RESUMO
Altered or aberrant expression of several splicing factors leads to the progression of different cancers. Though there are several ongoing studies underscoring the role of the splicing regulator polypyrimidine tract binding protein 2 (PTBP2) in neuronal cells, we unveil the role of PTBP2 in chronic myeloid leukemia (CML). Different RNA binding proteins (RBP's) earlier reported in chronic myeloid leukemia blast crisis (CML-BC) cases (nâ¯=â¯28) from Radich Oncomine leukemia dataset, were compared. We observed increased expression of MSI2 followed by PTBP2 in BC cases and increased PTBP2 expression in relapsed cases (nâ¯=â¯10) from the same dataset compared to other RBPs. We also observed increased PTBP2 exon 10 inclusion in KCL22, a granulocytic lineage CML cell line when compared to other CML cell lines of different lineages. As PTBP2 protein expression is associated with PTBP2 exon 10 inclusion, we observed in cell lines and in a set of progressed cases (nâ¯=â¯4) that increased BCR-ABL1 expression potentiates PTBP2 exon 10 inclusion and thus confers the existence of a functional protein. Inhibition of BCR-ABL1 with imatinib not only blocks the inclusion of exon 10 but also deregulates PTBP2 expression in CML cells. Knockdown of PTBP2 in KCL22 cells leads to reduced cell proliferation, increased G2/M cell cycle arrest and increased apoptosis. Taken together our study portrays PTBP2 as a new possible target for CML and progressive inclusion/exclusion of PTBP2 exon 10 might play an important role in CML progression.
Assuntos
Progressão da Doença , Éxons/genética , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Proteínas do Tecido Nervoso/genética , Proteína de Ligação a Regiões Ricas em Polipirimidinas/genética , Apoptose/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Pontos de Checagem da Fase G2 do Ciclo Celular/genética , Regulação Neoplásica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , Pontos de Checagem da Fase M do Ciclo Celular/genética , RecidivaRESUMO
Although BCR-ABL is the hallmark genetic abnormality of chronic myeloid leukemia (CML), secondary molecular events responsible for the evolution of the disease to blast crisis are yet to be deciphered. Taking into account the significant association of ecotropic viral integration site I (EVI1) in CML drug resistance, it is necessary to decipher the other roles played by EVI1 in CML disease progression. In this regard, we cross-hybridized three microarray datasets and deduced a set of 11 genes that seems to be regulated by EVI1 in CML. We observed a strong correlation between EVI1 and alpha1, 6-fucosyltransferase (FUT8) in the chronic phase of the disease and both of them were found to be up-regulated with the progression of the disease. Knockdown of EVI1 in a CML cell line not only down-regulated FUT8, but also rendered the cells towards erythroid differentiation. Our study shows the involvement of EVI1 and FUT8 axis in blocking erythropoiesis in CML.
Assuntos
Eritropoese/genética , Fucosiltransferases/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Proteína do Locus do Complexo MDS1 e EVI1/metabolismo , Animais , Linhagem Celular Tumoral , Análise por Conglomerados , Biologia Computacional/métodos , Regulação Leucêmica da Expressão Gênica , Técnicas de Silenciamento de Genes , Estudos de Associação Genética , Humanos , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/sangue , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Camundongos , Estadiamento de NeoplasiasRESUMO
Chronic myelogenous leukemia (CML), a hematopoietic malignancy, characterized initially by a chronic phase (CP) progresses into blast crisis (BC) with the accumulation of secondary abnormalities. We have reported earlier that MEF2C, a target of miR-223, was significantly up regulated in CML and also showed a negative correlation with miR-223. In this study, gene expression arrays were used to identify the genes regulated by MEF2C during myelopoiesis. Statistical tools were used to understand the correlation between MEF2C and the targets in different phases of CML. Different CML cell lines and CML patient samples were treated with imatinib to study the effect of MEF2C on the target genes. We observed that MEF2C targets a set of myeloid genes including the myeloid transcription factor CEBPA. MEF2C and CEBPA expression patterns are negatively correlated in CML patient samples. We further show that the expression of MEF2C and CEBPA along with CSF3R is sufficient to molecularly classify different stages of CML. Imatinib, the drug of choice for CML, abrogates MEF2C expression and reverses CEBPA repression both in the cell line and the primary cells. We report the existence of a MEF2C and CEBPA correlation in CML disease progression.
