RESUMEN

Cancer cell lines are widely used as in vitro models of tumorigenesis, facilitating fundamental discoveries in cancer biology and translational medicine. Currently, there are few options for glioblastoma (GBM) treatment and limited in vitro models with accurate genomic and transcriptomic characterization. Here, a detailed characterization of a new GBM cell line, namely AHOL1, was conducted in order to fully characterize its molecular composition based on its karyotype, copy number alteration (CNA), and transcriptome profiling, followed by the validation of key elements associated with GBM tumorigenesis. Large numbers of CNAs and differentially expressed genes (DEGs) were identified. CNAs were distributed throughout the genome, including gains at Xq11.1-q28, Xp22.33-p11.1, Xq21.1-q21.33, 4p15.1-p14, 8q23.2-q23.3 and losses at Yq11.21-q12, Yp11.31-p11.2, and 15q11.1-q11.2 positions. Nine druggable genes were identified, including HCRTR2, ETV1, PTPRD, PRKX, STS, RPS6KA6, ZFY, USP9Y, and KDM5D. By integrating DEGs and CNAs, we identified 57 overlapping genes enriched in fourteen pathways. Altered expression of several cancer-related candidates found in the DEGs-CNA dataset was confirmed by RT-qPCR. Taken together, this first comprehensive genomic and transcriptomic landscape of AHOL1 provides unique resources for further studies and identifies several druggable targets that may be useful for therapeutics and biologic and molecular investigation of GBM.

Asunto(s)

Glioblastoma , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Genoma , Genómica , Glioblastoma/genética , Histona Demetilasas , Humanos , Antígenos de Histocompatibilidad Menor , Transcriptoma

RESUMEN

Cancer cell lines are widely used as in vitro models of tumorigenesis, facilitating fundamental discoveries in cancer biology and translational medicine. Currently, there are few options for glioblastoma (GBM) treatment and limited in vitro models with accurate genomic and transcriptomic characterization. Here, a detailed characterization of a new GBM cell line, namely AHOL1, was conducted in order to fully characterize its molecular composition based on its karyotype, copy number alteration (CNA), and transcriptome profiling, followed by the validation of key elements associated with GBM tumorigenesis. Large numbers of CNAs and differentially expressed genes (DEGs) were identified. CNAs were distributed throughout the genome, including gains at Xq11.1-q28, Xp22.33-p11.1, Xq21.1-q21.33, 4p15.1-p14, 8q23.2-q23.3 and losses at Yq11.21-q12, Yp11.31-p11.2, and 15q11.1-q11.2 positions. Nine druggable genes were identified, including HCRTR2, ETV1, PTPRD, PRKX, STS, RPS6KA6, ZFY, USP9Y, and KDM5D. By integrating DEGs and CNAs, we identified 57 overlapping genes enriched in fourteen pathways. Altered expression of several cancer-related candidates found in the DEGs-CNA dataset was confirmed by RT-qPCR. Taken together, this first comprehensive genomic and transcriptomic landscape of AHOL1 provides unique resources for further studies and identifies several druggable targets that may be useful for therapeutics and biologic and molecular investigation of GBM.

Asunto(s)

Humanos , Glioblastoma/genética , Regulación Neoplásica de la Expresión Génica , Antígenos de Histocompatibilidad Menor , Genoma , Genómica , Línea Celular Tumoral , Histona Demetilasas , Transcriptoma

RESUMEN

Chemokines are low-molecular weight proteins that play a key role in inflammatory processes. Genomic variations in chemokine receptors are associated with the susceptibility to various diseases. Polymorphisms in chemokine receptor type 5 (CCR5)-Δ32 and CCR2-V64I are related to human immunodeficiency virus infection resistance, which has led to genetic association studies for several other diseases. Given the heterogeneous distribution of these polymorphisms in different global populations and within Brazilian populations, we analyzed the prevalence of CCR5-Δ32 and CCR2-V64I polymorphisms in a mixed population from northeastern Brazil. The study included 223 individuals from the general population of the city of Parnaíba, Piauí, who had a mean age of 73 years. Of these individuals, 37.2% were men and 62.8% were women. Polymorphisms were analyzed using DNA extracted from peripheral blood leukocytes by using polymerase chain reaction alone (CCR5-Δ32) or accompanied by restriction endonuclease digestion (CCR2-V64I). In both cases, the genotypes were determined using 8% polyacrylamide gel electrophoresis and silver nitrate staining. The population conformed to Hardy-Weinberg equilibrium for both the loci studied. No individuals were homozygous for allele-Δ32, which was present in 1.8% of the population, whereas allele-64I was present in 13.9% of the participants studied; 74.9% were homozygous for the wild-type allele, while 22.4 and 2.7% were heterozygous and homozygous for the mutant allele, respectively. Additional studies are needed to investigate the relationship between these polymorphisms and disease etiopathogenesis in reference populations.

