miR expression profiling at diagnosis predicts relapse in pediatric precursor B-cell acute lymphoblastic leukemia

miRNAs as predictive biomarkers of response to treatment in pediatric patients with acute lymphoblastic leukemia

MicroRNAs (miRNAs/miRs) are promising prognostic biomarkers in pediatric acute lymphoblastic leukemia (ALL). The present study aimed to identify miRNAs that could serve as prognostic biomarkers or as novel therapeutic targets in ALL. The expression levels of 84 miRNAs were assessed in the bone marrow aspirates of 10 pediatric patients with newly diagnosed ALL at diagnosis and on day 33 of induction of the ALL Intercontinental Berlin-Frankfurt-Münster 2009 protocol, and associations with established prognostic factors were evaluated. The levels at diagnosis of 25 miRNAs were associated with ≥2 prognostic factors. Higher expression levels of let-7c-5p, miR-106b-5p, miR-26a-5p, miR-155-5p, miR-191-5p, miR-30b-5p and miR-31-5p were significantly associated with a good prednisone response. The expression levels of miR-125b-5p, miR-150-5p and miR-99a-5p were significantly higher in standard- or intermediate-risk patients compared with those in high-risk patients (P=0.017, P=0.033 and P=0.017, respectively), as well as in those with a complete response at the end of induction (P=0.044 for all three miRNAs). The change in expression levels between diagnosis and the end of induction differed significantly between risk groups for three miRNAs: miR-206, miR-210 and miR-99a (P=0.033, P=0.047 and P=0.008, respectively), with the post induction levels of miR-206 increased in high-risk patients, whilst miR-210 and miR-99a levels were increased in intermediate/standard risk patients. Therefore, miRNAs that could be integrated into the risk stratification of pediatric ALL after further evaluation in larger patient cohorts were identified.

Clinical Significance of microRNAs in Hematologic Malignancies and Hematopoietic Stem Cell Transplantation

Hematologic malignancies are a group of neoplastic conditions that can develop from any stage of the hematopoiesis cascade. Small non-coding microRNAs (miRNAs) play a crucial role in the post-transcriptional regulation of gene expression. Mounting evidence highlights the role of miRNAs in malignant hematopoiesis via the regulation of oncogenes and tumor suppressors involved in proliferation, differentiation, and cell death. In this review, we provide current knowledge about dysregulated miRNA expression in the pathogenesis of hematological malignancies. We summarize data about the clinical utility of aberrant miRNA expression profiles in hematologic cancer patients and their associations with diagnosis, prognosis, and the monitoring of treatment response. Moreover, we will discuss the emerging role of miRNAs in hematopoietic stem cell transplantation (HSCT), and severe post-HSCT complications, such as graft-versus-host disease (GvHD). The therapeutical potential of the miRNA-based approach in hemato-oncology will be outlined, including studies with specific antagomiRs, mimetics, and circular RNAs (circRNAs). Since hematologic malignancies represent a full spectrum of disorders with different treatment paradigms and prognoses, the potential use of miRNAs as novel diagnostic and prognostic biomarkers might lead to improvements, resulting in a more accurate diagnosis and better patient outcomes.

MiRNAs in Hematopoiesis and Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common kind of pediatric cancer. Although the cure rates in ALL have significantly increased in developed countries, still 15–20% of patients relapse, with even higher rates in developing countries. The role of non-coding RNA genes as microRNAs (miRNAs) has gained interest from researchers in regard to improving our knowledge of the molecular mechanisms underlying ALL development, as well as identifying biomarkers with clinical relevance. Despite the wide heterogeneity reveled in miRNA studies in ALL, consistent findings give us confidence that miRNAs could be useful to discriminate between leukemia linages, immunophenotypes, molecular groups, high-risk-for-relapse groups, and poor/good responders to chemotherapy. For instance, miR-125b has been associated with prognosis and chemoresistance in ALL, miR-21 has an oncogenic role in lymphoid malignancies, and the miR-181 family can act either as a oncomiR or tumor suppressor in several hematological malignancies. However, few of these studies have explored the molecular interplay between miRNAs and their targeted genes. This review aims to state the different ways in which miRNAs could be involved in ALL and their clinical implications.

