, ATP Translocases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D009765:Obesity / Q000188:drug therapy / Q000473:pathology; D010101:Oxygen Consumption / Q000187:drug effects; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000819:agonists / Q000378:metabolism; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000578:Amidines; D019440:Anti-Obesity Agents; D063387:Cannabinoid Receptor Antagonists; D045222:Electron Transport Chain Complex Proteins; D011720:Pyrazoles; D017382:Reactive Oxygen Species; D043884:Receptor, Cannabinoid, CB1; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000226:Mitochondrial ADP, ATP Translocases; C569626:ibipinabant