RESUMO
Acute lymphoblastic leukemia (ALL) is an aggressive malignant disorder of lymphoid progenitor cells that affects children and adults. Despite the high cure rates, drug resistance still remains a significant clinical problem, which stimulates the development of new therapeutic strategies and drugs to improve the disease outcome. Antipsychotic phenothiazines have emerged as potential candidates to be repositioned as antitumor drugs. It was previously shown that the anti-histaminic phenothiazine derivative promethazine induced autophagy-associated cell death in chronic myeloid leukemia cells, although autophagy can act as a "double-edged sword" contributing to cell survival or cell death. Here we evaluated the role of autophagy in thioridazine (TR)-induced cell death in the human ALL model. TR induced apoptosis in ALL Jurkat cells and it was not cytotoxic to normal peripheral mononuclear blood cells. TR promoted the activation of caspase-8 and -3, which was associated with increased NOXA/MCL-1 ratio and autophagy triggering. AMPK/PI3K/AKT/mTOR and MAPK/ERK pathways are involved in TR-induced cell death. The inhibition of the autophagic process enhanced the cytotoxicity of TR in Jurkat cells, highlighting autophagy as a targetable process for drug development purposes in ALL.
RESUMO
Relapse and drug resistance is still major challenges in the treatment of leukemia. Promethazine, an antihistaminic phenothiazine derivative, has been used to prevent chemotherapy-induced emesis, although there is no report about its antitumor potential. Thus, we evaluated the promethazine cytotoxicity against several leukemia cells and the underlying mechanisms were investigated. Promethazine exhibited potent and selective cytotoxicity against all leukemia cell types in vitro at clinically relevant concentrations. Philadelphia positive chronic myeloid leukemia (CML) K562â¯cells were the most sensitive cell line. The cytotoxicity of promethazine in these cells was triggered by the activation of AMPK and inhibition of PI3K/AKT/mTOR pathway. The subsequent downstream effects were NOXA increase, MCL-1 decrease, and Beclin-1 activation, resulting in autophagy-associated apoptosis. These data highlight targeting autophagy may represent an interesting strategy in CML therapy, and also the antitumor potential of promethazine by acting in AMPK and PI3K/AKT/mTOR signaling pathways. Since this drug is currently used with relative low side effects, its repurposing may represent a new therapeutic opportunity for leukemia treatment.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Proteína Beclina-1/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Fosforilação/efeitos dos fármacos , Prometazina/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Células Jurkat , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismoRESUMO
BACKGROUND: Gossypol is a chemical present in the seeds of cotton plants (Gossypium sp.) that reduces fertility in farm animals. Vitamin E is an antioxidant and may help to protect cells and tissues against the deleterious effects of free radicals. The aim of this study was to evaluate the mechanisms of reproductive toxicity of gossypol in rats and the protective effects of vitamin E. Forty Wistar rats were used, divided into four experimental groups (n = 10): DMSO/saline + corn oil; DMSO/saline + vitamin E; gossypol + corn oil; and gossypol + vitamin E. RESULTS: Fertility was significantly reduced in male rats treated with gossypol in that a significant decrease in epididymal sperm count was observed (P < 0.05) and the number of offspring was significantly reduced in females mated with them (P < 0.05). This dysfunction was prevented by vitamin E. Gossypol caused a significant increase in the activity of the enzymes glutathione peroxidase (P < 0.01) and glutathione reductase (P < 0.01), but vitamin E did not reduce the enzyme activities (P > 0.05). The levels of reduced glutathione and pyridine nucleotides in testis homogenate were significantly reduced by gossypol (P < 0.05 and P < 0.01, respectively) and this reduction was accompanied by increased levels of oxidized glutathione (P < 0.05). Vitamin E showed a preventive effect on the changes in the levels of these substances. Gossypol significantly increased the levels of malondialdehyde (P < 0.01), a lipid peroxidation indicator, whereas treatment with vitamin E inhibited the action of the gossypol. Vitamin E prevented a decrease in mitochondrial ATP induced by gossypol (P < 0.05). CONCLUSIONS: This study suggests that the reproductive dysfunction caused by gossypol may be related to oxidative stress and mitochondrial bioenergetic damage and that treatment with vitamin E can prevent the infertility caused by the toxin.
