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Objective: To investigate the middle ear function of the patients with cleft palate pre and post palatoplasty. Methods: 76 patients with cleft palate were investigated by clinical history and audiology examinations including electric otoscopy,tympanometry and click-ABR threshold. Results: The risk for middle ear function decreased with advancing age in the first 5 years. It was noticed that the otologic outcomes was related to the CP type. During long time follow-up, the frequency with the middle ear function disorder was always high within the CP patients but the proportion of the patients received tympanostomy tubes was low relatively. The prevalence of middle ear dysfunction did not differ with the time of cleft palate repair. Conclusion: The patients with cleft palate have middle ear function dysfunction in a long period of time,therefore a standard long-time follow-up system is necessary.
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Fisura del Paladar , Otitis Media con Derrame , Pruebas de Impedancia Acústica , Preescolar , Fisura del Paladar/cirugía , Oído Medio , Humanos , Ventilación del Oído Medio , Otitis Media con Derrame/etiología , Otitis Media con Derrame/cirugíaRESUMEN
Objective:The cochlea of children with congenital sensorineural hearing loss with normal inner ear structure was measured and analyzed by high-resolution temporal bone CT(HRCT) imaging technique,its application value before cochlear implantation was evaluated and the appropriate electrode was selected.Method:We collected temporal bone HRCT images of 120 patients with congenital sensorineural hearing loss,according to gender divided into two groups,including 60 males and 60 females.We used the PACS software to measure the distance A(the largest distance from the round window to the lateral wall) and the distance H(height of the cochlea) and calculate the cochlear duct length. Reproducibility of these data were evaluated and the results between the different groups were compared.Result:Measurement of parameter values between the intraobserver and interobserver showed great reproducibility. In the male children group,the measured values are shown as distance Aï¼»(8.55±0.31)mmï¼½,distance Hï¼»(4.57±0.28)mmï¼½and the cochlear duct length(CDL)ï¼»(27.59±1.23)mmï¼½; and in the female children group, the measured values are shown as distance Aï¼»(8.45±0.32)mmï¼½,distance Hï¼»(4.42±0.34)mmï¼½and the cochlear duct length(CDL)ï¼»(27.20±1.17)mm.The A,H,and CDL of the male cochlea were greater than those of the female, the difference was statistically significant(P<0.05).Conclusion:Measuring the distance A and distance H of the cochlea and calculating the cochlear duct length CDL can be used to select a suitable length of electrode or to customize a personalized electrode. This is a simple and effective assessment method before cochlear implantation..
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BACKGROUND: It has been suggested that the p300 transcriptional coactivator participates in the regulation of a wide range of cell biological processes, and mutations in p300 have been identified in various cancers. OBJECTIVES: To investigate p300 expression in cutaneous squamous cell carcinoma (cSCC) tissues and its effect on the outcome of patients with cSCC. METHODS: Immunohistochemistry (IHC) was performed on a tissue microarray to investigate p300 expression levels in cSCC tissues. Receiver operating characteristic (ROC) curve analysis, Kaplan-Meier plots and a Cox proportional hazards regression model were used to analyse the data. RESULTS: Based on the ROC curves, we defined the cut-off score for high p300 expression as > 55% of tumour cells positively stained. High expression of p300 was observed in 86 of 165 (52·1%) of the cSCC samples and six of 30 (20%) of the adjacent normal skin tissue samples (P < 0·001). High expression of p300 was positively correlated with lymph node metastasis (P = 0·006) and advanced clinical stage (P < 0·001). In univariate survival analysis, high expression of p300 was correlated with poor patient outcomes in terms of recurrence-free survival (P = 0·006) and overall survival (P < 0·001). Moreover, p300 expression was evaluated as an independent prognostic factor in a multivariate analysis (P = 0·004). CONCLUSIONS: Our results indicate that high p300 expression is associated with aggressive features of cSCC and suggest that p300 expression, as examined by IHC, will be a promising biomarker for predicting clinical outcomes in patients with cSCC.
