RESUMEN

Reactive oxygen species (ROS) and free radicals, which have been implicated in inflammation, pain, carcinogenesis, and aging, are actually used in dental treatments such as tooth bleaching and composite resin polymerization. Recently, numerous studies have investigated the application of ROS in the medical and dental fields. In previous studies, ROS were generated intentionally through pathways such as photolysis, photocatalytic methods, and photodynamic therapy, which are used in the medical field to target cancer. In the field of dentistry, generated ROS are applied mainly for periodontal treatment and sterilization of the root canal, and its effectiveness as an antibacterial photodynamic therapy has been widely reported.. Given this background, the present article aimed to review the basic effects of ROS in dental medicine, especially endodontic therapy, and to discuss future applications of ROS.

RESUMEN

PURPOSE: Implant component fractures are one of the most serious complications in implant treatment. With a better understanding of the risk factors for fracture in the preoperative, surgery, superstructure, and post-loading phases of implant treatment, low-risk treatment could reduce implant component fractures, leading to a better prognosis. The aim of this study was to clarify the risk factors for abutment and implant fractures that occur after loading, and to perform a retrospective, approximately 10-year follow-up study to explore the risk factors in each treatment phase. METHODS: Subjects were fitted with an implant prosthesis between January 2008 and December 2009. In total, 1,126 Ankylos implants in 430 patients were included for analysis. Binary logistic regression analysis was performed to extract factors related to non-fracture and fracture of the abutment or implant as a dependent variable. RESULTS: Gender (OR = 3.466, 95% CI 1.296-9.268, P = 0.013), gonial angle (OR = 3.420, 95% CI 1.308-8.945, P = 0.012), and splinting status of the superstructure (OR = 4.456, 95% CI 1.861-10.669, P = 0.001) were identified as significant risk factors. CONCLUSION: The risk of fracture is increased in males, especially those with a mandibular angle of less than 120° on panoramic radiographs, and those with a non-splinted superstructure.

Asunto(s)

Implantes Dentales , Implantes Dentales/efectos adversos , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración Dental , Estudios de Seguimiento , Humanos , Masculino , Mandíbula , Estudios Retrospectivos , Factores de Riesgo

RESUMEN

Exposure to endocrine-disrupting chemicals may adversely affect animals, particularly during development. Tris(1,3-dichloroisopropyl) phosphate (TDCIPP) is an organophosphate with anti-androgen function in vitro that is present in indoor dust at relatively high concentrations. In male rats, androgens are necessary for the development of reproductive organs, as well as the endocrine and central nervous systems. However, we currently do not know the exact effects of TDCIPP exposure through suckling on subsequent reproductive behavior in males. Here, we show that TDCIPP exposure (25-250 mg kg-1 via oral administration over 28 consecutive days post-birth) suppressed male sexual behavior and reduced testes size. These changes were dose-dependent and appeared first in adults rather than in juveniles. These results demonstrate that TDCIPP exposure led to normal body growth and appearance in juveniles, but disrupted the endocrine system and physiology in adults. Therefore, assays should be performed using adult animals to ensure accuracy, and to confirm the influence of chemical substances given during early mammalian life.

Asunto(s)

Disruptores Endocrinos/toxicidad , Conducta Sexual Animal/efectos de los fármacos , Animales , Relación Dosis-Respuesta a Droga , Masculino , Ratas , Ratas Wistar , Testosterona/sangre

RESUMEN

Correct perinatal oestrogen levels are critical for sexual differentiation. For example, perinatal exposure to oestrogen causes masculinization and defeminization of the brain in female rats and also induces delayed effects after maturation characterized by early onset of abnormal oestrus cycling. However, the mechanisms underlying the above effects of oestrogen remain to be fully determined. 17α-ethinyloestradiol (EE), a common synthetic oestrogen widely used in oral contraceptives, binds specifically to oestrogen receptors. In this study, we demonstrated the effects of a single neonatal injection of high- or low-dose EE on reproductive behaviours. Female rats within 24 h after birth were subcutaneously injected with sesame oil, EE (0.02, 2 mg kg-1 ) and 17ß-oestradiol (E2 ) (20 mg kg-1 ). Between 11 and 15 weeks of age, sexual behaviour was tested twice in a paced mating situation. Latency to enter, lordosis and soliciting behaviour were recorded. Both high-dose EE- and E2 -treated females showed a significantly lower lordosis quotient, decreased soliciting behaviours, increased rejection and fighting numbers. Accessibility to males was also delayed by neonatal E2 exposure, although it was shortened by high-dose EE exposure. In contrast, low-dose EE-treated females did not exhibit impaired sexual behaviour. These results suggest that single neonatal exposure to a high dose of EE or E2 disturbs the normal development of the female brain, resulting in impaired sexual behaviours in a female-paced mating situation. Besides, the differences noted between high-dose EE- and E2 -treated females might be caused by different affinities of the oestrogen receptors, metabolic rates or mechanisms of action. Copyright © 2017 John Wiley & Sons, Ltd.

