Análise do padrão de metilação do gene SOX17 e expressão de microRNAs ao diagnóstico de síndrome mielodisplásica e citopenia Idiopática de significado indeterminado
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Data
2018-05-07
Autores
Monteiro, Fernanda de Souza
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Universidade Estadual Paulista (Unesp)
Resumo
Síndromes Mielodisplásicas (SMDs) é a denominação de um grupo de doenças neoplásicas clonais das células hematopoéticas, mais frequentemente observadas em idosos, caracterizadas por citopenias, displasia, hematopoese ineficaz e risco elevado para leucemia mielóide aguda (LMA). Citopenia(s) persistente(s), por mais de seis meses, e ausência de critérios diagnósticos para SMD, caracteriza a Citopenia Idiopática de Significado Indeterminado (ICUS). ICUS foi definida recentemente e é pouco conhecida quanto aos fatores etiológicos. Já as SMDs são consideradas protótipos de doenças epigenéticas, uma vez que distúrbios na metilação de alguns genes que regulam proliferação e diferenciação celular têm sido considerados fatores causais. O gene SOX17, por exemplo, é um supressor de tumor expresso em vários tecidos e alterações no seu padrão de metilação já foram observadas em tumores sólidos e neoplasias hematológicas, entretanto, foram pouco estudadas nas SMDs e não há descrições de estudos em ICUS. Do mesmo modo, alguns microRNAs vem sendo utilizados como marcadores moleculares para diagnóstico e prognóstico para diversas anormalidades hematológicas, mas seu papel na etiologia e desenvolvimento das SMDs também é pouco conhecido. Neste contexto, este estudo propos investigar o padrão de metilação do gene SOX17 por MSP-PCR em células da medula óssea (MO) de pacientes com SMD e ICUS ao diagnóstico, e analisar alterações no padrão de expressão de microRNAs por RT-PCR em células da MO de adultos e de crianças com SMD. Em adultos foram investigados os microRNAs miR126, miR29a, miR20a, miR181a, miR19b, miR21, miR155, miR146, miR22, miR193, miR26a e miR29b, e em crianças, os microRNAs miR193, miR29b miR22 e miR26a. O padrão de metilação do gene SOX17 foi analisado em 26 pacientes com SMD e em 15 pacientes com ICUS. A hipermetilação da região promotora do gene foi identificada em 57,7% dos indivíduos com SMD e em 53,3% daqueles com ICUS, sugerindo que o silenciamento do SOX17 pode ser um evento frequente e participar do curso inicial destas doenças. A análise dos microRNAs foi realizada em 55 pacientes adultos com SMD e em oito controles saudáveis. Dos 12 microRNAs testados, sete apresentaram padrão de expressão anormal em relação ao grupo controle, e dos quatro micros investigados em 28 pacientes com SMD infantil, os micros, miR193, miR29b apresentaram expressão diminuída em relação ao grupo controle em aproximadamente 70% dos pacientes analisados e a expressão do miR22 foi maior em mais da metade das amostras analisadas, enquanto uma expressão diminuída do miR26a foi observada em 28 (100%) dos pacientes analisados. Considerando-se que os microRNAs estudados podem atuar como reguladores da hematopoese, os dados revelam a importância dos microRNAS na etiologia das SMDs, sugerindo esses como possíveis biomarcadores diagnósticos para a SMD adulto e infantil.