Assuntos
Anticoncepcionais Masculinos/farmacologia , Fertilidade/efeitos dos fármacos , Gossipol/farmacologia , Vitamina E/farmacologia , Animais , Feminino , Glutationa Peroxidase , Glutationa Redutase , Gossipol/efeitos adversos , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Malondialdeído , Estresse Oxidativo/efeitos dos fármacos , Gravidez , Ratos , Ratos Wistar , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacosRESUMO
Fipronil is an insecticide extensively used to control pests in crops and animals. There are relates of poisoning due to exposure of fipronil in mammals and the liver has been suggested as potential target. In this study, we evaluated the effects of fipronil and its metabolites sulfone and desulfinyl on the bioenergetics, reactive oxygen species (ROS) production and calcium efflux from mitochondria isolated from rat liver. Fipronil (5-25 µM) inhibited state-3 respiration in mitochondria energized with glutamate plus malate, substrates of complex I of the respiratory chain and decreased the mitochondrial membrane potential resulting in inhibition of ATP synthesis. Fipronil also caused uncoupling in succinate-energized mitochondria and calcium efflux. The metabolites sulfone and desulfinyl also acted as mitochondrial inhibitors and uncouplers and caused calcium efflux, but with different potencies, being the sulfone the more potent one. These effects of fipronil and its metabolites on mitochondrial bioenergetics and calcium homeostasis may be related to toxic effects of the insecticide in the liver.
Assuntos
Mitocôndrias Hepáticas/efeitos dos fármacos , Pirazóis/toxicidade , Sulfonas/toxicidade , Trifosfato de Adenosina/metabolismo , Animais , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Pirazóis/metabolismo , Ratos , Ratos WistarRESUMO
BACKGROUND: Gossypol is a chemical present in the seeds of cotton plants (Gossypium sp.) that reduces fertility in farm animals. Vitamin E is an antioxidant and may help to protect cells and tissues against the deleterious effects of free radicals. The aim of this study was to evaluate the mechanisms of reproductive toxicity of gossypol in rats and the protective effects of vitamin E. Forty Wistar rats were used, divided into four experimental groups (n = 10): DMSO/ saline + corn oil; DMSO/saline + vitamin E; gossypol + corn oil; and gossypol + vitamin E. RESULTS: Fertility was significantly reduced in male rats treated with gossypol in that a significant decrease in epididy-mal sperm count was observed (P < 0.05) and the number of offspring was significantly reduced in females mated with them (P < 0.05). This dysfunction was prevented by vitamin E. Gossypol caused a significant increase in the activity of the enzymes glutathione peroxidase (P < 0.01) and glutathione reductase (P < 0.01), but vitamin E did not reduce the enzyme activities (P > 0.05). The levels of reduced glutathione and pyridine nucleotides in testis homogen-ate were significantly reduced by gossypol (P < 0.05 and P < 0.01, respectively) and this reduction was accompanied by increased levels of oxidized glutathione (P < 0.05). Vitamin E showed a preventive effect on the changes in the levels of these substances. Gossypol significantly increased the levels of malondialdehyde (P < 0.01), a lipid peroxida-tion indicator, whereas treatment with vitamin E inhibited the action of the gossypol. Vitamin E prevented a decrease in mitochondrial ATP induced by gossypol (P < 0.05). CONCLUSIONS: This study suggests that the reproductive dysfunction caused by gossypol may be related to oxidative stress and mitochondrial bioenergetic damage and that treatment with vitamin E can prevent the infertility caused by the toxin.
