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INTRODUCTION: The aim of the study was to retrospectively identify the metastatic influence factors and predict the prognosis and develop an individualized prognostic prediction model for patients with N3-stage nasopharyngeal carcinoma (NPC). METHODS: The study collected 446 NPC patients with N3 stage from the Surveillance, Epidemiology, and End Results database between 2010 and 2015. The patients were classified into subgroups based on the histological types and metastatic status. Multivariable logistic, Cox regression, and Kaplan-Meier method with the log-rank test were performed. The nomogram model was created using the prognostic factors identified from Cox regression analysis. The predictive accuracy was determined based on the concordance index (c-index) and calibration curves. RESULTS: The 5-year overall survival (OS) of the NPC patients with N3 stage was 43.9%, and the prognosis of patients without any distant metastases was largely longer than that with metastases. No difference was observed between different pathological types in the entire cohort. However, patients with non-keratinized squamous cell carcinoma had a better OS than that of the patients with keratinized squamous cell carcinoma in a nonmetastatic subgroup. Using the Cox regression analysis results, the nomogram successfully classified these patients into low- and high-risk subgroups and presented the survival difference. The c-index of the nomogram for predicting the prognosis was satisfactory. CONCLUSION: This study identified metastatic risk factors and developed a convenient clinical tool for the prognosis of NPC patients. This tool can be used for individualized risk classification and decision-making regarding treatment of NPC patients with N3 stage.
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Carcinoma de Células Escamosas , Neoplasias Nasofaríngeas , Humanos , Nomogramas , Pronóstico , Carcinoma Nasofaríngeo/patología , Estadificación de Neoplasias , Estudios Retrospectivos , Carcinoma de Células Escamosas/patología , Neoplasias Nasofaríngeas/terapia , Neoplasias Nasofaríngeas/patologíaRESUMEN
The mammalian bromodomain and extra-terminal domain (BET) family of proteins consists of four conserved members (Brd2, Brd3, Brd4, and Brdt) that regulate numerous cancer-related and immunity-associated genes. They are epigenetic readers of histone acetylation with broad specificity. BET proteins are linked to cancer progression due to their interaction with numerous cellular proteins including chromatin-modifying factors, transcription factors, and histone modification enzymes. The spectacular growth in the clinical development of small-molecule BET inhibitors underscores the interest and importance of this protein family as an anticancer target. Current approaches targeting BET proteins for cancer therapy rely on acetylation mimics to block the bromodomains from binding chromatin. However, bromodomain-targeted agents are suffering from dose-limiting toxicities because of their effects on other bromodomain-containing proteins. In this review, we provided an updated summary about the evolution of small-molecule BET inhibitors. The design of bivalent BET inhibitors, kinase and BET dual inhibitors, BET protein proteolysis-targeting chimeras (PROTACs), and Brd4-selective inhibitors are discussed. The novel strategy of targeting the unique C-terminal extra-terminal (ET) domain of BET proteins and its therapeutic significance will also be highlighted. Apart from single agent treatment alone, BET inhibitors have also been combined with other chemotherapeutic modalities for cancer treatment demonstrating favorable clinical outcomes. The investigation of specific biomarkers for predicting the efficacy and resistance of BET inhibitors is needed to fully realize their therapeutic potential in the clinical setting.
