RESUMO
BACKGROUND/AIM: Individuals with type 2 Neurofibromatosis are predisposed for the appearance of schwannomas. In the present study we analyzed the loss of heterozygosity and mutations in the NF2 gene in patients with sporadic Schwannoma without Neurofibromatosis type 2. MATERIALS AND METHODS: We analyzed 39 patients with sporadic spinal schwannoma. We quantified the number of alleles by FISH and sequenced the NF2 gene. RESULTS: We identified 16/39 patients with point mutations and/or LOHs in the tumor samples analyzed. The LOHs were found in 7/39 patients. Two homozygous mutations were detected in 4/39 tumors, and the presence of the mutation in heterozygosis was revealed in 3/39 patients. In two tumors, we detected the loss of one allele of the NF2 gene, with no mutation. CONCLUSION: The genetic alterations observed in the NF2 gene indicated that spinal schwannomas are associated with genetic alterations also found in other schwannomas and type 2 Neurofibromatosis, which reinforces the etiological role of this gene.
Assuntos
Genes da Neurofibromatose 2 , Perda de Heterozigosidade , Neurilemoma/epidemiologia , Neurilemoma/genética , Neoplasias da Coluna Vertebral/epidemiologia , Neoplasias da Coluna Vertebral/genética , Adulto , Brasil/epidemiologia , Feminino , Frequência do Gene , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Neurofibromatose 2/epidemiologia , Neurofibromatose 2/genéticaRESUMO
We previously observed reduced YWHAE (14-3-3ε) protein expression in a small set of gastric cancer samples. YWHAE may act as a negative regulator of the cyclin CDC25B, which is a transcriptional target of MYC oncogene. The understanding of YWHAE role and its targets is important for the better knowledge of gastric carcinogenesis. Thus, we aimed to evaluate the relationship among YWHAE, CDC25B, and MYC in vitro and in vivo. For this, we analyzed the YWHAE, CDC25B, and MYC expression in YWHA-silenced, CDC25B-silenced, and MYC-silenced gastric cancer cell lines, as well as in gastric cancer and non-neoplastic gastric samples. In gastric cancer cell lines, YWHAE was able to inhibit the cell proliferation, invasion and migration through the reduction of MYC and CDC25B expression. Conversely, MYC induced the cell proliferation, invasion and migration through the induction of CDC25B and the reduction of YWHAE. Most of the tumors presented reduced YWHAE and increased CDC25B expression, which seems to be important for tumor development. Increased MYC expression was a common finding in gastric cancer and has a role in poor prognosis. In the tumor initiation, the opposite role of YWHAE and CDC25B in gastric carcinogenesis seems to be independent of MYC expression. However, the inversely correlation between YWHAE and MYC expression seems to be important for gastric cancer cells invasion and migration. The interaction between YWHAE and MYC and the activation of the pathways related to this interaction play a role in the metastasis process.
Assuntos
Proteínas 14-3-3/metabolismo , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-myc/metabolismo , Neoplasias Gástricas/enzimologia , Fosfatases cdc25/metabolismo , Proteínas 14-3-3/genética , Adulto , Linhagem Celular Tumoral , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Proteínas Proto-Oncogênicas c-myc/genética , Interferência de RNA , Transdução de Sinais/efeitos dos fármacos , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Fatores de Tempo , Transfecção , Regulação para Cima , Fosfatases cdc25/genéticaRESUMO
Kinases are downstream modulators and effectors of several cellular signaling cascades and play key roles in the development of neoplastic disease. In this study, we aimed to evaluate SRC, LYN and CKB protein and mRNA expression, as well as their promoter methylation, in gastric cancer. We found elevated expression of SRC and LYN kinase mRNA and protein but decreased levels of CKB kinase, alterations that may have a role in the invasiveness and metastasis of gastric tumors. Expression of the three studied kinases was also associated with MYC oncogene expression, a possible biomarker for gastric cancer. To understand the mechanisms that regulate the expression of these genes, we evaluated the DNA promoter methylation of the three kinases. We found that reduced SRC and LYN methylation and increased CKB methylation was associated with gastric cancer. The reduced SRC and LYN methylation was associated with increased levels of mRNA and protein expression, suggesting that DNA methylation is involved in regulating the expression of these kinases. Conversely, reduced CKB methylation was observed in samples with reduced mRNA and protein expression, suggesting CKB expression was found to be only partly regulated by DNA methylation. Additionally, we found that alterations in the DNA methylation pattern of the three studied kinases were also associated with the gastric cancer onset, advanced gastric cancer, deeper tumor invasion and the presence of metastasis. Therefore, SRC, LYN and CKB expression or DNA methylation could be useful markers for predicting tumor progression and targeting in anti-cancer strategies.
