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1.
Toxicology ; 506: 153840, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38830481

RESUMO

Cisplatin (CDDP) is administered as an anticancer drug across a broad spectrum of cancer treatments, but it causes severe renal damage. Several studies have attempted to elucidate the cause of CDDP-induced renal injury, but the detailed mechanism remains unclear. We previously found that S3 cells are more sensitive to CDDP than S1 and S2 cells by using immortalized cells derived from S1, S2, and S3 segments of proximal tubules. In this study, we investigated the potential contribution of reactive oxygen species (ROS) to the sensitivity of S3 cells to CDDP. The results showed that S3 cells have high sensitivity to CDDP, paraquat (PQ) and three ROS substances. To examine the mechanisms underlying the sensitivity to ROS in S3 cells, we compared the cellular responses of CDDP- and PQ-exposed S3 cells. The results indicated that the levels of intracellular ROS and lipid peroxides were increased in S3 cells after CDDP and PQ exposure. The intracellular levels of antioxidant proteins such as thioredoxin, thioredoxin reductase 1 and glutathione peroxidase 4 were also increased by exposure to PQ, but these proteins were decreased by CDDP exposure in S3 cells. Furthermore, the levels of intracellular free Fe2+ were increased by CDDP exposure only in S3 cells but not S1 or S2 cells, and cytotoxicity by exposure to CDDP in S3 cells was suppressed by ferroptosis inhibitors. These results suggested that the induction of ferroptosis due to the ROS production through attenuation of the antioxidant system and elevated free Fe2+ is partly responsible for the sensitivity of S3 cells to CDDP.


Assuntos
Antineoplásicos , Cisplatino , Ferroptose , Túbulos Renais Proximais , Espécies Reativas de Oxigênio , Cisplatino/toxicidade , Cisplatino/farmacologia , Ferroptose/efeitos dos fármacos , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/patologia , Espécies Reativas de Oxigênio/metabolismo , Antineoplásicos/toxicidade , Antineoplásicos/farmacologia , Animais , Paraquat/toxicidade , Linhagem Celular , Linhagem Celular Transformada , Camundongos , Sobrevivência Celular/efeitos dos fármacos
2.
PLoS One ; 18(1): e0279893, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36598904

RESUMO

Arsenic is a potent environmental toxicant and human carcinogen. Skin lesions are the most common manifestations of chronic exposure to arsenic. Advanced-stage skin lesions, particularly hyperkeratosis have been recognized as precancerous diseases. However, the underlying mechanism of arsenic-induced skin lesions remains unknown. Periostin, a matricellular protein, is implicated in the pathogenesis of many forms of skin lesions. The objective of this study was to examine whether periostin is associated with arsenic-induced skin lesions. A total of 442 individuals from low- (n = 123) and high-arsenic exposure areas (n = 319) in rural Bangladesh were evaluated for the presence of arsenic-induced skin lesions (Yes/No). Participants with skin lesions were further categorized into two groups: early-stage skin lesions (melanosis and keratosis) and advanced-stage skin lesions (hyperkeratosis). Drinking water, hair, and nail arsenic concentrations were considered as the participants' exposure levels. The higher levels of arsenic and serum periostin were significantly associated with skin lesions. Causal mediation analysis revealed the significant effect of arsenic on skin lesions through the mediator, periostin, suggesting that periostin contributes to the development of skin lesions. When skin lesion was used as a three-category outcome (none, early-stage, and advanced-stage skin lesions), higher serum periostin levels were significantly associated with both early-stage and advanced-stage skin lesions. Median (IQR) periostin levels were progressively increased with the increasing severity of skin lesions. Furthermore, there were general trends in increasing serum type 2 cytokines (IL-4, IL-5, IL-13, and eotaxin) and immunoglobulin E (IgE) levels with the progression of the disease. The median (IQR) of IL-4, IL-5, IL-13, eotaxin, and IgE levels were significantly higher in the early-and advanced-stage skin lesions compared to the group of participants without skin lesions. The results of this study suggest that periostin is implicated in the pathogenesis and progression of arsenic-induced skin lesions through the dysregulation of type 2 immune response.