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Antineoplásicos , Neoplasias , Animales , Humanos , Proteínas Nucleares/genética , Factores de Transcripción/metabolismo , Proteínas de Ciclo Celular/genética , Neoplasias/metabolismo , Antineoplásicos/farmacología , Cromatina , Mamíferos/metabolismoRESUMEN
Hepatocellular carcinoma (HCC) is the predominant type of liver cancer and a leading cause of cancer-related death globally. It is also a sexually dimorphic disease with a male predominance both in HCC and in its precursors, non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH). The role of the androgen receptor (AR) in HCC has been well documented; however, AR-targeted therapies have failed to demonstrate efficacy in HCC. Building upon understandings of AR in prostate cancer (PCa), this review examines the role of AR in HCC, non-androgen-mediated mechanisms of induced AR expression, the existence of AR splice variants (AR-SV) in HCC and concludes by surveying current AR-targeted therapeutic approaches in PCa that show potential for efficacy in HCC in light of AR-SV expression.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Enfermedad del Hígado Graso no Alcohólico , Masculino , Humanos , Femenino , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Receptores Androgénicos/genética , Receptores Androgénicos/metabolismo , Enfermedad del Hígado Graso no Alcohólico/patologíaRESUMEN
Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 is a novel and highly pathogenic coronavirus and is the causative agent of the coronavirus disease 2019 (COVID-19). The high morbidity and mortality associated with COVID-19 and the lack of an approved drug or vaccine for SARS-CoV-2 underscores the urgent need for developing effective antiviral therapies. Therapeutics that target essential viral proteins are effective at controlling virus replication and spread. Coronavirus Spike glycoproteins mediate viral entry and fusion with the host cell, and thus are essential for viral replication. To enter host cells, the Spike proteins of SARS-CoV-2 and related coronavirus, SARS-CoV, bind the host angiotensin-converting enzyme 2 (ACE2) receptor through their receptor binding domains (RBDs). Here, we rationally designed a panel of ACE2-derived peptides based on the RBD-ACE2 binding interfaces of SARS-CoV-2 and SARS-CoV. Using SARS-CoV-2 and SARS-CoV Spike-pseudotyped viruses, we found that a subset of peptides inhibits Spike-mediated infection with IC50 values in the low millimolar range. We identified two peptides that bound Spike RBD in affinity precipitation assays and inhibited infection with genuine SARS-CoV-2. Moreover, these peptides inhibited the replication of a common cold causing coronavirus, which also uses ACE2 as its entry receptor. Results from the infection experiments and modeling of the peptides with Spike RBD identified a 6-amino-acid (Glu37-Gln42) ACE2 motif that is important for SARS-CoV-2 inhibition. Our work demonstrates the feasibility of inhibiting SARS-CoV-2 with peptide-based inhibitors. These findings will allow for the successful development of engineered peptides and peptidomimetic-based compounds for the treatment of COVID-19.
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Enzima Convertidora de Angiotensina 2/química , Antivirales/farmacología , Diseño de Fármacos , Fragmentos de Péptidos/farmacología , SARS-CoV-2/efectos de los fármacos , Antivirales/metabolismo , Células HEK293 , Humanos , Simulación del Acoplamiento Molecular , Fragmentos de Péptidos/metabolismo , Conformación Proteica , SARS-CoV-2/metabolismo , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/metabolismoRESUMEN
An androgen receptor (AR) is an intensively studied treatment target for castration-resistant prostate cancer that is irresponsive to conventional antiandrogen therapeutics. Binding function 3 (BF3) inhibitors with alternative modes of action have emerged as a promising approach to overcoming antiandrogen resistance. However, how these BF3 inhibitors modulate AR function remains elusive, hindering the development of BF3-targeting agents. Here, we performed an integrated computational study to interrogate the binding mechanism of several known BF3 inhibitors with ARs. Our results show that the inhibitory effect of the BF3 antagonists arises from their allosteric modulation of the activation function (AF2) site, which alters the dynamic coupling between the BF3 and AF2 sites as well as the AF2-coactivator (SRC2-3) interaction. Moreover, the per-residue binding energy analyses reveal the "anchor" role of the linker connecting the phenyl ring and benzimidazole/indole in these BF3 inhibitors. Furthermore, the allosteric driver-interacting residues are found to include both "positive", e.g., Phe673 and Asn833, and "negative" ones, e.g., Phe826, and the differential interactions with these residues provide an explanation why stronger binding does not necessarily result in higher inhibitory activities. Finally, our allosteric communication pathway analyses delineate how the allosteric signals triggered by BF3 binding are propagated to the AF2 pocket through multiple short- and/or long-ranged transmission pathways. Collectively, our combined computational study provides a comprehensive structural mechanism underlying how the selected set of BF3 inhibitors modulate AR function, which will help guide future development of BF3 antagonists.
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Neoplasias de la Próstata , Receptores Androgénicos , Antagonistas de Andrógenos , Antagonistas de Receptores Androgénicos/farmacología , Sitios de Unión , Humanos , Masculino , Modelos MolecularesRESUMEN
GPR120 is an attractive target for the treatment of type 2 diabetes. In this study, a series of biphenyl derivatives were designed, synthesized by hybrid design. The selected compound 6a exhibited potent GPR120 agonist activity (EC50â¯=â¯93â¯nM) and high selectivity over GPR40. The results of oral glucose tolerance test (OGTT) demonstrated that 6a exhibited significant glucose-lowering effect in glucose-loaded ICR male mice. Analysis of the structure-activity relationship is also presented. Compound 6a deserves further biological evaluation and structural modifications.