Asunto(s)

Frecuencia de los Genes , Genética de Población , Polimorfismo Genético , Receptores CCR2/genética , Receptores CCR5/genética , Anciano , Alelos , Indio Americano o Nativo de Alaska , Población Negra , Brasil , Femenino , Expresión Génica/inmunología , Genotipo , Heterocigoto , Homocigoto , Humanos , Masculino , Receptores CCR2/inmunología , Receptores CCR5/inmunología , Población Blanca

RESUMEN

Approximately 200 million people suffer from type 2 diabetes (T2D) worldwide, and the rapid increase in the prevalence of this disease is likely a result of multiple environmental factors, such as increased food intake and decreased physical activity in genetically predisposed individuals. Different population studies have demonstrated a strong association of two polymorphic variations in the TCF7L2 gene, the noncoding single nucleotide polymorphisms (SNPs) rs7903146 (C/T) and rs12255372 (G/T), with T2D. Herein, we analyzed the association of these SNPs with T2D in a population from northeastern Brazil. Our results showed that the genotype and allele frequencies in TCF7L2 rs7903146 and rs12255372 were similar in the patient and control groups (P > 0.05). In addition, the allele frequencies were not significantly associated with T2D risk [rs7903146: odds ratio (OR) = 0.95, 95% confidence interval (CI) = 0.52-1.76, P = 1.00, and rs12255372: OR = 1.38, 95%CI = 0.72-2.62, P = 0.41]. These data suggest that the TCF7L2 SNPs rs7903146 and rs12255372 may not significantly contribute to T2D susceptibility in this population. However, our results may reflect the small number of subjects. Alternatively, these results may be attributable to specific ethnic effects, as most of the previously reported associations were demonstrated with predominantly European populations. To reach a definitive conclusion on the role of such gene variants for T2D in mixed populations, additional efforts are necessary to replicate this study with larger populations from areas with more ethnic heterogeneity.

Asunto(s)

Diabetes Mellitus Tipo 2/genética , Polimorfismo Genético , Proteína 2 Similar al Factor de Transcripción 7/genética , Secuencia de Bases , Brasil , Cartilla de ADN , Humanos , Reacción en Cadena de la Polimerasa

RESUMEN

There is a constant search for new cancer treatments that are less aggressive and economically affordable. In this context, natural products extracted from plants, fungi, and microorganisms are of great interest. Pestheic acid, or dihidromaldoxin, is a chlorinated diphenylic ether extracted from the phytopathogenic fungus Pestalotiopsis guepinii (Amphisphaeriaceae). We assessed the cytotoxic, cytostatic, and genotoxic effects of pestheic acid in a gastric adenocarcinoma cell line (PG100). A decrease in clonogenic survival was observed. Pestheic acid also induced significant increases in both micronucleus and nucleoplasmic bridge frequency. However, we did not observe changes in cell cycle kinetics or apoptosis induction. Reactive oxygen species induced by diphenylic ethers may explain the genotoxicity and mutagenicity of pestheic acid. The absence of repair checkpoints that we observed is probably due to the fact that the PG100 cell line lacks the TP53 gene, which is common in gastric cancers. Even though pestheic acid has had a clear cytotoxic effect, the minimal inhibitory concentration was high, which shows that pestheic acid is not an active anticancer compound under these conditions.