MicroRNAs and the Diagnosis of Childhood Acute Lymphoblastic Leukemia: Systematic Review, Meta-Analysis and Re-Analysis with Novel Small RNA-Seq Tools

Simple Summary

MicroRNAs (miRNAs) have been under the spotlight for the last three decades. These non-coding RNAs seem to be dynamic regulators of mRNA stability and translation, in addition to interfering with transcription. Circulating miRNAs play a critical role in cell-to-cell interplay; therefore, they can serve as disease biomarkers. Meta-analysis of published data revealed that the CC genotype of rs4938723 in pri-miR-34b/c and the TT genotype of rs543412 in miR-100 confer protection against acute lymphoblastic leukemia (ALL) in children. Reanalysis of small RNA-seq data with novel tools identified significantly overexpressed members of the miR-128, miR-181, miR-130 and miR-17 families and significantly lower expression of miR-30, miR-24-2 and miR143~145 clusters, miR-574 and miR-618 in pediatric T-ALL cases compared with controls. Inconsistencies in methodology and study designs in most published material preclude reproducibility, and further cohort studies need to be conducted in order to empower novel tools, such as ALLSorts and RNAseqCNV.

Abstract

MicroRNAs (miRNAs) have been implicated in childhood acute lymphoblastic leukemia (ALL) pathogenesis. We performed a systematic review and meta-analysis of miRNA single-nucleotide polymorphisms (SNPs) in childhood ALL compared with healthy children, which revealed (i) that the CC genotype of rs4938723 in pri-miR-34b/c and the TT genotype of rs543412 in miR-100 confer protection against ALL occurrence in children; (ii) no significant association between rs2910164 genotypes in miR-146a and childhood ALL; and (iii) SNPs in DROSHA, miR-449b, miR-938, miR-3117 and miR-3689d-2 genes seem to be associated with susceptibility to B-ALL in childhood. A review of published literature on differential expression of miRNAs in children with ALL compared with controls revealed a significant upregulation of the miR-128 family, miR-130b, miR-155, miR-181 family, miR-210, miR-222, miR-363 and miR-708, along with significant downregulation of miR-143 and miR-148a, seem to have a definite role in childhood ALL development. MicroRNA signatures among childhood ALL subtypes, along with differential miRNA expression patterns between B-ALL and T-ALL cases, were scrutinized. With respect to T-ALL pediatric cases, we reanalyzed RNA-seq datasets with a robust and sensitive pipeline and confirmed the significant differential expression of hsa-miR-16-5p, hsa-miR-19b-3p, hsa-miR-92a-2-5p, hsa-miR-128-3p (ranked first), hsa-miR-130b-3p and -5p, hsa-miR-181a-5p, -2-3p and -3p, hsa-miR-181b-5p and -3p, hsa-miR-145-5p and hsa-miR-574-3p, as described in the literature, along with novel identified miRNAs.

Implication of microRNAs in Carcinogenesis with Emphasis on Hematological Malignancies and Clinical Translation

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs, that are involved in the multistep process of carcinogenesis, contributing to all established hallmarks of cancer. In this review, implications of miRNAs in hematological malignancies and their clinical utilization fields are discussed. As components of the complex regulatory network of gene expression, influenced by the tissue microenvironment and epigenetic modifiers, miRNAs are “micromanagers” of all physiological processes including the regulation of hematopoiesis and metabolic pathways. Dysregulated miRNA expression levels contribute to both the initiation and progression of acute leukemias, the metabolic reprogramming of malignantly transformed hematopoietic precursors, and to the development of chemoresistance. Since they are highly stable and can be easily quantified in body fluids and tissue specimens, miRNAs are promising biomarkers for the early detection of hematological malignancies. Besides novel opportunities for differential diagnosis, miRNAs can contribute to advanced chemoresistance prediction and prognostic stratification of acute leukemias. Synthetic oligonucleotides and delivery vehicles aim the therapeutic modulation of miRNA expression levels. However, major challenges such as efficient delivery to specific locations, differences of miRNA expression patterns between pediatric and adult hematological malignancies, and potential side effects of miRNA-based therapies should be considered.

Epigenetic Regulation in Exposome-Induced Tumorigenesis: Emerging Roles of ncRNAs

Environmental factors, including pollutants and lifestyle, constitute a significant role in severe, chronic pathologies with an essential societal, economic burden. The measurement of all environmental exposures and assessing their correlation with effects on individual health is defined as the exposome, which interacts with our unique characteristics such as genetics, physiology, and epigenetics. Epigenetics investigates modifications in the expression of genes that do not depend on the underlying DNA sequence. Some studies have confirmed that environmental factors may promote disease in individuals or subsequent progeny through epigenetic alterations. Variations in the epigenetic machinery cause a spectrum of different disorders since these mechanisms are more sensitive to the environment than the genome, due to the inherent reversible nature of the epigenetic landscape. Several epigenetic mechanisms, including modifications in DNA (e.g., methylation), histones, and noncoding RNAs can change genome expression under the exogenous influence. Notably, the role of long noncoding RNAs in epigenetic processes has not been well explored in the context of exposome-induced tumorigenesis. In the present review, our scope is to provide relevant evidence indicating that epigenetic alterations mediate those detrimental effects caused by exposure to environmental toxicants, focusing mainly on a multi-step regulation by diverse noncoding RNAs subtypes.