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Compuestos de Bifenilo/farmacología , Descubrimiento de Drogas , Hipoglucemiantes/farmacología , Receptores Acoplados a Proteínas G/agonistas , Animales , Compuestos de Bifenilo/administración & dosificación , Compuestos de Bifenilo/química , Compuestos de Bifenilo/uso terapéutico , Glucemia/análisis , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Relación Dosis-Respuesta a Droga , Prueba de Tolerancia a la Glucosa , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/química , Hipoglucemiantes/uso terapéutico , Masculino , Ratones Endogámicos ICR , Relación Estructura-ActividadRESUMEN
Cu2O nanocubes with different size (ranging from 20 nm to 400 nm) were prepared by a seed-mediated method to systematically explore the strong size-dependent properties in photocatalytic degradation of methyl orange (MO). Cu2O nanotubes were characterized by TEM, XRD, UV-Vis measurements. The size-dependent photocatalytic efficiency of the Cu2O nanocubes was evaluated by degradation of methyl orange (MO) in water under visible light (λ > 420 nm) irradiation. Furthermore, the photocurrent, linear sweep voltammetry (LSV) and electrochemical impedance spectra (EIS) measurements were applied to elucidate the size-dependent properties of Cu2O nanocubes, which demonstrated that smaller Cu2O nanocubes with certain length (30 nm) showed higher current density, faster electron transfer and lower rate of charge recombination in their exposed (100) facet. Therefore, 30 nm Cu2O nanocubes showed stronger visible light absorption capacity and higher photocatalytic activity in MO degradation among a series of nanocubes (20, 30, 100, 130, 200 and 400 nm) and their corresponding photocatalytic activities decreased with increasing the particles sizes.
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The development of resistance to current standard-of-care treatments, such as androgen receptor (AR) targeting therapies, remains a major challenge in the management of advanced prostate cancer. There is an urgent need for therapeutic strategies targeting key resistance drivers, such as AR variants like AR-V7 and steroidogenic enzymes like AKR1C3, to improve outcomes for patients with advanced prostate cancer. Here, we designed, synthesized, and characterized a class of LX compounds targeting both AR/AR variants and AKR1C3. Molecular docking indicated that LX compounds bound to the AKR1C3 active sites. LX1 blocked AKR1C3 enzymatic activity, suppressing the conversion of androstenedione into testosterone. LX compounds also reduced AR/AR-V7 expression and downregulated their target genes. In vitro, LX1 inhibited the growth of prostate cancer cells resistant to antiandrogens, including enzalutamide, abiraterone, apalutamide, and darolutamide. Treatment with LX1 in vivo significantly decreased tumor growth, lowered serum PSA levels, and reduced intratumoral testosterone levels, without affecting mouse body weight. Furthermore, LX1 overcame resistance to enzalutamide treatment, and the combination of LX1 with enzalutamide further suppressed tumor growth. Collectively, the dual effect of LX1 in reducing intratumoral testosterone and AR signaling, along with its synergy with standard therapies in resistant models, underscores its potential as a valuable treatment option for advanced prostate cancer.
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The purpose of this study was to develop docetaxel-poly (lactide-co-glycolide) (PLGA) loaded nanoparticles by using nanoprecipitation method and optimize the relative parameters to obtain nanoparticles with higher encapsulation efficiency and smaller size. The physicochemical characteristics of nanoparticles were studied. The optimized parameters were as follows: the oil phase was mixture of acetone and ethanol, concentration of tocopheryl polyethylene glycol succinate (TPGS) was 0.2%, the ratio of oil phase to water phase was 1:5, and the theoretical drug concentration was 5%. The optimized nanoparticles were spherical with size between 130 and 150 nm. The encapsulation efficiency was (40.83±2.1)%. The in vitro release exhibited biphasic pattern. The results indicate that docetaxel-PLGA nanoparticles were successfully fabricated and may be used as the novel vehicles for docetaxel, which would replace Taxotere® and play great roles in future.