Asunto(s)

Estrógenos/toxicidad , Etinilestradiol/toxicidad , Conducta Sexual Animal/efectos de los fármacos , Animales , Animales Recién Nacidos , Anticonceptivos Orales , Relación Dosis-Respuesta a Droga , Estrógenos/administración & dosificación , Etinilestradiol/administración & dosificación , Femenino , Inyecciones Subcutáneas , Masculino , Ratas Wistar

RESUMEN

Although perinatal exposure of female rats to estrogenic compounds produces irreversible changes in brain function, it is still unclear how the amount and timing of exposure to those substances affect learning function, or if exposure alters estrogen receptor α (ERα) expression in the hippocampus and cortex. In adult female rats, we investigated the effects of neonatal exposure to a model estrogenic compound, ethinyl estradiol (EE), on passive avoidance learning and ERα expression. Female Wistar-Imamichi rats were subcutaneously injected with oil, 0.02 mg/kg EE, 2 mg/kg EE, or 20 mg/kg 17ß-estradiol within 24 h after birth. All females were tested for passive avoidance learning at the age of 6 weeks. Neonatal 0.02 mg/kg EE administration significantly disrupted passive avoidance compared with oil treatment in gonadally intact females. In a second experiment, another set of experimental females, treated as described above, was ovariectomized under pentobarbital anesthesia at 10 weeks of age. At 15-17 weeks of age, half of each group received a subcutaneous injection of 5 µg estradiol benzoate a day before the passive avoidance learning test. Passive avoidance learning behavior was impaired by the 0.02 mg/kg EE dose, but notably only in the estradiol benzoate-injected group. At 17-19 weeks of age, hippocampal and cortical samples were collected from rats with or without the 5 µg estradiol benzoate injection, and western blots used to determine ERα expression. A significant decrease in ERα expression was observed in the hippocampus of the estradiol-injected, neonatal EE-treated females. The results demonstrated that exposure to EE immediately after birth decreased learning ability in adult female rats, and that this may be at least partly mediated by the decreased expression of ERα in the hippocampus.

Asunto(s)

Reacción de Prevención/efectos de los fármacos , Corteza Cerebral/efectos de los fármacos , Receptor alfa de Estrógeno/antagonistas & inhibidores , Estrógenos/farmacología , Etinilestradiol/farmacología , Hipocampo/efectos de los fármacos , Animales , Animales Recién Nacidos , Corteza Cerebral/fisiología , Estradiol/análogos & derivados , Estradiol/farmacología , Receptor alfa de Estrógeno/genética , Receptor alfa de Estrógeno/metabolismo , Femenino , Expresión Génica/efectos de los fármacos , Hipocampo/fisiología , Inyecciones Subcutáneas , Ovariectomía , Ovario/fisiología , Ovario/cirugía , Ratas , Ratas Wistar

RESUMEN

INTRODUCTION: The present study aimed to clarify the relationship between the amount of singlet oxygen ((1)O(2)) generated from excited methylene blue (MB) and the bactericidal effects on Enterococcus faecalis. METHODS: A diode laser was used as the laser irradiation source (λ = 660 nm, 200 mW). The laser irradiation time periods were 300, 600, and 900 seconds. In experiment 1, the amount of (1)O(2) generated from each concentration (0.0001%-1.0%) of excited MB was examined by using electron spin resonance to determine the optimal concentration of MB. In experiment 2, the bactericidal effects of (1)O(2) on E. faecalis were examined. Experimental groups were with laser irradiation, L(+); without laser irradiation, L(-); including MB, M(+); and not including MB, M(-). These were combined to form 4 groups: L(+)M(+), L(+)M(-), L(-)M(+), and L(-)M(-). After treatment, E. faecalis was incubated for 48 hours at 37°C, and the bactericidal effects of (1)O(2) on E. faecalis were determined on the basis of the number of colony-forming units per milliliter. RESULTS: The largest amount of (1)O(2) was generated from 0.01% excited MB. After 300, 600, and 900 seconds of irradiation, 35.2, 87.2, and 117.1 µmol/L (1)O(2) were detected, respectively. In group L(+)M(+),colony-forming units per milliliter of E. faecalis dramatically decreased depending on the amount of (1)O(2) generated. No other groups showed any bactericidal effects. CONCLUSIONS: Our findings suggest that 0.001%-0.01% of MB is the most effective range for generating (1)O(2) during the application of antimicrobial photodynamic therapy. At least 35.2 µmol/L generated (1)O(2) was necessary to achieve the sterilization of E. faecalis.

Asunto(s)

Enterococcus faecalis/efectos de los fármacos , Azul de Metileno/química , Fotoquimioterapia/métodos , Oxígeno Singlete/farmacología , Análisis de Varianza , Recuento de Colonia Microbiana , Espectroscopía de Resonancia por Spin del Electrón , Láseres de Semiconductores , Detección de Spin , Estadísticas no Paramétricas