An Insight into miR-1290: An Oncogenic miRNA with Diagnostic Potential

For more than two decades, the view of the roles of non-coding RNAs (ncRNAs) has been radically changing. These RNA molecules that are transcribed from our genome do not have the capacity to encode proteins, but are critical regulators of gene expression at different levels. Our knowledge is constantly enriched by new reports revealing the role of these new molecular players in the development of many pathological conditions, including cancer. One of the ncRNA classes includes short RNA molecules called microRNAs (miRNAs), which are involved in the post-transcriptional control of gene expression affecting various cellular processes. The aberrant expression of miRNAs with oncogenic and tumor-suppressive function is associated with cancer initiation, promotion, malignant transformation, progression and metastasis. Oncogenic miRNAs, also known as oncomirs, mediate the downregulation of tumor-suppressor genes and their expression is upregulated in cancer. Nowadays, miRNAs show promising application in diagnosis, prediction, disease monitoring and therapy response. Our review presents a current view of the oncogenic role of miR-1290 with emphasis on its properties as a cancer biomarker in clinical medicine.

The potential role of miR-1290 in cancer progression, diagnosis, prognosis, and treatment: An oncomiR or onco-suppressor microRNA?

Cancer is one of the leading causes of death in humans because of the lack of early diagnosis, distant metastases, and the resistance to adjuvant therapies, including chemotherapy and radiotherapy. In addition to playing an essential role in tumor progression and development, microRNAs (miRNAs) can be used as a robust biomarker in the early detection of cancer. MiR-1290 was discovered for the first time in human embryonic stem cells, and under typical physiological situations, plays an essential role in neuronal differentiation and neural stem cell proliferation. Its coding sequence is located at the 1p36.13 regions in the first intron of the aldehyde dehydrogenase 4 gene member A1. miR-1290 is out of control in many cancers such as breast cancer, colorectal cancer, esophageal squamous cell carcinoma, gastric cancer, lung cancer, pancreatic cancer, and plays a vital role in their development. Therefore, it is suggested that miR-1290 can be considered as a potential diagnostic and therapeutic target in many cancers. In addition to the importance of miR-1290 in the noninvasive diagnosis of various cancers, this systematic review study discussed the role of miR-1290 in altering the expression of different genes involved in cancer development and chemo-radiation resistance. Moreover, it considered the regulatory effect of natural products on miR-1290 expression and the interaction of lncRNAs by miR-1290.

Dysregulation of miRNA in Leukemia: Exploiting miRNA Expression Profiles as Biomarkers

Micro RNAs (miRNAs) are a class of small non-coding RNAs that have a crucial role in cellular processes such as differentiation, proliferation, migration, and apoptosis. miRNAs may act as oncogenes or tumor suppressors; therefore, they prevent or promote tumorigenesis, and abnormal expression has been reported in many malignancies. The role of miRNA in leukemia pathogenesis is still emerging, but several studies have suggested using miRNA expression profiles as biomarkers for diagnosis, prognosis, and response to therapy in leukemia. In this review, the role of miRNAs most frequently involved in leukemia pathogenesis is discussed, focusing on the class of circulating miRNAs, consisting of cell-free RNA molecules detected in several body fluids. Circulating miRNAs could represent new potential non-invasive diagnostic and prognostic biomarkers of leukemia that are easy to isolate and characterize. The dysregulation of some miRNAs involved in both myeloid and lymphoid leukemia, such as miR-155, miR-29, let-7, and miR-15a/miR-16-1 clusters is discussed, showing their possible employment as therapeutic targets.

Non-Coding RNA Signatures of B-Cell Acute Lymphoblastic Leukemia

Non-coding RNAs (ncRNAs) comprise a diverse class of non-protein coding transcripts that regulate critical cellular processes associated with cancer. Advances in RNA-sequencing (RNA-Seq) have led to the characterization of non-coding RNA expression across different types of human cancers. Through comprehensive RNA-Seq profiling, a growing number of studies demonstrate that ncRNAs, including long non-coding RNA (lncRNAs) and microRNAs (miRNA), play central roles in progenitor B-cell acute lymphoblastic leukemia (B-ALL) pathogenesis. Furthermore, due to their central roles in cellular homeostasis and their potential as biomarkers, the study of ncRNAs continues to provide new insight into the molecular mechanisms of B-ALL. This article reviews the ncRNA signatures reported for all B-ALL subtypes, focusing on technological developments in transcriptome profiling and recently discovered examples of ncRNAs with biologic and therapeutic relevance in B-ALL.

