MicroRNAs in Acute Myeloid Leukemia and Other Blood Disorders

Development and validation of GMI signature based random survival forest prognosis model to predict clinical outcome in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is a disease with marked molecular heterogeneity and a high early death rate. Our aim was to investigate an integrated Gene expression, Mirna and miRNA-mRNA Interactions (GMI) signature for improving risk stratification of AML.

Methods

We identified differentially expressed genes by pooling a large number of 861 human AML patients and 75 normal cases. We then used miRWalk to identify the functional miRNA-mRNA regulatory module. The GMI signature based random survival forest (RSF) prognosis model was developed from training data set and evaluated in independent patient cohorts from The Cancer Genome Atlas (TCGA) dataset (N = 147). Univariate and multivariate Cox proportional hazards regression analyses were applied to evaluate the prognostic value of GMI signature.

Results

We identified 139 differentially expressed genes between normal and abnormal AML samples. We discovered the functional miRNA-mRNA regulatory module which participate in the network of cancer progression. We named 23 differentially expressed genes and 16 validated target miRNAs as the GMI signature. The RSF model-based scores separated independent patient cohorts into two groups with significantly different overall survival (C-index = 0.59, hazard ratio [HR], 2.12; 95% confidence interval [CI], 1.11–4.03; p = 0.019). Similar results were obtained with reversed training and testing datasets (C-index = 0.58, hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.02–4.24; p = 0.038). The GMI signature score contributed more information about recurrence than standard clinical covariates.

Conclusion

The GMI signature based RSF prognosis model not only reflects regulatory relationships from identified miRNA-mRNA module but also informs patient prognosis. While in the TCGA data set the GMI signature score contributed additional information about recurrence in comparison to standard clinical covariates, further studies are needed to determine its clinical significance.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0540-5) contains supplementary material, which is available to authorized users.

Antiproliferative effect of upregulation of hsa-let-7c-5p in human acute erythroleukemia cells

New achievements in the field of cancer treatment are results of recent advances in molecular medicine and gene therapy. Usage of microRNAs (miRNAs) which are small noncoding RNAs is one of the molecular research lines for the diagnosis and treatment of cancers. miRNAs have an important role in post-transcriptional regulation of the gene expression and are involved in cellular activities such as growth, differentiation, cell death and cancer development. One of the miRNAs that showed downregulation in human acute erythroleukemia is hsa-let-7c-5p. Down-regulation of hsa-let-7c-5p has been reported in in vitro studies of different cancers. In the present study, upregulation of hsa-let-7c-5p is performed in human acute erythroleukemia cell line (KG-1) using miRNA mimic. qRT-PCR, MTT assay, Annexin-V, and propidium iodide staining at different time points after miRNA mimic transfection were accomplished to assess the expression level of hsa-let-7c-5p, cell viability, apoptosis and late apoptosis. In addition, the expression level of PBX2 oncogene, a validated target gene of hsa-let-7c-5p, is evaluated by RT-qPCR to show the effectivity of this approach on erythroleukemia cancer cells. Our results can be used in translational medicine for future investigation in acute erythroleukemia and to approach treatment based on miRNA mimic therapy.

Knockdown of miR-128a induces Lin28a expression and reverts myeloid differentiation blockage in acute myeloid leukemia

Lin28A is a highly conserved RNA-binding protein that concurs to control the balance between stemness and differentiation in several tissue lineages. Here, we report the role of miR-128a/Lin28A axis in blocking cell differentiation in acute myeloid leukemia (AML), a genetically heterogeneous disease characterized by abnormally controlled proliferation of myeloid progenitor cells accompanied by partial or total inability to undergo terminal differentiation. First, we found Lin28A underexpressed in blast cells from AML patients and AML cell lines as compared with CD34+ normal precursors. In vitro transfection of Lin28A in NPM1-mutated OCI-AML3 cell line significantly triggered cell-cycle arrest and myeloid differentiation, with increased expression of macrophage associate genes (EGR2, ZFP36 and ANXA1). Furthermore, miR-128a, a negative regulator of Lin28A, was found overexpressed in AML cells compared with normal precursors, especially in acute promyelocytic leukemia (APL) and in ‘AML with maturation’ (according to 2016 WHO classification of myeloid neoplasms and acute leukemia). Its forced overexpression by lentiviral infection in OCI-AML3 downregulated Lin28A with ensuing repression of macrophage-oriented differentiation. Finally, knockdown of miR-128a in OCI-AML3 and in APL/AML leukemic cells (by transfection and lentiviral infection, respectively) induced myeloid cell differentiation and increased expression of Lin28A, EGR2, ZFP36 and ANXA1, reverting myeloid differentiation blockage. In conclusion, our findings revealed a new mechanism for AML differentiation blockage, suggesting new strategies for AML therapy based upon miR-128a inhibition.