Assuntos
Creatina Quinase/genética , Metilação de DNA/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Quinases da Família src/genética , Creatina Quinase/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Regiões Promotoras Genéticas , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Neoplasias Gástricas/enzimologia , Quinases da Família src/metabolismoRESUMO
AIM: To characterize APC gene mutations and correlate them with patient phenotypes in individuals diagnosed with familial adenomatous polyposis (FAP) in northern Brazil. METHODS: A total of 15 individuals diagnosed with FAP from 5 different families from the north of Brazil were analyzed in this study. In addition to patients with histopathological diagnosis of FAP, family members who had not developed the disease were also tested in order to identify mutations and for possible genetic counseling. All analyzed patients or their guardians signed a consent form approved by the Research Ethics Committee of the João de Barros Barreto University Hospital (Belem, Brazil). DNA extracted from the peripheral blood of a member of each of the affected families was subjected to direct sequencing. The proband of each family was sequenced to identify germline mutations using the Ion Torrent platform. To validate the detected mutations, Sanger sequencing was also performed. The samples from all patients were also tested for the identification of mutations by real-time quantitative polymerase chain reaction using the amplification refractory mutation system. RESULTS: Through interviews with relatives and a search of medical records, it was possible to construct genograms for three of the five families included in the study. All 15 patients from the five families with FAP exhibited mutations in the APC gene, and all mutations were detected in exon 15 of the APC gene. In addition to the patients with a histological diagnosis of FAP, family members without disease symptoms showed the mutation in the APC gene. In the present study, we detected two of the three most frequent germline mutations in the literature: the mutation at codon 1309 and the mutation at codon 1061. The presence of c.3956delC mutation was found in all families from this study, and suggests that this mutation was introduced in the population of the State of Pará through ancestor immigration (i.e., a de novo mutation that arose in one member belonging to this state from Brazil). CONCLUSION: Regardless of its origin, the c.3956delC mutation is a strong candidate biomarker of this hereditary cancer syndrome in families of northern Brazil.
Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/genética , Biomarcadores Tumorais/genética , Mutação em Linhagem Germinativa , Polipose Adenomatosa do Colo/diagnóstico , Adolescente , Adulto , Brasil , Análise Mutacional de DNA , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença , Hereditariedade , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Masculino , Linhagem , Fenótipo , Valor Preditivo dos Testes , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Adulto JovemRESUMO
Clinical and molecular prognostic factors in gliomas include age, IDH mutation, the glioma CpG island methylator phenotype (G-CIMP+) and promoter methylation of the O(6)-methylguanine DNA-methyltransferase (MGMT) gene. Among these markers, a predictive value was reported in glioblastomas (GBM) for MGMT promoter methylation, in particular in elderly GBM patients. In this study, methylation data from 46 glioma samples with the Illumina 450K platform were obtained and extended using external data to include a total of 247 glioma samples. Methylation analysis of the whole MGMT gene with this platform revealed two strongly survival-associated CpG regions within the promoter and the gene body, which were confirmed in a reported dataset of high grade-gliomas. Methylation at the promoter (CpG 25, cg12981137 and the prognostic model MGMT-STP27) and at the gene body CpG 165 (cg07933035), were significantly associated with better overall survival, and strongly correlated with G-CIMP+ status. In this series, the prognostic value of MGMT methylation at the promoter was not observed in G-CIMP- cases, although around 50 % of them were MGMT-methylated. These results were also obtained in an homogeneously-treated series of chemoradiated G-CIMP- GBMs analyzed by MSP and qMSP, and confirmed in a reported pyrosequencing-analyzed series of gliomas. Interestingly, in contrast to the MGMT promoter, gene body methylation was of prognostic value in G-CIMP-patients older than 65 years. Our study highlights the relevance of the prognostic value of the different regions of methylation throughout the MGMT gene that could be affected by specific G-CIMP profiles and age groups.
