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1.
Clin Transl Oncol ; 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38592638

RESUMO

INTRODUCTION: Neoadjuvant systemic therapy (NAST) is vital in the management of HER2-positive (HER2+) breast cancer. Nevertheless, the indications for NAST in tumors <2 cm remain controversial. METHOD: A total of 7961 patients were screened from the Surveillance, Epidemiology, and End Result database. Independent prognostic factors were identified using multivariate Cox analysis. Subgroup analyses and Kaplan-Meier analyses were used to simulate whether NAST would provide a survival benefit with different high-risk characteristics. Nomograms were constructed, and an internal validation cohort was employed. RESULTS: Of the 7961 included patients, 1137 (14.3%) underwent NAST. In the total population, NAST was associated with poorer overall survival (OS) and breast cancer-specific survival (BCSS) (OS: P = 0.00093; BCSS: P  <  0.0001). Multivariate Cox analysis confirmed that NAST markedly affected the prognosis of enrolled patients. Besides, a direct association between T, N, age, subtype, and prognosis was observed. Subgroup analyses yielded in these three subgroups, T1c, hormone receptor-negative, and 61-69 years of age, NAST and AST had comparable OS, while NAST possessed worse BCSS. Notably, even in the N3, we still did not observe any additional benefit of NAST. The calculated C-index of 0.72 and 0.73 confirmed the predictability of the nomograms. The AUCs exhibit consistency in the training and validation cohorts. CONCLUSION: Our findings suggest that NAST does not provide additional benefit to patients with T1 HER2+ breast cancer, even in the presence of lymph node metastasis, T1c, or hormone receptor negativity. This study facilitates the implementation of individualized management strategies.

2.
J Cancer Res Clin Oncol ; 150(3): 119, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38466449

RESUMO

PURPOSE: Gene mutations drive tumor immune microenvironment (TIME) heterogeneity, in turn affecting prognosis and immunotherapy efficacy. PIK3CA is the most frequently mutated gene in breast cancer (BC), yet its relevance to BC prognosis remains controversial. Herein, we sought to determine the impact of PIK3CA mutation-driven immune genes (PDIGs) on BC prognosis in relation to TIME heterogeneity. METHODS: PIK3CA mutation characteristics were compared and verified between the TCGA-BRCA dataset and a patient cohort from our hospital. PIK3CA mutation-driven differentially expressed genes were identified for consensus clustering and weighted gene co-expression network analysis to select the modules most relevant to the immune subtype. Thereafter, the two were intersected to obtain PDIGs. Univariate Cox, LASSO, and multivariate Cox regression analyses were sequentially performed on PDIGs to obtain a PIK3CA mutation-driven immune signature (PDIS), which was then validated using the Gene Expression Omnibus (GEO) database. Differences in functional enrichment, mutation landscape, immune infiltration, checkpoint gene expression, and drug response were compared between different risk groups. RESULTS: PIK3CA mutation frequencies in the TCGA and validation cohorts were 34.49% and 40.83%, respectively. PIK3CA mutants were significantly associated with ER, PR, and molecular BC subtypes in our hospital cohort. The PDIS allowed for effective risk stratification and exhibited prognostic power in TCGA and GEO sets. The low-risk patients exhibited greater immune infiltration, higher expression of common immune checkpoint factors, and lower scores for tumor immune dysfunction and exclusion. CONCLUSION: The PDIS can be used as an effective prognostic model for predicting immunotherapy response to guide clinical decision-making.


Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/genética , Neoplasias da Mama/terapia , Prognóstico , Classe I de Fosfatidilinositol 3-Quinases/genética , Tomada de Decisão Clínica , Análise por Conglomerados , Microambiente Tumoral/genética
3.
Clin Breast Cancer ; 24(4): e232-e243.e1, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38368246