Rare Cytogenetic Abnormalities and Alteration of microRNAs in Acute Myeloid Leukemia and Response to Therapy

Acute myeloid leukemia (AML) is the most common acute leukemia in adults, which is heterogeneous in terms of morphological, cytogenetic and clinical features. Cytogenetic abnormalities, including karyotype aberrations, gene mutations and gene expression abnormalities are the most important diagnostic tools in diagnosis, classification and prognosis in acute myeloid leukemias. Based on World Health Organization (WHO) classification, acute myeloid leukemias can be divided to four groups. Due to the heterogeneous nature of AML and since most therapeutic protocols in AML are based on genetic alterations, gathering further information in the field of rare disorders as well as common cytogenetic abnormalities would be helpful in determining the prognosis and treatment in this group of diseases. Recently, the role of microRNAs (miRNAs) in both normal hematopoiesis and myeloid leukemic cell differentiation in myeloid lineage has been specified. miRNAs can be used instead of genes for AML diagnosis and classification in the future, and can also play a decisive role in the evaluation of relapse as well as response to treatment in the patients. Therefore, their use in clinical trials can affect treatment protocols and play a role in therapeutic strategies for these patients. In this review, we have examined rare cytogenetic abnormalities in different groups of acute myeloid leukemias according to WHO classification, and the role of miRNA expression in classification, diagnosis and response to treatment of these disorders has also been dealt with.

The pathological role and prognostic impact of miR-181 in acute myeloid leukemia

In addition to genetic abnormalities, such as chromosomal translocations and somatic mutations that have been widely acknowledged in the leukemogenesis of acute myeloid leukemia (AML), epigenetic modifications also play a vital role in this process. MicroRNA (miRNA) regulation is emerging as a new layer of epigenetic regulation besides DNA methylation and histone modifications. Among the miRNAs first identified to be specifically expressed in hematopoietic cells, the miR-181 family has been implicated in regulating the differentiation of B cells, T cells, and natural killer cells during normal hematopoiesis, and has been linked tightly to the pathogenesis and prognosis of AML. Accumulating evidence indicates that miR-181 acts as a tumor suppressor in the pathogenesis of AML and exhibits a significant impact on the survival of patients with AML. Herein, we review the role of miR-181 as a diagnostic marker and prognostic predictor in AML, and discuss the potential use of miR-181 as a therapeutic target for AML.

Association of Chromosomal Translocation and MiRNA Expression with The Pathogenesis of Multiple Myeloma

Multiple myeloma (MM), is the second most common blood cancer after non-Hodgkin's lymphoma. Genetic changes, structural and numerical chromosome anomalies, are involved in pathogenesis of MM, and are among the most important prognostic factors of disease-associated patient survival. MicroRNAs (miRNAs) are small 19-22 nucleotide single-stranded RNAs involved in important cellular processes. Cytogenetic changes in plasma cells alter miRNA expression and function. MiRNAs act as tumor suppressors and oncogenes by affecting intracellular signaling pathways. MiRNA expression is associated with a specific genetic change and may assist with diagnosis and disease prognosis. This study aims to evaluate recent findings in MM-associated cytogenetic changes and their relationship with changes in the expression of miRNAs. We have determined that MM-associated cytogenetic changes are related to changes in the expression of miRNAs and CD markers (cluster of differentiation) are associated with disease survival. Information about these changes can be used for therapeutic purposes and disease prognosis.