MicroRNA as a prognostic biomarker for survival in childhood acute lymphoblastic leukemia: a systematic review

Recent studies suggest abnormal microRNA (miRNA) expression may have potential prognostic value in childhood acute lymphoblastic leukemia (ALL). In this systematic review, we searched different databases (PubMed, ASH, ASCO, and SIOP) for studies published from 2008 to 2018 that evaluated the prognostic impact of miRNAs in childhood ALL. We also used DIANA-miRPath v3.0 to further characterize the functional role of the significant prognostic miRNAs identified in our systematic review. Here we evaluate 15 studies with a total of 38 different miRNAs and 1545 children with B-cell ALL (B-ALL) or T-cell ALL (T-ALL) recruited over approximately 3 decades (1984-2016) with different treatment protocols and ethnicities. Out of the 15 studies examined, 14 reported 32 dysregulated miRNAs with significant prognostic impact in pediatric ALL patients. Only one Brazilian study reported no significant prognostic effect of 7 miRNAs, while the seventh miRNA (miR-100) showed prognostic significance in a Chinese study. Using DIANA-TarBase v7.0 of DIANA-miRPath v3.0, pathway enrichment analysis revealed 25 miRNAs modulated 24 molecular pathways involved in cancer development. To remove the effect of salvage therapy, 9 studies carried out multivariate cox regression analysis for both relapse-free survival and disease-free survival to develop a panel of 23 miRNAs acting as independent prognostic biomarkers. To enhance the clinical application, utility, and validity of the miRNAs discussed here, their potential prognostic value should be confirmed in larger cohort studies within different ethnicities and different ALL protocols adjusted for other contemporary validated prognostic factors in childhood ALL.

miRNA deregulation in childhood acute lymphoblastic leukemia: a systematic review

Despite remarkable improvements in survival of childhood acute lymphoblastic leukemia (ALL), nonresponding or relapsing patients still represent one of the most frequent causes of death by disease in children. Accurate patient risk stratification based on genetic markers could increases survival rates. miRNAs can represent novel candidates with diagnostic, predictive and prognostic potential; however, many groups investigated their involvement with contradictory results. Aim: To clarify the role of miRNAs as biomarkers through a systematic review. Results: From a revision of 45 manuscripts, we found that miR-128 and miR-181 overexpression could represent markers for ALL diagnosis and underexpression of miR-708 and miR-99a could be markers for bad prognosis. Conclusion: These signatures could refine classification and risk stratification of patients and improve ALL outcome.

The role of microRNAs in acute lymphoblastic leukaemia: From biology to applications

MicroRNAs (miRNAs) that are characterized by small, noncoding RNA have an essential role in the pathogenesis of human diseases, including cancer. Furthermore, miRNAs, as a new paradigm of epigenetic regulators, play an important role in normal development and cellular function. This literature review summarizes the recurrent mechanism of gene regulation through miRNAs and, consequently, the impact of regulated genes on different cellular processes, including proliferation, metastasis, prognosis, and apoptosis. Additionally, what is important to note is that the expression of miRNAs in various cancer cells is different, and miRNAs have various target genes in various cancers. Accordingly, a proper understanding of gene regulation by miRNAs contributes to new perspectives in miRNA-based therapeutic strategies. SIGNIFICANCE OF THE STUDY: MiRNAs are considered as a crucial regulator of gene expression. The genes also play an important role in the expression of miRNAs; as a result, there is a relationship between them. In recent years, targeted therapy with miRNAs has been a significant challenge. Studying the mechanisms through which miRNAs regulate various cancer cell processes, including apoptosis, proliferation, and metastasis, is very critical in the treatment of cancer through miRNAs. Definitely, a proper understanding of the impacts of aberrant expression of miRNAs on cancer cell processes leads to new therapeutic strategies in the targeted therapy with miRNAs.

Circulating microRNAs as minimal residual disease biomarkers in childhood acute lymphoblastic leukemia

Background

Treatment stratification based on bone marrow minimal residual disease (MRD) at set time points has resulted in considerably improved survival in pediatric acute lymphoblastic leukemia (ALL). Treatment response is assessed using bone marrow samples. MicroRNAs (miRs) easily traffic among fluid spaces and are more stable than most other RNA classes. We examined the role of circulating miRs as putative less invasive MRD biomarkers.

Methods

In an exploratory experiment, expression of 46 preselected miRs was studied in platelet-free blood plasma samples of 15 de novo, 5 relapsed ALL patients and 10 controls by Custom TaqMan Array Advanced MicroRNA Card. Based on their high expression in ALL compared to controls, and on the reduction observed along the induction therapy, four miRs were selected for further analyses: miR-128-3p, -181a-5p, -181b-5p and 222-3p. Their expression was measured by qPCR at 4 time points in 27 de novo ALL patients treated in the ALL IC-BFM 2009 study.