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Biomarcadores de Tumor/metabolismo , Proteína p300 Asociada a E1A/metabolismo , Neoplasias de Cabeza y Cuello/mortalidad , Neoplasias Cutáneas/mortalidad , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/mortalidad , Carcinoma de Células Escamosas/patología , Métodos Epidemiológicos , Femenino , Neoplasias de Cabeza y Cuello/metabolismo , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Pronóstico , Neoplasias Cutáneas/metabolismo , Neoplasias Cutáneas/patología , Análisis de Matrices Tisulares , Carga TumoralRESUMEN
Dicer is crucial for the maturation of microRNAs (miRNAs) and its dysregulation may contribute to tumor initiation and progression. The study explored the clinical implications of Dicer and its post-transcriptional regulation by microRNAs in cervical cancer. qRT-PCR and immunohistochemistry investigated Dicer mRNA and protein levels in cervical cancer tissues. The relationship between Dicer expression and survival was analyzed. MiRNA target prediction identified miRNAs that might target Dicer. Luciferase reporter and gain- or loss-of-function assays were performed. The results showed that 36.7% of cervical cancer cases showed low expression of Dicer mRNA and 63.3% cases showed high expression. At the protein level, 51% cases showed negative expression and 49% cases showed positive expression. Dicer mRNA and protein expressions were significantly associated with distant metastasis and recurrence in cervical cancer (P=0.002 and P=0.012, respectively). Multivariate Cox analysis indicated that low Dicer expression (P=0.016) and tumor stage (P=0.047) were independent predictors. Among the miRNAs predicted to target Dicer, 10 were detected by RT-PCR; their expressions were significantly higher in cervical cancers with lower Dicer expression than in those with higher Dicer expression and were negatively correlated with Dicer expression level (P<0.05). In vitro experiments demonstrated that miR-130a directly targeted Dicer mRNA to enhance migration and invasion in SiHa cells. Finally, survival analysis indicated that higher expression of miR-130a was significantly associated with poor disease-free survival. Taken together, Dicer expression regulated by miR-130a is an important potential prognostic factor in cervical cancer.
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ARN Helicasas DEAD-box/genética , Regulación Neoplásica de la Expresión Génica , MicroARNs/metabolismo , Ribonucleasa III/genética , Neoplasias del Cuello Uterino/genética , Adulto , Secuencia de Bases , Línea Celular Tumoral , Movimiento Celular/genética , Análisis por Conglomerados , ARN Helicasas DEAD-box/metabolismo , Supervivencia sin Enfermedad , Femenino , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , MicroARNs/genética , Datos de Secuencia Molecular , Invasividad Neoplásica , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/patología , Estadificación de Neoplasias , Pronóstico , Modelos de Riesgos Proporcionales , ARN Mensajero/genética , ARN Mensajero/metabolismo , Curva ROC , Ribonucleasa III/metabolismo , Neoplasias del Cuello Uterino/patologíaRESUMEN
Previously, we found that sperm-associated antigen 5 (SPAG5) was upregulated in pelvic lymph node metastasis-positive cervical cancer. The aim of this study is to examine the role of SPAG5 in the proliferation and tumorigenicity of cervical cancer and its clinical significance in tumor progression. In our study, SPAG5 expression in cervical cancer patients was detected using quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry; cervical cancer cell function with downregulated SPAG5 in vitro was explored using tetrazolium assay, flow cytometry, and colony formation and Transwell assays. SPAG5 was upregulated in tumor tissue compared with paired adjacent noncancerous tissues; SPAG5 upregulation in tumor tissues indicated poor disease-free survival, which was also an independent prognostic indicator for cervical cancer patients. In vitro study demonstrated that SPAG5 downregulation inhibited cell proliferation and growth significantly by G2/M arrest and induction of apoptosis, and hindered cell migration and invasion. Under SPAG5 downregulation, the sensitivity of cervical cancer cells differed according to taxol dose, which correlated with mammalian target of rapamycin (mTOR) signaling pathway activity. In general, SPAG5 upregulation relates to poor prognosis in cervical cancer patients, and SPAG5 is a regulator of mTOR activity during taxol treatment in cervical cancer.