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Precipitación Fraccionada/métodos , Ácido Láctico/química , Nanopartículas/química , Nanotecnología/métodos , Ácido Poliglicólico/química , Taxoides/química , Acetona/química , Antineoplásicos/química , Antineoplásicos/farmacocinética , Cromatografía Líquida de Alta Presión , Docetaxel , Composición de Medicamentos/métodos , Etanol/química , Microscopía Electrónica de Rastreo , Nanopartículas/ultraestructura , Tamaño de la Partícula , Polietilenglicoles/química , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Succinatos/química , Propiedades de Superficie , Taxoides/farmacocinéticaRESUMEN
The paper is written to investigate the levels and significance of tumor markers [carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125), and carbohydrate antigen 19-9 (CA19-9)] and cytokines [interleukin-6 (IL-6), IL-4, and IL-2] in serum and peritoneal lavage fluid of patients with peritoneal metastasis of gastric cancer. For this research, 145 patients with gastric cancer treated in our hospital were divided into peritoneal metastasis group (n = 25), other metastasis group (n = 32), and nonmetastasis group (n = 88) according to the occurrence of metastasis. At the same time, the levels of serum tumor markers and cytokines and tumor markers and cytokines in intraoperative peritoneal lavage fluid were compared among the three groups. The results showed that the proportion of TNM stage III in peritoneal metastasis group and other metastasis group was 68.00% and 62.50%, respectively, and the proportion of tumor >5 cm was 64.00% and 59.38%, respectively, which was significantly higher than that in the control group. The 1-year survival rate of peritoneal metastasis group and other metastasis group was 44.00% and 40.63%, respectively, which was significantly lower than that of nonmetastasis group (P < 0.05).The serum levels of CEA, CA125, CA19-9, IL-6, IL-4, and IL-2 in peritoneal metastasis group and other metastasis group were higher than those in nonmetastasis group. The intraoperative peritoneal lavage fluid CEA, CA125, and IL-6 were 13.41 ± 3.72 ng/ml, 8.97 ± 1.33 U/ml, and 1.85 ± 0.44 pg/ml, respectively, which were higher than those in other metastasis groups and nonmetastasis groups (P < 0.05). There was no significant difference in the levels of CA19-9, IL-4, and IL-2 in peritoneal lavage fluid among peritoneal metastasis group, other metastasis groups, and nonmetastasis groups (P > 0.05); the areas under the ROC curve of intraoperative peritoneal lavage fluid CEA, CA125, and IL-6 in predicting peritoneal metastasis were 0.850, 0.902, and 0.806, respectively, P < 0.05. Thus, the conclusion is that peritoneal lavage fluid CEA, CA125, and IL-6 have certain application value in predicting and diagnosing peritoneal metastasis of gastric cancer, while the other indexes have no application value.
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Neoplasias Peritoneales , Neoplasias Gástricas , Biomarcadores de Tumor , Antígeno Ca-125 , Antígeno CA-19-9 , Carbohidratos , Antígeno Carcinoembrionario , Citocinas , Humanos , Interleucina-2 , Interleucina-4 , Interleucina-6 , Lavado Peritoneal , Pronóstico , Neoplasias Gástricas/patologíaRESUMEN
Background: Gastrointestinal stromal tumors (GIST) is the most common interstitial tumor of the digestive tract. GIST, like other malignancies, can recur, metastasize, and even metastasize to the brain, leading to death. Therefore, the prevention and treatment of GIST is very important. The clinical features of GIST are uniquely different to those of other common malignancies. Therefore, it is of great significance to explore the relationship between the pathological features and prognosis of GIST to strengthen the prevention and treatment of GIST. The objectives of this study were to study the clinical features of Ki67, Cluster Differentiation 34 (CD34), and their correlations in the Jianghuai region of China in recent years, and to analyze their relationship with prognosis. Methods: A total of 423 cases of GIST in Northern Jiangsu People's Hospital in Yangzhou from 2013 to 2020 were retrospectively analyzed. The data of CD34, Ki67 and layer of invasion was collected, and their associations with the clinical pathological characteristics, prognosis outcomes of GIST were studied. CD34 and Ki67 were tested by immunohistochemistry (IHC) And data was analyzed by chi-square test, t-test, Kaplan-Meier (KM) method survival curve, Log-rank test, and Cox regression. Results: The results showed that CD34 was associated with the clinical features of primary site, tumor size, risk, recurrence, and progression-free survival (PFS) (P<0.001, =0.01, <0.001, =0.039 and =0.018), but not with nuclear division or overall survival (OS) (P>0.05). Further, Ki67 was associated with nuclear division, tumor size, risk, recurrence, and PFS (P<0.001, <0.001, <0.001, <0.001 and <0.001), but there was no significant correlation with the primary site and CD34 (P>0.05), and Ki67 was associated with OS, but there was no statistical significance (P=0.0507). The layer of invasion was associated with the primary site, nuclear division, tumor size, risk, CD34, smooth muscle actin (SMA), recurrence, Ki67, and PFS (P<0.001, <0.001, <0.001, <0.001, <0.001, <0.001, <0.001, <0.001 and =0.0025), but not with OS (P=0.6680). Conclusions: CD34, Ki67, and layer of invasion may play important roles in the occurrence and development of GIST, affecting the prognosis of GIST.