Myelodysplastic syndromes (MDS) denominates a group of neoplastic diseases of the hematopoietic cells, most commonly observed in elderly patients, characterized by cytopenias, dysplasia, ineffective hematopoiesis and high risk of acute myeloid leukemia (AML). Persistent cytopenia (s), for more than six months, and absence of diagnostic criteria for MDS, characterizes Idiopathic Cytopenia of Undetermined Significance (ICUS). ICUS has been recently defined, and little is known about its etiological factors. The MDSs are considered as prototypes of epigenetic diseases, due to the fact that methylation disorders of some genes that regulate cell proliferation and differentiation have been considered as causal factors. The SOX17 gene, for example, is a tumor suppressor expressed in several tissues and changes in its methylation pattern have already been observed in solid tumors and hematological malignancy, however, these changes have been little studied in MDS and there are no descriptions of studies in ICUS. Similarly, some microRNAs are being used as molecular markers for diagnosis and prognosis for various hematological abnormalities, but its role in the etiology and development of MDS is also poorly understood. In this context, this study aimed to investigate the methylation pattern of the SOX17 gene by MSP-PCR in bone marrow (BM) cells of patients diagnosed with MDS and ICUS, and to analyze changes in the expression pattern of microRNAs by RT-PCR in cells of BM for adults and children with MDS. In adults, the microRNAs miR29a, miR20a, miR181a, miR19b, miR21, miR155, miR146, miR22, miR193, miR26a and miR29b were tested, and in children, microRNAs miR193, miR29b miR22 and miR26a. The methylation pattern of the SOX17 gene was analyzed in 26 patients with MDS and in 15 patients with ICUS. The hypermethylation of the SOX17 promoter region was identified in 57.7% of the individuals with MDS and in 53.3% of those with ICUS, suggesting that the silencing of SOX17 can be a frequent event and participate in the initial course of these diseases. MicroRNAs were analyzed in 55 adult MDS patients and in 8 healthy controls. Among the 12 microRNAs tested in MDS adults, seven presented an abnormal expression pattern in relation to the control group, and of the four microRNAs investigated in 28 children with MDS, miR193 and miR29b presented decreased expression in relation to the control group in approximately 70% of the analyzed patients and miR22 expression was higher in more than half of the analyzed samples, whereas diminished expression of miR26a was observed in 28 (100%) of the patients analyzed. Considering that the studied microRNAs may act as regulators of hematopoese, the data reveal the importance of microRNAS in the etiology of MDS, suggesting these as possible diagnostic biomarkers and prognostic of adult and infant MDS.
Myelodysplastic syndromes (MDS) denominates a group of neoplastic diseases of the hematopoietic cells, most commonly observed in elderly patients, characterized by cytopenias, dysplasia, ineffective hematopoiesis and high risk of acute myeloid leukemia (AML). Persistent cytopenia (s), for more than six months, and absence of diagnostic criteria for MDS, characterizes Idiopathic Cytopenia of Undetermined Significance (ICUS). ICUS has been recently defined, and little is known about its etiological factors. The MDSs are considered as prototypes of epigenetic diseases, due to the fact that methylation disorders of some genes that regulate cell proliferation and differentiation have been considered as causal factors. The SOX17 gene, for example, is a tumor suppressor expressed in several tissues and changes in its methylation pattern have already been observed in solid tumors and hematological malignancy, however, these changes have been little studied in MDS and there are no descriptions of studies in ICUS. Similarly, some microRNAs are being used as molecular markers for diagnosis and prognosis for various hematological abnormalities, but its role in the etiology and development of MDS is also poorly understood. In this context, this study aimed to investigate the methylation pattern of the SOX17 gene by MSP-PCR in bone marrow (BM) cells of patients diagnosed with MDS and ICUS, and to analyze changes in the expression pattern of microRNAs by RT-PCR in cells of BM for adults and children with MDS. In adults, the microRNAs miR29a, miR20a, miR181a, miR19b, miR21, miR155, miR146, miR22, miR193, miR26a and miR29b were tested, and in children, microRNAs miR193, miR29b miR22 and miR26a. The methylation pattern of the SOX17 gene was analyzed in 26 patients with MDS and in 15 patients with ICUS. The hypermethylation of the SOX17 promoter region was identified in 57.7% of the individuals with MDS and in 53.3% of those with ICUS, suggesting that the silencing of SOX17 can be a frequent event and participate in the initial course of these diseases. MicroRNAs were analyzed in 55 adult MDS patients and in 8 healthy controls. Among the 12 microRNAs tested in MDS adults, seven presented an abnormal expression pattern in relation to the control group, and of the four microRNAs investigated in 28 children with MDS, miR193 and miR29b presented decreased expression in relation to the control group in approximately 70% of the analyzed patients and miR22 expression was higher in more than half of the analyzed samples, whereas diminished expression of miR26a was observed in 28 (100%) of the patients analyzed. Considering that the studied microRNAs may act as regulators of hematopoese, the data reveal the importance of microRNAS in the etiology of MDS, suggesting these as possible diagnostic biomarkers and prognostic of adult and infant MDS.
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Palavras-chave
Mielodisplasia, Epigenética, Expressão gênica, MicroRNA, Myelodysplasia, Epigenetics, Gene expression