Results

The expression of all 4 miRs significantly decreased over the first week of therapy (miR-128-3p: log₂ fold change − 2.86; adjusted p 3.6 × 10⁻⁷; miR-181b-5p: log₂ fold change − 1.75; adjusted p 1.48 × 10⁻²; miR-181a-5p: log₂ fold change -1.33; adjusted p 3.12 × 10⁻²; miR-222-3p: log₂ fold change − 1.25; adjusted p 1.66 × 10⁻²). However, no significant further reduction in miR expression was found after the 8th day of therapy. Measured drop in expression of 2 miRs at day 8 strongly correlated with day 15 bone marrow flow cytometry MRD results (miR-128-3p: Pearson’s r = 0.88, adjusted p = 2.71 × 10⁻⁴; miR-222-3p: r = 0.81, adjusted p = 2.99 × 10⁻³).

Conclusion

In conclusion, these circulating miRs might act as biomarkers of residual leukemia. MiR-128-3p and miR-222-3p in blood predict day 15 flow cytometry MRD results 7 days earlier. Although, their sensitivity falls behind that of bone marrow flow cytometry MRD at day 15.

Prognostic value of microRNA-451 in various cancers: A meta-analysis

BACKGROUND

Increasing evidence shows microRNA-451 plays a crucial role in various tumors, but there is inconsistency. The aim of this study was to explore the prognostic role of miR-451 in various tumors.

METHODS

Online PubMed, EMBASE, Web of Science, and the Cochrane library database were searched through February 2019. Hazard ratios (HRs) were extracted and used to describe the association between expression of microRNA-451 and survival outcome, and the correlation between microRNA-451 and clinicopathologic features were described by pooled odds ratios (ORs).

RESULTS

Sixteen retrospective studies containing 2122 patients were incorporated in this meta-analysis. High expression of miR-451 was considered statistically associated with prolonged overall survival (OS) (HR = 0.62, 95% CI 0.49-0.80, p < 0.001) as well as RFS/DFS (HR = 0.55, 95% CI 0.42-0.71, p < 0.001) compared with low expression of miR-451. Besides, the pooled ORs revealed significant association between high expression of miR-451 with lymph node invasion (yes vs. no) (OR = 0.64, 95% CI 0.46-0.90, P = 0.01), tumor diameter (big vs. small) (OR = 0.77, 95% CI 0.60-0.97, P = 0.028) and tumor stage (III + IV vs. I + II) (OR = 0.62, 95% CI 0.42-0.93, P = 0.019).

CONCLUSION

MicroRNA-451 may serve as a promising clinical prognostic biomarker in various carcinomas.

MicroRNA signature refine response prediction in CML

microRNAs (miRs) dysregulation have emerged as a crucial step in tumorigenesis, being related with cancer development, progression and response to treatment. In chronic myeloid leukaemia (CML), the resistance to tyrosine kinase inhibitors (TKI) is responsible for treatment failure and could be linked to changes in miRs expression. This work aimed to correlate the expression levels of 3 miRs, miR-21, miR-26b and miR-451, with response to TKI treatment in CML patients. miR-451 levels at diagnosis were significantly higher in patients with optimal response after 6 and 12 months of therapy. Conversely, patients without optimal response had highest levels of miR-21. miR-21 and miR-451 appear to be good biomarkers of response, able to predict optimal TKI responders (p < 0.05). Using the combined profile of both miRs, we create a predictive model of optimal response after one year of treatment. This study highlights the role of miR-21 and miR-451 expression levels at diagnosis in predicting which patients achieve the optimal response.

Plasma miR-1290 Is a Novel and Specific Biomarker for Early Diagnosis of Necrotizing Enterocolitis-Biomarker Discovery with Prospective Cohort Evaluation

OBJECTIVE

To discover specific circulating microRNA (miRNA) biomarkers for the early differentiation of necrotizing enterocolitis (NEC) from neonatal sepsis and inflammatory conditions.

STUDY DESIGN

The study comprised 3 distinct phases: differential microarray analysis to compare plasma miRNA expression profiles of NEC vs sepsis and non-NEC/nonsepsis cases, a case-control study to quantify dysregulated miRNAs as potential specific biomarkers of NEC, and a prospective cohort study to assess the diagnostic usefulness of the best miRNA biomarker(s).