Asunto(s)

Antineoplásicos/farmacología , Hidrocarburos Clorados/farmacología , Éteres Fenílicos/farmacología , Adenocarcinoma , Adulto , Apoptosis/efectos de los fármacos , Ascomicetos/química , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Doxorrubicina/farmacología , Humanos , Masculino , Pruebas de Micronúcleos , Neoplasias Gástricas

RESUMEN

Iron is the most important metallic chemical element on Earth. Poisoning caused by excessive iron in humans has been associated with pulmonary diseases including neoplasms caused by inhalation of iron oxides. The involvement of iron in neurodegenerative processes has already been described. DNA alterations are induced by iron and other chemical compounds containing this metal; however, the data are controversial and the mechanism by which iron induces mutagenesis remains unknown. This study assessed in vitro iron-induced cytotoxic and genotoxic responses in an astrocytic cell line. Short- and long-term cytotoxicity and genotoxicity were evaluated with the Cell Proliferation Kit II and micronucleus test, respectively. Results indicated that the highest concentration of iron sulfate tested was cytotoxic in long-term cytotoxic assays and increased micronucleus frequency in comparison to controls. The significant cytotoxicity observed here might be due to the intrinsic ability of iron to induce apoptosis and possible changes in cell cycle kinetics; the genotoxic effects are probably due to the oxidant properties of iron itself. This was the first study to investigate the induction of micronuclei by iron in central nervous system cells.

Asunto(s)

Sistema Nervioso Central/citología , Hierro/farmacología , Adulto , Muerte Celular/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Humanos , Pruebas de Micronúcleos

RESUMEN

Venous thromboembolism (VTE) is an important cause of morbidity and mortality stemming from cardiovascular disease. It is a multifactorial disease caused by a combination of acquired risk factors, of which advanced age is the most significant, and genetic factors, including the variants FV G1691A, FII G20210A, and MTHFR C677T. We estimated the prevalence of these genomic variants in an elderly population of northeastern Brazil. The study included 188 elderly persons (65-93 years), of which 68 (36.2%) were men and 120 (63.8%) were women. Variants were detected by polymerase chain reaction-restriction fragment length polymorphism analysis, and subsequent electrophoresis on an 8% polyacrylamide gel stained with silver nitrate. The study population was in Hardy-Weinberg equilibrium for the 3 loci. Of the individuals analyzed, none carried variants of FV or FII (0%), and 24.7% had the MTHFR C677T polymorphism: 59 subjects (31.4%) were heterozygous (CT) and 17 subjects (9%) were homozygous (TT). Based on the analysis of these particular genes, we conclude that the study population does not present an increased risk for the development of VTE. Faced with a growing aging population worldwide, similar studies in other countries will help in the prevention of VTE in older individuals.

Asunto(s)

Variación Genética , Tromboembolia Venosa/genética , Anciano , Anciano de 80 o más Años , Brasil , Factor V/genética , Femenino , Sitios Genéticos , Genotipo , Heterocigoto , Homocigoto , Humanos , Masculino , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Mutación , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Polimorfismo de Longitud del Fragmento de Restricción , Protrombina/genética , Factores de Riesgo , Análisis de Secuencia de ADN

RESUMEN

Apolipoproteins have an important role in lipid metabolism and transport. Polymorphisms in the APOA1/C3/A4/A5 gene cluster have been associated with lipid alterations and cardiovascular diseases. We investigated APOA1 XmnI, APOA5 S19W, and APOA5 -1131T>C polymorphisms in 377 individuals from a cohort of a longitudinal Brazilian elderly study. Allele frequencies, genotype distribution, and association with major morbidities as well as with lipids, creatinine, albumin, urea, glycated hemoglobin, and fasting glucose serum levels were investigated. Linkage disequilibrium and haplotype associations were also analyzed. This is the first time that haplotypes involving these polymorphisms were evaluated. Genotyping was performed by PCR-RFLP. Minor allele frequencies were 0.119, 0.071, and 0.158 for XmnI, S19W, and -1131T>C polymorphisms, respectively. We found a significant association of the -1131C allele with low LDL-C levels. We also observed that XmnI and S19W polymorphisms were in linkage disequilibrium. The C/G haplotype, which is composed of the wild-type allele of XmnI and the minor allele of S19W, was associated with high total cholesterol serum levels in this elderly population. We conclude that the -1131T>C polymorphism and the C/G haplotype, including XmnI and S19W polymorphisms, are associated with alterations in lipid levels and may be risk factors for cardiovascular disease in the Brazilian elderly.