RESUMEN

The aim of the present study was to elucidate genetic alterations that are critically involved in astrocytoma progression. We characterized 27 World Health Organization grade II fibrillary astrocytomas which later underwent recurrence or progression, paying specific attention to the CpG island methylation status of critical growth regulatory genes. p14(ARF) and O(6)-methylguanine-DNA methyltransferase (MGMT) hypermethylation represented frequent events (26% and 63%, respectively), which were mutually exclusive except in one case, with alternate or simultaneous methylation of these two genes occurring in 85% of our tumor series. Seventeen tumors (63%) contained TP53 mutations, which were closely related to the presence of MGMT methylation. Methylation of the p21(Waf1/Cip1), p27(Kip1) and p73 genes and homozygous deletion of the p16(INK4a), p15(INK4b) and p14(ARF) genes were not detected in any of the primary low-grade tumors. The presence of p14(ARF) methylation at first biopsy was associated with shorter patient survival, whereas the presence of MGMT methylation carried a better clinical outcome after salvage therapy. Examination of 20 cases whose histological data for recurrent tumors were available revealed that malignant progression occurred in all of the tumors with p14(ARF) methylation but less frequently (50%) in the lesions with MGMT methylation. On analysis of their respective recurrent tumors, five of six patients whose primary low-grade tumors carried p14(ARF) methylation exhibited homozygous co-deletions of the p14(ARF), p15(INK4b) and p16(INK4a) genes, which were restricted to glioblastoma as the most malignant end point. Our findings suggest that p14(ARF) hypermethylation and MGMT hypermethylation constitute distinct molecular pathways of astrocytoma progression, which could differ in biological behavior and clinical outcome.

Asunto(s)

Astrocitoma/metabolismo , Neoplasias Encefálicas/metabolismo , Islas de CpG/fisiología , Recurrencia Local de Neoplasia/metabolismo , O(6)-Metilguanina-ADN Metiltransferasa/metabolismo , Proteína p14ARF Supresora de Tumor/metabolismo , Adulto , Anciano , Astrocitoma/genética , Astrocitoma/mortalidad , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidad , Femenino , Humanos , Masculino , Metilación , Persona de Mediana Edad , Mutación/genética , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/mortalidad , Regiones Promotoras Genéticas/fisiología , Análisis de Supervivencia , Proteína p53 Supresora de Tumor/genética

RESUMEN

Aberrant hypermethylation of CpG islands in the promoter region plays a causal role in the inactivation of various key genes involved in the cell cycle regulatory cascade, which could result in a loss of cell cycle control. The aim of the present study was to examine in more detail the prevalence and role of the promoter methylation of genes with a proven involvement in the cell cycle regulation of pituitary adenomas, since their tumorigenesis has not yet been clearly defined. We profiled the CpG island methylation status of a series of well-characterized cell cycle regulation genes: the RB1, p14(ARF), p15(INK4b), p16(INK4a), p21(Waf1/Cip1), p27(Kip1), and p73 genes, in 34 pituitary adenomas as determined by a methylation-specific polymerase chain reaction assay. Promoter hypermethylation of the RB1, p14(ARF), p15(INK4b), p16(INK4a), p21(Waf1/Cip1), p27(Kip1), and p73 genes was detected in 12 (35%), 2 (6%), 11 (32%), 20 (59%), 1 (3%), 0 (0%), and 4 (12%) of the adenomas, respectively. In total, 88% (30 of 34) of the adenomas displayed methylation of at least one of such cell cycle regulatory genes, especially methylation of the member genes of the RB1 pathway (29 of 34; 85%). Promoter hypermethylation of p15(INK4b) coincided with RB1 and/or p16(INK4a) methylation, whereas RB1 and p16(INK4a) methylations tended to be mutually exclusive (p = 0.0048). Furthermore, promoter hypermethylations of p14(ARF), p21(Waf1/Cip1), and p73 (not belonging to the member genes of the RB1 pathway) were also coincident with RB1 and/or p16(INK4a) methylation except in one p73 methylated case. In contrast, none of the clinicopathological features, including the cell proliferation index, was significantly correlated with any particular methylation status. Our results suggested that aberrant hypermethylation of the key cell cycle regulatory genes occurs at a relatively high frequency in pituitary adenomas, especially in RB1 pathway genes with promoter hypermethylation of the p16(INK4a) gene being the most common deregulation. We further obtained evidence to indicate that RB1 and p16(INK4a) methylations tended to be mutually exclusive, but did occasionally coincide with other cell cycle regulation gene methylations.

Asunto(s)

Adenoma/metabolismo , Proteínas de Ciclo Celular/metabolismo , Islas de CpG/fisiología , Regulación Neoplásica de la Expresión Génica/fisiología , Neoplasias Hipofisarias/metabolismo , Adenoma/genética , Adolescente , Adulto , Anciano , Proteínas de Ciclo Celular/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Femenino , Humanos , Masculino , Metilación , Persona de Mediana Edad , Neoplasias Hipofisarias/genética , Regiones Promotoras Genéticas/fisiología , Proteína de Retinoblastoma/metabolismo

