RESUMEN
PURPOSE: Both IDH1-mutated and wild-type gliomas abundantly display aberrant CpG island hypermethylation. However, the potential role of hypermethylation in promoting gliomas, especially the most aggressive form, glioblastoma (GBM), remains poorly understood. METHODS: We analyzed RRBS-generated methylation profiles for 11 IDH1WT gliomas (including 7 GBMs), 24 IDH1MUT gliomas (including 6 GBMs), and 5 normal brain samples and employed TCGA GBM methylation profiles as a validation set. Upon classification of differentially methylated CpG islands by IDH1 status, we used integrated analysis of methylation and gene expression to identify SPINT2 as a top cancer related gene. To explore functional consequences of SPINT2 methylation in GBM, we validated SPINT2 methylation status using targeted bisulfite sequencing in a large cohort of GBM samples. We assessed DNA methylation-mediated SPINT2 gene regulation using 5-aza-2'-deoxycytidine treatment, DNMT1 knockdown and luciferase reporter assays. We conducted functional analyses of SPINT2 in GBM cell lines in vitro and in vivo. RESULTS: We identified SPINT2 as a candidate tumor-suppressor gene within a group of CpG islands (designated GT-CMG) that are hypermethylated in both IDH1MUT and IDH1WT gliomas but not in normal brain. We established that SPINT2 downregulation results from promoter hypermethylation, and that restoration of SPINT2 expression reduces c-Met activation and tumorigenic properties of GBM cells. CONCLUSIONS: We defined a previously under-recognized group of coordinately methylated CpG islands common to both IDH1WT and IDH1MUT gliomas (GT-CMG). Within GT-CMG, we identified SPINT2 as a top cancer-related candidate and demonstrated that SPINT2 suppressed GBM via down-regulation of c-Met activation.
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Metilación de ADN , Regulación Neoplásica de la Expresión Génica , Glioblastoma/prevención & control , Isocitrato Deshidrogenasa/genética , Glicoproteínas de Membrana/genética , Mutación , Proteínas Proto-Oncogénicas c-met/metabolismo , Animales , Apoptosis , Proliferación Celular , Islas de CpG , Glioblastoma/genética , Glioblastoma/patología , Humanos , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos NOD , Ratones SCID , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-met/genética , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
PURPOSE: IDH1/2-mutant gliomas harbor a distinct glioma-CpG island methylation phenotype (G-CIMP) that may promote the initiation and progression of secondary pathway gliomas by silencing tumor-suppressive genes. The potential role of tumor-suppressive microRNAs (miRNA; miR) in this process is not understood. EXPERIMENTAL DESIGN: To identify potential tumor-suppressive miRNA hypermethylated in glioma, the methylation profiles of IDH1/2(WT) gliomas (n = 11) and IDH1(MUT) glioma (n = 20) were compared by using massively parallel reduced representation bisulfite sequencing (RRBS). The methylation status of selected miRNA was validated by using targeted bisulfite sequencing (BiSEQ) in a large cohort of glioma tissue samples including 219 IDH1(WT) and 72 IDH1/2(MUT) samples. The expression of selected miRNAs was determined by using the TaqMan qPCR. Functional analyses of miR148a were conducted and target genes were identified. RESULTS: We identify miR148a as a novel, G-CIMP-associated miRNA whose methylation is tightly correlated with IDH1 mutation and associated with improved survival in patients with malignant glioma. We confirm that downregulation of miR148a can occur via DNA methylation. We demonstrate that IDH1 mutation provides a mechanism of miR148a methylation and downregulation, and that restoration of miR148a reduced tumorigenic properties of glioma cells, possibly by targeting DNMT1. CONCLUSIONS: We identify miR148a as a novel G-CIMP-associated miRNA, and provide results suggesting that miR148a restoration may have therapeutic implications.