Asunto(s)

Apolipoproteína A-I/genética , Apolipoproteínas A/genética , Enfermedades Cardiovasculares/genética , LDL-Colesterol/genética , Colesterol/genética , Anciano , Anciano de 80 o más Años , Apolipoproteína A-V , Brasil , Colesterol/sangre , LDL-Colesterol/sangre , Femenino , Frecuencia de los Genes , Estudios de Asociación Genética , Haplotipos , Humanos , Desequilibrio de Ligamiento , Masculino , Polimorfismo de Nucleótido Simple , Factores de Riesgo

RESUMEN

There is considerable evidence indicating an increase in neurodegenerative disorders in industrialized countries. The clinical symptoms and the possible mutagenic effects produced by acute poisoning and by chronic exposure to metals are of major interest. This study is a review of the data found concerning the genotoxic potential of three metals: aluminum (Al), iron (Fe) and manganese (Mn), with emphasis on their action on human cells.

Asunto(s)

Aluminio/toxicidad , Hierro/toxicidad , Manganeso/toxicidad , Mutágenos/toxicidad , Animales , Células Cultivadas , Aberraciones Cromosómicas/inducido químicamente , Humanos , Mutación

RESUMEN

Gastric cancer is the fourth most frequent type of cancer and the second cause of cancer mortality worldwide. The genetic alterations described so far for gastric carcinomas include amplifications and mutations of the c-ERBB2, KRAS, MET, TP53, and c-MYC genes. Chromosomal instability described for gastric cancer includes gains and losses of whole chromosomes or parts of them and these events might lead to oncogene overexpression, showing the need for a better understanding of the cytogenetic aspects of this neoplasia. Very few gastric carcinoma cell lines have been isolated. The establishment and characterization of the biological properties of gastric cancer cell lines is a powerful tool to gather information about the evolution of this malignancy, and also to test new therapeutic approaches. The present study characterized cytogenetically PG-100, the first commercially available gastric cancer cell line derived from a Brazilian patient who had a gastric adenocarcinoma, using GTG banding and fluorescent in situ hybridization to determine MYC amplification. Twenty metaphases were karyotyped; 19 (95 percent) of them presented chromosome 8 trisomy, where the MYC gene is located, and 17 (85 percent) presented a deletion in the 17p region, where the TP53 is located. These are common findings for gastric carcinomas, validating PG100 as an experimental model for this neoplasia. Eighty-six percent of 200 cells analyzed by fluorescent in situ hybridization presented MYC overexpression. Less frequent findings, such as 5p deletions and trisomy 16, open new perspectives for the study of this tumor.

Asunto(s)

Humanos , Adenocarcinoma/genética , Línea Celular Tumoral , Genes myc/genética , Neoplasias Gástricas/genética , Adenocarcinoma/patología , Brasil , Análisis Citogenético , Amplificación de Genes , Cariotipificación , Neoplasias Gástricas/patología

RESUMEN

Gastric cancer is the fourth most frequent type of cancer and the second cause of cancer mortality worldwide. The genetic alterations described so far for gastric carcinomas include amplifications and mutations of the c-ERBB2, KRAS, MET, TP53, and c-MYC genes. Chromosomal instability described for gastric cancer includes gains and losses of whole chromosomes or parts of them and these events might lead to oncogene overexpression, showing the need for a better understanding of the cytogenetic aspects of this neoplasia. Very few gastric carcinoma cell lines have been isolated. The establishment and characterization of the biological properties of gastric cancer cell lines is a powerful tool to gather information about the evolution of this malignancy, and also to test new therapeutic approaches. The present study characterized cytogenetically PG-100, the first commercially available gastric cancer cell line derived from a Brazilian patient who had a gastric adenocarcinoma, using GTG banding and fluorescent in situ hybridization to determine MYC amplification. Twenty metaphases were karyotyped; 19 (95%) of them presented chromosome 8 trisomy, where the MYC gene is located, and 17 (85%) presented a deletion in the 17p region, where the TP53 is located. These are common findings for gastric carcinomas, validating PG100 as an experimental model for this neoplasia. Eighty-six percent of 200 cells analyzed by fluorescent in situ hybridization presented MYC overexpression. Less frequent findings, such as 5p deletions and trisomy 16, open new perspectives for the study of this tumor.