RESUMEN

Aberrant hypermethylation of the CpG islands in the promoter region plays a casual role in the inactivation of various key genes involved in the cell cycle regulatory cascade, which could result in loss of cell cycle control. The aim of the present study was to investigate the role of promoter methylation of genes with a proven involvement in the cell cycle regulation of malignant astrocytomas. We profiled the CpG island methylation status of the RB1, p14ARF, p15INK4b, p16INK4a, p21Waf1/Cip1, p27Kip1, and p73 genes by methylation-specific polymerase chain reaction assay in a homogeneous cohort of patients with malignant astrocytomas, and assessed their relationships with clinical behavior. Promoter hypermethylation of the RB1, p14ARF, p15INK4b, p16INK4a, p21Waf1/Cip1, p27Kip1, and p73 genes was detected in 3 (6%), 7 (13%), 4 (7%), 2 (4%), 1 (2%), 3 (6%), and 12 samples (22%) among 54 newly diagnosed malignant astrocytomas, respectively. A total of 50% of the cases carried methylation of at least one gene, and only 9% of the cases displayed concordant hypermethylation of two genes. None of the tumors disclosed three or more methylated loci. The presence of methylation of these genes or a group of genes was not associated with any distinct clinicopathological characteristics including tumor grade, proliferation activity, responsiveness to adjuvant therapy, or patient survival. p73 protein accumulation was demonstrated by immunohistochemical staining in 6 (15%) of the 40 samples examined, with no significant association with the methylation status of p73 and any of the clinicopathological parameters tested. Our results demonstrated that a significant fraction of malignant astrocytomas displayed at least one methylated locus of the key cell cycle-related genes, although the genes were rarely hypermethylated, independent of the clinicopathological parameters. Thus, this epigenetic change is unlikely to play an important role in the evolution and development of malignant astrocytomas.

Asunto(s)

Astrocitoma/genética , Proteínas de Ciclo Celular/genética , Glioblastoma/genética , Adulto , Anciano , Anciano de 80 o más Años , Astrocitoma/patología , Astrocitoma/cirugía , Metilación de ADN , Proteínas de Unión al ADN/genética , Femenino , Glioblastoma/patología , Glioblastoma/cirugía , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Proteínas Nucleares/genética , Regiones Promotoras Genéticas , Estudios Prospectivos , Proteína de Retinoblastoma/genética , Proteína Tumoral p73 , Proteínas Supresoras de Tumor/genética

RESUMEN

The precise mechanisms governing the direct effect of IFN-beta, including apoptosis induction, are not yet fully understood. To gain a better insight into these mechanisms, we investigated the signaling pathways focusing particularly on interferon regulatory factor 1 (IRF-1) and IRF-2 in glioblastoma cell lines. Furthermore, we attempted to determine whether or not IRF-1 and IRF-2 act as additional prognostic indicators in diffusely infiltrating astrocytomas (DIA). We first assessed the cytotoxic effects of IFN-beta based on a cell growth study and modified MTT assay, and then quantified the apoptosis using a sandwich enzyme immunoassay following IFN-beta treatment in the cell lines, U-87MG, T98G, and A-172. Subsequently, we carried out an analysis of apoptosis-related molecules as evaluated by densitometric analysis of Western blots, focusing on IRF-1 and IRF-2, and two major initiator caspases, caspase-8 and caspase-9. Furthermore, we assessed the expression of type I IFN receptor, IRF-1, and IRF-2 using immunohistochemical techniques in 63 DIA (15 of WHO grade II, 18 of grade III, and 30 of grade IV), and analyzed their impact on prognosis. An increase in apoptosis was apparent after 48 h of IFN-beta treatment (1 x 10(4) IU/ml) in T98G but not in U-87MG or A-172. IFN-beta treatment for 6 h significantly enhanced the expression of IRF-1 in all three cell lines. However, an enhanced expression of IRF-2 was observed only in the not-most-sensitive, non-apoptosis-induced U-87MG and A-172. While minimal processing of caspase-8 was noted in the three cell lines throughout the experiment, caspase-9 activation was observed in the apoptosis-detected T98G after 48 h of treatment, as indicated by a 1.33-fold increase (P=0.037). On the other hand, the IRF-1 LI and IRF-1/IRF-2 LI ratio were greater in low-grade DAI, and were negatively correlated with the histopathological grade in DIA (P=0.017 and P=0.001, respectively). Furthermore, the IRF-1/IRF-2 LI ratio was negatively correlated with the MIB-1 LI in DIA (P=0.004), and represented an independent and most powerful determinant of overall survival compared to other conventional prognostic factors (P=0.018). However, the relation was not statistically significant when only patients with high-grade DIA were assessed. Our findings suggest that up-regulation of IRF-1 and IRF-2 might be an important determinant of susceptibility to IFN-beta mediated cytotoxicity including apoptosis. Furthermore, the IRF-1/IRF-2 LI ratio may reflect the proliferative state of DIA and constitute an important prognostic marker in DIA. Thus, IRF-1 and IRF-2 could represent one of the therapeutic target sites for the regulation of cell growth in DIA.

Asunto(s)

Astrocitoma/tratamiento farmacológico , Neoplasias Encefálicas/tratamiento farmacológico , Glioblastoma/tratamiento farmacológico , Factor 1 Regulador del Interferón/metabolismo , Factor 2 Regulador del Interferón/metabolismo , Interferón beta/farmacología , Adulto , Anciano , Anciano de 80 o más Años , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Astrocitoma/metabolismo , Astrocitoma/patología , Western Blotting , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Caspasas/efectos de los fármacos , Caspasas/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Activación Enzimática/efectos de los fármacos , Activación Enzimática/fisiología , Femenino , Glioblastoma/metabolismo , Glioblastoma/patología , Humanos , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Pronóstico , Receptores de Interferón/metabolismo

RESUMEN

Gangliogliomas are characterized by their different phenotypic composition of ganglion cells and glial cells. In contrast to the glial cells that are capable of mitotic activity, the ganglion cells are generally considered to lack a neoplastic nature. The authors report here the first unequivocal case of a ganglioglioma harboring aberrant TP53 product that was expressed predominantly in the neuronal component. GeneChip TP53 assay revealed a point mutation resulting in an exchange of amino acid. This case suggests that ganglion cells can participate in the neoplastic process of gangliogliomas.