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Antineoplásicos/farmacología , Proteínas de Ciclo Celular/metabolismo , Paclitaxel/farmacología , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/metabolismo , Neoplasias del Cuello Uterino/enzimología , Apoptosis/efectos de los fármacos , Proteínas de Ciclo Celular/genética , Movimiento Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Supervivencia sin Enfermedad , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos , Femenino , Puntos de Control de la Fase G2 del Ciclo Celular/efectos de los fármacos , Células HEK293 , Células HeLa , Humanos , Estimación de Kaplan-Meier , Invasividad Neoplásica , Interferencia de ARN , Factores de Riesgo , Factores de Tiempo , Transfección , Regulación hacia Arriba , Neoplasias del Cuello Uterino/genética , Neoplasias del Cuello Uterino/mortalidad , Neoplasias del Cuello Uterino/patologíaRESUMEN
BACKGROUND: We aim to develop effective models for predicting postoperative distant metastasis for oesophageal squamous cell carcinoma (OSCC) for the purpose of guiding tailored therapy. METHODS: We used data from two centres to establish training (n=319) and validation (n=164) cohorts. All patients underwent curative surgical treatment. The clinicopathological features and 23 immunomarkers detected by immunohistochemistry were involved for variable selection. We constructed eight support vector machine (SVM)-based nomograms (SVM1-SVM4 and SVM1'-SVM4'). The nomogram constructed with the training cohort was tested further with the validation cohort. RESULTS: The outcome of the SVM1 model in predicting postoperative distant metastasis was as follows: sensitivity, 44.7%; specificity, 90.9%; positive predictive value, 81.0%; negative predictive value, 65.6%; and overall accuracy, 69.5%. The corresponding outcome of the SVM2 model was as follows: 44.7%, 92.1%, 82.9%, 65.9%, and 70.1%, respectively. The corresponding outcome of the SVM3 model was as follows: 55.3%, 93.2%, 87.5%, 70.7%, and 75.6%, respectively. The SVM4 model was the most effective nomogram in prediction, and the corresponding outcome was as follows: 56.6%, 97.7%, 95.6%, 72.3%, and 78.7%, respectively.Similar results were observed in SVM1', SVM2', SVM3', and SVM4', respectively. CONCLUSION: The SVM-based models integrating clinicopathological features and molecular markers as variables are helpful in selecting the patients of OSCC with high risk of postoperative distant metastasis.
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Carcinoma de Células Escamosas/patología , Neoplasias Esofágicas/patología , Metástasis de la Neoplasia , Nomogramas , Máquina de Vectores de Soporte , Biomarcadores de Tumor , Carcinoma de Células Escamosas/cirugía , Neoplasias Esofágicas/cirugía , Carcinoma de Células Escamosas de Esófago , Femenino , Humanos , Metástasis Linfática , Masculino , Persona de Mediana EdadRESUMEN
Karyopherin alpha 2 (KPNA2), a member of the karyopherin family, has a central role in nucleocytoplasmic transport and is overexpressed in many cancers. Our previous study identified KPNA2 as significantly upregulated in epithelial ovarian carcinoma (EOC), correlating with poor survival of patients. However, the precise mechanism of this effect remains unclear. The aim of the present study was to examine the role of KPNA2 in the proliferation and tumorigenicity of EOC cells, and its clinical significance in tumor progression. Real-time quantitative RT-PCR analysis revealed high expression levels of KPNA2 in 162 out of 191 (84.8%) fresh EOC tissues, which was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage, differentiation, histological type, recurrence, and prognosis of EOC patients. Our results showed that upregulation of KPNA2 expression significantly increased the proliferation and tumorigenicity of EOC cells (EFO-21 and SK-OV3) in vitro and in vivo, by promoting cell growth rate, foci formation, soft agar colony formation, and tumor formation in nude mice. By contrast, knockdown of KPNA2 effectively suppressed the proliferation and tumorigenicity of these EOC cells in vitro and in vivo. Our results also indicated that the molecular mechanisms of the effect of KPNA2 in EOC included promotion of G1/S cell cycle transition through upregulation of c-Myc, enhanced transcriptional activity of c-Myc, activation of Akt activity, suppression of FOXO3a activity, downregulation of cyclin-dependent kinase (CDK) inhibitor p21Cip1 and p27Kip1, and upregulation of CDK regulator cyclin D1. Our results show that KPNA2 has an important role in promoting proliferation and tumorigenicity of EOC, and may represent a novel prognostic biomarker and therapeutic target for this disease.