Assuntos
Animais , Masculino , Feminino , Gravidez , Ratos , Vitamina E/farmacologia , Gossipol/farmacologia , Anticoncepcionais Masculinos/farmacologia , Fertilidade/efeitos dos fármacos , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacos , Gossipol/efeitos adversos , Peroxidação de Lipídeos/efeitos dos fármacos , Ratos Wistar , Estresse Oxidativo/efeitos dos fármacos , Glutationa Peroxidase , Glutationa Redutase , MalondialdeídoRESUMO
BACKGROUND: The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl4) in rats. RESULTS: The animals were divided into four groups with six rats in each group. CCl4 (0.125 mL kg(-1) body wt.) was injected intraperitoneally, and bixin (5.0 mg kg(-1) body wt.) was given by gavage 7 days before the CCl4 injection. Bixin prevented the liver damage caused by CCl4, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl4 by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment. CONCLUSION: Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl4 is related to the antioxidant activity of the compound.
Assuntos
Antioxidantes/farmacologia , Tetracloreto de Carbono/antagonistas & inibidores , Carotenoides/farmacologia , Doença Hepática Induzida por Substâncias e Drogas/prevenção & controle , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/análise , Animais , Bixaceae/química , Carotenoides/química , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Glutationa/análise , Glutationa Redutase/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/enzimologia , Masculino , Malondialdeído/análise , NADP/análise , Extratos Vegetais/química , Ratos Wistar , Transaminases/sangueRESUMO
Bees have a crucial role in pollination; therefore, it is important to determine the causes of their recent decline. Fipronil and imidacloprid are insecticides used worldwide to eliminate or control insect pests. Because they are broad-spectrum insecticides, they can also affect honeybees. Many researchers have studied the lethal and sublethal effects of these and other insecticides on honeybees, and some of these studies have demonstrated a correlation between the insecticides and colony collapse disorder in bees. The authors investigated the effects of fipronil and imidacloprid on the bioenergetic functioning of mitochondria isolated from the heads and thoraces of Africanized honeybees. Fipronil caused dose-dependent inhibition of adenosine 5'-diphosphate-stimulated (state 3) respiration in mitochondria energized by either pyruvate or succinate, albeit with different potentials, in thoracic mitochondria; inhibition was strongest when respiring with complex I substrate. Fipronil affected adenosine 5'-triphosphate (ATP) production in a dose-dependent manner in both tissues and substrates, though with different sensitivities. Imidacloprid also affected state-3 respiration in both the thorax and head, being more potent in head pyruvate-energized mitochondria; it also inhibited ATP production. Fipronil and imidacloprid had no effect on mitochondrial state-4 respiration. The authors concluded that fipronil and imidacloprid are inhibitors of mitochondrial bioenergetics, resulting in depleted ATP. This action can explain the toxicity of these compounds to honeybees.
Assuntos
Abelhas/efeitos dos fármacos , Imidazóis/toxicidade , Inseticidas/toxicidade , Mitocôndrias/efeitos dos fármacos , Nitrocompostos/toxicidade , Pirazóis/toxicidade , Animais , Abelhas/citologia , Abelhas/metabolismo , Controle de Insetos , Mitocôndrias/metabolismo , NeonicotinoidesRESUMO
Abamectin (ABA), which belongs to the family of avermectins, is used as a parasiticide; however, ABA poisoning can impair liver function. In a previous study using isolated rat liver mitochondria, we observed that ABA inhibited the activity of adenine nucleotide translocator and FoF1-ATPase. The aim of this study was to characterize the mechanism of ABA toxicity in isolated rat hepatocytes and to evaluate whether this effect is dependent on its metabolism. The toxicity of ABA was assessed by monitoring oxygen consumption and mitochondrial membrane potential, intracellular ATP concentration, cell viability, intracellular Ca(2+) homeostasis, release of cytochrome c, caspase 3 activity and necrotic cell death. ABA reduces cellular respiration in cells energized with glutamate and malate or succinate. The hepatocytes that were previously incubated with proadifen, a cytochrome P450 inhibitor, are more sensitive to the compound as observed by a rapid decrease in the mitochondrial membrane potential accompanied by reductions in ATP concentration and cell viability and a disruption of intracellular Ca(2+) homeostasis followed by necrosis. Our results indicate that ABA biotransformation reduces its toxicity, and its toxic action is related to the inhibition of mitochondrial activity, which leads to decreased synthesis of ATP followed by cell death.
