Apoptosis-related genes induced in response to ketamine during early life stages of zebrafish
TOXICOLOGY LETTERS
Authors: Felix, Luis M.; Serafim, Cindy; Valentim, Ana M.; Antunes, Luis M.; Matos, Manuela; Coimbra, Ana M.
Abstract
Increasing evidence supports that ketamine, a widely used anaesthetic, potentiates apoptosis during development through the mitochondrial pathway of apoptosis. Defects in the apoptotic machinery can cause or contribute to the developmental abnormalities previously described in ketamine-exposed zebrafish. The involvement of the apoptotic machinery in ketamine-induced teratogenicity was addressed by assessing the apoptotic signals at 8 and 24 hpf following 20 min exposure to ketamine at three stages of early zebrafish embryo development (256 cell, 50% epiboly and 1-4 somites stages). Exposure at the 256-cell stage to ketamine induced an up-regulation of casp8 and pcna at 8 hpf while changes in pcna at the mRNA level were observed at 24 hpf. After the 50% epiboly stage exposure, the mRNA levels of casp9 were increased at 8 and 24 hpf while aifm1 was affected at 24 hpf. Both tp53 and pcna expressions were increased at 8 hpf. After exposure during the 1-4 somites stage, no meaningful changes on transcript levels were observed. The distribution of apoptotic cells and the caspase-like enzymatic activities of caspase-3 and -9 were not affected by ketamine exposure. It is proposed that ketamine exposure at the 256-cell stage induced a cooperative mechanism between proliferation and cellular death while following exposure at the 50% epiboly, a p53-dependent and-independent caspase activation may occur. Finally, at the 1-4 somites stage, the defence mechanisms are already fully in place to protect against ketamine-insult. Thus, ketamine teratogenicity seems to be dependent on the functional mechanisms present in each developmental stage.
Lethal Poisoning of Cancer Cells by Respiratory Chain Inhibition plus Dimethyl alpha-Ketoglutarate
CELL REPORTS
Authors: Sica, Valentina; Bravo-San Pedro, Jose Manuel; Izzo, Valentina; Pol, Jonathan; Pierredon, Sandra; Enot, David; Durand, Sylvere; Bossut, Noelie; Chery, Alexis; Souquere, Sylvie; Pierron, Gerard; Vartholomaiou, Evangelia; Zamzami, Naoufal; Soussi, Thierry; Sauvat, Allan; Mondragon, Laura; Kepp, Oliver; Galluzzi, Lorenzo; Martinou, Jean-Claude; Hess-Stumpp, Holger; Ziegelbauer, Karl; Kroemer, Guido; Maiuri, Maria Chiara
Abstract
Inhibition of oxidative phosphorylation (OXPHOS) by 1-cyclopropyl-4-(4-[(5-methyl-3-(3-[4-(trifluoromethoxy) phenyl]-1,2,4-oxadiazol-5-yl)-1H-pyrazol-1-yl) methyl] pyridin-2-yl) piperazine (BAY87-2243, abbreviated as B87), a complex I inhibitor, fails to kill human cancer cells in vitro. Driven by this consideration, we attempted to identify agents that engage in synthetically lethal interactions with B87. Here, we report that dimethyl alpha-ketoglutarate (DMKG), a cell-permeable precursor of alpha-ketoglutarate that lacks toxicity on its own, kills cancer cells when combined with B87 or other inhibitors of OXPHOS. DMKG improved the antineoplastic effect of B87, both in vitro and in vivo. This combination caused MDM2-dependent, tumor suppressor protein p53 (TP53)-independent transcriptional reprogramming and alternative exon usage affecting multiple glycolytic enzymes, completely blocking glycolysis. Simultaneous inhibition of OXPHOS and glycolysis provoked a bioenergetic catastrophe culminating in the activation of a cell death program that involved disruption of the mitochondrial network and activation of PARP1, AIFM1, and APEX1. These results unveil a metabolic liability of human cancer cells that may be harnessed for the development of therapeutic regimens.