RESUMO

INTRODUCTION: The survival benefit of axillary lymph node dissection (ALND), sentinel lymph node biopsy (SLNB) combined with radiation, and ALND combined with radiation remains unclear in breast cancer (BC) patients with 1-2 metastatic sentinel lymph nodes (SLNs). This study aims to rigorously evaluate the prognostic impact of these axillary evaluation modalities on BC patients with varying T-stages and to construct a survival prediction nomogram. METHODS: Following screening for inclusion and exclusion criteria, data pertaining to BC patients were extracted from the SEER database. Overall survival (OS) and breast cancer-specific survival (BCSS) were assessed using Kaplan-Meier curves and Cox proportional hazards model among patients with different stages who underwent various axillary evaluation modalities. A nomogram was constructed to predict the probability of OS and BCSS. RESULTS: A total of 20,283 patients were included, comprising 9626 who underwent breast-conserving surgery (BCS) and 10,657 who underwent mastectomy. In the T4 stage stratified analysis, both BCS and mastectomy groups exhibited superior OS and BCSS with ALND compared to SLNB combined with radiation. Further, ALND combined with radiation improved OS. However, for T1-3 stages, patients treated with ALND experienced similar or worse survival compared to those treated with SLNB combined with radiation. The calibration curve and C-index (0.746-0.794) of the nomogram demonstrated the efficacy of the survival prediction model. CONCLUSION: In T1-3 BC patients with 1-2 metastatic SLNs, SLNB combined with radiation is a safe alternative to ALND. Conversely, for T4 patients, ALND combined with radiation may offer a preferable choice.


Assuntos
Axila , Neoplasias da Mama , Excisão de Linfonodo , Metástase Linfática , Estadiamento de Neoplasias , Nomogramas , Programa de SEER , Biópsia de Linfonodo Sentinela , Linfonodo Sentinela , Humanos , Neoplasias da Mama/patologia , Neoplasias da Mama/mortalidade , Neoplasias da Mama/cirurgia , Feminino , Pessoa de Meia-Idade , Biópsia de Linfonodo Sentinela/métodos , Metástase Linfática/patologia , Idoso , Linfonodo Sentinela/patologia , Linfonodo Sentinela/cirurgia , Adulto , Prognóstico , Mastectomia , Mastectomia Segmentar , Estudos Retrospectivos , Linfonodos/patologia , Linfonodos/cirurgia , Taxa de Sobrevida
4.
J Cancer Res Clin Oncol ; 149(17): 16001-16013, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37689588

RESUMO

BACKGROUND: Anaplastic thyroid cancer (ATC) is a highly aggressive malignancy with dismal prognosis. This study aimed to identify the independent risk factors and construct a readily-to-use nomogram to predict the probability of early death in ATC patients. METHOD: Patients diagnosed with ATC between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database were enrolled in this study for model development and internal validation. Univariate and multivariate logistic regression analyses were conducted to identify independent risk factors for early death of ATC. Nomograms for predicting the probability of all-cause early death (ACED) and cancer-specific early death (CSED) of ATC were subsequently developed. The performance of the nomograms was comprehensively evaluated and validated in an internal cohort. RESULT: A total of 696 ATC patients were included in this study, of which 488 patients in the training cohort and 208 patients in the validation cohort. The univariate and multivariate logistic regression analyses identified five independent factors (tumor size, M stage, surgery, radiotherapy and chemotherapy) in the ACED model and six variables in the CSED (gender, tumor size, M stage, surgery, radiotherapy and chemotherapy) model for the establishment of the nomograms. Calibration curves and receiver operating characteristic (ROC) curves showed satisfactory efficacy and consistency both in the training (ACED: AUC values: 0.814 (0.776-0.852); CSED: 0.778 (0.736-0.820)) and validation sets (ACED: 0.762 (0.696-0.827); CSED: 0.745 (0.678-0.812)). In addition, the decision curve analysis (DCA) demonstrated the favorable potential of the two nomograms in clinical application. CONCLUSION: The two nomograms assist clinicians to identify risk factors and predict the early death probability among ATC patients, thus guide individualized treatment to improve the prognosis.


Assuntos
Carcinoma Anaplásico da Tireoide , Neoplasias da Glândula Tireoide , Humanos , Nomogramas , Calibragem , Divisão Celular , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/terapia , Programa de SEER , Prognóstico
5.
J Cancer Res Clin Oncol ; 149(15): 13591-13605, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37515611