Assuntos
Arsênio , Ceratose Actínica , Dermatopatias , Humanos , Arsênio/toxicidade , Arsênio/análise , Interleucina-13 , Interleucina-4 , Interleucina-5 , Exposição Ambiental , Abastecimento de Água , Dermatopatias/induzido quimicamente , Imunoglobulina E/efeitos adversos
3.
J Toxicol Sci ; 47(12): 507-517, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36450495

RESUMO

Chronic exposure to cadmium (Cd) leads to an accumulation of Cd in the kidneys. Metallothionein (MT) is a low-molecular-weight protein having a high affinity for Cd. Cd bound to MT in serum is filtered through the glomeruli of kidney nephrons and reabsorbed by endocytosis into the proximal tubules from the luminal side. Accumulation of Cd in renal cells induces MT synthesis, leading to long-term deposition of Cd and the suppression of Cd toxicity. Recently, many studies have investigated the tissue distribution of metals using laser ablation ICP-MS (LA-ICP-MS). However, little information has been available regarding renal Cd distribution. Hence, we dually investigated the renal distribution of Cd by LA-ICP-MS and that of MT by immunohistochemistry to clarify the dose- and time-dependent changes in the distributions of Cd and MT in mice exposed to Cd from drinking water for 1, 2, and 4 months. Both Cd and MT exhibited characteristic heterogeneous distribution patterns in the renal cortex. The accumulation of Cd and MT near the surface of the cortex suggests a preferential accumulation of Cd in the surface nephrons. MT distribution was more pronounced in the proximal tubules than in the distal tubules, and there were clear differences in MT immunostaining even among the proximal tubules. The heterogeneous localization of MT may reflect the nephron-specific accumulation of Cd. Combining elemental imaging of Cd with immunostaining of MT proved a successful strategy to reveal the characteristic renal Cd distribution, especially in the early stages of Cd accumulation.


Assuntos
Cádmio , Metalotioneína , Camundongos , Animais , Rim , Néfrons , Túbulos Renais Proximais
4.
Biochem Biophys Res Commun ; 616: 26-32, 2022 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-35636252

RESUMO

Zinc (Zn) transporter ZIP8, encoded by SLC39A8, is a unique transporter that can transport divalent manganese (Mn) and cadmium (Cd) in addition to Zn. Recently, associations between various human diseases and variant forms of ZIP8 have been reported. Four amino acid residues, V33, G38, S335, and I340, of human ZIP8 (hZIP8) are mutated in patients with congenital disorders of glycosylation (CDG), whose blood Mn levels are extremely low. Many genome-wide association studies have reported that the A391T mutation of hZIP8 caused by rs13107325 is associated with a wide range of diseases. However, the roles of individual mutations of hZIP8 on metal-transporting activity remain elusive. We established DT40 cells respectively expressing the four mutant hZIP8s and compared the Mn- and Cd-transporting activity between the mutants and wild-type hZIP8. Among the four mutations observed in the ZIP8-mutated CDG patients, the S335T and I340 N mutations in the predicted transmembrane domain 5 (TMD5) completely abolished Mn- and Cd-transporting activity, while V33 M or G35R mutations at the N-terminus did not. We also examined the A391T mutation, which slightly reduced metal transporting activity. Finally, we examined the effects of artificial mutations in the metal-binding motif EEXXH in the TMD5. Replacing EEXXH with HEXXH, which exists in most ZIP transporters, abolished the Mn- and Cd-transporting activity of hZIP8, indicating that glutamic acid in this motif plays a critical role in the unique affinity of ZIP8 for Mn and Cd. Thus, the utilization of DT40 cells enabled us to clarify the different functions of each residue of hZIP8 on metal transport.


Assuntos
Cádmio , Proteínas de Transporte de Cátions , Manganês , Aminoácidos/genética , Aminoácidos/metabolismo , Cádmio/metabolismo , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Estudo de Associação Genômica Ampla , Humanos , Manganês/metabolismo , Mutação
5.
Chemosphere ; 298: 134277, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35278445

RESUMO

Chronic exposure to arsenic via drinking water is a serious public health issue in many countries. Arsenic causes not only cancers but also non-malignant diseases, including asthma. We have previously reported that arsenic exposure increases the risk of Th2-mediated allergic asthma. The serum level of periostin, an extracellular matrix protein activated by Th2 cytokines, is recognized as a biomarker for Th2-mediated eosinophilic asthma and contributes to enhanced airway inflammation and remodeling. However, the role of periostin in arsenic-related asthma is unknown. Therefore, this study was designed to explore the associations of serum periostin levels with arsenic exposure and the features of asthma in 442 individuals in Bangladesh who participated in our previous study. Exposure levels of the participants were determined by measuring the arsenic concentrations in drinking water, hair, and nails through inductively coupled plasma mass spectroscopy. Periostin levels in serum were assessed by immunoassay. In this study, we found that serum periostin levels of the participants were increased with increasing exposure to arsenic. Notably, even the participants with 10.1-50 µg/L arsenic in drinking water had significantly higher levels of periostin than participants with <10 µg/L of water arsenic. Elevated serum periostin levels were positively associated with serum levels of Th2 mediators, such as interleukin (IL)-4, IL-5, IL-13, and eotaxin. Each log increase in periostin levels was associated with approximately eight- and three-fold increases in the odds ratios (ORs) for reversible airway obstruction (RAO) and asthma symptoms, respectively. Additionally, causal mediation analyses revealed that arsenic exposure metrics had both direct and indirect (periostin-mediated) effects on the risk of RAO and asthma symptoms. Thus, the results suggested that periostin may be involved in the arsenic-related pathogenesis of Th2-mediated asthma. The elevated serum periostin levels may predict the greater risk of asthma among the people living in arsenic-endemic areas.