Asunto(s)

Neoplasias Encefálicas/genética , Transformación Celular Neoplásica/genética , Ganglioglioma/genética , Neuronas/metabolismo , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/cirugía , Transformación Celular Neoplásica/metabolismo , Niño , Ganglioglioma/metabolismo , Ganglioglioma/patología , Ganglioglioma/cirugía , Humanos , Imagen por Resonancia Magnética , Masculino , Mutación , Neuronas/patología , Resultado del Tratamiento

RESUMEN

Pituitary adenomas are common benign intracranial neoplasms. However, their tumorigenesis is not yet clearly defined. Inactivation of genes involved in the negative cell-cycle regulatory p15(INK4b) - p16(INK4a) -cyclin D/CDK4-RB1-mediated pathway (RB1 pathway) is one of the most common and important mechanisms in the growth advantage of tumor cells. Recently, much attention has been focused on the importance of alternative mechanisms of gene inactivation, particularly promoter hypermethylation in the transcriptional silencing of such tumor-suppressor genes. Based on the rare occurrence of inactivation by gene mutations and deletions of the RB1 pathway in pituitary adenomas, we investigated the deregulation of the RB1 pathway in 42 sporadic human pituitary adenomas, especially focusing on the methylation status of this pathway as determined by a methylation-specific polymerase chain reaction assay. Homozygous deletion of the p15(INK4b) or p16(INK4a) gene was detected in one adenoma each. Amplification of the CDK4 gene was not apparent in any of the pituitary adenomas presently examined. Promoter hypermethylation of the p15(INK4b), p16(INK4a), and RB1 genes was detected in 15 (35.7%), 30 (71.4%), and 12 (28.6%) of the adenomas, respectively. Promoter hypermethylation of the p15(INK4b) gene coincided with p16(INK4a) alteration and/or RB1 methylation, whereas p16(INK4a) and RB1 methylations tended to be mutually exclusive (p = 0.019). Thus, the vast majority of the adenomas (38 of 42, 90.5%) displayed alterations of the RB1 pathway. None of the clinicopathologic features, including the proliferation cell index, was significantly correlated with any particular methylation status. Our results suggest that inactivation of the RB1 pathway may play a causal role in pituitary tumorigenesis, with hypermethylation of the p16(INK4a) gene being the most common deregulation, and further provide evidence that RB1 and p16(INK4a) methylations tend to be mutually exclusive but occasionally coincide with p15(INK4b) methylation.

Asunto(s)

Adenoma/metabolismo , Proteínas de Ciclo Celular/metabolismo , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Neoplasias Hipofisarias/metabolismo , Retinoblastoma/genética , Proteínas Supresoras de Tumor/metabolismo , Adenoma/genética , Adenoma/fisiopatología , Adulto , Northern Blotting/métodos , Proteínas de Ciclo Celular/genética , Distribución de Chi-Cuadrado , Inhibidor p15 de las Quinasas Dependientes de la Ciclina , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Metilación de ADN , Análisis Mutacional de ADN , Femenino , Eliminación de Gen , Humanos , Inmunohistoquímica/métodos , Masculino , Persona de Mediana Edad , Neoplasias Hipofisarias/genética , Neoplasias Hipofisarias/fisiopatología , Reacción en Cadena de la Polimerasa/métodos , Retinoblastoma/metabolismo , Proteínas Supresoras de Tumor/genética

RESUMEN

PURPOSE: In certain types of human cancers, transcriptional inactivation of hMLH1 by promoter hypermethylation plays a causal role in the loss of mismatch repair functions that modulate cytotoxic pathways in response to DNA-damaging agents. The aim of the present study was to investigate the role of promoter methylation of the hMLH1 gene in malignant astrocytomas. EXPERIMENTAL DESIGN: We examined the hMLH1 promoter methylation in a homogeneous cohort of patients with 41 malignant astrocytomas treated by 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-2(2-chloroethyl)-3-nitrosourea chemotherapy in combination with radiation and interferon therapy, and assessed the correlation of such methylation with clinical outcome. RESULTS: hMLH1 promoter methylation was found in 6 (15%) of the 41 newly diagnosed malignant astrocytomas. Hypermethylation of the hMLH1 promoter corresponded closely with a loss of immunohistochemical staining for hMLH1 protein (P = 0.0013). Patients with hMLH1-methylated tumors displayed a greater chance of responding to adjuvant therapy as compared with those with hMLH1-unmethylated tumors (P = 0.0150). The presence of hMLH1 hypermethylation was significantly associated with a longer progression-free survival on both univariate analysis (P = 0.0340) and multivariate analysis (P = 0.0161). CONCLUSIONS: The present study identified hMLH1 methylation status as a predictor of the clinical response of malignant astrocytomas to chloroethylnitrosourea-based adjuvant therapy. The findings obtained suggest that determination of the methylation status of hMLH1 could provide a potential basis for designing rational chemotherapeutic strategies, as well as for predicting prognosis.

