title: Mechanism of neem limonoids-induced cell death in cancer: Role of oxidative phosphorylation.
abstract: We have previously reported that neem limonoids (neem) induce multiple cancer cell death pathways. Here we dissect the underlying mechanisms of neem-induced apoptotic cell death in cancer. We observed that neem-induced caspase activation does not require Bax/Bak channel-mediated mitochondrial outer membrane permeabilization, permeability transition pore, and mitochondrial fragmentation. Neem enhanced mitochondrial DNA and mitochondrial biomass. While oxidative phosphorylation (OXPHOS) Complex-I activity was decreased, the activities of other OXPHOS complexes including Complex-II and -IV were unaltered. Increased reactive oxygen species (ROS) levels were associated with an increase in mitochondrial biomass and apoptosis upon neem exposure. Complex-I deficiency due to the loss of Ndufa1-encoded MWFE protein inhibited neem-induced caspase activation and apoptosis, but cell death induction was enhanced. Complex II-deficiency due to the loss of succinate dehydrogenase complex subunit C (SDHC) robustly decreased caspase activation, apoptosis, and cell death. Additionally, the ablation of Complexes-I, -III, -IV, and -V together did not inhibit caspase activation. Together, we demonstrate that neem limonoids target OXPHOS system to induce cancer cell death, which does not require upregulation or activation of proapoptotic Bcl-2 family proteins.
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. Electronic address: neelu.yadav@roswellpark.org.
authors.forename: Neelu
authors.initials: N
authors.lastname: Yadav
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Pragya
authors.initials: P
authors.lastname: Srivastava
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA; Gastroenterology Department, Sir Run Run Shaw Hospital, Zhejiang University Medical School, Hangzhou 310016, China.
authors.forename: Leimin
authors.initials: L
authors.lastname: Sun
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Rapali
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Marlowe
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Schneider
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Inigo
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: O'Malley
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Londonkar
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Raghu
authors.initials: R
authors.lastname: Gogada
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Chaudhary
authors.affiliation: Pioneer Valley Life Sciences Institute, Springfield, MA 01107, USA.
authors.forename: Nagendra
authors.initials: N
authors.lastname: Yadava
authors.affiliation: Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA. Electronic address: dhyan.chandra@roswellpark.org.
authors.forename: Dhyan
authors.initials: D
authors.lastname: Chandra
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D031601:Azadirachta / Q000737:chemistry*; D020169:Caspases / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000502:physiology; D004272:DNA, Mitochondrial / Q000032:analysis; D034281:Dynamins; D042967:Electron Transport Complex I / Q000502:physiology; D020558:GTP Phosphohydrolases / Q000032:analysis; D045325:HCT116 Cells; D006801:Humans; D036701:Limonins / Q000494:pharmacology*; D008869:Microtubule-Associated Proteins / Q000032:analysis; D033681:Mitochondrial Membrane Transport Proteins / Q000502:physiology; D000083162:Mitochondrial Permeability Transition Pore; D024101:Mitochondrial Proteins / Q000032:analysis; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology*; D010085:Oxidative Phosphorylation; D016159:Tumor Suppressor Protein p53 / Q000502:physiology
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004272:DNA, Mitochondrial; D036701:Limonins; D008869:Microtubule-Associated Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D024101:Mitochondrial Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D020169:Caspases; D020558:GTP Phosphohydrolases; C110768:DNM1L protein, human; D034281:Dynamins; D042967:Electron Transport Complex I
keywords: Apoptosis; Mitochondrial DNA; Necroptosis; Neem; Oxidative phosphorylation complex; ROS