In acute myeloid leukemia (AML), specific genomic aberrations induce aberrant methylation, thus directly influencing the transcriptional programing of leukemic cells. Therefore, therapies targeting epigenetic processes are advocated as a promising therapeutic tool for AML treatment. However, to develop new therapies, a comprehensive understanding of the mechanism(s) driving the epigenetic changes as a result of acquired genetic abnormalities is necessary. This understanding is still lacking. In this study, we performed genome-wide CpG-island methylation profiling on pediatric AML samples. Six differentially methylated genomic regions within two genes, discriminating inv(16)(p13;q22) from non-inv(16) pediatric AML samples, were identified. All six regions had a hypomethylated phenotype in inv(16) AML samples, and this was most prominent at the regions encompassing the meningioma (disrupted in balanced translocation) 1 (MN1) oncogene. MN1 expression primarily correlated with the methylation level of the 3' end of the MN1 exon-1 locus. Decitabine treatment of different cell lines showed that induced loss of methylation at the MN1 locus can result in an increase of MN1 expression, indicating that MN1 expression is coregulated by DNA methylation. To investigate this methylation-associated mechanism, we determined the expression of DNA methyltransferases in inv(16) AML. We found that DNMT3B expression was significantly lower in inv(16) samples. Furthermore, DNMT3B expression correlated negatively with MN1 expression in pediatric AML samples. Importantly, depletion of DNMT3B impaired remethylation efficiency of the MN1 exon-1 locus in AML cells after decitabine exposure. These findings identify DNMT3B as an important coregulator of MN1 methylation. Taken together, this study shows that the methylation level of the MN1 exon-1 locus regulates MN1 expression levels in inv(16) pediatric AML. This methylation level is dependent on DNMT3B, thus suggesting a role for DNMT3B in leukemogenesis in inv(16) AML, through MN1 methylation regulation.

• MeSH
• akutní myeloidní leukemie krev   genetika   patologie   MeSH
• azacytidin analogy a deriváty   farmakologie   MeSH
• CpG ostrůvky genetika   MeSH
• decitabin MeSH
• dítě MeSH
• DNA-(cytosin-5-)methyltransferasa metabolismus   MeSH
• epigeneze genetická genetika   MeSH
• exony genetika   MeSH
• fúzní onkogenní proteiny genetika   MeSH
• hybridizace nukleových kyselin metody   MeSH
• karcinogeneze genetika   MeSH
• kojenec MeSH
• lidé MeSH
• metylace DNA účinky léků   genetika   MeSH
• mladiství MeSH
• nádorové buněčné linie MeSH
• nádorové supresorové proteiny genetika   MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• promotorové oblasti (genetika) genetika   MeSH
• regulace genové exprese u leukemie * MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů metody   MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• novorozenec MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

MicroRNAs (miRNAs) are crucial components of homeostatic and developmental gene regulation. In turn, dysregulation of miRNA expression is a common feature of different types of cancer, which can be harnessed therapeutically. Here we identify miR-139-5p suppression across several cytogenetically defined acute myeloid leukemia (AML) subgroups. The promoter of mir-139 was transcriptionally silenced and could be reactivated by histone deacetylase inhibitors in a dose-dependent manner. Restoration of mir-139 expression in cell lines representing the major AML subgroups (t[8;21], inv[16], mixed lineage leukemia-rearranged and complex karyotype AML) caused cell cycle arrest and apoptosis in vitro and in xenograft mouse models in vivo. During normal hematopoiesis, mir-139 is exclusively expressed in terminally differentiated neutrophils and macrophages. Ectopic expression of mir-139 repressed proliferation of normal CD34(+)-hematopoietic stem and progenitor cells and perturbed myelomonocytic in vitro differentiation. Mechanistically, mir-139 exerts its effects by repressing the translation initiation factor EIF4G2, thereby reducing overall protein synthesis while specifically inducing the translation of cell cycle inhibitor p27(Kip1). Knockdown of EIF4G2 recapitulated the effects of mir-139, whereas restoring EIF4G2 expression rescued the mir-139 phenotype. Moreover, elevated miR-139-5p expression is associated with a favorable outcome in a cohort of 165 pediatric patients with AML. Thus, mir-139 acts as a global tumor suppressor-miR in AML by controlling protein translation. As AML cells are dependent on high protein synthesis rates controlling the expression of mir-139 constitutes a novel path for the treatment of AML.

• MeSH
• buněčná diferenciace genetika   MeSH
• eukaryotický iniciační faktor 4G biosyntéza   genetika   MeSH
• genový knockdown MeSH
• lidé MeSH
• mikro RNA biosyntéza   genetika   MeSH
• myeloidní leukemie genetika   patologie   MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• proliferace buněk genetika   MeSH
• proteosyntéza * MeSH
• regulace genové exprese u leukemie MeSH
• xenogenní modely - testy protinádorové aktivity MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• akutní myeloidní leukemie genetika   MeSH
• dítě MeSH
• exprese genu * MeSH
• lidé MeSH
• lidské chromozomy, pár 11 * MeSH
• lidské chromozomy, pár 6 * MeSH
• mutace MeSH
• transkripční faktory bHLH genetika   MeSH
• translokace genetická * MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• Publikační typ
• dopisy MeSH
• práce podpořená grantem MeSH

MicroRNAs (miRNAs) play a pivotal role in the regulation of hematopoiesis and development of leukemia. Great interest emerged in modulating miRNA expression for therapeutic purposes. In order to identify miRNAs, which specifically suppress leukemic growth of acute myeloid leukemia (AML) with t(8;21), inv(16) or mixed lineage leukemia (MLL) rearrangement by inducing differentiation, we conducted a miRNA expression profiling in a cohort of 90 cytogenetically characterized, de novo pediatric AML cases. Four miRNAs, specifically downregulated in MLL-rearranged, t(8;21) or inv(16) AMLs, were characterized by their tumor-suppressive properties in cell lines representing those respective cytogenetic groups. Among those, forced expression of miR-9 reduced leukemic growth and induced monocytic differentiation of t(8;21) AML cell lines in vitro and in vivo. The tumor-suppressive functions of miR-9 were specifically restricted to AML cell lines and primary leukemic blasts with t(8;21). On the other hand, these functions were not evident in AML blasts from patients with MLL rearrangements. We showed that miR-9 exerts its effects through the cooperation with let-7 to repress the oncogenic LIN28B/HMGA2 axis. Thus, miR-9 is a tumor suppressor-miR which acts in a stringent cell context-dependent manner.

• MeSH
• akutní myeloidní leukemie genetika   patologie   MeSH
• buněčné dělení MeSH
• dítě MeSH
• heterografty MeSH
• lidé MeSH
• lidské chromozomy, pár 21 * MeSH
• lidské chromozomy, pár 8 * MeSH
• mikro RNA genetika   MeSH
• myši nahé MeSH
• myši MeSH
• průtoková cytometrie MeSH
• translokace genetická * MeSH
• tumor supresorové geny * MeSH
• zvířata MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH