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1.
Nanoscale ; 11(24): 11789-11807, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31184642

RESUMO

Autophagy may represent a common cellular response to nanomaterials. In the present study, it was demonstrated that zinc oxide nanoparticle (ZON)-elicited autophagy contributes to tumor cell killing by accelerating the intracellular dissolution of ZONs and reactive oxygen species (ROS) generation. In particular, ZONs could promote Atg5-regulated autophagy flux without the impairment of autophagosome-lysosome fusion, which is responsible for ZON-elicited cell death in cancer cells. On the other hand, a further study revealed that a significant free zinc ion release in lysosomal acid compartments and sequential ROS generation in cells treated with ZONs were also associated with tumor cytotoxicity. Intriguingly, the colocalization between FITC-labeled ZONs and autophagic vacuoles indicates that the intracellular fate of ZONs is associated with autophagy. Moreover, the chemical or genetic inhibition of autophagy significantly reduced the level of intracellular zinc ion release and ROS generation separately, demonstrating that ZON-induced autophagy contributed toward cancer cell death by accelerating zinc ion release and sequentially increasing intracellular ROS generation. The modulation of autophagy holds great promise for improving the efficacy of tumor chemotherapy. Herein, ZONs were verified to enhance chemotherapy in both normal and drug-resistant cancer cells via synergistic autophagy elicitation. Further, this elicitation resulted in tremendous zinc ion release and ROS generation, which accounted for enhancing the tumor chemotherapy and overcoming drug resistance. No obvious changes in the expression level of P-gp proteins or the amount of doxorubicin uptake induced by ZONs in MCF-7/ADR cells also indicated that the increased zinc ion release and ROS generation via synergistic autophagy induction were responsible for overcoming the drug resistance. Finally, in vivo experiments involving animal models of 4T1 tumor cells revealed that the antitumor therapeutic effect of a combinatory administration obviously outperformed those of ZONs or free doxorubicin treatment alone at the same dose, which could be attenuated by the autophagy inhibitor wortmannin or ion-chelating agent EDTA. Taken together, our results reveal the mechanism wherein the autophagy induction by ZONs potentiates cancer cell death and a novel biological application for ZONs in adjunct chemotherapy in which autophagy reinforces zinc ion release and ROS generation.


Assuntos
Antineoplásicos , Doxorrubicina , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Nanopartículas , Neoplasias Experimentais/tratamento farmacológico , Óxido de Zinco , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Doxorrubicina/química , Doxorrubicina/farmacologia , Feminino , Células HeLa , Humanos , Células MCF-7 , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/química , Nanopartículas/uso terapêutico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Espécies Reativas de Oxigênio/metabolismo , Óxido de Zinco/química , Óxido de Zinco/farmacologia
2.
Small ; 13(7)2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27925395

RESUMO

The diverse biological effects of nanomaterials form the basis for their applications in biomedicine but also cause safety issues. Induction of autophagy is a cellular response after nanoparticles exposure. It may be beneficial in some circumstances, yet autophagy-mediated toxicity raises an alarming concern. Previously, it has been reported that upconversion nanoparticles (UCNs) elicit liver damage, with autophagy contributing most of this toxicity. However, the detailed mechanism is unclear. This study reveals persistent presence of enlarged autolysosomes in hepatocytes after exposure to UCNs and SiO2 nanoparticles both in vitro and in vivo. This phenomenon is due to anomaly in the autophagy termination process named autophagic lysosome reformation (ALR). Phosphatidylinositol 4-phosphate (PI(4)P) relocates onto autolysosome membrane, which is a key event of ALR. PI(4)P is then converted into phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2 ) by phosphatidylinositol-4-phosphate 5-kinase. Clathrin is subsequently recruited by PI(4,5)P2 and leads to tubule budding of ALR. Yet it is observed that PI(4)P cannot be converted in nanoparticle-treated hepatocytes cells. Exogenous supplement of PI(4,5)P2 suppresses the enlarged autolysosomes in vitro. Abolishment of these enlarged autolysosomes by autophagy inhibitor relieves the hepatotoxicity of UCNs in vivo. The results provide evidence for disrupted ALR in nanoparticle-treated hepatocytes, suggesting that the termination of nanoparticle-induced autophagy is of equal importance as the initiation.


Assuntos
Autofagia , Hepatócitos/citologia , Hepatócitos/metabolismo , Lisossomos/metabolismo , Nanopartículas/química , Animais , Autofagia/efeitos dos fármacos , Células Cultivadas , Hepatócitos/efeitos dos fármacos , Fígado/metabolismo , Lisossomos/efeitos dos fármacos , Masculino , Camundongos Endogâmicos C57BL , Modelos Biológicos , Nanopartículas/toxicidade , Fosfatos de Fosfatidilinositol/metabolismo
3.
Small ; 12(41): 5759-5768, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27593892