Assuntos
Intoxicação por Arsênico , Arsênio , Asma , Água Potável , Arsênio/análise , Asma/induzido quimicamente , Asma/epidemiologia , Biomarcadores/análise , Água Potável/análise , Humanos , Unhas/química
6.
Yakugaku Zasshi ; 141(5): 695-703, 2021.
Artigo em Japonês | MEDLINE | ID: mdl-33952754

RESUMO

Cellular transport systems for both essential and toxic trace elements remain elusive. In our studies on the transport systems for cadmium (Cd), we found that the cellular uptake of Cd is mediated by the transporter for manganese (Mn). We identified ZIP8 and ZIP14, members of the ZIP zinc (Zn) transporter family, as transporters having high affinities for both Cd and Mn. Notably, the uptake of Cd into rice root from soil is mediated by a transporter for Mn as well. We found that ZIP8 is highly expressed at the S3 segment of the kidney proximal tubule and can transport glomerulus-filtered Cd and Mn ions in the lumen into epithelial cells of the proximal tubule, suggesting that ZIP8 has an important role in the renal reabsorption of both toxic Cd and essential Mn. Mutations in ZIP8 and ZIP14 genes were found in humans having congenital disorders associated with the disturbed transport of Mn, although ZIP8 mutation causes whole-body Mn deficiency while ZIP14 mutation causes Mn accumulation in the brain. Mutations in ZnT10, a Zn transporter responsible for Mn excretion, also cause hyperaccumulation of Mn in the brain. Results of genome-wide association studies have indicated that ZIP8 SNPs are involved in a variety of common diseases. Thus, ZIP8, ZIP14, and ZnT10 play crucial roles in the transport of Mn and thereby control Mn- and Cd-related biological events in the body.


Assuntos
Cádmio/metabolismo , Cádmio/toxicidade , Proteínas de Transporte/fisiologia , Manganês/metabolismo , Manganês/toxicidade , Animais , Encéfalo/metabolismo , Proteínas de Transporte/metabolismo , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Proteínas de Transporte de Cátions/fisiologia , Estudo de Associação Genômica Ampla , Humanos , Túbulos Renais Proximais/metabolismo , Mutação , Oryza/metabolismo , Raízes de Plantas/metabolismo , Reabsorção Renal
7.
Toxicol In Vitro ; 75: 105179, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33905841

RESUMO

Renal toxicants such as cisplatin and cadmium cause segment-specific damages in kidney proximal tubules. Recently, we established an in vitro experimental system for evaluating segment-specific toxicity and transport of chemicals using immortalized S1, S2, and S3 cells derived from the S1, S2, and S3 regions of mouse kidney proximal tubules. In the present study, we examined the toxicity and accumulation of cisplatin, carboplatin, oxaliplatin, and cadmium in S1, S2, and S3 cells. We found that not only cisplatin but also carboplatin and oxaliplatin exhibited higher lethal toxicity in S3 cells than in S1 and S2 cells. At sublethal doses, cisplatin showed delayed induction of Kim-1 and clusterin on days 3 and 6, which may reflect the latent renal toxicity of cisplatin in vivo. The high sensitivities of S3 cells to the platinum-based agents were not due to the high accumulation of Pt in S3 cells. Exposure to cadmium resulted in similar toxicity among these cells, suggesting that S3 cells were not sensitive to any renal toxicants. Thus, the utilization of S1, S2, and S3 cells may provide a useful tool for the in vitro evaluation of the proximal tubule segment-specific toxicity of chemicals.


Assuntos
Antineoplásicos/toxicidade , Cloreto de Cádmio/toxicidade , Carboplatina/toxicidade , Cisplatino/toxicidade , Túbulos Renais Proximais/citologia , Oxaliplatina/toxicidade , Animais , Cádmio/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Clusterina/genética , Transportador de Cobre 1/metabolismo , Receptor Celular 1 do Vírus da Hepatite A/genética , Camundongos , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Transportador 2 de Cátion Orgânico/metabolismo , Platina/metabolismo
8.
Toxicol Appl Pharmacol ; 420: 115532, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33845054