RESUMO

PURPOSE: This study aimed to assess the actual prognostic significance of different locoregional treatment (LRT) (surgery and radiotherapy) modalities for stage-IV  breast cancer (BC) patients and construct a competing risk nomogram to make precise predictions of the breast cancer-specific death (BCSD) risk among LRT recipients. METHODS: A total of 9279 eligible stage-IV BC patients from the Surveillance Epidemiology and End Results (SEER) database were included in this study. Initially, we evaluated the impact of LRT on survival both before and after the propensity score matching (PSM). Then, we used the Cox hazard proportional model and competing risk model to identify the independent prognostic factors for LRT recipients. Based on the screened variables, a comprehensive nomogram was established. RESULTS: Kaplan-Meier curves demonstrated that LRT significantly prolonged overall survival (OS) and breast cancer-specific survival (BCSS) (P < 0.001). In addition, patients treated with surgery combined with postoperative radiotherapy (PORT) possessed the optimal survival (P < 0.001). Regardless of the surgical modalities, primary tumor resection combined with radiotherapy could ameliorate the prognosis (P < 0.05). Subgroup analysis showed that in patients with T2-T4 stage, PORT had a survival benefit compared with those undergoing surgery combined with preoperative radiotherapy (PRRT) and surgery only. Based on the screened independent prognostic factors, we established a comprehensive nomogram to forecast BCSD in 1 year, 2 years and 3 years, which showed robust predictive ability. CONCLUSION: PORT was associated with a lower BCSD in stage-IV BC patients. The practical nomogram could provide a precise prediction of BCSD for LRT recipients, which was meaningful for patients' individualized management.

6.
Ecotoxicol Environ Saf ; 249: 114376, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36508821

RESUMO

Cadmium (Cd) is a ubiquitous toxic metal and environmental pollutant. Increasing studies have shown that Cd exposure increases the incidence of various endocrine system diseases, including thyrotoxicity reflected by thyroid structural damage and endocrine toxicity. However, the observed outcomes are complex and conflicting, leading to the mechanism of Cd-induced thyrotoxicity remaining obscure. In this study, 4-week-old male C57BL/6 mice were given 2 or 7 mg/kg Cadmium Chloride (CdCl2) intragastrically for 4 and 8 weeks, and the Cd-mediated thyrotoxicity was evaluated by determining alterations in thyroid structure and endocrine function, and alterations of oxidant stress, apoptosis, and pyroptosis. Our data showed that Cd exposure could reduce body weight and induce thyrotoxicity by impairing thyroid follicular morphology and endocrine function, accompanied by elevated oxidative stress and apoptosis, macrophage infiltration, and inflammatory cytokine secretion. Importantly, Cd significantly promoted thyroid follicular cell pyroptosis by increasing Nlrp3, Asc, Caspase-1, Gsdmd, IL-1ß, and IL-18 expression. Mechanistical analysis suggested that Cd treatment could inhibit antioxidant pathway by downregulating antioxidant response protein, Nrf2, and upregulating its negative feedback regulator, Keap1. Collectively, our in vivo findings suggest that Cd exposure could facilitate thyroid follicular cell pyroptosis by inhibiting Nrf2/Keap1 signaling, thereby disrupting thyroid tissue structure and endocrine function, which offers novel insights into the Cd-mediated detrimental consequences on thyroid homeostasis.


Assuntos
Antioxidantes , Cádmio , Exposição Ambiental , Proteína 1 Associada a ECH Semelhante a Kelch , Fator 2 Relacionado a NF-E2 , Piroptose , Glândula Tireoide , Animais , Masculino , Camundongos , Antioxidantes/metabolismo , Cádmio/toxicidade , Proteína 1 Associada a ECH Semelhante a Kelch/antagonistas & inibidores , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Camundongos Endogâmicos C57BL , Fator 2 Relacionado a NF-E2/antagonistas & inibidores , Fator 2 Relacionado a NF-E2/metabolismo , Piroptose/efeitos dos fármacos , Glândula Tireoide/efeitos dos fármacos , Glândula Tireoide/patologia
7.
Front Oncol ; 12: 854284, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36185271