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Neoplasias Encefálicas/genética , Islas de CpG , Metilación de ADN , Silenciador del Gen , Glioma/genética , Isocitrato Deshidrogenasa/genética , MicroARNs/genética , Mutación , Animales , Antineoplásicos/farmacología , Neoplasias Encefálicas/mortalidad , Neoplasias Encefálicas/patología , Línea Celular Tumoral , Análisis por Conglomerados , Estudios de Cohortes , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Glioma/mortalidad , Glioma/patología , Xenoinjertos , Humanos , Pronóstico , Carga Tumoral/efectos de los fármacos , Carga Tumoral/genéticaRESUMEN
BACKGROUND: The optimal timing to initiate bevacizumab (BV) therapy for recurrent glioblastoma (GBM) is currently unclear. To address this issue, we examined progression-free survival (PFS) and survival time (ST) in a large retrospective cohort of GBM patients treated with BV at different recurrences. METHODS: We identified 468 primary GBM patients who underwent biopsy or surgery followed by radiation therapy and temozolomide (RT/TMZ), and then received BV. PFS and ST were compared between patients stratified by the recurrence that BV was initiated (upfront, first recurrence, second recurrence, or 3+ recurrences). We also examined the effect on PFS and ST of the addition of chemotherapy to BV. In a larger cohort of GBM patients, we determined overall treatment continuation rates at each recurrence and identified variables predictive of inability to continue treatment. RESULTS: BV PFS was similar for all 3 recurrence groups (median, 4.1 months). There were no differences in BV ST (median, 9.8 months). The addition of chemotherapy to BV improved PFS but not ST. Analysis of treatment continuation rates indicated that the number of patients unable to undergo further treatments is modest, and that patients unable to tolerate BV delay can be identified by age ≥60 years and low extent of resection. CONCLUSIONS: Deferred use of bevacizumab is not associated with diminished efficacy. Analysis of treatment continuation rates identified patients who may be unable to delay BV therapy. Our findings suggest that there is a fixed survival after BV initiation and that delayed BV treatment is preferable for most patients.
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Inhibidores de la Angiogénesis/uso terapéutico , Anticuerpos Monoclonales Humanizados/uso terapéutico , Neoplasias Encefálicas/tratamiento farmacológico , Glioblastoma/tratamiento farmacológico , Recurrencia Local de Neoplasia/tratamiento farmacológico , Adulto , Anciano , Inhibidores de la Angiogénesis/administración & dosificación , Anticuerpos Monoclonales Humanizados/administración & dosificación , Bevacizumab , Estudios de Cohortes , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
BACKGROUND: Promoter methylation of the DNA repair gene, O-6-methylguanine-DNA methyltransferase (MGMT), is associated with improved treatment outcome for newly diagnosed glioblastoma (GBM) treated with standard chemoradiation. To determine the prognostic significance of MGMT protein expression as assessed by immunohistochemistry (IHC) and its relationship with methylation, we analyzed MGMT expression and promoter methylation with survival in a retrospective patient cohort. METHODS: We identified 418 patients with newly diagnosed GBM at University of California Los Angeles Kaiser Permanente Los Angeles, nearly all of whom received chemoradiation, and determined MGMT expression by IHC, and MGMT promoter methylation by methylation-specific PCR (MSP) and bisulfite sequencing (BiSEQ) of 24 neighboring CpG sites. RESULTS: With use of the median percentage of cells staining by IHC as the threshold, patients with <30% staining had progression-free survival (PFS) of 10.9 months and overall survival (OS) of 20.5 months, compared with PFS of 7.8 months (P < .0001) and OS of 16.7 months (P < .0001) among patients with ≥30% staining. Inter- and intrareader correlation of IHC staining was high. Promoter methylation status by MSP was correlated with IHC staining. However, low IHC staining was frequently observed in the absence of promoter methylation. Increased methylation density determined by BiSEQ correlated with both decreased IHC staining and increased survival, providing a practical semiquantitative alternative to MSP. On the basis of multivariate analysis validated by bootstrap analysis, patients with tandem promoter methylation and low expression demonstrated improved OS and PFS, compared with the other combinations. CONCLUSIONS: Optimal assessment of MGMT status as a prognostic biomarker for patients with newly diagnosed GBM treated with chemoradiation requires determination of both promoter methylation and IHC protein expression.
