microRNAs in acute myeloid leukemia: expression patterns, correlations with genetic and clinical parameters, and prognostic significance

miR-153-3p Suppresses Inhibitor of Growth Protein 2 Expression to Function as Tumor Suppressor in Acute Lymphoblastic Leukemia

Alterations in microRNAs expression can accelerate the development of human cancers. However, the role of miR-153-3p in acute lymphoblastic leukemia remains unknown. The expression of miR-153-3p in acute lymphoblastic leukemia cell lines was measured by quantitative real-time polymerase chain reaction. Effects of miR-153-3p expression on acute lymphoblastic leukemia cell proliferation, migration, and invasion were examined by Cell Counting Kit-8 assay, wound healing assay, and Transwell invasion assay, respectively. We then validated inhibitor of growth protein 2 as a direct target of miR-153-3p through bioinformatics analysis, luciferase activity reporter assay, and Western blot assay. The miR-153-3p expression was decreased in acute lymphoblastic leukemia cell lines. Cell proliferation, migration, and invasion of acute lymphoblastic leukemia were obviously decreased by miR-153-3p overexpression. Moreover, inhibitor of growth protein 2 was validated as a direct target of miR-153-3p and the overexpression of inhibitor of growth protein 2 reversed the suppressive effects of miR-153-3p on acute lymphoblastic leukemia cell behaviors. Based on these results, we provided evidence that miR-153-3p might be a target for the treatment of acute lymphoblastic leukemia.

MicroRNA-9 suppresses cancer proliferation and cell cycle progression in acute lymphoblastic leukemia with inverse association of neuropilin-1

Acute lymphoblastic leukemia (ALL) is one of the most common and most malign childhood cancers. In this work, we investigated the expression and function of human mature microRNA-9 (miR-9) in ALL. In ALL in vitro cell lines and in situ clinical specimens, gene expression of miR-9 was tested by qRT-PCR. MiR-9 was overexpressed in CEM/C1 and Molt-3 cells to investigate its possible anti-cancer effects on ALL in vitro proliferation, cell-cycle progression, and in vivo explant growth. The possible downstream target of miR-9, neuropilin-1 (NRP1), was examined by dual-luciferase activity assay, qRT-PCR, and Western blot. NRP1was upregulated in miR-9-overexpressed CEM/C1 and Molt-3 cells to investigate the functional involvement of NRP1 in miR-9-mediated regulation on ALL in vitro proliferation and cell-cycle progression. MiR-9 was downregulated in ALL cell lines and leukemic T-cells of ALL patients. Lentivirus-mediated miR-9 overexpression inhibited ALL in vitro proliferation, cell-cycle progression, and in vivo explant growth. NRP1 was confirmed be the downstream target of miR-9, and inversely modulated by miR-9 in ALL. NRP1 upregulation reversed the anti-cancer regulations of miR-9 on ALL in vitro proliferation and cell-cycle progression. MiR-9 is downregulated in ALL. Overexpressing miR-9 may inhibit ALL development, possible through its downstream target of NRP1.

Circulating miR-92a, miR-143 and miR-342 in Plasma are Novel Potential Biomarkers for Acute Myeloid Leukemia

MicroRNAs (miRNAs) are small non-coding RNAs that function as post-transcriptional gene expression regulators. The expression profiling of miRNAs has already entered into cancer clinics as diagnostic and prognostic biomarkers to assess tumor initiation, progression and response to treatment in cancer patients. Recent studies have opened the way for the use of circulating miRNAs as non-invasive diagnosis and prognosis of Acute myeloid leukemia (AML). The aim of this study was to identify plasma miR-92a, miR-143 and miR-342 expression signatures in AML patients to introduce new markers for establishing AML diagnosis and prognosis. Blood samples were collected from 65 AML patients and 50 controls. The expression of three target miRNAs (miR-92a, miR-143 and miR-342) was measured using quantitative real-time PCR method. Plasma levels of miR-92a, miR-143 and miR-342 were significantly lower in AML patients in comparison with control group. Receiver operator characteristic (ROC) analysis revealed that the sensitivity and specificity values of miR-92a were 81.5% and 94%, respectively, with a cut-off value of 0.704. The sensitivity and specificity values of miR-143 were 87.7% and 80%, respectively, with a cut-off value of 0.65. The sensitivity and specificity values of miR-342 were 75.4% and 90%, respectively, with a cut-off value of 0.479. Our findings suggest that plasma miR-92a, miR-143 and miR-342 could be promising novel circulating biomarkers in clinical detection of AML.

Molecular and genetic alterations associated with therapy resistance and relapse of acute myeloid leukemia

Background

The majority of individuals with acute myeloid leukemia (AML) respond to initial chemotherapy and achieve a complete remission, yet only a minority experience long-term survival because a large proportion of patients eventually relapse with therapy-resistant disease. Relapse therefore represents a central problem in the treatment of AML. Despite this, and in contrast to the extensive knowledge about the molecular events underlying the process of leukemogenesis, information about the mechanisms leading to therapy resistance and relapse is still limited.

Purpose and content of review

Recently, a number of studies have aimed to fill this gap and provided valuable information about the clonal composition and evolution of leukemic cell populations during the course of disease, and about genetic, epigenetic, and gene expression changes associated with relapse. In this review, these studies are summarized and discussed, and the data reported in them are compiled in order to provide a resource for the identification of molecular aberrations recurrently acquired at, and thus potentially contributing to, disease recurrence and the associated therapy resistance. This survey indeed uncovered genetic aberrations with known associations with therapy resistance that were newly gained at relapse in a subset of patients. Furthermore, the expression of a number of protein coding and microRNA genes was reported to change between diagnosis and relapse in a statistically significant manner.