Asunto(s)

Adenocarcinoma/genética , Línea Celular Tumoral , Genes myc/genética , Neoplasias Gástricas/genética , Adenocarcinoma/patología , Brasil , Análisis Citogenético , Amplificación de Genes , Humanos , Cariotipificación , Neoplasias Gástricas/patología

RESUMEN

Kaurane diterpenes are considered important compounds in the development of new highly effective anticancer chemotherapeutic agents. Genotoxic effects of anticancer drugs in non-tumour cells are of special significance due to the possibility that they induce secondary tumours in cancer patients. In this context, we evaluated the genotoxic and mutagenic potential of the natural diterpenoid kaurenoic acid (KA), i.e. (-)-kaur-16-en-19-oic acid, isolated from Xylopia sericeae St. Hill, using several standard in vitro and in vivo protocols (comet, chromosomal aberration, micronucleus and Saccharomyces cerevisiae assays). Also, an analysis of structure-activity relationships was performed with two natural diterpenoid compounds, 14-hydroxy-kaurane (1) and xylopic acid (2), isolated from X. sericeae, and three semi-synthetic derivatives of KA (3-5). In addition, considering the importance of the exocyclic double bond (C16) moiety as an active pharmacophore of KA cytotoxicity, we also evaluated the hydrogenated derivative of KA, (-)-kauran-19-oic acid (KAH), to determine the role of the exocyclic bond (C16) in the genotoxic activity of KA. In summary, the present study shows that KA is genotoxic and mutagenic in human peripheral blood leukocytes (PBLs), yeast (S. cerevisiae) and mice (bone marrow, liver and kidney) probably due to the generation of DNA double-strand breaks (DSB) and/or inhibition of topoisomerase I. Unlike KA, compounds 1-5 and KAH are completely devoid of genotoxic and mutagenic effects under the experimental conditions used in this study, suggesting that the exocyclic double bond (C16) moiety may be the active pharmacophore of the genetic toxicity of KA.

Asunto(s)

Diterpenos/química , Diterpenos/toxicidad , Mutágenos/toxicidad , Extractos Vegetales/toxicidad , Animales , Línea Celular Tumoral , Humanos , Masculino , Ratones , Pruebas de Mutagenicidad , Relación Estructura-Actividad

RESUMEN

The leukaemia cell line HL60 is widely used in studies of the cell cycle, apoptosis and adhesion mechanisms in cancer cells. One marked characteristic of HL60 cells is the c-MYC proto-oncogene amplification, resulting in the formation of homogeneously staining regions (HSRs) at 8p24. We conducted a fluorescence in situ hybridization study in an HL60 cell line, using a locus-specific probe for c-MYC, before and after treatment with pisosterol (at 0.5, 1.0 and 1.8 microg/mL), a triterpene isolated from the fungus Pisolithus tinctorius. Before treatment, 87.5% of the cells showed HSRs. After treatment, no effects were detected at lower concentrations of pisosterol (0.5 and 1.0 microg/mL). However, at 1.8 microg/mL only 15% of the cells presented HSRs, and 39.5% presented few fluorescent signals (3 or 4 alleles), suggesting that pisosterol probably blocks the cells with HSRs at interphase. This result is particularly interesting because cells that do not show a high degree of c-MYC gene amplification have a less aggressive and invasive behaviour and are easy targets for chemotherapy. Therefore, further studies are needed to examine the use of pisosterol in combination with conventional anti-cancer therapy.