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Neoplasias Encefálicas/mortalidad , Metilación de ADN , Metilasas de Modificación del ADN/genética , Metilasas de Modificación del ADN/metabolismo , Enzimas Reparadoras del ADN/genética , Enzimas Reparadoras del ADN/metabolismo , Glioblastoma/mortalidad , Regiones Promotoras Genéticas/genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Adulto , Antineoplásicos Alquilantes/uso terapéutico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Quimioradioterapia , ADN de Neoplasias/genética , Dacarbazina/análogos & derivados , Dacarbazina/uso terapéutico , Femenino , Estudios de Seguimiento , Glioblastoma/genética , Glioblastoma/terapia , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Reacción en Cadena de la Polimerasa , Pronóstico , Estudios Retrospectivos , Tasa de Supervivencia , TemozolomidaRESUMEN
Mutations in isocitrate dehydrogenase 1 (IDH1) or 2 (IDH2) are found in a subset of gliomas. Among the many phenotypic differences between mutant and wild-type IDH1/2 gliomas, the most salient is that IDH1/2 mutant glioma patients demonstrate markedly improved survival compared with IDH1/2 wild-type glioma patients. To address the mechanism underlying the superior clinical outcome of IDH1/2 mutant glioma patients, we investigated whether overexpression of the IDH1(R132H) protein could affect response to therapy in the context of an isogenic glioma cell background. Stable clonal U87MG and U373MG cell lines overexpressing IDH1(WT) and IDH1(R132H) were generated, as well as U87MG cell lines overexpressing IDH2(WT) and IDH2(R172K). In vitro experiments were conducted to characterize baseline growth and migration and response to radiation and temozolomide. In addition, reactive oxygen species (ROS) levels were measured under various conditions. U87MG-IDH1(R132H) cells, U373MG-IDH1(R132H) cells, and U87MG-IDH2(R172K) cells demonstrated increased sensitivity to radiation but not to temozolomide. Radiosensitization of U87MG-IDH1(R132H) cells was accompanied by increased apoptosis and accentuated ROS generation, and this effect was abrogated by the presence of the ROS scavenger N-acetyl-cysteine. Interestingly, U87MG-IDH1(R132H) cells also displayed decreased growth at higher cell density and in soft agar, as well as decreased migration. Overexpression of IDH1(R132H) and IDH2(R172K) mutant protein in glioblastoma cells resulted in increased radiation sensitivity and altered ROS metabolism and suppression of growth and migration in vitro. These findings provide insight into possible mechanisms contributing to the improved outcomes observed in patients with IDH1/2 mutant gliomas.
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Neoplasias Encefálicas/radioterapia , Glioma/radioterapia , Isocitrato Deshidrogenasa/genética , Proteínas Mutantes/genética , Mutación/genética , Tolerancia a Radiación/genética , Antineoplásicos Alquilantes/farmacología , Apoptosis , Western Blotting , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Adhesión Celular , Movimiento Celular , Proliferación Celular , Dacarbazina/análogos & derivados , Dacarbazina/farmacología , Radiación Electromagnética , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Regulación Neoplásica de la Expresión Génica/efectos de la radiación , Glioma/tratamiento farmacológico , Glioma/metabolismo , Glioma/patología , Humanos , Isocitrato Deshidrogenasa/metabolismo , Proteínas Mutantes/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Temozolomida , Células Tumorales CultivadasRESUMEN
BACKGROUND: Mutations in isocitrate dehydrogenase 1 (IDH1) and associated CpG island hypermethylation represent early events in the development of low-grade gliomas and secondary glioblastomas. To identify candidate tumor suppressor genes whose promoter methylation may contribute to gliomagenesis, we compared methylation profiles of IDH1 mutant (MUT) and IDH1 wild-type (WT) tumors using massively parallel reduced representation bisulfite sequencing. METHODS: Reduced representation bisulfite sequencing was performed on ten pathologically matched WT and MUT glioma samples and compared with data from a methylation-sensitive restriction enzyme technique and data from The Cancer Genome Atlas (TCGA). Methylation in the gene retinol-binding protein 1 (RBP1) was identified in IDH1 mutant tumors and further analyzed with primer-based bisulfite sequencing. Correlation between IDH1/IDH2 mutation status and RBP1 methylation was evaluated with Spearman correlation. Survival data were collected retrospectively and analyzed with Kaplan-Meier and Cox proportional hazards analysis. All statistical tests were two-sided. RESULTS: Methylome analysis identified coordinated CpG island hypermethylation in IDH1 MUT gliomas, consistent with previous reports. RBP1, important in retinoic acid metabolism, was found to be hypermethylated in 76 of 79 IDH1 MUT, 3 of 3 IDH2 MUT, and 0 of 116 IDH1/IDH2 WT tumors. IDH1/IDH2 mutation was highly correlated with RBP1 hypermethylation (n = 198; Spearman R = 0.94, 95% confidence interval = 0.92 to 0.95, P < .001). The Cancer Genome Atlas showed IDH1 MUT tumors (n = 23) to be RBP1-hypermethylated with decreased RBP1 expression compared with WT tumors (n = 124). Among patients with primary glioblastoma, patients with RBP1-unmethylated tumors (n = 102) had decreased median overall survival compared with patients with RBP1-methylated tumors (n = 22) (20.3 months vs 36.8 months, respectively; hazard ratio of death = 2.48, 95% confidence interval = 1.30 to 4.75, P = .006). CONCLUSION: RBP1 promoter hypermethylation is found in nearly all IDH1 and IDH2 mutant gliomas and is associated with improved patient survival. Because RBP1 is involved in retinoic acid synthesis, our results suggest that dysregulation of retinoic acid metabolism may contribute to glioma formation along the IDH1/IDH2-mutant pathway.