RESUMO

Background: Breast cancer is one of the most important diseases in women around the world. Glycosylation modification correlates with carcinogenesis and roles of glycogenes in the clinical outcome and immune microenvironment of breast cancer are unclear. Methods: A total of 1297 breast cancer and normal cases in the TCGA and GTEx databases were enrolled and the transcriptional and survival information were extracted to identify prognostic glycogenes using Univariate Cox, LASSO regression, Multivariate Cox analyses and Kaplan-Meier method. The immune infiltration pattern was explored by the single sample gene set enrichment method. The HLA and immune checkpoint genes expression were also compared in different risk groups. The expressions of a glycogene MGAT5 as well as its products were validated by immunohistochemistry and western blotting in breast cancer tissues and cells. Results: A 19-glycogene signature was identified to separate breast cancer patients into high- and low-risk groups with distinct overall survival rates (P < 0.001). Compared with the high-risk group, proportion of naive B cells, plasma cells and CD8+ T cells increased in the low-risk group (P < 0.001). Besides, expressions of HLA and checkpoint genes, such as CD274, CTLA4, LAG3 and TIGIT3, were upregulated in low-risk group. Additionally, highly expressed MGAT5 was validated in breast cancer tissues and cells. Downstream glycosylation products of MGAT5 were all increased in breast cancer. Conclusions: We identified a 19-glycogene signature for risk prediction of breast cancer patients. Patients in the low-risk group demonstrated a higher immune infiltration and better immunotherapy response. The validation of MGAT5 protein suggests a probable pathway and target for the development and treatment of breast cancer.

8.
Angew Chem Int Ed Engl ; 58(51): 18388-18393, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31692199

RESUMO

A surface digging effect of supported Ni NPs on an amorphous N-doped carbon is described, during which the surface-loaded Ni NPs would etch and sink into the underneath carbon support to prevent sintering. This process is driven by the strong coordination interaction between the surface Ni atoms and N-rich defects. In the aim of activation of C-H bonds for methane oxidation, those sinking Ni NPs could be further transformed into thermodynamically stable and active metal-defect sites within the as-generated surface holes by simply elevating the temperature. In situ transmission electron microscopy images reveal the sunk Ni NPs dig themselves adaptive surface holes, which would largely prevent the migration of Ni NPs without weakening their accessibility. The reported two-step strategy opens up a new route to manufacture sintering-resistant supported metal catalysts without degrading their catalytic efficiency.

9.
Nan Fang Yi Ke Da Xue Xue Bao ; 36(4): 506-13, 2016 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-27113178

RESUMO

OBJECTIVE: To explore whether MG-132 could enhance the anti-tumor activity of obatoclax against esophageal cancer cell line CaES-17. METHODS: MTT assay was used to determine the cytotoxicity of obatoclax and MG-132 in CaES-17 cells. The IC(50) of obatoclax and MG-132 were used to determine the molar ratio (1:2.4) of the two drugs for combined treatment of the cells. The concentrations of obatoclax and MG-132 ranged from 1/8 IC(50) to 4 IC(50) after serial dilution, and their combination index (CI) was calculated using CompuSyn software. The expression of ubiquitin and the cleavage of PARP, caspase-9, phospho-histone H3 and phospho-aurora A/B/C in the exposed cells were examined with Western blotting; the cell apoptosis was measured by flow cytometry with Annexin V staining, and the percentage of cells in each cell cycle phase was also determined by flow cytometry. RESULTS: The CI of obatoclax and MG-132 was 0.296 for a 50% inhibition of Caes-17 cells and was 0.104 for a 95% inhibition. The cells treated with obatoclax or MG-132 alone showed increased expression of ubiquitin and cleavage of PARP and caspase-9. Compared with the cells treated with obatoclax or MG-132 alone, the cells with a combined treatment exhibited significantly increased expression of ubiquitin, cleavage of PARP and caspase-9, and expression of phospho-Histone H3 (P<0.05). The combined treatment of the cells also resulted in significantly increased expression of phospho-Aurora A/B/C compared with obatoclax treatment alone. The cells with the combined treatment showed significantly higher percentages of apoptotic cells and cells in sub-G(1) and G(2)/M phases compared with the cells treated with either of the drugs (P<0.05). CONCLUSION: Obatoclax combined with MG-132 shows a significant synergistic anti-tumor effect against esophageal cancer CaES-17 cells by inducing apoptosis and cell cycle arrest.