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As a key regulator for hormone activity, human aldo-keto reductase family 1 member C3 (AKR1C3) plays crucial roles in the occurrence of various hormone-dependent or independent malignancies. It is a promising target for treating castration-resistant prostate cancer (CRPC). However, the development of AKR1C3 specific inhibitors remains challenging due to the high sequence similarity to its isoform AKR1C2. Here, we performed a combined in silico study to illuminate the inhibitory preference of 3-(3,4-dihydroisoquinolin-2(1H)-ylsulfonyl)benzoic acids for AKR1C3 over AKR1C2, of which compound 38 can achieve up to 5000-fold anti-AKR1C3 selectivity. Our umbrella sampling (US) simulations together with end-point binding free energy calculation MM/GBSA uncover that the high inhibition selectivity originates from the different binding modes, namely "Inward" and "Outward," of this compound series in AKR1C3 and AKR1C2, respectively. In AKR1C3/38, the tetrahydroquinoline moiety of 38 is accommodated inside the SP1 pocket and interacts favorably with surrounding residues, while, in AKR1C2/38, the SP1 pocket is too small to hold the bulky tetrahydroquinoline group that instead moves out of the pocket with 38 transitioning from an "Inward" to an "Outward" state. Further 3D-QSAR and energy decomposition analyses suggest that SP1 in AKR1C3 prefers to bind with a rigid bicyclic moiety and the modification of the R3 group has important implication for the compound's activity. This work is the first attempt to elucidate the selectivity mechanism of inhibitors toward AKR1C3 at the atomic level, which is anticipated to propel the development of next-generation AKR1C3 inhibitors with enhanced efficacy and reduced "off-target" effect for CRPC therapy.
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Hidroxiprostaglandina Deshidrogenasas , Neoplasias de la Próstata Resistentes a la Castración , Masculino , Humanos , Miembro C3 de la Familia 1 de las Aldo-Ceto Reductasas/metabolismo , Hidroxiprostaglandina Deshidrogenasas/metabolismo , 3-Hidroxiesteroide Deshidrogenasas/metabolismo , Benzoatos/química , Simulación por Computador , Isoformas de Proteínas , HormonasRESUMEN
The synthesis and the evaluation of the efficacy of a cycloruthenated complex, RuZ, is reported, to overcome multi-drug resistance (MDR) in cancer cells. RuZ can self-assemble into nanoaggregates in the cell culture medium, resulting in a high intracellular concentration of RuZ in MDR cancer cells. The self-assembly significantly decreases oxygen consumption and inhibits glycolysis, which decreases cellular adenosine triphosphate (ATP) levels. The decrease in ATP levels and its low affinity for the ABCB1 and ABCG2 transporters (which mediate MDR) significantly increase the retention of RuZ by MDR cancer cells. Furthermore, RuZ increases cellular oxidative stress, inducing DNA damage, and, in combination with the aforementioned effects of RuZ, increases the apoptosis of cancer cells. Proteomic profiling analysis suggests that the RuZ primarily decreases the expression of proteins that mediate glycolysis and aerobic mitochondrial respiration and increases the expression of proteins involved in apoptosis. RuZ inhibits the proliferation of 35 cancer cell lines, of which 7 cell lines are resistant to clinical drugs. It is also active in doxorubicin-resistant MDA-MB-231/Adr mouse tumor xenografts. To the best of our knowledge, the results are the first to show that self-assembled cycloruthenated complexes are efficacious in inhibiting the growth of MDR cancer cells.