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Biomarcadores de Tumor/genética , Neoplasias Encefálicas/genética , Metilación de ADN , Glioma/genética , Isocitrato Deshidrogenasa/genética , Mutación , Proteínas Celulares de Unión al Retinol/genética , Adulto , Anciano , Western Blotting , Neoplasias Encefálicas/química , Islas de CpG/genética , Análisis Mutacional de ADN/métodos , Femenino , Perfilación de la Expresión Génica , Glioma/química , Humanos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Regiones Promotoras Genéticas/genética , Modelos de Riesgos Proporcionales , Reacción en Cadena en Tiempo Real de la Polimerasa , Mapeo Restrictivo , Proteínas Celulares de Unión al Retinol/análisis , Estudios Retrospectivos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Sulfitos/metabolismo , Tretinoina/metabolismoRESUMEN
Mutations of the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are commonly found in primary brain cancers. We previously reported that a novel enzymatic activity of these mutations results in the production of the putative oncometabolite, R(-)-2-hydroxyglutarate (2-HG). Here we investigated the ability of magnetic resonance spectroscopy (MRS) to detect 2-HG production in order to non-invasively identify patients with IDH1 mutant brain tumors. Patients with intrinsic glial brain tumors (n = 27) underwent structural and spectroscopic magnetic resonance imaging prior to surgery. 2-HG levels from MRS data were quantified using LC-Model software, based upon a simulated spectrum obtained from a GAMMA library added to the existing prior knowledge database. The resected tumors were then analyzed for IDH1 mutational status by genomic DNA sequencing, Ki-67 proliferation index by immunohistochemistry, and concentrations of 2-HG and other metabolites by liquid chromatography-mass spectrometry (LC-MS). MRS detected elevated 2-HG levels in gliomas with IDH1 mutations compared to those with wild-type IDH1 (P = 0.003). The 2-HG levels measured in vivo with MRS were significantly correlated with those measured ex vivo from the corresponding tumor samples using LC-MS (r (2) = 0.56; P = 0.0001). Compared with wild-type tumors, those with IDH1 mutations had elevated choline (P = 0.01) and decreased glutathione (P = 0.03) on MRS. Among the IDH1 mutated gliomas, quantitative 2-HG values were correlated with the Ki-67 proliferation index of the tumors (r ( 2 ) = 0.59; P = 0.026). In conclusion, water-suppressed proton ((1)H) MRS provides a non-invasive measure of 2-HG in gliomas, and may serve as a potential biomarker for patients with IDH1 mutant brain tumors. In addition to 2-HG, alterations in several other metabolites measured by MRS correlate with IDH1 mutation status.
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Biomarcadores de Tumor/metabolismo , Glioma/genética , Glioma/metabolismo , Glutaratos/metabolismo , Isocitrato Deshidrogenasa/genética , Espectroscopía de Resonancia Magnética , Mutación/genética , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Cromatografía Liquida , ADN de Neoplasias/genética , Femenino , Estudios de Seguimiento , Glioma/patología , Humanos , Imagen por Resonancia Magnética , Masculino , Espectrometría de Masas , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Pronóstico , Estudios Prospectivos , Adulto JovenRESUMEN
BACKGROUND: Post-transplantation primary central nervous system lymphoma (PT-PCNSL) is a rare neoplasm that can develop within months to years after transplantation, and imaging often reveals multiple lesions with homogeneous or ring enhancement. The clinical and imaging presentation of PT-PCNSL can often be nonspecific and present a diagnostic challenge. CASE DESCRIPTION: A 56-year-old woman presented to a tertiary university emergency room with altered mental status 15 months after undergoing renal transplantation. On brain MRI, she was found to have three rim-enhancing mass lesions, and biopsy revealed PT-PCNSL. CONCLUSION: There has been a steady increase in the number of patients living following organ transplantation in the United States and an increasing likelihood that PT-PCNSL will increasingly be encountered in neurosurgical practice. We present here a case of PT-PCNSL and a brief review of the relevant clinical characteristics, treatment options, and prognosis of PT-PCNSL.