Assuntos
Neoplasias Esofágicas/patologia , Leupeptinas/farmacologia , Pirróis/farmacologia , Apoptose , Caspase 9/metabolismo , Pontos de Checagem do Ciclo Celular , Linhagem Celular Tumoral/efeitos dos fármacos , Histonas/metabolismo , Humanos , Indóis , Poli(ADP-Ribose) Polimerase-1 , Poli(ADP-Ribose) Polimerases/metabolismo
10.
Oncotarget ; 7(12): 14693-707, 2016 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-26910910

RESUMO

Obatoclax, a pan-inhibitor of anti-apoptotic Bcl-2 proteins, exhibits cytotoxic effect on cancer cells through both apoptosis-dependent and -independent pathways. Here we show that obatoclax caused cytotoxicity in both cisplatin-sensitive and -resistant esophageal cancer cells. Although obatoclax showed differential apoptogenic effects in these cells, it consistently blocked autophagic flux, which was evidenced by concomitant accumulation of LC3-II and p62. Obatoclax was trapped in lysosomes and induced lysosome clustering. Obatoclax also substantially reduced the expression of lysosomal cathepsins B, D and L. Moreover, cathepsin knockdown was sufficient to induce cytotoxicity, connecting lysosomal function to cell viability. Consistent with the known function of autophagy, obatoclax caused the accumulation of polyubiquitinated proteins and showed synergy with proteasome inhibition. Taken together, our studies unveiled impaired lysosomal function as a novel mechanism whereby obatoclax mediates its cytotoxic effect in esophageal cancer cells.


Assuntos
Apoptose/efeitos dos fármacos , Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Neoplasias Esofágicas/patologia , Lisossomos/patologia , Pirróis/farmacologia , Antineoplásicos/farmacologia , Proteínas Reguladoras de Apoptose/metabolismo , Autofagia/efeitos dos fármacos , Catepsina B/metabolismo , Proliferação de Células/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias Esofágicas/metabolismo , Humanos , Indóis , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Células Tumorais Cultivadas
11.
Eur J Pharm Sci ; 81: 137-48, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26474693

RESUMO

It has been demonstrated that COX-2-selective inhibitor celecoxib shows synergy with oxaliplatin for suppressing tumor growth. However, the benefit of adding celecoxib to oxaliplatin-based regimen in human esophageal cancer is largely unknown. In the present study, we demonstrated that celecoxib antagonized oxaliplatin-induced cytotoxicity and apoptosis independent of COX-2 inhibition in human esophageal cancer cells. Celecoxib decreased cellular oxaliplatin accumulation and Pt-DNA adduction formation due to reduced drug influx. Celecoxib alone or combined with oxaliplatin substantially reduced the expression of organic cation transporter 2 (OCT2). To this end, OCT2 knockdown was sufficient to reduce oxaliplatin uptake, connecting OCT2 expression to oxaliplatin accumulation. Moreover, oxaliplatin combined with celecoxib also showed no beneficial effect when compared with monotherapy in esophageal cancer cell-xenografted nude mice. To conclude, our data provide evidence that the addition of celecoxib to oxaliplatin-containing regimens for patients with OCT2-expressing cancers should be cautious.


Assuntos
Antineoplásicos/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Celecoxib/farmacologia , Inibidores de Ciclo-Oxigenase 2/farmacologia , Neoplasias Esofágicas/metabolismo , Compostos Organoplatínicos/farmacologia , Animais , Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Apoptose/efeitos dos fármacos , Celecoxib/uso terapêutico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Inibidores de Ciclo-Oxigenase 2/uso terapêutico , Interações Medicamentosas , Neoplasias Esofágicas/tratamento farmacológico , Neoplasias Esofágicas/patologia , Feminino , Humanos , Camundongos Nus , Proteínas de Transporte de Cátions Orgânicos/genética , Proteínas de Transporte de Cátions Orgânicos/metabolismo , Transportador 2 de Cátion Orgânico , Compostos Organoplatínicos/uso terapêutico , Oxaliplatina , RNA Interferente Pequeno/genética , Carga Tumoral/efeitos dos fármacos
12.
Lab Invest ; 94(7): 777-87, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24840331