RESUMO

Limited information is available regarding the effects of arsenic exposure on immune function. We have recently reported that chronic exposure to As was associated asthma, as determined by spirometry and respiratory symptoms. Because T helper 2 (Th2)-driven immune responses are implicated in the pathogenesis of allergic diseases, including asthma, we studied the associations of serum Th1 and Th2 mediators with the As exposure markers and the features of asthma among individuals exposed to As. A total of 553 blood samples were selected from the same study subjects recruited in our previous asthma study. Serum levels of Th1 and Th2 cytokines were analyzed by immunoassay. Subjects' arsenic exposure levels (drinking water, hair and nail arsenic concentrations) were determined by inductively coupled plasma mass spectroscopy. Arsenic exposure levels of the subjects showed significant positive associations with serum Th2-mediators- interleukin (IL)-4, IL-5, IL-13, and eotaxin without any significant changes in Th1 mediators- interferon-γ and tumor necrosis factor-α. The ratios of Th2 to Th1 mediators were significantly increased with increasing exposure to As. Notably, most of the Th2 mediators were positively associated with serum levels of total immunoglobulin E and eotaxin. The serum levels of Th2 mediators were significantly higher in the subjects with asthma than those without asthma. The results of our study suggest that the exacerbated Th2-driven immune responses are involved in the increased susceptibility to allergic asthma among individuals chronically exposed to As.


Assuntos
Arsênio/efeitos adversos , Asma/induzido quimicamente , Citocinas/sangue , Células Th1/efeitos dos fármacos , Equilíbrio Th1-Th2/efeitos dos fármacos , Células Th2/efeitos dos fármacos , Poluentes Químicos da Água/efeitos adversos , Adolescente , Adulto , Asma/diagnóstico , Asma/imunologia , Asma/metabolismo , Bangladesh , Carga Corporal (Radioterapia) , Estudos Transversais , Feminino , Humanos , Imunoglobulina E/sangue , Masculino , Pessoa de Meia-Idade , Medição de Risco , Fatores de Risco , Células Th1/imunologia , Células Th1/metabolismo , Células Th2/imunologia , Células Th2/metabolismo , Adulto Jovem
9.
Toxicol Appl Pharmacol ; 412: 115353, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-33301752

RESUMO

Chronic exposure to arsenic causes cancers in various organs including the skin, liver, lung, and bladder in humans, but the mechanisms of the multi-organ carcinogenicity of arsenic remain unknown. Natural killer (NK) cells play important roles in the immune surveillance and elimination of tumor cells. Although accumulating evidence has indicated that arsenic has immunosuppressive properties, little is known about the effects of arsenic on the tumoricidal functions of NK cells. We examined the effects of arsenite on the cytotoxic activities of human and mouse NK cells toward target tumor cells. Exposure of human NK-92 cells and primary mouse NK cells to sublethal doses of arsenite reduced the IL-2-activated cytotoxic activities toward human K562 cells and murine YAC-1 cells, respectively. NK cells recognize target cells via integrated signals from both activating and inhibitory receptors and induce apoptosis of target cells via a granzyme/perforin system. We found that exposure of NK-92 cells to arsenite diminished the IL-2-activated down-regulation of the inhibitory receptors, KIR2DL2 and KIR2DL3, and the up-regulation of granzyme B and lymphotoxin-α. The IL-2-activated increases in secretion of interferon-γ and IL-10 were also slightly reduced by arsenite. Thus, arsenite suppressed the IL-2-activated cytotoxic activity of NK cells by disrupting multiple pathways required for the recognition and killing of target tumor cells. Our findings provide new insights into the roles of NK cell-mediated tumor immunity in cancer development by arsenic.


Assuntos
Arsenitos/toxicidade , Citotoxicidade Imunológica/efeitos dos fármacos , Interleucina-2/farmacologia , Células Matadoras Naturais/efeitos dos fármacos , Leucemia Mielogênica Crônica BCR-ABL Positiva/imunologia , Compostos de Sódio/toxicidade , Evasão Tumoral/efeitos dos fármacos , Animais , Técnicas de Cocultura , Granzimas/genética , Granzimas/metabolismo , Humanos , Interferon gama/genética , Interferon gama/metabolismo , Interleucina-10/metabolismo , Células K562 , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Linfotoxina-alfa/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Receptores KIR2DL2/genética , Receptores KIR2DL2/metabolismo , Receptores KIR2DL3/genética , Receptores KIR2DL3/metabolismo
10.
Biochem Biophys Res Commun ; 529(4): 910-915, 2020 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-32819598