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The etiology of Parkinson's disease is unclear but appears to involve mitochondrial dysfunction, proteasome inhibition, and environmental toxins. It has been shown that pesticides, including the complex I inhibitor rotenone, cause proteasome inhibition but the mechanism of rotenone-induced proteasome dysfunction remains largely unknown. In this study, we examined the role of mitochondrial inhibition, oxidative stress, and microtubule dysfunction as potential mediators of rotenone-induced proteasome inhibition. Proteasome activity (26S) was measured in HEK and SK-N-MC cells expressing an EGFP-U degron fusion protein that is selectively degraded by the proteasome. We found that complexes I and III inhibition led to the production of peroxides and decreased proteasome activity. We also found that rotenone increased nitric oxide production and nitric oxide and peroxynitrites led to proteasome inhibition. The effects of rotenone were attenuated by anti-oxidants and nitric oxide synthase inhibition. Since rotenone can also inhibit microtubule assembly, we tested a specific MT inhibitor and found it led to proteasome dysfunction. Rotenone also led to a decrease in 20S proteasome activity and 20S proteasome subunit immunoreactivity without a change in subunit mRNA. Together, these data suggest that rotenone-induced decreases in proteasome activity are due to increased degradation of proteasome components secondary to oxidative damage and possibly microtubule dysfunction.
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Proteínas del Complejo de Cadena de Transporte de Electrón/antagonistas & inhibidores , Insecticidas/farmacología , Inhibidores de Proteasoma , Rotenona/farmacología , Antioxidantes/farmacología , Línea Celular , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Humanos , Microtúbulos/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Estrés Oxidativo/efectos de los fármacos , Complejo de la Endopetidasa Proteasomal/metabolismo , Especies de Nitrógeno Reactivo/metabolismoRESUMEN
Genome wide methylation profiling of gliomas is likely to provide important clues to improving treatment outcomes. Restriction enzyme based approaches have been widely utilized for methylation profiling of cancer genomes and will continue to have importance in combination with higher density microarrays. With the availability of the human genome sequence and microarray probe sequences, these approaches can be readily characterized and optimized via in silico modeling. We adapted the previously described HpaII/MspI based Methylation Sensitive Restriction Enzyme (MSRE) assay for use with two-color Agilent 244K CpG island microarrays. In this assay, fragmented genomic DNA is digested in separate reactions with isoschizomeric HpaII (methylation-sensitive) and MspI (methylation-insensitive) restriction enzymes. Using in silico hybridization, we found that genomic fragmentation with BfaI was superior to MseI, providing a maximum effective coverage of 22,362 CpG islands in the human genome. In addition, we confirmed the presence of an internal control group of fragments lacking HpaII/MspI sites which enable separation of methylated and unmethylated fragments. We used this method on genomic DNA isolated from normal brain, U87MG cells, and a glioblastoma patient tumor sample and confirmed selected differentially methylated CpG islands using bisulfite sequencing. Along with additional validation points, we performed a receiver operating characteristics (ROC) analysis to determine the optimal threshold (p = 0.001). Based on this threshold, we identified approximately 2,400 CpG islands common to all three samples and 145 CpG islands unique to glioblastoma. These data provide general guidance to individuals seeking to maximize effective coverage using restriction enzyme based methylation profiling approaches.
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The etiology of Parkinson disease (PD) is unclear but may involve environmental toxins such as pesticides leading to dysfunction of the ubiquitin proteasome system (UPS). Here, we measured the relative toxicity of ziram (a UPS inhibitor) and analogs to dopaminergic neurons and examined the mechanism of cell death. UPS (26 S) activity was measured in cell lines after exposure to ziram and related compounds. Dimethyl- and diethyldithiocarbamates including ziram were potent UPS inhibitors. Primary ventral mesencephalic cultures were exposed to ziram, and cell toxicity was assessed by staining for tyrosine hydroxylase (TH) and NeuN antigen. Ziram caused a preferential damage to TH+ neurons and elevated alpha-synuclein levels but did not increase aggregate formation. Mechanistically, ziram altered UPS function through interfering with the targeting of substrates by inhibiting ubiquitin E1 ligase. Sodium dimethyldithiocarbamate administered to mice for 2 weeks resulted in persistent motor deficits and a mild reduction in striatal TH staining but no nigral cell loss. These results demonstrate that ziram causes selective dopaminergic cell damage in vitro by inhibiting an important degradative pathway implicated in the etiology of PD. Chronic exposure to widely used dithiocarbamate fungicides may contribute to the development of PD, and elucidation of its mechanism would identify a new potential therapeutic target.