Asunto(s)

Antineoplásicos/farmacología , Proliferación Celular/efectos de los fármacos , Amplificación de Genes , Regulación Neoplásica de la Expresión Génica , Interfase , Proteínas Proto-Oncogénicas c-myc/genética , Terpenos/farmacología , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Células HL-60 , Humanos , Hibridación Fluorescente in Situ , Proto-Oncogenes Mas

RESUMEN

The leukemia cell line HL60 is widely used in studies of the cell cycle, apoptosis, and adhesion mechanisms in cancer cells. We conducted a focused cytogenetic study in an HL60 cell line, by analyzing GTG-banded chromosomes before and after treatment with pisosterol (at 0.5, 1.0, and 1.8 microg/ml), a triterpene isolated from Pisolithus tinctorius, a fungus collected in the Northeast of Brazil. Before treatment, 99% of the cells showed the homogeneously staining region (HSR) 8q24 aberration. After treatment with 1.8 microg/ml pisosterol, 90% of the analyzed cells lacked this aberration. We further performed a pulse test, in which the cells treated with pisosterol (0.5, 1.0, and 1.8 microg/ml) were washed and re-incubated in the absence of pisosterol. Only 30% of the analyzed cells lacked the HSR 8q24 aberration, suggesting that pisosterol probably blocks the cells with HSRs at interphase. No effects were detected at lower concentrations. At the highest concentration examined (1.8 microg/ml), pisosterol also inhibited cell growth, but this effect was not observed in the pulse test, reinforcing our hypothesis that, at the concentrations tested, pisosterol probably does not induce cell death in the HL60 line. The results found for pisosterol were compared with those for doxorubicin. Cells that do not show a high degree of gene amplification (HSRs and double-minute chromosomes) have a less aggressive and invasive behavior and are easy targets for chemotherapy. Therefore, further studies are needed to examine the use of pisosterol in combination with conventional anti-cancer therapy.

Asunto(s)

Antineoplásicos/toxicidad , Basidiomycota/química , Ciclo Celular/efectos de los fármacos , Amplificación de Genes/efectos de los fármacos , Células HL-60/efectos de los fármacos , Leucemia Promielocítica Aguda/tratamiento farmacológico , Terpenos/toxicidad , Aberraciones Cromosómicas/efectos de los fármacos , Bandeo Cromosómico , Doxorrubicina/toxicidad , Ensayos de Selección de Medicamentos Antitumorales , Células HL-60/fisiología , Humanos , Índice Mitótico , Extractos Vegetales/toxicidad

RESUMEN

Gastric cancer is the forth most frequent malignancy and the second most common cause of cancer death worldwide. DNA methylation is the most studied epigenetic alteration, occurring through a methyl radical addition to the cytosine base adjacent to guanine. Many tumor genes are inactivated by DNA methylation in gastric cancer. We evaluated the DNA methylation status of ANAPC1, CDKN2A and TP53 by methylation-specific PCR in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosa in individuals from Northern Brazil. All gastric cancer samples were advanced stage adenocarcinomas. Gastric samples were surgically obtained at the João de Barros Barreto University Hospital, State of Pará, and were stored at -80 degrees C before DNA extraction. Patients had never been submitted to chemotherapy or radiotherapy, nor did they have any other diagnosed cancer. None of the gastric cancer samples presented methylated DNA sequences for ANAPC1 and TP53. CDKN2A methylation was not detected in any normal gastric mucosa; however, the CDKN2A promoter was methylated in 30.4% of gastric cancer samples, with 35% methylation in diffuse-type and 26.9% in intestinal-type cancers. CDKN2A methylation was associated with the carcinogenesis process for ~30% diffuse-type and intestinal-type compared to non-neoplastic samples. Thus, ANAPC1 and TP53 methylation was probably not implicated in gastric carcinogenesis in our samples. CDKN2A can be implicated in the carcinogenesis process of only a subset of gastric neoplasias.

Asunto(s)

Adenocarcinoma/genética , Metilación de ADN/genética , Genes p16 , Genes p53 , Neoplasias Gástricas/genética , Complejos de Ubiquitina-Proteína Ligasa/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Adulto , Anciano , Ciclosoma-Complejo Promotor de la Anafase , Subunidad Apc1 del Ciclosoma-Complejo Promotor de la Anafase , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas/genética , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patología