Asunto(s)

Astrocitoma/tratamiento farmacológico , Metilación de ADN , Proteínas de Neoplasias/genética , Compuestos de Nitrosourea/uso terapéutico , Proteínas Nucleares/genética , Regiones Promotoras Genéticas/genética , Proteínas Adaptadoras Transductoras de Señales , Astrocitoma/genética , Astrocitoma/radioterapia , Proteínas Portadoras , Terapia Combinada , ADN de Neoplasias/genética , ADN de Neoplasias/metabolismo , Humanos , Inmunohistoquímica , Persona de Mediana Edad , Homólogo 1 de la Proteína MutL , Proteínas de Neoplasias/análisis , Proteínas Nucleares/análisis , Reacción en Cadena de la Polimerasa , Análisis de Supervivencia , Resultado del Tratamiento

RESUMEN

Epigenetic silencing of O(6)-methylguanine-DNA methyltransferase (MGMT) by promoter methylation can confer cancer cells with an increased sensitivity to alkylating chemotherapeutic agents and a higher susceptibility to TP53 transition mutations. The aim of our study was to assess the correlation of promoter methylation of the MGMT gene with TP53 mutations and the clinical characteristics of malignant astrocytomas. We analyzed the MGMT promoter methylation and TP53 mutations in 45 malignant astrocytomas (16 anaplastic astrocytomas and 29 glioblastomas multiforme) treated prospectively with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-2(2-chloroethyl)-3-nitrosourea, interferon-beta and radiation therapy, and evaluated their clinical usefulness. MGMT promoter methylation was found in 17 (38%) of the 45 newly diagnosed malignant astrocytomas. A clear trend existed between MGMT methylation and G:C to A:T transition mutations of TP53 (p = 0.0596). Patients with MGMT-methylated tumors displayed a greater chance of responding to adjuvant therapy as compared with those with MGMT-unmethylated tumors (p = 0.0393). TP53 mutation was not significantly associated with the clinical response (p = 0.1310). While neither MGMT methylation nor TP53 mutation had a significant effect on prognosis of the whole population, the presence of MGMT methylation emerged as a significant predictor of a longer survival when exclusively analyzing 29 patients with glioblastomas multiforme. These findings highlight the importance of MGMT methylation as a specific predictive factor for responsiveness to nitrosourea chemotherapy.

Asunto(s)

Astrocitoma/genética , Neoplasias Encefálicas/genética , Metilación de ADN , Mutación/genética , O(6)-Metilguanina-ADN Metiltransferasa/genética , Proteína p53 Supresora de Tumor/genética , Adulto , Anciano , Anciano de 80 o más Años , Astrocitoma/enzimología , Astrocitoma/terapia , Neoplasias Encefálicas/enzimología , Neoplasias Encefálicas/terapia , Quimioterapia Adyuvante , Femenino , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Interferón beta/farmacología , Masculino , Persona de Mediana Edad , Nimustina/farmacología , Pronóstico , Regiones Promotoras Genéticas/genética , Estudios Prospectivos , Dosis de Radiación , Radioterapia Adyuvante , Tasa de Supervivencia

RESUMEN

PURPOSE: The chromosome 9p21 region harbors three tumor suppressor genes, p14(ARF), p15(INK4b), and p16(INK4a), all of which can be targets for hypermethylation-associated inactivation in low-grade gliomas. p16(INK4a) and p15(INK4b) are critically involved in the RB1 pathway, whereas p14(ARF) acts as an upstream regulator of the TP53 pathway. The role of each tumor suppressor pathway in low-grade diffuse astrocytomas and their relationships with clinical behavior remain to be elucidated. EXPERIMENTAL DESIGN: We assessed the alterations of the RB1/CDK4/p16(INK4a)/p15(INK4b) and the TP53/MDM2/p14(ARF) pathways in 46 WHO grade II astrocytomas and analyzed their impact on prognosis. RESULTS: The TP53/MDM2/p14(ARF) pathway was altered in 32 of 46 cases (70%) by either TP53 mutation (25 cases) or p14(ARF) methylation (9 cases). The RB1/CDK4/p16(INK4a)/p15(INK4b) pathway was disrupted in 6 of 46 cases (13%) by either RB1 methylation (1 case), p16(INK4a) methylation (3 cases), or p15(INK4b) methylation or homozygous deletion (3 cases). Generally speaking, individual tumors thus tended to display alteration of only one component from both pathways. Any independently analyzed genetic alteration failed to provide statistically prognostic information. The alternate or simultaneous presence of TP53 mutation and p14(ARF) methylation emerged as a univariate predictor of a shorter progression-free survival (P = 0.0456) but was not statistically significant when age and extent of surgery were included in the analysis. CONCLUSIONS: Alternative disruption of the TP53/p14(ARF) pathway represents a frequent event in low-grade diffuse astrocytomas and correlates with an unfavorable clinical course. However, its value is unlikely to include prognostic utility that is independent of other conventional prognostic factors.