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Proliferación Celular , Factores de Transcripción Forkhead/metabolismo , Neoplasias Glandulares y Epiteliales/metabolismo , Neoplasias Ováricas/metabolismo , Proteínas Proto-Oncogénicas c-myc/metabolismo , alfa Carioferinas/fisiología , Animales , Carcinoma Epitelial de Ovario , Línea Celular Tumoral , Factor de Transcripción E2F1/metabolismo , Femenino , Proteína Forkhead Box O3 , Factores de Transcripción Forkhead/genética , Puntos de Control de la Fase G1 del Ciclo Celular , Humanos , Estimación de Kaplan-Meier , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Persona de Mediana Edad , Análisis Multivariante , Trasplante de Neoplasias , Neoplasias Glandulares y Epiteliales/mortalidad , Neoplasias Glandulares y Epiteliales/patología , Neoplasias Ováricas/mortalidad , Neoplasias Ováricas/patología , Pronóstico , Transporte de Proteínas , Proteínas Proto-Oncogénicas c-myc/genética , Transcripción Genética , Carga Tumoral , Regulación hacia ArribaRESUMEN
PURPOSE: To investigate the correlation between p300 (a transcriptional co-activator) expression and clinical/prognostic characteristics in surgically resected NSCLC patients for the purpose of identifying patients with increased risk of cancer recurrence and providing them with tailored therapy. METHODS: One hundred and sixty-nine completely resected NSCLC patients were included in this study. Paraffin-embedded primary tumour tissues of patients were supplied to produce a tissue microarray, and immunohistochemistry was used for the evaluation of p300 expression. The clinical/prognostic significance of p300 expression was analysed for statistical significance. Survival was calculated by the Kaplan-Meier method, and the log-rank test was used to assess differences in survival between the groups. The prognostic impact of clinicopathologic variables and p300 expression was evaluated using a Cox proportional hazards model. RESULTS: High expression of p300 was associated with poor disease-free survival (p = 0.027) and overall survival (p = 0.006) in NSCLC patients. Further analysis suggested that this difference in overall survival also existed in patients with T2 (p = 0.040), positive lymph nodes (p = 0.023), stage IIIA (p = 0.003), adenocarcinoma (p = 0.021), and a well-differentiated histological grade score (p = 0.011). The multivariate Cox regression analysis showed that low p300 expression is an independent marker of better disease-free survival (relative risk = 0.628, p = 0.047) and overall survival (relative risk = 0.545, p = 0.024) in operable NSCLC patients. CONCLUSIONS: Low p300 expression is an independent prognostic marker of better survival in operable NSCLC patients. The combination of clinicopathological TNM staging classification with p300 expression may be useful in identifying patients with increased risk of cancer recurrence to provide them with tailored therapy.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biomarcadores de Tumor/análisis , Carcinoma de Pulmón de Células no Pequeñas/química , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Proteína p300 Asociada a E1A/análisis , Neoplasias Pulmonares/química , Neoplasias Pulmonares/mortalidad , Adulto , Anciano , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/secundario , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Quimioterapia Adyuvante , Supervivencia sin Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/cirugía , Masculino , Persona de Mediana Edad , Análisis Multivariante , Estadificación de Neoplasias , Compuestos de Platino/administración & dosificación , Valor Predictivo de las Pruebas , Pronóstico , Modelos de Riesgos Proporcionales , Análisis por Matrices de Proteínas , Recurrencia , Estudios Retrospectivos , Medición de Riesgo , Factores de Riesgo , Regulación hacia ArribaRESUMEN