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Dopamina/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Ziram/farmacología , Animales , Dimetilditiocarbamato/farmacología , Inhibidores Enzimáticos/farmacología , Fungicidas Industriales/farmacología , Humanos , Masculino , Ratones , Neuronas/metabolismo , Enfermedad de Parkinson , Ratas , Tirosina 3-Monooxigenasa/farmacologíaRESUMEN
A good understanding about the structure and function of the envelope glycoprotein (Env) from primary human immunodeficiency virus-1 (HIV-1) isolates is important in facilitating the development of effective neutralizing antibody responses as a component of an effective HIV-1 vaccine. In the current study, the antigenicity of a panel of diverse HIV-1 primary Env from different clades of HIV-1 Group M was analyzed using rabbit sera produced by either 3- or 9-valent gp120 DNA vaccine formulations. Both the 3- and 9-valent gp120 DNA vaccine formulations elicited HIV-1 gp120-specific antibodies in immunized rabbits. However, we observed two levels of primary envelope antigenicity to the same set of rabbit immune sera and that the level of glycosylation, particularly in the V1 loop, may contribute to such diversity. Bioinformatics analysis on the distribution and average number of the N-linked glycosylation sites in all variable regions (V1-V5) was conducted. A linear plot demonstrated that the average number of potential N-glycosylation sites in the V1 and V4 loops correlates to the size of the loop. These data provide further evidence on the complexity of primary HIV-1 Env antigens and offers new insight into the mechanisms that HIV-1 uses to escape protective immune responses.
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Vacunas contra el SIDA/inmunología , Anticuerpos Anti-VIH/sangre , Antígenos VIH/inmunología , Proteína gp120 de Envoltorio del VIH/química , VIH-1/inmunología , Fragmentos de Péptidos/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/inmunología , Vacunas contra el SIDA/administración & dosificación , Secuencia de Aminoácidos , Animales , Variación Antigénica , Femenino , Glicosilación , Antígenos VIH/química , Antígenos VIH/genética , Antígenos VIH/metabolismo , Proteína gp120 de Envoltorio del VIH/genética , Proteína gp120 de Envoltorio del VIH/metabolismo , Infecciones por VIH/inmunología , Infecciones por VIH/prevención & control , Infecciones por VIH/virología , VIH-1/clasificación , VIH-1/aislamiento & purificación , Humanos , Masculino , Datos de Secuencia Molecular , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Conejos , Relación Estructura-Actividad , Vacunas de ADN/administración & dosificación , Vacunas de ADN/inmunología , Productos del Gen env del Virus de la Inmunodeficiencia Humana/química , Productos del Gen env del Virus de la Inmunodeficiencia Humana/genética , Productos del Gen env del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
Epidemiological studies have suggested a correlation of pesticides and Parkinson's disease (PD) while genetic and biochemical studies have implicated the ubiquitin-proteasome system (UPS) in the pathogenesis of PD. In the present studies, we tested the hypothesis that pesticide exposure increases the risk of developing PD by inhibiting the UPS. The effects of pesticides on proteasome activity were examined in SK-N-MC neuroblastoma cells overexpressing a GFP-conjugated proteasome degradation signal, GFP(u). Six out of 25 representative pesticides, including rotenone, ziram, diethyldithiocarbamate, endosulfan, benomyl, and dieldrin, showed inhibitory effects on proteasome activities at low concentrations (10 nM to 10 microM). Unlike proteasome inhibitors, they did not inhibit 20 S proteasome activities in cell lysates. Except for rotenone, the other five pesticides did not induce significantly cellular oxidative stress. The cytotoxic effects of these pesticides were closely correlated with proteasome inhibition. Our results suggest proteasome inhibition as a potential mechanism for the epidemiological association of pesticides and PD.