RESULTS

A distinct miRNA expression profile was observed in the NEC compared with the sepsis and non-NEC/nonsepsis groups. miR-1290, miR-1246, and miR-375 were discovered to be specific biomarkers of NEC in the case-control study. In the cohort study (n = 301), plasma miR-1290 (day 0; >220 copies/µL) provided the greatest diagnostic usefulness for identifying both mild medical and severe surgical NEC cases. Of 20 infants with miR-1290 >650 copies/µL, 15 were diagnosed with NEC. Incorporating C-reactive protein (day 1; >15.8 mg/L) for cases with intermediate levels (220-650 copies/µL) in a 2-stage algorithm further optimized the diagnostic profile with a sensitivity of 0.83, a specificity of 0.96, a positive predictive value of 0.75, and a negative predictive value of 0.98. Importantly, 7 of 36 infants with NEC (19.4%) could be diagnosed 7.8-32.2 hours earlier (median, 13.3 hours) using miR-1290.

CONCLUSIONS

Plasma miR-1290 is a novel and specific biomarker that can effectively differentiate NEC cases from neonatal sepsis. miR-1290 facilitates neonatologists to confidently and timely reach a decision for early transfer of sick infants with NEC from community-based hospitals to tertiary surgical centers.

MicroRNA in leukemia: Tumor suppressors and oncogenes with prognostic potential

Leukemia is known as a progressive malignant disease, which destroys the blood-forming organs and results in adverse effects on the proliferation and development of leukocytes and their precursors in the blood and bone marrow. There are four main classes of leukemia including acute leukemia, chronic leukemia, myelogenous leukemia, and lymphocytic leukemia. Given that a variety of internal and external factors could be associated with the initiation and progression of different types of leukemia. One of the important factors is epigenetic regulators such as microRNAs (miRNAs) and long noncoding RNAs (ncRNA). MiRNAs are short ncRNAs which act as tumor suppressor (i.e., miR-15, miR-16, let-7, and miR-127) or oncogene (i.e., miR-155, miR-17-92, miR-21, miR-125b, miR-93, miR-143-p3, miR-196b, and miR-223) in leukemia. It has been shown that deregulation of these molecules are associated with the initiation and progression of leukemia. Hence, miRNAs could be used as potential therapeutic candidates in the treatment of patients with leukemia. Moreover, increasing evidence revealed that miRNAs could be used as diagnostic and prognostic biomarkers in monitoring patients in early stages of disease or after received chemotherapy regimen. It seems that identification and development of new miRNAs could pave to the way to the development new therapeutic platforms for patients with leukemia. Here, we summarized various miRNAs as tumor suppressor and oncogene which could be introduced as therapeutic targets in treatment of leukemia.

MiRNA Dysregulation in Childhood Hematological Cancer

For decades, cancer biology focused largely on the protein-encoding genes that have clear roles in tumor development or progression: cell-cycle control, apoptotic evasion, genome instability, drug resistance, or signaling pathways that stimulate growth, angiogenesis, or metastasis. MicroRNAs (miRNAs), however, represent one of the more abundant classes of cell modulators in multicellular organisms and largely contribute to regulating gene expression. Many of the ~2500 miRNAs discovered to date in humans regulate vital biological processes, and their aberrant expression results in pathological and malignant outcomes. In this review, we highlight what has been learned about the roles of miRNAs in some of the most common human pediatric leukemias and lymphomas, along with their value as diagnostic/prognostic factors.

Differential Co-expression and Regulatory Network Analysis Uncover the Relapse Factor and Mechanism of T Cell Acute Leukemia

The pediatric T cell acute lymphoblastic leukemia (T-ALL) still remains a cancer with worst prognosis for high recurrence. Massive studies were conducted for the leukemia relapse based on diagnosis and relapse paired samples. However, the initially diagnostic samples may contain the relapse information and mechanism, which were rarely studied. In this study, we collected mRNA and microRNA (miRNA) data from initially diagnosed pediatric T-ALL samples with their relapse or remission status after treatment. Integrated differential co-expression and miRNA-transcription factor (TF)-gene regulatory network analyses were used to reveal the possible relapse mechanisms for pediatric T-ALL. We detected miR-1246/1248 and NOTCH2 served as key nodes in the relapse network, and they combined with TF WT1/SOX4/REL to form regulatory modules that influence the progress of T-ALL. A regulatory loop miR-429-MYCN-MFHAS1 was found potentially associated with the remission of T-ALL. Furthermore, we proved miR-1246/1248 combined with NOTCH2 could promote cell proliferation in the T-ALL cell line by experiments. Meanwhile, analysis based on the miRNA-drug relationships demonstrated that drugs 5-fluorouracil, ascorbate, and trastuzumab targeting miR-1246 could serve as potential supplements for the standard therapy. In conclusion, our findings revealed the potential molecular mechanisms of T-ALL relapse by the combination of co-expression and regulatory network, and they provide preliminary clues for precise treatment of T-ALL patients.