OBJECTIVE: This study aimed to quantify intratumoural viable tissue perfusion with contrast-enhanced greyscale ultrasound to evaluate tumour response to anti-angiogenic treatment. METHODS: H22 hepatoma-bearing mice were treated with low-dose thalidomide (Group B), high-dose thalidomide (Group C) or 0.5% carboxylmethylcellulose (Group A). Contrast-enhanced greyscale ultrasound was performed after 7 days of treatments to evaluate the percentage of non-enhanced area for each tumour; regions of interest within the enhanced area were analysed offline to determine the area under the curve (AUC), maximum intensity (IMAX), perfusion index (PI), mean transit time (MTT), time to peak (TTP) and quality of fit (QOF). Immunohistochemical analysis was performed for evaluation of microvascular density (MVD). RESULTS: The percentage of non-enhanced area was significantly larger in Group C than in Groups A and B (p<0.05); however, there was no significant difference between Groups A and B. Treatment with thalidomide resulted in a significant decrease in AUC, PI and IMAX compared with Group A (p<0.05). Immunohistochemistry showed significant decreases in MVD in Groups B and C compared with Group A (p<0.05); however, there was no significant difference in MVD between Groups B and C. MVD was positively correlated with IMAX (r = 0.419, p = 0.023) and PI (r = 0.455, p = 0.013). CONCLUSION: Quantitatively analysing intratumoural viable tissue perfusion enables early evaluation of tumour response to anti-angiogenic therapy before apparent changes in tumour necrosis.
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Inhibidores de la Angiogénesis/administración & dosificación , Carcinoma Hepatocelular/diagnóstico por imagen , Neoplasias Hepáticas Experimentales/diagnóstico por imagen , Talidomida/administración & dosificación , Animales , Carcinoma Hepatocelular/tratamiento farmacológico , Carcinoma Hepatocelular/patología , Medios de Contraste , Relación Dosis-Respuesta a Droga , Inmunohistoquímica , Neoplasias Hepáticas Experimentales/tratamiento farmacológico , Neoplasias Hepáticas Experimentales/patología , Ratones , UltrasonografíaRESUMEN
ARHI is a maternally imprinted tumor suppressor gene whose expression is markedly downregulated in breast cancer. Reactivation of ARHI expression in breast cancer cells is associated with increased histone H3 acetylation and decreased lysine 9 methylation of histone H3. An ARHI promoter segment that spanned bases -420 to +58 (designated the P2 region) exhibits significantly higher promoter activity in normal cells than in cancer cells. To better understand the molecular mechanisms contributing to this differential transcriptional activity, we sought to identify transcription factors that bind to the P2 region of the ARHI promoter and regulate its activity. Sequence analysis and oligonucleotide competition in electrophoretic mobility shift assays identified an A2 fragment containing an E2F-binding site. Using specific antibodies in supershift assays, we have shown that anti-E2F1 and 4 antibodies can supershift the A2-protein complexes, whereas anti-E2F2 and 6 antibodies cannot, demonstrating that the A2 fragment interacts with specific members of the E2F family proteins. When compared with normal breast epithelial cells, breast cancer cells have significantly elevated expression of E2F1, 4 and increased E2F DNA-binding activity. Moreover, chromatin immunoprecipitation experiments revealed that both E2F1 and 4 bind to the ARHI promoter in breast cancer cells in vivo. This binding was reduced when the cells were treated with the histone deacetylase (HDAC) inhibitor--trichostatin A (TSA). When SKBr3 cells were cotransfected with an ARHI/luciferase reporter and E2F-expression vectors, E2F1 and 4 reduced ARHI promoter activity 2-3-fold, and this reduction could be reversed by TSA treatment. The negative regulation by E2F-HDAC complexes could also be reduced by small interfering RNA of E2F1 and 4. While the retinoblastoma protein, pRB, alone had no effect on ARHI promoter activity, repression by E2F1, but not E2F4, was enhanced by the coexpression of pRB. Taken together, our results suggest that E2F1, 4 and their complexes with HDAC play an important role in downregulating the expression of the tumor suppressor gene ARHI in breast cancer cells.