RESUMEN

Gastric cancer is the forth most frequent malignancy and the second most common cause of cancer death worldwide. DNA methylation is the most studied epigenetic alteration, occurring through a methyl radical addition to the cytosine base adjacent to guanine. Many tumor genes are inactivated by DNA methylation in gastric cancer. We evaluated the DNA methylation status of ANAPC1, CDKN2A and TP53 by methylation-specific PCR in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosa in individuals from Northern Brazil. All gastric cancer samples were advanced stage adenocarcinomas. Gastric samples were surgically obtained at the João de Barros Barreto University Hospital, State of Pará, and were stored at -80°C before DNA extraction. Patients had never been submitted to chemotherapy or radiotherapy, nor did they have any other diagnosed cancer. None of the gastric cancer samples presented methylated DNA sequences for ANAPC1 and TP53. CDKN2A methylation was not detected in any normal gastric mucosa; however, the CDKN2A promoter was methylated in 30.4 percent of gastric cancer samples, with 35 percent methylation in diffuse-type and 26.9 percent in intestinal-type cancers. CDKN2A methylation was associated with the carcinogenesis process for ~30 percent diffuse-type and intestinal-type compared to non-neoplastic samples. Thus, ANAPC1 and TP53 methylation was probably not implicated in gastric carcinogenesis in our samples. CDKN2A can be implicated in the carcinogenesis process of only a subset of gastric neoplasias.

Asunto(s)

Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adenocarcinoma/genética , Metilación de ADN/genética , Neoplasias Gástricas/genética , Complejos de Ubiquitina-Proteína Ligasa/metabolismo , Adenocarcinoma/metabolismo , Adenocarcinoma/patología , Estudios de Casos y Controles , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas/genética , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patología

RESUMEN

The TP53 tumor suppressor gene codifies a protein responsible for preventing cells with genetic damage from growing and dividing by blocking cell growth or apoptosis pathways. A common single nucleotide polymorphism (SNP) in TP53 codon 72 (Arg72Pro) induces a 15-fold decrease of apoptosis-inducing ability and has been associated with susceptibility to human cancers. Recently, another TP53 SNP at codon 47 (Pro47Ser) was reported to have a low apoptosis-inducing ability; however, there are no association studies between this SNP and cancer. Aiming to study the role of TP53 Pro47Ser and Arg72Pro on glioma susceptibility and oncologic prognosis of patients, we investigated the genotype distribution of these SNPs in 94 gliomas (81 astrocytomas, 8 ependymomas and 5 oligodendrogliomas) and in 100 healthy subjects by the polymerase chain reaction-restriction fragment length polymorphism approach. Chi-square and Fisher exact test comparisons for genotype distributions and allele frequencies did not reveal any significant difference between patients and control groups. Overall and disease-free survivals were calculated by the Kaplan-Meier method, and the log-rank test was used for comparisons, but no significant statistical difference was observed between the two groups. Our data suggest that TP53 Pro47Ser and Arg72Pro SNPs are not involved either in susceptibility to developing gliomas or in patient survival, at least in the Brazilian population.

Asunto(s)

Glioma/genética , Polimorfismo de Nucleótido Simple , Proteína p53 Supresora de Tumor/genética , Adolescente , Adulto , Anciano , Apoptosis/genética , Brasil , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Frecuencia de los Genes , Genes p53 , Predisposición Genética a la Enfermedad , Genotipo , Glioma/etiología , Glioma/mortalidad , Humanos , Lactante , Masculino , Persona de Mediana Edad , Pronóstico , Análisis de Supervivencia

RESUMEN

Manganese (Mn) has a natural occurrence and is necessary during the initial periods of the development. However, in high concentrations, Mn can be related to neurodegenerative disorders. The aim of the present study was to evaluate the mutagenic potential of manganese chloride (MnCl2.4H2O). Comet assay and chromosome aberrations analysis were applied to determine the DNA-damaging and clastogenic effects of MnCl2.4H2O. Cultured human lymphocytes were treated with 15, 20 and 25 microM manganese chloride during the G1, G1/S, S (pulses of 1 and 6h), and G2 phases of the cell cycle. All tested concentrations were cytotoxic and reduced significantly the mitotic index in G1, G1/S and S (1 and 6h) treatments, while in G2 treatment only the higher concentrations (20 and 25 microM) showed cytotoxic effects. Clastogenicity and DNA damage were found only in treatments with the highest concentration (25 microM). Chromosome aberrations were found exclusively in the G2 phase of the cell cycle. The absence of polyploidy in mitosis, suggests that manganese does not affect the formation of the mitotic spindle with the concentrations tested. The genotoxicity found in G2 phase and in the comet assay can be related to the short time of treatment in both cases.