RESUMO

Transcription factor EVI1 is essential for normal hematopoiesis in embryos but is aberrantly elevated in bone marrow cells of myelodysplastic syndrome (MDS) patients. EVI1 and its downstream GATA-2 appear to be a possible therapeutic target of MDS. Here we found that treatment of EVI1-expressing K562 cells with arsenite (As(III)) reduced the mRNA and protein levels of EVI1 and GATA-2. A gel shift assay using the nuclear extract of K562 cells showed that As(III) suppressed the DNA-binding activity of EVI1. The DNA-binding activity of the recombinant EVI1 protein was also suppressed by As(III) but was recovered by excess amounts of dithiothreitol, suggesting the involvement of cysteine residues of EVI1. Since the 7th Zn finger domain of EVI1, having a motif of CCHC, is known to be involved in DNA-binding, the synthetic peptide of 7th Zn finger domain was reacted with As(III) and subjected to MALDI-TOF-MS analysis. The results showed that As(III) binds to this peptide via three cysteine residues. As(III)-induced reduction of the DNA-binding activity of the recombinant EVI1 was abolished by the mutations of each of three cysteine residues to alanine in the 7th Zn finger domain. These results demonstrate that As(III) causes the down-regulation of EVI1 and GATA-2 by inhibiting the transcriptional activity of EVI1 through the binding to the cysteine residues of CCHC-type Zn finger domain.


Assuntos
Arsenitos/farmacologia , Cisteína/metabolismo , Fator de Transcrição GATA2/genética , Proteína do Locus do Complexo MDS1 e EVI1/genética , Compostos de Sódio/farmacologia , Dedos de Zinco/genética , Alanina/genética , Alanina/metabolismo , Substituição de Aminoácidos , Sítios de Ligação , Núcleo Celular/química , Núcleo Celular/metabolismo , Misturas Complexas/química , Misturas Complexas/metabolismo , Cisteína/genética , Ditiotreitol/farmacologia , Ensaio de Desvio de Mobilidade Eletroforética , Fator de Transcrição GATA2/antagonistas & inibidores , Fator de Transcrição GATA2/metabolismo , Regulação da Expressão Gênica , Humanos , Células K562 , Proteína do Locus do Complexo MDS1 e EVI1/antagonistas & inibidores , Proteína do Locus do Complexo MDS1 e EVI1/metabolismo , Peptídeos/síntese química , Peptídeos/metabolismo , Ligação Proteica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Transdução de Sinais
11.
Toxics ; 8(2)2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32244724

RESUMO

Cadmium (Cd) is an environmental pollutant known to cause dysfunctions of the tubular reabsorption of biomolecules in the kidney. Elevated levels of urinary excretion of low-molecular-weight proteins such as ß2-microglobulin (ß2-MG) have been used as an indicator of Cd-induced renal tubular dysfunctions. However, very few studies have examined the direct effects of Cd on the reabsorption efficiency of proteins using cultured renal cells. Here, we developed an in vitro assay system for quantifying the endocytic uptakes of fluorescent-labeled proteins by flow cytometry in S1 and S2 cells derived from mouse kidney proximal tubules. Endocytic uptakes of fluorescent-labeled albumin, transferrin, ß2-MG, and metallothionein into S1 cells were confirmed by fluorescence imaging and flow cytometry. The exposure of S1 and S2 cells to Cd at 1 and 3 µM for 3 days resulted in significant decreases in the uptakes of ß2-MG and metallothionein but not in those of albumin or transferrin. These results suggest that Cd affects the tubular reabsorption of low-molecular-weight proteins even at nonlethal concentrations. The in vitro assay system developed in this study to evaluate the endocytic uptakes of proteins may serve as a useful tool for detecting toxicants that cause renal tubular dysfunctions.

12.
Toxicol Res ; 35(4): 311-317, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31636842

RESUMO

The transport systems for metals play crucial roles in both the physiological functions of essential metals and the toxic effects of hazardous metals in mammals and plants. In mammalian cells, Zn transporters such as ZIP8 and ZIP14 have been found to function as the transporters for Mn(II) and Cd(II), contributing to the maintenance of Mn homeostasis and metallothionein-independent transports of Cd, respectively. In rice, the Mn transporter OsNramp5 expressed in the root is used for the uptake of Cd from the soil. Japan began to cultivate OsNramp5 mutant rice, which was found to accumulate little Cd, to prevent Cd accumulation. Inorganic trivalent arsenic (As(III)) is absorbed into mammalian cells via aquaglyceroporin, a water and glycerol channel. The ortholog of aquaporin in rice, OsLsi1, was found to be an Si transporter expressed in rice root, and is responsible for the absorption of soil As(III) into the root. Since rice is a hyperaccumulator of Si, higher amounts of As(III) are incorporated into rice compared to other plants. Thus, the transporters of essential metals are also utilized to incorporate toxic metals in both mammals and plants, and understanding the mechanisms of metal transports is important for the development of mitigation strategies against food contamination.