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Neoplasias de la Mama/genética , Factor de Transcripción E2F1/metabolismo , Factor de Transcripción E2F4/metabolismo , Regulación de la Expresión Génica/genética , Histona Desacetilasas/metabolismo , Proteínas de Unión al GTP rho/genética , Acetilación , Sitios de Unión , Neoplasias Óseas/genética , Neoplasias Óseas/metabolismo , Neoplasias Óseas/patología , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Núcleo Celular/metabolismo , Células Cultivadas , Inmunoprecipitación de Cromatina , Factor de Transcripción E2F1/antagonistas & inhibidores , Factor de Transcripción E2F1/genética , Factor de Transcripción E2F2/antagonistas & inhibidores , Factor de Transcripción E2F2/genética , Factor de Transcripción E2F2/metabolismo , Factor de Transcripción E2F4/antagonistas & inhibidores , Factor de Transcripción E2F4/genética , Factor de Transcripción E2F6/antagonistas & inhibidores , Factor de Transcripción E2F6/genética , Factor de Transcripción E2F6/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Inhibidores Enzimáticos/farmacología , Células Epiteliales/citología , Células Epiteliales/metabolismo , Femenino , Genes Supresores de Tumor , Inhibidores de Histona Desacetilasas , Histonas/metabolismo , Humanos , Ácidos Hidroxámicos/farmacología , Luciferasas/metabolismo , Glándulas Mamarias Humanas/citología , Glándulas Mamarias Humanas/metabolismo , Osteosarcoma/genética , Osteosarcoma/metabolismo , Osteosarcoma/patología , Regiones Promotoras Genéticas/genética , ARN Interferente Pequeño/farmacología , Elementos de Respuesta , Proteína de Retinoblastoma/metabolismo , Proteínas de Unión al GTP rho/metabolismoRESUMEN
We have recently identified a maternally imprinted tumor suppressor gene, ARHI (aplysia ras homolog I), the expression of which is lost in ovarian and breast cancers. We have now characterized the genomic structure of the gene including its promoter and the methylation status of its upstream CpG islands. The ARHI gene spans approximately 8 kb containing two exons and one intron. Exon 1 contains 81 non-translated nucleotides, connected to exon 2 with a 3.2-kb intron. The entire protein-coding region is located within exon 2 and encodes a 229-residue small GTP-binding protein belonging to the Ras superfamily. Genomic structure analysis has identified three potential CpG islands. Two of them (CpG island I and II) are located within the promoter and adjacent exon 1 of the ARHI gene. Aberrant methylation of these CpG islands has been detected in breast cancer cells but not in normal epithelial cells, supporting the possibility that appropriate methylation status of the CpG islands in the promoter region may play a role in the downregulation of ARHI gene expression. A TATA box is found 27 bp upstream of the transcription start site associated with several putative transcription factor binding sites. Transient transfection with nested deletion constructs of the 2-kb ARHI promoter regions fused to a luciferase reporter indicated a 121-bp sequence upstream of the transcription initiation site is required for basal promoter activity. Interestingly, this is the region where lower promoter activity has been observed in cancer cells than in normal cells.