Assuntos
Neoplasias Encefálicas/genética , Ilhas de CpG/genética , Metilação de DNA/genética , Metilases de Modificação do DNA/genética , Enzimas Reparadoras do DNA/genética , Glioma/genética , Proteínas Supressoras de Tumor/genética , Adulto , Fatores Etários , Idoso , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/mortalidade , Feminino , Perfilação da Expressão Gênica , Glioma/diagnóstico , Glioma/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Análise de Componente Principal , Prognóstico , Regiões Promotoras Genéticas/genética , Análise de Sobrevida , Adulto JovemRESUMO
BACKGROUND: Hereditary diffuse gastric cancer (HDGC) is a hereditary autosomal inherited syndrome associated with CDH1 germline mutations. In Brazil, gastrointestinal tumors are among the most prevalent tumor types and constitute a serious public health problem, especially in the northern and northeastern regions. This study aimed to investigate germline mutations, methylation pattern and genomic rearrangements in the CDH1 gene and quantitative changes in the DNA of HDGC patients in northern and northeastern Brazil. METHODS: Twenty-seven DNA samples from the members of four families affected by HDGC were analyzed using array comparative genomic hybridization (aCGH), DNA sequencing and methylation pattern. RESULTS: No evidence of gain and loss events or any rearrangements were found in any of the samples tested using aCGH. No promoter region hypermethylation was observed either. Two of the four families presented different types of germline mutations. The 185G > T and 1018A > G germline mutations detected in this study have been described in Asian and European families, respectively. The ancestors of the two families carrying these mutations had originated from those continents. CONCLUSION: This is the first study to evaluate CDH1 gene germline mutations in Brazilian families with HDGC. In our study, 50% of the families showed no CDH1 gene alterations, and it is possible that in regions with a high incidence of gastric cancer, such as northern and northeastern Brazil, environmental factors might have induced the different genetic alterations analyzed in this study.
RESUMO
Breast cancer is a complex disease, with heterogeneous clinical evolution. Several analyses have been performed to identify the risk factors for breast cancer progression and the patients who respond best to a specific treatment. We aimed to evaluate whether the hormone receptor expression, HER2 and MYC genes and their protein status, and KRAS codon 12 mutations may be prognostic or predictive biomarkers of breast cancer. Protein, gene and mutation status were concomitantly evaluated in 116 breast tumors from women who underwent neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide. We observed that MYC expression was associated with luminal B and HER2 overexpression phenotypes compared to luminal A (p<0.05). The presence of MYC duplication or polysomy 8, as well as KRAS mutation, were also associated with the HER2 overexpression subtype (p<0.05). MYC expression and MYC gain were more frequently observed in early-onset compared to late-onset tumors (p<0.05). KRAS mutation was a risk factor of grade 3 tumors (p<0.05). A multivariate logistic regression demonstrated that MYC amplification defined as MYC/nucleus ratio of ≥2.5 was a protective factor for chemotherapy resistance. On the other hand, age and grade 2 tumors were a risk factor. Additionally, luminal B, HER2 overexpression, and triple-negative tumors presented increased odds of being resistant to chemotherapy relative to luminal A tumors. Thus, breast tumors with KRAS codon 12 mutations seem to present a worse prognosis. Additionally, MYC amplification may help in the identification of tumors that are sensitive to doxorubicin plus cyclophosphamide treatment. If confirmed in a large set of samples, these markers may be useful for clinical stratification and prognosis.