13.
Arch Toxicol ; 93(12): 3523-3534, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31616959

RESUMO

Chronic arsenic exposure causes cancers in multiple organs in humans. However, the mechanisms underlying arsenic-induced carcinogenesis remain obscure. Here, we examined whether chronic arsenite (As(III)) exposure promotes cell migration induced by heparin-binding EGF-like growth factor (HB-EGF) in human esophageal immortalized Het1A cells. When Het1A cells were exposed to 0.5 µM As(III) for 4 months, HB-EGF-induced migration was enhanced in As(III)-exposed Het1A cells compared to controls. To elucidate the mechanisms underlying the promotion of HB-EGF-induced migration by chronic exposure to As(III), we compared ERK phosphorylation between As(III)-exposed and control Het1A cells and found that HB-EGF-induced ERK phosphorylation was enhanced in the As(III)-exposed cells. We next measured mRNA levels of 88 genes related to cell cycle regulation. The results showed elevated cyclin D1 mRNA levels in As(III)-exposed Het1A cells. The inhibitors of ERK and cyclin D/Cdk4 markedly suppressed HB-EGF-induced upregulation of cyclin D1 and the migration of Het1A cells, respectively, suggesting that cyclin D1 is located downstream of ERK and is required for HB-EGF-induced migration of Het1A cells. Collectively, these findings indicate that the promotion of HB-EGF-induced migration of Het1A cells chronically exposed to submicromolar As(III) might be caused by increased expression of cyclin D1 mediated by enhanced activation of the ERK pathway.


Assuntos
Arsenitos/toxicidade , Esôfago/citologia , Fator de Crescimento Semelhante a EGF de Ligação à Heparina/farmacologia , Arsenitos/administração & dosagem , Linhagem Celular , Movimento Celular/efeitos dos fármacos , Ciclina D1/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Fosforilação/efeitos dos fármacos , Testes de Toxicidade Crônica
14.
J Toxicol Sci ; 44(9): 611-619, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31474742

RESUMO

The kidney proximal tubule is a target of many renal toxicants, including cadmium (Cd), and also a place of reabsorption of essential metals in glomerular filtrate to systemic circulation. Although the mechanisms of metal transport in the convoluted proximal tubule (S1 and S2 segments) and the straight proximal tubule (S3 segment) may differ, little is known about the segment-specific modes of metal transport. Here, we utilized immortalized cell lines derived from the S1, S2, and S3 segments of mouse kidney proximal tubules, and examined the segment-specific and direction-dependent transport of Cd and manganese (Mn) using a trans-well culture system. The results showed that the uptakes of Cd2+ and Mn2+ from apical sides were the highest in S3 cells, and Cd2+, Mn2+, and Zn2+ mutually inhibited the apical uptake of each metal. As the expression of ZIP8, a zinc transporter having affinities for Cd2+ and Mn2+, was the highest in S3 cells, ZIP8 may contribute largely to the apical uptakes of these metals. The efficient uptake of Mn2+ from apical side of S3 cells may suggest an important role of ZIP8 in proximal tubule in reabsorption of Mn, an essential metal. Our study demonstrated that S1, S2, and S3 cells provide a useful tool for studying the segment-specific and direction-dependent transport of both toxic and essential metals in the kidney's proximal tubules.


Assuntos
Compostos de Cádmio/metabolismo , Compostos de Cádmio/toxicidade , Cádmio/metabolismo , Cádmio/toxicidade , Túbulos Renais Proximais/citologia , Túbulos Renais Proximais/metabolismo , Manganês/metabolismo , Manganês/toxicidade , Animais , Proteínas de Transporte de Cátions/metabolismo , Proteínas de Transporte de Cátions/fisiologia , Células Cultivadas , Camundongos , Transcitose
15.
Biol Pharm Bull ; 42(7): 1076-1082, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31257283

RESUMO

ZIP8, a Zrt-/Irt-related protein encoded by Slc39A8, was originally discovered as a zinc transporter, but since then its roles as a transporter for cadmium (Cd) and manganese (Mn) have also been well characterized. ZIP8 is highly expressed in the S3 segment of the proximal tubules of the mouse kidney and may play a significant role in reabsorption of both toxic Cd and essential Mn from the lumen to the epithelial cells of the proximal tubule. In recent years, associations between various human diseases and genetic variations of ZIP8 have been reported. Missense mutations in the human SLC39A8 gene are associated with serious disorders of Mn metabolism, showing symptoms similar to congenital glycosylation deficiency. Enhanced excretion of Mn via bile or urine might be the cause of extremely low blood Mn levels in ZIP8-mutated patients, leading to the defects in Mn-dependent glycosylation. Several genome-wide association studies have demonstrated the associations of multiple diseases and ZIP8 SNPs constituting missense mutations. These findings suggest that ZIP8 plays more important roles than previously expected as a modulator of Mn homeostasis in the body. Elucidation of biochemical mechanisms regarding the metal-transporting ability of ZIP8 and its alteration by mutation is required for better understanding of the role of ZIP8 in human diseases.