Conclusions

Together, these findings foster the expectation that future studies on larger and more homogeneous patient cohorts will uncover pathways that are robustly associated with relapse, thus representing potential targets for rationally designed therapies that may improve the treatment of patients with relapsed AML, or even facilitate the prevention of relapse in the first place.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0416-0) contains supplementary material, which is available to authorized users.

Overexpression of miR-125a in myelodysplastic syndrome CD34+ cells modulates NF-κB activation and enhances erythroid differentiation arrest

Myelodysplastic syndromes (MDS) are characterized by impaired proliferation and differentiation of hematopoietic stem cells. The participation of toll-like receptor (TLR)-mediated signaling in MDS is well documented. Increased TLR signaling leads to the constitutive activation of NF-κB, which mediates inflammation, cell proliferation and apoptosis. In addition, the TLR pathway induces the expression of miRNAs which participate in the fine-tuning of the inflammatory response. miRNAs also regulate other biological processes, including hematopoiesis. miR-125a and miR-125b are known modulators of hematopoiesis and are abnormally expressed in several hematologic malignancies. However, little is known about their role in MDS. NF-κB-activating ability has been described for both miRNAs. We studied the role of miR-125a/miR-125b in MDS and their relationship with TLR signaling and hematopoietic differentiation. Our results indicate that miR-125a is significantly overexpressed in MDS patients and correlates negatively with patient survival. Expression of miR-99b, which is clustered with miR-125a, is also directly correlated with prognosis of MDS. Both miR-125a and miR-99b activated NF-κB in vitro; however, we observed a negative correlation between miR-99b expression and the levels of TLR2, TLR7 and two downstream genes, suggesting that NF-κB activation by the miRNA cluster occurs in the absence of TLR signaling. We also show that TLR7 is negatively correlated with patient survival in MDS. In addition, our data suggest that miR-125a may act as an NF-κB inhibitor upon TLR stimulation. These results indicate that miR-125a is involved in the fine-tuning of NF-κB activity and that its effects may depend on the status of the TLR pathway. Furthermore, we observed that miR-125a inhibits erythroid differentiation in leukemia and MDS cell lines. Therefore, this miRNA could serve as a prognostic marker and a potential therapeutic target in MDS.

Overexpression of primary microRNA 221/222 in acute myeloid leukemia

Background

Acute myeloid leukemia (AML) is a hematopoietic malignancy with a dismal outcome in the majority of cases. A detailed understanding of the genetic alterations and gene expression changes that contribute to its pathogenesis is important to improve prognostication, disease monitoring, and therapy. In this context, leukemia-associated misexpression of microRNAs (miRNAs) has been studied, but no coherent picture has emerged yet, thus warranting further investigations.

Methods

The expression of 636 human miRNAs was compared between samples from 52 patients with AML and 13 healthy individuals by highly specific locked nucleic acid (LNA) based microarray technology. The levels of individual mature miRNAs and of primary miRNAs (pri-miRs) were determined by quantitative reverse transcriptase (qRT) PCR. Transfections and infections of human cell lines were performed using standard procedures.

Results

64 miRNAs were significantly differentially expressed between AML and controls. Further studies on the clustered miRNAs 221 and 222, already known to act as oncogenes in other tumor types, revealed a deficiency of human myeloid cell lines to process vector derived precursor transcripts. Moreover, endogenous pri-miR-221/222 was overexpressed to a substantially higher extent than its mature products in most primary AML samples, indicating that its transcription was enhanced, but processing was rate limiting, in these cells. Comparison of samples from the times of diagnosis, remission, and relapse of AML demonstrated that pri-miR-221/222 levels faithfully reflected the stage of disease.

Conclusions

Expression of some miRNAs is strongly regulated at the posttranscriptional level in AML. Pri-miR-221/222 represents a novel molecular marker and putative oncogene in this disease.

WITHDRAWN: Inhibition of MicroRNA miR-92a Inhibits Cell Proliferation in Human Acute Promyelocytic Leukemia

This article has been withdrawn due to the fact that it is published in three different journals.

Distinctive microRNA signature is associated with the diagnosis and prognosis of acute leukemia

MicroRNAs (miRNAs) are of great importance in pathogenesis, diagnosis and prognosis of acute leukemia (AL). We studied five AL-related miRNAs to confirm the significance of these miRNAs in AL. Samples tested included acute myeloid leukemia (AML), 107 cases; acute lymphoblastic leukemia (ALL), 40 cases. Five AL-related miRNAs: miR-128, let-7b, miR-223, miR-181a and miR-155 expression were detected by qRT-PCR. Analysis showed that miRNA-128 expression was significantly higher in ALL (P<0.001). However, the let-7b and miR-223 expressions in ALL were significantly lower than in AML (P<0.001). Compared with normal controls, miR-128 expression was significantly higher in ALL (P<0.001), but there was no significant difference in AML (P=0.900). The expressions of Let-7b and miR-223 in AL group were higher than in normal controls (P<0.001). MiR-181a was quantitatively detected in 107 AML patients, and we found that the expression of miR181a in M1 or M2 patients was significantly higher compared with it in M4 or M5 (P=0.013). According to karyotype, 84 cases of AML were classified into three groups named favorable, moderate and poor. It was found that the expression of miR-181a in favorable prognosis group was significantly lower than in poor prognosis group (P=0.015). In FLT3-ITD mutation positive patients, the miR-155 expression was significantly higher than in the negative group (P=0.002). These results support that miR-128, let-7b, miR-223 and miR181a have a diagnosis value in AL, while miR-181a and miR-155 are of great prognostic significance in AML.