Assuntos
Neoplasias da Mama/diagnóstico , Neoplasias da Mama/tratamento farmacológico , Mama/patologia , Regulação Neoplásica da Expressão Gênica , Proteínas Proto-Oncogênicas c-myc , Proteínas Proto-Oncogênicas , Proteínas ras , Adulto , Idoso , Idoso de 80 Anos ou mais , Mama/efeitos dos fármacos , Mama/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Estudos de Coortes , Feminino , Genes myc , Humanos , Pessoa de Meia-Idade , Mutação , Terapia Neoadjuvante , Prognóstico , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas p21(ras) , Receptor ErbB-2/genética , Proteínas ras/genéticaRESUMO
DNA copy gains are a common event in tumor growth. This study determines the gene dosage/amplification of seven tumor-related genes in patients undergoing vestibular schwannoma (VS) surgery and analyzes its clinical implications. Thirty-three patients undergoing surgery for VS were studied. Seven genes (EGFR, ERBB2, ERBB3, ERBB4, MDM2, MDM4, and NMYC) were analyzed by Quantitative real-time PCR. Copy gains were correlated with demographic, clinical and radiological data. Of the 33 samples, 48 % were positive for copy gains in at least one gene. There were no positive samples for gene amplification. A clinical correlation between tumor size and copy gains of ERBB2 was found. Patients with copy gains of this gene had larger tumors measured by diameter (p = 0.027) and volume (p = 0.005). Copy gains of EGFR, ERBB2, ERBB4, and MDM4 were associated with preoperative tinnitus. Contrary to other tumors of the central nervous system, development of VS does not appear to involve gene amplification. However, copy gains of certain tumor-related genes may play a role in the biological behavior of these neoplasms. Our findings support the role of ERBB2 in VS development and growth.
Assuntos
Neoplasias dos Nervos Cranianos/genética , Amplificação de Genes , Dosagem de Genes , Regulação Neoplásica da Expressão Gênica , Genes erbB-2 , Neuroma Acústico/genética , Proto-Oncogenes , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase em Tempo Real , Carga TumoralRESUMO
Gastric cancer is one of the most common malignancies. DNA methylation is implicated in DNA mismatch repair genes deficiency. In the present study, we evaluated the methylation status of MLH1, MSH2, MSH6 and PMS2 in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosal of gastric cancer patients from Northern Brazil. We found that none of the nonneoplastic samples showed methylation of any gene promoter and 50% of gastric cancer samples showed at least one methylated gene promoter. Methylation frequencies of MLH1, MSH2, MSH6 and PMS2 promoter were 21.74%, 17.39%, 0% and 28.26% respectively in gastric cancer samples. MLH1 and PMS2 methylation were associated with neoplastic samples compared to nonneoplastic ones. PMS2 methylation was associated with diffuse- and intestinal-type cancer compared with normal controls. Intestinal-type cancer showed significant association with MLH1 methylation. Diffuse-type cancer was significantly associated with MSH2 methylation. Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that methylation is associated with gastric carcinogenesis. Methylation of mismatch repair genes was associated with gastric carcinogenesis and may be a helpful tool for diagnosis, prognosis and therapies. However, MSH6 does not seem to be regulated by methylation in our samples.
Assuntos
Reparo de Erro de Pareamento de DNA , Enzimas Reparadoras do DNA/genética , Neoplasias Gástricas/genética , Adulto , Idoso , Brasil , Metilação de DNA , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Regiões Promotoras Genéticas , Análise de Sequência de DNARESUMO
Astrocytomas represent the most common form of glial tumors. The most malignant grade of these tumors, glioblastoma multiforme, may arise as a malignant progression from low-grade astrocytoma through anaplastic astrocytoma to secondary GBM, or else it may arise "de novo" as primary GBM. Both types of glioblastoma are usually histologically indistinguishable. However, distinct molecular alterations have been described between them that potentially allow differentiation between the two mechanisms of origin. Since malignant transformation is a multistep process, we summarize in this review the earliest genetic changes that seem to be involved in the appearance and development of low-grade astrocytic tumors, where early detection and treatment could be possible.