Assuntos
Cádmio/metabolismo , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Manganês/metabolismo , Aminoácidos/genética , Animais , Humanos , Rim/metabolismo , Mutação , Polimorfismo de Nucleotídeo Único
16.
J Toxicol Sci ; 44(2): 83-92, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30726814

RESUMO

Immunological functions are disturbed in humans who have been chronically exposed to arsenic via contaminated groundwater. Little is known about the specific mechanisms underlying the impairment of immunological defense system caused by arsenic. The activation of macrophage cells upon infection with bacteria and viruses plays important roles in the defense against these pathogens. Here we show that exposure to arsenite (As(III)) suppresses nitric oxide (NO) production in murine RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS) and poly(I:C), the compounds mimicking bacterial and viral infection, respectively. As(III) suppressed the LPS- or poly(I:C)-evoked induction of inducible NO synthase (iNOS) without affecting the transactivation of NF-κB. As the interferon (IFN)-ß/STAT1 pathway is also involved in the induction of iNOS in addition to NF-κB, we examined the effects of As(III) on the expression and secretion of IFN-ß, the expression of the components of IFN-α/ß receptor, the phosphorylation of STAT1, and the levels of cytokines involved in STAT1 activation. The results showed that the expression and secretion of IFN-ß were specifically suppressed by As(III) treatment in RAW264.7 cells stimulated with LPS or poly(I:C). These results suggest that As(III) suppresses the expression and secretion of IFN-ß, leading to the reduced STAT1 activation and consequently the reduced iNOS induction in macrophage cells. Our data suggest an important role of the arsenic-induced suppression of IFN-ß on the disturbances in immunological defense against both bacteria and viruses.


Assuntos
Arsenitos/toxicidade , Interferon beta/metabolismo , Óxido Nítrico/metabolismo , Animais , Interferon beta/genética , Lipopolissacarídeos , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Óxido Nítrico Sintase Tipo II/metabolismo , Poli I-C , Células RAW 264.7 , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo
17.
J Toxicol Sci ; 42(5): 559-567, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28904291

RESUMO

Intestinal absorption of cadmium (Cd) is considered to be mediated mainly by the ferrous iron transporter DMT1, or the calcium transporter CaT1. The roles of zinc transporters such as ZIP8 and ZIP14 remain unclear, and the roles of these four transporters in the intestinal uptake of Cd under physiological conditions have not been compared. Here, we used a trans-well cell culture system to investigate the effects of the down-regulation of these four transporters on the uptake of Cd from the apical side of enterocytes. We used a Caco-2-kh cell line that can form tight junctions within a few days. The transfection of DMT1 siRNA significantly decreased the Cd uptake from the apical side at 5 µM, but not at 0.1 or 1 µM. The transfection of ZIP14 siRNA markedly decreased the Cd uptake at 0.1 and 1 µM, but not at 5 µM. The transfection of siRNA of CaT1 or ZIP8 did not alter the Cd uptake at any concentrations of Cd examined. These results suggest that DMT1 and ZIP14 play different roles in intestinal Cd absorption depending on the concentration of Cd.


Assuntos
Cloreto de Cádmio/metabolismo , Proteínas de Transporte de Cátions/fisiologia , Enterócitos/metabolismo , Absorção Intestinal/genética , Fatores de Transcrição/fisiologia , Células CACO-2 , Proteínas de Transporte de Cátions/genética , Relação Dose-Resposta a Droga , Regulação para Baixo , Humanos , RNA Interferente Pequeno , Fatores de Transcrição/genética , Transfecção
18.
Environ Health ; 16(1): 20, 2017 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-28270149

RESUMO

BACKGROUND: Chronic exposure to arsenic is associated with cancer and hypertension. Growing evidence suggests that altered methylation in long interspersed nuclear element-1 (LINE-1) is involved in many types of disorders, including cardiovascular disease. Here we evaluated the association between arsenic exposure and LINE-1 methylation levels, especially in relation to blood pressure (BP). METHODS: A total of 236 subjects (175 from arsenic-endemic areas and 61 from a non-endemic area) in rural Bangladesh were recruited. The subjects' arsenic exposure levels (i.e., drinking water, hair and nail arsenic concentrations) were measured by inductively coupled plasma mass spectroscopy. The subjects' LINE-1 methylation levels were determined by pyrosequencing. RESULTS: The average LINE-1 methylation levels of the subjects living in the arsenic-endemic areas were significantly (p < 0.01) lower than those of the subjects living in the non-endemic area. In a sex-stratified analysis, the arsenic exposure levels in female but not male subjects showed a significant inverse association with LINE-1 methylation levels before (water arsenic: p < 0.01, hair arsenic: p < 0.05, nail arsenic: p < 0.001) and after (water arsenic: p < 0.01, hair arsenic: p < 0.05, nail arsenic: p < 0.001) adjustment for age, body mass index and smoking. Analyses examining interactions among arsenic levels, BP and LINE-1 methylation showed that arsenic-related elevated levels of BP were associated with LINE-1 hypomethylation. CONCLUSIONS: Our findings demonstrated that chronic exposure to arsenic was inversely associated with LINE-1 methylation levels in blood leukocyte DNA and this was more pronounced in females than males; in addition, the decreased levels of LINE-1 methylation might be involved in the arsenic-induced elevation of BP.