RESUMO

The breakdown of human retinal pigment epithelial (HRPE) barrier is considered as the etiology of retinopathy, which affects the quality of life of HIV/AIDS patients. Here we demonstrate that HIV-1 could directly impair HRPE barrier function, which leads to the translocation of HIV-1 and bacteria. HRPE cells (D407) were grown to form polarized, confluent monolayers and treated with different HIV-1 infectious clones. A significant increase of monolayer permeability, as measured by trans-epithelial electrical resistance (TEER) and apical-basolateral movements of sodium fluorescein, was observed. Disrupted tightness of HRPE barrier was associated with the downregulation of several tight junction proteins in D407 cells, including ZO-1, Occludin, Claudin-1, Claudin-2, Claudin-3, Claudin-4, and Claudin-5, after exposure to HIV-1, without affecting the viability of cells. HIV-1 gp120 was shown to participate in the alteration of barrier properties, as evidenced by decreased TEER and weakened expression of tight junction proteins in D407 monolayers after exposure to pseudotyped HIV-1, UV-inactivated HIV-1, and free gp120, but not to an envelope (Env)-defective mutant of HIV. Furthermore, exposure to HIV-1 particles could induce the release of pro-inflammatory cytokines in D407, including IL-6 and MCP-1, both of which downregulated the expression of ZO-1 in the HRPE barrier. Disrupted HRPE monolayer allowed translocation of HIV-1 and bacteria across the epithelium. Overall, these findings suggest that HIV-1 may exploit its Env glycoprotein to induce an inflammatory state in HRPE cells, which could result in impairment of HRPE monolayer integrity, allowing virus and bacteria existing in ocular fluids to cross the epithelium and penetrate the HRPE barrier. Our study highlights the role of HIV-1 in the pathogenesis of HIV/AIDS-related retinopathy and suggests potential therapeutic targets for this ocular complication.


Assuntos
Infecções por HIV/fisiopatologia , HIV-1/metabolismo , Doenças Retinianas/fisiopatologia , Epitélio Pigmentado da Retina/fisiopatologia , Translocação Bacteriana , Western Blotting , Linhagem Celular , Quimiocina CCL2/metabolismo , Células Epiteliais/metabolismo , Escherichia coli/metabolismo , Proteína gp120 do Envelope de HIV/genética , Proteína gp120 do Envelope de HIV/metabolismo , Infecções por HIV/metabolismo , Infecções por HIV/virologia , HIV-1/genética , HIV-1/fisiologia , Interações Hospedeiro-Patógeno , Humanos , Interleucina-6/metabolismo , Microscopia de Fluorescência , Mutação , Permeabilidade , Doenças Retinianas/metabolismo , Doenças Retinianas/virologia , Epitélio Pigmentado da Retina/patologia , Epitélio Pigmentado da Retina/virologia , Proteínas de Junções Íntimas/genética , Proteínas de Junções Íntimas/metabolismo , Junções Íntimas/metabolismo , Junções Íntimas/fisiologia
13.
Chin Med J (Engl) ; 125(6): 1068-75, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22613533

RESUMO

BACKGROUND: The rapidly activating delayed rectifier potassium current (I(Kr)), whose pore-forming alpha subunit is encoded by the human ether-a-go-go-related gene (hERG), is a key contributor to the third phase of action potential repolarization. The aim of this study was to investigate the effect and mechanism of arecoline hydrobromide induced inhibition of hERG K(+) current (I(hERG)). METHODS: Transient transfection of hERG channel cDNA plasmid pcDNA3.1 into the cultured HEK293 cells was performed using Lipofectamine. A standard whole-cell patch-clamp technique was used to record the I(hERG) before and after the exposure to arecoline. RESULTS: Arecoline decreased the amplitude and the density of the I(hERG) in a concentration-dependent manner (IC(50) = 9.55 mmol/L). At test potential of +60 mV, the magnitude of I(hERG) tail at test pulse of -40 mV was reduced from (151.7 ± 6.2) pA/pF to (84.4 ± 7.6) pA/pF (P < 0.01, n = 20) and the magnitude of I(hERG) tail at test pulse of -110 mV was reduced from (-187.5 ± 9.8) pA/pF to (-97.6 ± 12.6) pA/pF (P < 0.01, n = 20). The blockade of arecoline in the open and inactivated state was significant in a state-dependent manner. The maximal blockade was achieved in the inactivated state. Studies of gating mechanism showed that the steady-state activation curve of I(hERG) was significantly negatively shifted by arecoline. Time constants of activation were shortened. Steady-state inactivation curve and time constants of fast inactivation were not significantly affected by arecoline. Furthermore, the inhibition of I(hERG) by arecoline was characterized markedly by a frequency-dependent manner from 0.03 to 1.00 Hz pulse. CONCLUSION: Arecoline could potently block I(hERG) in both frequency and state-dependent manner.


Assuntos
Arecolina/farmacologia , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Potenciais de Ação/efeitos dos fármacos , Relação Dose-Resposta a Droga , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/fisiologia , Células HEK293 , Humanos
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