Asunto(s)

Ciclo Celular/efectos de los fármacos , Cloruros/toxicidad , Contaminantes Ambientales/toxicidad , Linfocitos/efectos de los fármacos , Células Cultivadas , Cloruros/administración & dosificación , Aberraciones Cromosómicas/efectos de los fármacos , Ensayo Cometa , Contaminantes Ambientales/administración & dosificación , Humanos , Linfocitos/metabolismo , Compuestos de Manganeso/administración & dosificación , Índice Mitótico , Pruebas de Mutagenicidad , Mutágenos/administración & dosificación , Mutágenos/toxicidad , Factores de Tiempo

RESUMEN

Iron (Fe) is a common chemical element that is essential for organisms as a co-factor in oxygen transport, but that in high amounts presents a significant risk of neurodegenerative disorders. The objective of this study was to evaluate the mutagenic potential of iron sulfate. The comet assay and chromosome aberration (CA) analysis were applied to determine the DNA-damaging and clastogenic effects of iron sulfate. Human lymphocytes were treated in the quiescent phase for the comet assay and proliferative phase during the G1, G1/S, S (pulses of 1 and 6 h), and G2 phases of the cell cycle for CA analysis, with 1.25, 2.5 and 5 microg/mL concentrations of FeSO(4).7H2O. All tested concentrations were cytotoxic and reduced significantly the mitotic index (MI) in all phases of the cell cycle. They also induced CA in G1, G1/S and S (pulses of 1 and 6 h) phases. Iron sulfate also induced polyploidy in cells treated during G1. In the comet assay, this metal did not induce significant DNA damage. Our results show that Fe causes alteration and inhibition of DNA synthesis only in proliferative cells, which explain the concomitant occurrence of mutagenicity and cytotoxicity, respectively, in the lymphocytes studied.

Asunto(s)

Ciclo Celular/fisiología , Supervivencia Celular/efectos de los fármacos , Compuestos Férricos/toxicidad , Linfocitos/efectos de los fármacos , Mutágenos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Aberraciones Cromosómicas/efectos de los fármacos , Ensayo Cometa , Daño del ADN/efectos de los fármacos , Fase G1/efectos de los fármacos , Humanos , Índice Mitótico , Fase S/efectos de los fármacos

RESUMEN

The TP53 tumor suppressor gene codifies a protein responsible for preventing cells with genetic damage from growing and dividing by blocking cell growth or apoptosis pathways. A common single nucleotide polymorphism (SNP) in TP53 codon 72 (Arg72Pro) induces a 15-fold decrease of apoptosis-inducing ability and has been associated with susceptibility to human cancers. Recently, another TP53 SNP at codon 47 (Pro47Ser) was reported to have a low apoptosis-inducing ability; however, there are no association studies between this SNP and cancer. Aiming to study the role of TP53 Pro47Ser and Arg72Pro on glioma susceptibility and oncologic prognosis of patients, we investigated the genotype distribution of these SNPs in 94 gliomas (81 astrocytomas, 8 ependymomas and 5 oligodendrogliomas) and in 100 healthy subjects by the polymerase chain reaction-restriction fragment length polymorphism approach. Chi-square and Fisher exact test comparisons for genotype distributions and allele frequencies did not reveal any significant difference between patients and control groups. Overall and disease-free survivals were calculated by the Kaplan-Meier method, and the log-rank test was used for comparisons, but no significant statistical difference was observed between the two groups. Our data suggest that TP53 Pro47Ser and Arg72Pro SNPs are not involved either in susceptibility to developing gliomas or in patient survival, at least in the Brazilian population.

Asunto(s)

Humanos , Masculino , Femenino , Preescolar , Niño , Adolescente , Adulto , Persona de Mediana Edad , Glioma/genética , Polimorfismo de Nucleótido Simple , /genética , Apoptosis/genética , Brasil , Estudios de Casos y Controles , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Glioma/etiología , Glioma/mortalidad , Pronóstico , Análisis de Supervivencia