Asunto(s)

Astrocitoma/metabolismo , Proteína p14ARF Supresora de Tumor/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Adulto , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patología , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Codón , Islas de CpG , Quinasa 4 Dependiente de la Ciclina , Inhibidor p15 de las Quinasas Dependientes de la Ciclina , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Quinasas Ciclina-Dependientes/metabolismo , Metilación de ADN , Supervivencia sin Enfermedad , Exones , Femenino , Eliminación de Gen , Homocigoto , Humanos , Masculino , Persona de Mediana Edad , Mutación , Proteínas Nucleares/metabolismo , Reacción en Cadena de la Polimerasa , Pronóstico , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-mdm2 , Proteína de Retinoblastoma/metabolismo , Factores de Tiempo , Resultado del Tratamiento , Proteínas Supresoras de Tumor/metabolismo

RESUMEN

Diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. Considerable controversy exists as to the best therapeutic management for patients with such tumors. In the present study, we retrospectively analyzed a series of 64 patients with WHO grade II astrocytomas of the cerebral hemispheres. Gross total resection and interferon-beta therapy were significantly associated with both longer progression free survival (PFS) and overall survival (OS). Immediate postoperative radiation therapy did not prolong either the PFS or OS. The presence of promoter hypermethylation of the O6-methylguanine-DNA methyltransferase (MGMT) gene was an independent predictor of a shorter PFS. Our data suggest that radical surgery plus interferon-beta therapy may offer the best chance for long survival. Since the presence of MGMT methylation is a probable indication of an increased sensitivity to alkylating chemotherapeutic agents, determining the methylation status of MGMT could provide a potential basis for logical therapeutic intervention in identifying a subgroup of patients who could be candidates for early chemotherapy.

Asunto(s)

Astrocitoma/terapia , Neoplasias Encefálicas/terapia , Adolescente , Adulto , Anciano , Astrocitoma/genética , Neoplasias Encefálicas/genética , Terapia Combinada , Supervivencia sin Enfermedad , Femenino , Humanos , Interferón beta/uso terapéutico , Masculino , Metilación , Persona de Mediana Edad , Procedimientos Neuroquirúrgicos , O(6)-Metilguanina-ADN Metiltransferasa/genética , Pronóstico , Estudios Retrospectivos

RESUMEN

Clinical and histopathological evaluations are inadequate for assessing biological aggressiveness and regrowth potential in benign pituitary adenomas. To develop reliable and prognostically informative means of predicting behavior remains an intractable problem. Telomerase, a reverse transcriptase that extends telomere length, may facilitate tumorigenesis and tumor immortality. In the present study, we investigated the telomerase activity of pituitary adenomas, and attempted to assess the value of telomerase expression for predicting their clinical course. In total, 31 (30 patients) benign pituitary adenoma samples including 8 recurrent adenomas were studied. Telomerase expression was evaluated by polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay and telomerase activity levels were quantitated by improved PCR enzyme-linked immunosorbent assay (ELISA). The data were analyzed in relation to clinical course which was reviewed at 4-5.5 years (median follow-up time, 52.5 months) after surgery. The relative values of the telomerase expression for predicting the clinical course were compared with the MIB-1 antigen-based proliferative cell index (PCI) and p53 immunoreactivity which have recently been suggested to correlate with aggressive behavior in pituitary adenomas. Overall, telomerase expression was detected in 13% of the adenomas (4 tumor tissues, 3 patients). These adenomas comprised large, invasive, and functioning adenomas. The number of telomerase-positive adenomas was small; however, the PCI was higher in cases with telomerase expression (4 tumor tissues; mean, 4.2 +/- 2.4%) than in those without it (27 tumor tissues; 1.4 +/- 1.3%) (p = 0.01). One tumor with detectable telomerase expression, which did not undergo additional pharmacological or radiotherapeutic intervention after first surgery, recurred rapidly despite gross total surgical resection, although the PCI of both the primary and recurrent adenomas was not high. Detection of telomerase expression may represent an additional useful means of identifying aggressive behavior, complementing the histopathological evaluation of benign-appearing pituitary adenomas.

Asunto(s)

Adenoma/enzimología , Recurrencia Local de Neoplasia/enzimología , Neoplasias Hipofisarias/enzimología , Telomerasa/metabolismo , Adenoma/patología , Adulto , Anciano , División Celular , Ensayo de Inmunoadsorción Enzimática , Femenino , Estudios de Seguimiento , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Persona de Mediana Edad , Neoplasias Hipofisarias/patología , Reacción en Cadena de la Polimerasa , Pronóstico , Telomerasa/genética , Proteína p53 Supresora de Tumor/metabolismo