Assuntos
Arsênio/efeitos adversos , Pressão Sanguínea/efeitos dos fármacos , Metilação de DNA/efeitos dos fármacos , Exposição Ambiental/efeitos adversos , Elementos Nucleotídeos Longos e Dispersos/fisiologia , Poluentes Químicos da Água/efeitos adversos , Adulto , Arsênio/análise , Bangladesh , Estudos Transversais , Água Potável/análise , Exposição Ambiental/análise , Feminino , Cabelo/química , Humanos , Masculino , Pessoa de Meia-Idade , Unhas/química , Poluentes Químicos da Água/análise
19.
Biochem Biophys Res Commun ; 480(1): 18-22, 2016 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-27721063

RESUMO

We previously reported that two splicing variants of human AS3MT mRNA, exon-3 skipping form (Δ3) and exons-4 and -5 skipping form (Δ4,5), were detected in HepG2 cells and that both variants lacked arsenic methylation activity (Sumi et al., 2011). Here we studied whether hydrogen peroxide (H2O2) triggers alternative splicing of AS3MT mRNA. The results showed that exposure of HepG2 cells to H2O2 resulted in increased levels of a novel spliced form skipping exon-3 to exon-10 (Δ3-10) in an H2O2-concentration-dependent manner, although no change was detected in the mRNA levels of Δ3 AS3MT. We found decreased protein levels of serine/arginine-rich 40 (SRp40), which we determined to be a candidate splice factor for controlling the splicing of AS3MT mRNA. We next compared the amounts of methylated arsenic metabolites between control and H2O2-exposed HepG2 cells after the addition of arsenite as a substance. The results showed lower levels of methylated arsenic metabolites in HepG2 cells exposed to H2O2. These data suggest that the splicing of AS3MT pre-mRNA was disconcerted by oxidative stress and that abnormal alternative splicing of AS3MT mRNA may affect arsenic methylation ability.


Assuntos
Processamento Alternativo/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Metiltransferases/genética , Processamento Alternativo/genética , Arsênio/metabolismo , Arsênio/farmacocinética , Células Hep G2/efeitos dos fármacos , Células Hep G2/metabolismo , Humanos , Metilação , Metiltransferases/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo
20.
Life Sci ; 149: 42-50, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26892147

RESUMO

AIMS: All-trans retinoic acid (ATRA) is used to treat patients with acute promyelocytic leukemia (APL) due to its ability to resume the differentiation of APL cells. Recently, clinical trials have been started to evaluate ATRA plus arsenic trioxide (ATO) as a combination treatment for APL patients. However, little is known about the detailed mechanisms underlying its efficacy. We therefore investigated the effects of this combination on the differentiation and differentiation-related gene expression. MAIN METHODS: Human leukemia HL-60 cells differentiation was examined using nitro blue tetrazolium and CD11b. The levels of mRNA and protein were determined by RT-qPCR, microarray, western blot and ELISA, respectively. The promoter activity was assessed by luciferase activity. The arsenic concentration was determined by ICP-MS. KEY FINDINGS: ATRA-induced HL-60 differentiation was augmented by co-treatment with ATO. A microarray analysis showed that ATRA plus ATO treatment markedly down-regulated the expression of proteinase 3 (PRTN3), which is involved in the differentiation arrest of leukemia cells, compared with treatment with ATRA alone. The PRTN3 mRNA level was suppressed by treatment with ATRA alone, and then further suppressed by co-treatment with ATO, accompanied by a concomitant increase in Sp1 protein, which is known to facilitate differentiation. The expression levels of azurocidin, telomerase reverse transcriptase, ferritin, and interleukin-1ß were also altered by co-treatment with ATO. SIGNIFICANCE: Co-treatment with ATO enhances ATRA-induced HL-60 differentiation by altering the expression of genes involved in cell differentiation, providing the molecular basis for a combination therapy using ATO plus ATRA to treat leukemia patients.


Assuntos
Arsenicais/administração & dosagem , Diferenciação Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Óxidos/administração & dosagem , Tretinoína/administração & dosagem , Antineoplásicos/administração & dosagem , Trióxido de Arsênio , Diferenciação Celular/fisiologia , Sobrevivência Celular/fisiologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Células HL-60 , Humanos
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