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Antineoplásicos , Neoplasias , Transportador de Casetes de Unión a ATP, Subfamilia G, Miembro 2/metabolismo , Animales , Antineoplásicos/farmacología , Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Doxorrubicina/farmacología , Doxorrubicina/uso terapéutico , Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Humanos , Ratones , Neoplasias/tratamiento farmacológico , ProteómicaRESUMEN
The present study investigated the enhanced radiosensitivity of U-251 cells induced by sodium butyrate (NaB) and its possible mechanisms. Increased radiosensitivity of U251 cells was examined by clonogenic cell survival assays. The expression of Ku70 mRNA and protein was detected by using RT-PCR and Western blotting respectively. γ-H2AX foci were measured at different time points after ionizing irradiation alone or combined with NaB treatment. The results showed that cell survival rate was significantly reduced, both D0 and Dq values were decreased (D0: 1.43 Gy vs. 1.76 Gy; Dq: 1.22 Gy vs. 2.05 Gy) after the combined treatment as compared with irradiation alone, and sensitivity enhancing ratio (SER) reached 1.23. The average number of γ-H2AX foci per cell receiving the combined treatment was significantly increased at different time points, and the expression levels of Ku70 mRNA and protein were suppressed by NaB in a dose-dependent manner. It was concluded that enhanced radiosensitivity induced by NaB involves an inhibited expression of Ku70 and an increase in γ-H2AX foci, which suggests decreased ability in DSB repair.
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Antígenos Nucleares/metabolismo , Neoplasias Encefálicas , Butiratos/farmacología , Proteínas de Unión al ADN/metabolismo , Glioblastoma/metabolismo , Tolerancia a Radiación , Antígenos Nucleares/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Proteínas de Unión al ADN/genética , Glioblastoma/patología , Histonas/metabolismo , Humanos , Autoantígeno Ku , ARN Mensajero/genética , ARN Mensajero/metabolismoRESUMEN
The bromodomain and extra-terminal (BET) domain family of proteins, which include its prototypical member Brd4, is implicated in a variety of cancers and viral infections due to their interaction with cellular and viral proteins. BET proteins contain two bromodomains, a common protein motif that selectively binds acetylated lysine on histones. However, they are structurally distinct from other bromodomain-containing proteins because they encode a unique C-terminal extra-terminal (ET) domain that is important for the protein-protein interactions including jumonji C-domain-containing protein 6 (JMJD6) and histone-lysine N-methyltransferase NSD3 (NSD3). Brd4 functions primarily during transcription as a passive scaffold linking cellular and viral proteins to chromatin. The rapid development of clinical inhibitors targeting Brd4 highlights the importance of this protein as an anticancer target. Current therapeutic approaches focus on the development of small molecule acetylated lysine mimics of histone marks that block the ability of the bromodomains to bind their chromatin marks. Thus far, bromodomain-targeted agents have shown dose-limiting toxicities due to off-target effects on other bromodomain-containing proteins. Here, we exploited a viral-host protein interaction interface to design peptides for the disruption of BET protein function. A murine leukemia virus (MLV) integrase-derived peptide (ET binding motif, EBM) and its shorter minimal binding motif (pentapeptide LKIRL) were sufficient to directly bind the Brd4 ET domain and reduce cellular proliferation of an acute myeloid leukemia cell line. Using computational and biochemical approaches, we identified the minimal essential contacts between EBM and LKIRL peptides and the Brd4 ET domain. Our findings provide a structural foundation for inhibiting BET/Brd4-mediated cancers by targeting the ET domain with small peptide-based inhibitors.
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PURPOSE: The E3 ubiquitin ligase RNF8 regulates the accumulation or removal of a number of proteins at DNA lesions, thereby playing a critically important role in DNA damage response. The present study investigated the possibility of using RNF8 as a new target in the radiation treatment of human non-small cell lung cancer. METHODS AND MATERIALS: We used RNA interference technology to silence the expression of RNF8 in A549 cells, and then detected the radiation response by colony forming assays. DNA repair was monitored by γ-H2AX foci formation after RNF8 depletion. Expression of Ku70 and Rad51 were assessed by immunofluorescent staining and Western blotting. Cell cycle and apoptosis were measured by flow cytometry assays. RESULTS: After lentivirus-mediated siRNA transfection, expression of RNF8 in A549 cells downregulated which led to an increased radiosensitivity and impaired DNA repair. RNF8 knockdown did not affect Ku70 expression, however, Rad51, a key player in homologous recombination (HR) repair, was abrogated at sites of DNA damage. Furthermore, we observed an extended G2/M arrest and an increased induction of apoptosis after ionizing radiation in the absence of RNF8. CONCLUSIONS: RNF8 silencing effectively downregulates Rad51 therefore maybe impairing HR repair, and prolongs the G2/M accumulation as well as cell apoptosis upon radiation, which all suggest an enhanced radiosensitivity on A549 cells.