Assuntos
Anti-Helmínticos/toxicidade , Hepatócitos/efeitos dos fármacos , Ivermectina/análogos & derivados , Mitocôndrias Hepáticas/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo , Animais , Anti-Helmínticos/farmacocinética , Biotransformação , Cálcio/metabolismo , Caspase 3/metabolismo , Respiração Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Citocromos c/metabolismo , Hepatócitos/metabolismo , Ivermectina/farmacocinética , Ivermectina/toxicidade , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias Hepáticas/metabolismo , Necrose/induzido quimicamente , Consumo de Oxigênio/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Prosopis juliflora, popularly known as Algaroba, is a major problem because the lack of food during the driest times of the year and its high palatability and nutritional value make its fruits (pods) much appreciated by cattle, goats, sheep and other animals. However, the consumption of this plant for long periods can cause a disease called cara-torta (pie face), which is characterized by cranial nerve dysfunction, mainly due to the degeneration and disappearance of neurons in the trigeminal motor nucleus. Algaroba contains piperidine alkaloids that have been suggested as being responsible for its toxicity; one of these alkaloids is juliprosopine. This study was conducted to evaluate the mechanisms of action of juliprosopine in isolated rat brain mitochondria to evaluate the potential mechanisms that lead to neurotoxicity in animals intoxicated by algaroba. Juliprosopine stimulated state-4 respiration at concentrations of 10-25 µM, affected the membrane potential at all concentrations studied (5-25 µM) and affected ATP production only at higher concentrations (15 and 25 µM). Juliprosopine cannot be classified as a member of the protonophoric class of uncouplers, such as 2,4-dinitrophenol or CCCP (m-chlorophenylhydrazone), due to its inability to promote mitochondrial swelling in the hyposmotic medium of potassium acetate. In addition, carboxyatractyloside, Mg(2+), cyclosporine A and dithiothreitol did not protect the uncoupling induced by juliprosopine. Because juliprosopine increased the fluorescence responses of mitochondria labeled with 1-aniline-8-naphthalene sulfonate (ANS) and DPH (1,6-diphenyl-1,3,5-hexatriene), we suggested that its uncoupling action must be attributed to a modification of the arrangement of the inner mitochondrial membrane.
Assuntos
Alcaloides/farmacologia , Encéfalo/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Fosforilação Oxidativa/efeitos dos fármacos , Trifosfato de Adenosina/biossíntese , Animais , Encéfalo/metabolismo , Fluorescência , Peróxido de Hidrogênio/metabolismo , Masculino , Mitocôndrias/metabolismo , Ratos , Ratos WistarRESUMO
Abamectin (ABA) is a macrocyclic lactone of the avermectin family used worldwide as an antiparasitic agent in farm animals and pets and as the active ingredient of insecticides and nematicides. In this study, the effects of abamectin on the bioenergetics of mitochondria isolated from rat liver were evaluated. Mitochondria are responsible for converting the energy released by electron transport and stored as the binding energy molecule ATP. Xenobiotics that interfere with its synthesis or utilization can be acutely or chronically toxic. Abamectin (5-25µM) caused concentration-dependent inhibition of the respiratory chain without affecting the membrane potential or the activity of enzymes NADH dehydrogenase or succinate dehydrogenase. This behavior is similar to oligomycin and carboxyatractyloside and suggests direct action on F(o)F(1)-ATPase and/or the adenine nucleotide translocator (ANT). ABA more pronouncedly inhibited ATPase phosphohydrolase activity in intact, uncoupled mitochondria than in freeze-thawed disrupted mitochondria. ADP-stimulated depolarization of the mitochondrial membrane potential was also inhibited by ABA. Our results indicate that ABA interacts more specifically with the ANT, resulting in functional inhibition of the translocator with consequent impairment of mitochondrial bioenergetics. This effect could be involved in the ABA toxicity to hepatocytes.