RESUMO

Many nanomaterials are reported to disrupt lysosomal function and homeostasis, but how cells sense and then respond to nanomaterial-elicited lysosome stress is poorly understood. Nucleus translocation of transcription factor EB (TFEB) plays critical roles in lysosome biogenesis following lysosome stress induced by starvation. The authors previously reported massive cellular vacuolization, along with autophagy induction, in cells treated with rare earth oxide (REO) nanoparticles. Here, the authors identify these giant cellular vacuoles as abnormally enlarged and alkalinized endo/lysosomes whose formation is dependent on macropinocytosis. This vacuolization causes deactivation of mammalian target of rapamycin (mTOR), a TFEB-interacting kinase that resides on the lysosome membrane. Subsequently, TFEB is dephosphorylated at serine 142 and translocated into cell nucleus. This nucleus translocation of TFEB is observed only in vacuolated cells and it is critical for maintaining lysosome homeostasis after REO nanoparticle treatment, as knock-down of TFEB gene significantly compromises lysosome function and enhances cell death in nanoparticle-treated cells. Our results reveal that cellular vacuolization, which is commonly observed in cells treated with REOs and other nanomaterials, represents a condition of profound lysosome stress, and cells sense and respond to this stress by facilitating mTOR-dependent TFEB nucleus translocation in an effort to restore lysosome homeostasis.


Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Núcleo Celular/metabolismo , Lisossomos/metabolismo , Metais Terras Raras/química , Nanopartículas/química , Óxidos/química , Serina-Treonina Quinases TOR/metabolismo , Vacúolos/metabolismo , Álcalis/química , Sobrevivência Celular , Endossomos/metabolismo , Células HeLa , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Modelos Biológicos , Pinocitose , Transporte Proteico
4.
Biomaterials ; 73: 160-74, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26409001

RESUMO

Accelerating the clearance of intracellular protein aggregates through elevation of autophagy represents a viable approach for the treatment of neurodegenerative diseases. In our earlier report, we have demonstrated the enhanced degradation of mutant huntingtin protein aggregates through autophagy process induced by europium hydroxide nanorods [EHNs: Eu(III)(OH)3], but the underlying molecular mechanism of EHNs mediated autophagy was unclear. The present report reveals that EHNs induced autophagy does not follow the classical AKT-mTOR and AMPK signaling pathways. The inhibition of ERK1/2 phosphorylation using the specific MEK inhibitor U0126 partially abrogates the autophagy as well as the clearance of mutant huntingtin protein aggregates mediated by EHNs suggesting that nanorods stimulate the activation of MEK/ERK1/2 signaling pathway during autophagy process. In contrast, another mTOR-independent autophagy inducer trehalose has been found to induce autophagy without activating ERK1/2 signaling pathway. Interestingly, the combined treatment of EHNs and trehalose leads to more degradation of mutant huntingtin protein aggregates than that obtained with single treatment of either nanorods or trehalose. Our results demonstrate the rational that further enhanced clearance of intracellular protein aggregates, needed for diverse neurodegenerative diseases, may be achieved through the combined treatment of two or more autophagy inducers, which stimulate autophagy through different signaling pathways.


Assuntos
Európio/química , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Hidróxidos/química , Nanotubos/química , Proteínas do Tecido Nervoso/química , Trealose/química , Adenina/análogos & derivados , Adenina/química , Androstadienos/química , Animais , Autofagia , Proteína 5 Relacionada à Autofagia , Butadienos/química , Linhagem Celular Tumoral , Sobrevivência Celular , Cloroquina/química , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Proteína Huntingtina , Lisossomos/metabolismo , Macrolídeos/química , Camundongos , Microscopia de Fluorescência , Proteínas Associadas aos Microtúbulos/metabolismo , Doenças Neurodegenerativas/embriologia , Doenças Neurodegenerativas/metabolismo , Nitrilos/química , Fagossomos/química , Fosforilação , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Wortmanina
5.
ScientificWorldJournal ; 2014: 540496, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24578642

RESUMO

The mechanism of isoprenaline exerting its effects on cardiac pacemaking and driving in sick sinus syndrome is controversial and unresolved. In this paper, mathematical models for rabbit sinoatrial node cells were modified by incorporating equations for the known dose-dependent actions of isoprenaline on various ionic channel currents, the intracellular Ca²âº transient, and i(Na) changes induced by SCN5A gene mutations; the cell models were also incorporated into an intact SAN-atrium model of the rabbit heart that is based on both heterogeneities of the SAN electrophysiology and histological structure. Our results show that, in both central and peripheral cell models, isoprenaline could not only shorten the action potential duration, but also increase the amplitude of action potential. The mutation impaired the SAN pacemaking. Simulated vagal nerve activity amplified the bradycardic effects of the mutation. However, in tissue case, the pacemaker activity may show temporal, spatial, or even spatiotemporal cessation caused by the mutation. Addition of isoprenaline could significantly diminish the bradycardic effect of the mutation and the SAN could restart pacing and driving the surrounding tissue. Positive effects of isoprenaline may primarily be attributable to an increase in i(Na) and i(Ca,T) which were reduced by the mutation.


Assuntos
Agonistas Adrenérgicos beta/farmacologia , Isoproterenol/farmacologia , Modelos Cardiovasculares , Síndrome do Nó Sinusal , Animais , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/genética , Humanos , Mutação , Coelhos , Síndrome do Nó Sinusal/genética , Síndrome do Nó Sinusal/metabolismo , Síndrome do Nó Sinusal/fisiopatologia , Canais de Sódio Disparados por Voltagem/metabolismo
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