Role of miRNAs in treatment response and toxicity of childhood acute lymphoblastic leukemia

Childhood acute lymphoblastic leukemia survival rates have increased remarkably during last decades due, in part, to intensive treatment protocols. However, therapy resistance and toxicity are still two important barriers to survival. In this context, pharmacoepigenetics arises as a tool to identify new predictive markers, required to guide clinicians on risk stratification and dose individualization. The present study reviews current evidence about miRNA implication on childhood acute lymphoblastic leukemia therapy resistance and toxicity. A total of 12 studies analyzing differential miRNA expression in relation to drug resistance and six studies exploring the association between miRNAs-related SNPs and drug-induced toxicities were identified. We pointed out to miR-125b together with miR-99a and/or miR-100 overexpression as markers of vincristine resistance and rs2114358 in mir-1206 as mucositis marker as the most promising results.

Increased T-helper 17 cell differentiation mediated by exosome-mediated microRNA-451 redistribution in gastric cancer infiltrated T cells

MicroRNA (miR)‐451 is a cell metabolism‐related miRNA that can mediate cell energy‐consuming models by several targets. As miR‐451 can promote mechanistic target of rapamycin (mTOR) activity, and increased mTOR activity is related to increased differentiation of T‐helper 17 (Th17) cells, we sought to investigate whether miR‐451 can redistribute from cancer cells to infiltrated T cells and enhance the distribution of Th17 cells through mTOR. Real‐time PCR was used for detecting expression of miR‐451 in gastric cancer, tumor infiltrated T cells and exosomes, and distribution of Th17 was evaluated by both flow cytometry and immunohistochemistry (IHC). Immunofluorescence staining was used in monitoring the exosome‐enveloped miR‐451 from cancer cells to T cells with different treatments, and signaling pathway change was analyzed by western blot. miR‐451 decreased significantly in gastric cancer (GC) tissues but increased in infiltrated T cells and exosomes; tumor miR‐451 was negatively related to infiltrated T cells and exosome miR‐451. Exosome miR‐451 can not only serve as an indicator for poor prognosis of post‐operation GC patients but is also related to increased Th17 distribution in gastric cancer. miR‐451 can redistribute from cancer cells to T cells with low glucose treatment. Decreased 5′ AMP‐activated protein kinase (AMPK) and increased mTOR activity was investigated in miR‐451 redistributed T cells and the Th17 polarized differentiation of these T cells were also increased. Exosome miR‐451 derived from tumor tissues can serve as an indicator for poor prognosis and redistribution of miR‐451 from cancer cells to infiltrated T cells in low glucose treatment can enhance Th17 differentiation by enhancing mTOR activity.

Integrative Analysis of MicroRNA-Mediated Gene Signatures and Pathways Modulating White Blood Cell Count in Childhood Acute Lymphoblastic Leukemia

MicroRNAs (miRNAs) regulate the expression of protein-coding genes and represent potential biomarkers for childhood acute lymphoblastic leukemia (ALL). However, information linking miRNAs with their messenger RNA (mRNA) target genes modulating white blood cell (WBC) count is lacking. Here, we analyzed miRNAs and gene expression data from pediatric patients with ALL to identify a signature of miRNAs involved in ALL and their mRNA target genes, molecular networks, and biological pathways modulating WBC. We discovered a signature of miRNAs differentially expressed in ALL and a signature of mRNA target genes distinguishing patients with high WBC from patients with low WBC. In addition, we identified molecular networks and biological pathways, among them PI3/AKT, JAK/STAT, IL-17, TGF-β, apoptosis, IL-15, STAT3, IGF-1, FGF, mTOR, VEGF, NF-kB, and P53 signaling pathways, enriched for or targeted by miRNAs. The discovered miRNAs and their target genes and pathways represent potential clinically actionable biomarkers and therapeutic targets.

MicroRNAs as prognostic biomarker and relapse indicator in leukemia

Despite significant progress in the treatment of different types of leukemia, relapse remains a challenging clinical problem that is observed in a number of patients who are often resistant to chemotherapy and exhibit multi-drug resistance. Identification of new functional biomarkers, including microRNAs, is essential to determine prognosis and relapse at the time of diagnosis. The aim of this study was to detect the specific microRNAs involved in predicting relapse or progression in acute and chronic leukemias, as well as their relationship with overall survival (OS) and relapse-free survival (RFS). The relevant literature was identified through a PubMed and Scholar search (2008-2016) of English-language papers using the terms Leukemia, microRNAs, survival and relapse. Different leukemia types and subtypes show specific microRNA expression profile and different changes, which can be useful in the differentiation between leukemias and evaluation of relapse at the time of diagnosis. Altered microRNA expression profiles can turn these molecules into oncogenes or tumor suppressors, which affect the expression of relapse-related genes. Therefore, monitoring of specific microRNA expression profiles from diagnosis and during follow-up of patients can contribute to the assessment of outcome and determination of relapse and prognosis of leukemic patients.