RESUMEN

High-dose (1-3.5 g/m2) methotrexate (MTX) followed by whole-brain radiation therapy (WBRT) has consistently improved length of survival in primary central nervous system lymphoma (PCNSL), but the prognosis remains dismal. To optimize and enhance the dose intensity of MTX, we applied MTX at 8 g/m2 to 20 patients with PCNSL. In an effort to lower the risk of neurotoxic treatment sequelae, the WBRT dose was reduced to 30 Gy in cases of complete remission after MTX therapy. Further, omission of WBRT and administration of stereotactic radiotherapy (SRT) were undertaken in 3 older patients. The overall response rate to the MTX therapy was 83%. The median progression free survival (PFS) was 54 months with a median overall survival (OS) of 57 months. Achieving a complete response after MTX therapy was significantly associated with a longer PFS. Late neurotoxicity was encountered in 4 (50%) of 8 patients who were aged 60 years or older and received WBRT, but in none of 12 patients who were aged less than 60 years or avoided WBRT. All older patients who underwent SRT sustained complete remission without a dementing disease. Intensifying the MTX dosage to 8 g/m2 appears more promising in comparison to results reported with MTX doses of 1-3.5 g/m2. In younger patients, the establishment of complete remission by intensified MTX therapy and subsequent WBRT with a relatively lower dose could promise durable tumor remission with an acceptable neurotoxicity. In older patients, WBRT should be avoided to sustain a meaningful survival, and SRT may provide a valid strategy in terms of enhancing local disease control without undue risk.

Asunto(s)

Antimetabolitos Antineoplásicos/uso terapéutico , Neoplasias del Sistema Nervioso Central/tratamiento farmacológico , Neoplasias del Sistema Nervioso Central/radioterapia , Linfoma no Hodgkin/tratamiento farmacológico , Linfoma no Hodgkin/radioterapia , Metotrexato/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , Neoplasias del Sistema Nervioso Central/patología , Terapia Combinada , Femenino , Humanos , Linfoma de Células B Grandes Difuso/tratamiento farmacológico , Linfoma de Células B Grandes Difuso/patología , Linfoma de Células B Grandes Difuso/radioterapia , Linfoma no Hodgkin/patología , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia/tratamiento farmacológico , Recurrencia Local de Neoplasia/patología , Recurrencia Local de Neoplasia/radioterapia , Inducción de Remisión , Tasa de Supervivencia , Factores de Tiempo

RESUMEN

The O6-methylguanine-DNA methyltransferase (MGMT) plays a major role in repairing DNA damage from alkylating agents. In several human neoplasms including low-grade diffuse astrocytomas, promoter hypermethylation of MGMT has been shown to correlate with an increased frequency of p53 mutation. In the present study, we analyzed MGMT promoter methylation by the methylation-specific PCR in 49 newly diagnosed WHO grade II astrocytomas and evaluated its clinical usefulness. MGMT promoter methylation was found in 21 (43%) of the 49 tumors. A tight correlation existed between MGMT methylation and p53 protein accumulation (P=0.0424). The presence of MGMT methylation was significantly associated with a shorter progression free survival (PFS) on both univariate analysis (P=0.0014) and multivariate analysis (P=0.0081). It was a more powerful determinant of the PFS than age, sex, performance status, proliferative activity, or p53 expression, and was independent of the extent of surgery. In terms of the overall survival, MGMT methylation demonstrated a prognostic utility in the univariate analysis but not in the multivariate analysis. The present findings indicate that aberrant methylation of the MGMT promoter independently augurs for an unfavorable clinical course in patients with low-grade diffuse astrocytomas. Since the presence of MGMT methylation is expected to predict an increased sensitivity to alkylating chemotherapeutic agents, earlier chemotherapy could serve to improve an unfavorable natural history in tumors with MGMT methylation.

Asunto(s)

Astrocitoma/genética , Neoplasias Encefálicas/genética , Metilación de ADN , Recurrencia Local de Neoplasia/genética , O(6)-Metilguanina-ADN Metiltransferasa/genética , Adulto , Astrocitoma/enzimología , Astrocitoma/mortalidad , Neoplasias Encefálicas/enzimología , Neoplasias Encefálicas/mortalidad , Reparación del ADN/genética , Progresión de la Enfermedad , Supervivencia sin Enfermedad , Femenino , Regulación Enzimológica de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Genes p53/genética , Humanos , Masculino , Recurrencia Local de Neoplasia/enzimología , Recurrencia Local de Neoplasia/mortalidad , Valor Predictivo de las Pruebas , Pronóstico , Regiones Promotoras Genéticas , Análisis de Supervivencia

RESUMEN

Low-grade diffuse astrocytomas are slowly growing tumors with a relatively long overall survival. However, a substantial proportion undergoes dedifferentiation to a more malignant phenotype. Considerable controversy exists as to the best therapeutic management for patients with such tumors. Over the past decade, we have applied human fibroblast interferon (HFIF) therapy without radiation therapy to low-grade astrocytomas. We investigated 28 patients with WHO grade II astrocytomas of the cerebral hemispheres treated by surgery plus HFIF therapy. The overall response rate to the HFIF therapy was 36%. All side-effects of HFIF were transient, tolerable and manageable. The 5-year progression free survival and overall survival probabilities were 65% and 96%, respectively. Although our data from small cohort of patients may have modest value, our results suggest that HFIF may be useful in treating low-grade diffuse astrocytomas.

Asunto(s)

Antineoplásicos/uso terapéutico , Astrocitoma/tratamiento farmacológico , Astrocitoma/cirugía , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/cirugía , Interferón beta/uso terapéutico , Adolescente , Adulto , Estudios de Cohortes , Terapia Combinada , Femenino , Fibroblastos/metabolismo , Humanos , Imagen por Resonancia Magnética , Masculino , Dosis Máxima Tolerada , Persona de Mediana Edad , Tasa de Supervivencia