ASSOCIATION OF MIRNA EXPRESSION PROFILES WITH FUNCTIONAL AND MOLECULAR ACUTE MYELOID LEUKEMIA CATEGORIES
(Abstract release date: 05/18/17)
EHA Library. Sargas *. 05/18/17; 182375; PB1661
*Claudia Sargas
Contributions
Contributions
Abstract
Abstract: PB1661
Type: Publication Only
Background
Development of high-throughput technologies such as Next Generation Sequencing (NGS) allowed the identification of recurrent mutated genes in Acute Myeloid Leukemia (AML), and new molecular markers which help refine patients’ classification in different risk groups.
Epigenetic alterations such as aberrantly expressed microRNAs (miRNAs) also play an important role on the pathogenesis of AML. miRNAs control processes such as cell development, differentiation, proliferation and apoptosis. Therefore, aberrant miRNA expression can affect signaling and metabolic pathways, directing cancer cell biological behavior.
Recently, several studies have classified AML according to different criteria. TCGA proposed in 2013 a new classification where genes are grouped according to their biological function. Moreover, Papaemmanuil et al. suggested in 2016 a new classification based on molecular markers with not overlapping categories.
Aims
Our aim is to explore the miRNA profile of NK-AML and to find expression profiles associated with the categories proposed by TCGA and Papaemmanuil et al. Associations of miRNA expression profiles with altered categories could help understand the molecular mechanisms that lead to leukemogenesis.
Methods
CD34+ cord blood progenitor cells from 5 healthy donors and 7 CD34+ NK-AML samples with >70% blasts were obtained. Total RNA from these samples were hybridized onto an Array miRNA 3.0 chip (Affymetrix) in order to identify deregulated miRNAs. The most deregulated miRNAs were validated by qRT-PCR (miScript) in an independent cohort of 73 patients. Mutational analysis was performed by Next Generation Sequencing using the AML Community Panel with the Ion Torrent System (Life Technologies). Mann-Whitney U test was used to determine which miRNAs were differentially expressed among categories.
Results
We found a profile of 6 miRNAs up-regulated and 61 miRNAs down-regulated in NK-AML vs. CD34+ cells. Validation by qRT-PCR confirmed that miR-494 (p = 0.028) and miR-4507 (p = 0.035) were up-regulated and miR-27b (p = 0.022), miR-99a (p = 0.001), miR-146b (p = 0.031), miR-151b (p = 0.006) and miR-20b (p = 0.001) were down-regulated in NK-AML.
Interestingly, some of the deregulated miRNAs were significantly associated to a functional category according to the TCGA classification. Therefore miR-146b was down-regulated in AML with mutations in myeloid transcription factors (p = 0.025). Low expression of this miRNA causes the activation of the kB factor signaling pathway, which increases transcription. miR-4668 was down-regulated in AML with mutations in activation pathways genes (p=0.004), several target predictors propose RASGEF1A and BRAF as targets of this miRNA. Thus, under-expression of this miRNA could cooperate with mutations leading to the activation of signaling pathways.
Regarding to Papaemmanuil´s molecular classification, miR-494 was up-regulated in IDH2-R172 category (p = 0.009). High levels of this miRNA are associated with lower expression of TET, specially TET1. Therefore, high levels of miR-494 could contribute to the hypermethylation signature of IDH mutations.
Conclusion
In conclusion, the mutational landscape of significant functional and molecular groups in AML is accompanied by miRNA deregulation, which could cooperate in the development of this hematologic malignancy.
Session topic: 3. Acute myeloid leukemia - Biology
Keyword(s): Expression profiling, Acute Myeloid Leukemia, Molecular markers, Microarray analysis
Abstract: PB1661
Type: Publication Only
Background
Development of high-throughput technologies such as Next Generation Sequencing (NGS) allowed the identification of recurrent mutated genes in Acute Myeloid Leukemia (AML), and new molecular markers which help refine patients’ classification in different risk groups.
Epigenetic alterations such as aberrantly expressed microRNAs (miRNAs) also play an important role on the pathogenesis of AML. miRNAs control processes such as cell development, differentiation, proliferation and apoptosis. Therefore, aberrant miRNA expression can affect signaling and metabolic pathways, directing cancer cell biological behavior.
Recently, several studies have classified AML according to different criteria. TCGA proposed in 2013 a new classification where genes are grouped according to their biological function. Moreover, Papaemmanuil et al. suggested in 2016 a new classification based on molecular markers with not overlapping categories.
Aims
Our aim is to explore the miRNA profile of NK-AML and to find expression profiles associated with the categories proposed by TCGA and Papaemmanuil et al. Associations of miRNA expression profiles with altered categories could help understand the molecular mechanisms that lead to leukemogenesis.
Methods
CD34+ cord blood progenitor cells from 5 healthy donors and 7 CD34+ NK-AML samples with >70% blasts were obtained. Total RNA from these samples were hybridized onto an Array miRNA 3.0 chip (Affymetrix) in order to identify deregulated miRNAs. The most deregulated miRNAs were validated by qRT-PCR (miScript) in an independent cohort of 73 patients. Mutational analysis was performed by Next Generation Sequencing using the AML Community Panel with the Ion Torrent System (Life Technologies). Mann-Whitney U test was used to determine which miRNAs were differentially expressed among categories.
Results
We found a profile of 6 miRNAs up-regulated and 61 miRNAs down-regulated in NK-AML vs. CD34+ cells. Validation by qRT-PCR confirmed that miR-494 (p = 0.028) and miR-4507 (p = 0.035) were up-regulated and miR-27b (p = 0.022), miR-99a (p = 0.001), miR-146b (p = 0.031), miR-151b (p = 0.006) and miR-20b (p = 0.001) were down-regulated in NK-AML.
Interestingly, some of the deregulated miRNAs were significantly associated to a functional category according to the TCGA classification. Therefore miR-146b was down-regulated in AML with mutations in myeloid transcription factors (p = 0.025). Low expression of this miRNA causes the activation of the kB factor signaling pathway, which increases transcription. miR-4668 was down-regulated in AML with mutations in activation pathways genes (p=0.004), several target predictors propose RASGEF1A and BRAF as targets of this miRNA. Thus, under-expression of this miRNA could cooperate with mutations leading to the activation of signaling pathways.
Regarding to Papaemmanuil´s molecular classification, miR-494 was up-regulated in IDH2-R172 category (p = 0.009). High levels of this miRNA are associated with lower expression of TET, specially TET1. Therefore, high levels of miR-494 could contribute to the hypermethylation signature of IDH mutations.
Conclusion
In conclusion, the mutational landscape of significant functional and molecular groups in AML is accompanied by miRNA deregulation, which could cooperate in the development of this hematologic malignancy.
Session topic: 3. Acute myeloid leukemia - Biology
Keyword(s): Expression profiling, Acute Myeloid Leukemia, Molecular markers, Microarray analysis
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