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Genes Supresores de Tumor , Impresión Genómica , Inhibidores de Crecimiento/genética , Regiones Promotoras Genéticas , Proteínas de Unión al GTP rho , Secuencia de Aminoácidos , Secuencia de Bases , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Islas de CpG , ADN Complementario , Exones , Femenino , Humanos , Intrones , Datos de Secuencia Molecular , Neoplasias Ováricas/genética , Neoplasias Ováricas/patología , Células Tumorales CultivadasRESUMEN
Transmembrane signaling via receptor tyrosine kinases generally requires oligomerization of receptor monomers, with the formation of ligand-induced dimers or higher multimers of the extracellular domains of the receptors. Such formations are expected to juxtapose the intracellular kinase domains at the correct distances and orientations for transphosphorylation. For receptors of the insulin receptor family that are constitutively dimeric, or those that form noncovalent dimers without ligands, the mechanism must be more complex. For these, the conformation must be changed by the ligand from one that prevents activation to one that is permissive for kinase phosphorylation. How the insulin ligand accomplishes this action has remained a puzzle since the discovery of the insulin receptor over 2 decades ago, primarily because membrane proteins in general have been refractory to structure determination by crystallography. However, high-resolution structural evidence on individual separate subdomains of the insulin receptor and of analogous proteins has been obtained. The recently solved quaternary structure of the complete dimeric insulin receptor in the presence of insulin has now served as the structural envelope into which such individual domains were fitted. The combined structure has provided answers on the details of insulin/receptor interactions in the binding site and on the mechanism of transmembrane signaling of this covalent dimer. The structure explains many observations on the behavior of the receptor, from greater or lesser binding of insulin and its variants, point and deletion mutants of the receptor, to antibody-binding patterns, and to the effects on basal and insulin-stimulated autophosphorylation under mild reducing conditions.
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Comunicación Celular/fisiología , Insulina/química , Insulina/metabolismo , Receptor de Insulina/química , Receptor de Insulina/fisiología , Transducción de Señal , Membrana Celular/química , Membrana Celular/fisiología , Humanos , Modelos Biológicos , Modelos MolecularesRESUMEN
ARHI is a novel imprinted tumor suppressor gene. To study its function in vivo, we have developed transgenic mice that overexpress ARHI. Offspring bearing the transgene had significantly lower body weights than did nontransgenic littermates. In addition, strong expression of the ARHI transgene was associated with greatly impaired mammary gland development and lactation, failure of ovarian folliculogenesis resulting in decreased fertility, loss of neurons in the cerebellar cortex, and impaired development of the thymus. Decrease in body size and defects in the mammary glands correlated with the level of transgene expression. Immunohistochemical analysis indicated that expression of prolactin (PRL), but not growth hormone, was lower in the pituitary glands of mice with defective mammary gland development. The defect in pregnancy-associated mammary tissue proliferation was associated with decreased serum PRL and progesterone levels. Moreover, lower levels of estrogen receptor and progesterone receptor were observed in postpartum mammary glands and in the ovaries of mice that overexpressed ARHI. Our data suggest that ARHI can inhibit PRL secretion and act as a negative regulator in murine growth and development.
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Genes Supresores de Tumor/fisiología , Inhibidores de Crecimiento/genética , Trastornos de la Lactancia/genética , Glándulas Mamarias Animales/fisiología , Proteínas de Unión al GTP rho , Animales , Peso Corporal/genética , Citomegalovirus/genética , Estradiol/sangre , Femenino , Expresión Génica , Hormona del Crecimiento/sangre , Inhibidores de Crecimiento/biosíntesis , Inhibidores de Crecimiento/fisiología , Masculino , Glándulas Mamarias Animales/crecimiento & desarrollo , Glándulas Mamarias Animales/metabolismo , Ratones , Ratones Endogámicos ICR , Ratones Transgénicos , Ovario/crecimiento & desarrollo , Ovario/fisiología , Fenotipo , Periodo Posparto , Embarazo , Progesterona/sangre , Prolactina/sangre , Prolactina/metabolismo , Regiones Promotoras Genéticas , Receptores de Estrógenos/metabolismo , Receptores de Progesterona/metabolismoRESUMEN
The three-dimensional (3D) structure of the intrinsically dimeric insulin receptor bound to its ligand, insulin, was determined by electron cryomicroscopy. Gold-labeled insulin served to locate the insulin-binding domain. The 3D structure was then fitted with available known high-resolution domain substructures to obtain a detailed contiguous model for this heterotetrameric transmembrane receptor. The 3D reconstruction indicates that the two alpha subunits jointly participate in insulin binding and that the kinase domains in the two beta subunits are in a juxtaposition that permits autophosphorylation of tyrosine residues in the first step of insulin receptor activation.