MicroRNA profiling in peripheral T-cell lymphoma, not otherwise specified

BACKGROUND

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is an obviously heterogeneous and highly invasive malignancy without definite phenotype. MicroRNAs (miRNAs) are powerful gene regulators and have been reported as biomarkers in many malignancies.

OBJECTIVE

To discover potential signaling miRNAs in PTCL-NOS distinguished from reactive lymphoid hyperplasia (RLH) and to explore the molecular characteristics based on the discovery.

METHODS

We measured the expression profile of miRNAs in PTCL-NOS and RLH from our patients using a panel PCR array. We used GO-Analysis to evaluate the function of the targets regulated by the detected miRNAs. Then using pathway enrichment analysis, we defined potential pathways connected with the selected miRNAs.

RESULTS

We found 20 miRNAs which were remarkably up/down-regulated in PTCL-NOS. GO-Analysis and pathway analysis indicated 61 GOs and 34 signaling pathways that were significantly increased or decreased regarding tumorigenesis, tumor progression, invasion, metastasis, and drug resistance.

CONCLUSIONS

Briefly, our results suggest that 20 miRNAs have the potential to be used as biomarker for identification of patients with PTCL-NOS.

miR-196b/miR-1290 participate in the antitumor effect of resveratrol via regulation of IGFBP3 expression in acute lymphoblastic leukemia

MicroRNAs play critical roles in the progression of acute lymphoblastic leukemia (ALL). Previous studies have indicated that miR-196b and miR-1290 play critical roles in T-cell ALL (T-ALL) and B-cell ALL (B-ALL), respectively. Resveratrol, a natural edible polyphenolic phytoalexin, possesses certain anticancer activities. Nevertheless, the mechanism involved in the regulation of ALL by resveratrol is still poorly understood. The present study aimed to reveal the potential mechanism underlying the antitumor effect of resveratrol in ALL focusing on miRNAs. Research indicates that insulin-like growth factor binding protein 3 (IGFBP3) plays a critical role in the aetiology of ALL. In the present study, we first demonstrated that the expression of IGFBP3 was decreased in ALL patients. We further identified that miR-196b and miR-1290 were overexpressed in T-ALL TALL-104 and B-ALL SUP-B15 cell lines, respectively. Moreover, resveratrol markedly decreased the overexpression of miR-196b/miR-1290 and elevated IGFBP3 expression in the ALL cell lines. As an miR-196b/miR-1290 inhibitor, resveratrol was further demonstrated to exert antitumor effects on ALL cells including antiproliferation, cell cycle arrest, apoptosis and inhibition of migration. Dual-luciferase reporter assay revealed that miR-196b/miR-1290 directly bound to the 3'-untranslated (3'-UTR) region of IGFBP3 mRNA. Moreover, we observed that IGFBP3 short interfering RNA reversed the antitumor activity of resveratrol against ALL cells. Taken together, the present study provides evidence that resveratrol targets miR-196b and miR-1290 for its antitumor activity in T-ALL and B-ALL, respectively. The present study also confirms that both miR‑196b and miR-1290 target the IGFBP3 3'-UTR and are potential therapeutic targets for ALL.

Clinical significance of microRNAs in chronic and acute human leukemia

Small non-coding microRNAs (miRNAs) are epigenetic regulators that target specific cellular mRNA to modulate gene expression patterns and cellular signaling pathways. miRNAs are involved in a wide range of biological processes and are frequently deregulated in human cancers. Numerous miRNAs promote tumorigenesis and cancer progression by enhancing tumor growth, angiogenesis, invasion and immune evasion, while others have tumor suppressive effects (Hayes, et al., Trends Mol Med 20(8): 460-9, 2014; Stahlhut and Slack, Genome Med 5 (12): 111, 2013). The expression profile of cancer miRNAs can be used to predict patient prognosis and clinical response to treatment (Bouchie, Nat Biotechnol 31(7): 577, 2013). The majority of miRNAs are intracellular localized, however circulating miRNAs have been detected in various body fluids and represent new biomarkers of solid and hematologic cancers (Fabris and Calin, Mol Oncol 10(3):503-8, 2016; Allegra, et al., Int J Oncol 41(6): 1897-912, 2012). This review describes the clinical relevance of miRNAs, lncRNAs and snoRNAs in the diagnosis, prognosis and treatment response in patients with chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML) and acute adult T-cell leukemia (ATL).