microRNA-181a enhances cell proliferation in acute lymphoblastic leukemia by targeting EGR1

EBV and 1q Gains Affect Gene and miRNA Expression in Burkitt Lymphoma

Abnormalities of the long arm of chromosome 1 (1q) represent the most frequent secondary chromosomal aberrations in Burkitt lymphoma (BL) and are observed almost exclusively in EBV-negative BL cell lines (BL-CLs). To verify chromosomal abnormalities, we cytogenetically investigated EBV-negative BL patient material, and to elucidate the 1q gain impact on gene expression, we performed qPCR with six 1q-resident genes and analyzed miRNA expression in BL-CLs. We observed 1q aberrations in the form of duplications, inverted duplications, isodicentric chromosome idic(1)(q10), and the accumulation of 1q12 breakpoints, and we assigned 1q21.2-q32 as a commonly gained region in EBV-negative BL patients. We detected MCL1, ARNT, MLLT11, PDBXIP1, and FCRL5, and 64 miRNAs, showing EBV- and 1q-gain-dependent dysregulation in BL-CLs. We observed MCL1, MLLT11, PDBXIP1, and 1q-resident miRNAs, hsa-miR-9, hsa-miR-9*, hsa-miR-92b, hsa-miR-181a, and hsa-miR-181b, showing copy-number-dependent upregulation in BL-CLs with 1q gains. MLLT11, hsa-miR-181a, hsa-miR-181b, and hsa-miR-183 showed exclusive 1q-gains-dependent and FCRL5, hsa-miR-21, hsa-miR-155, hsa-miR-155*, hsa-miR-221, and hsa-miR-222 showed exclusive EBV-dependent upregulation. We confirmed previous data, e.g., regarding the EBV dependence of hsa-miR-17-92 cluster members, and obtained detailed information considering 1q gains in EBV-negative and EBV-positive BL-CLs. Altogether, our data provide evidence for a non-random involvement of 1q gains in BL and contribute to enlightening and understanding the EBV-negative and EBV-positive BL pathogenesis.

The Importance of Selected Dysregulated microRNAs in Diagnosis and Prognosis of Childhood B-Cell Precursor Acute Lymphoblastic Leukemia

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a frequent type of childhood hematological malignancy. The disease is classified into several subtypes according to genetic abnormalities. MicroRNAs (miRNAs) are involved in pathological processes (e.g., proliferation, apoptosis, differentiation). A miRNA is a group of short non-coding RNAs with relevant regulatory effects on gene expression achieved by suppression of the translation or degradation of messenger RNA (mRNA). These molecules act as tumor suppressors and/or oncogenes in the pathogenesis of pediatric leukemias. The characteristic features of miRNAs are their stable form and the possibility of secretion to the circulatory system. The role of miRNA in BCP-ALL pathogenesis is still emerging, but several studies have suggested using miRNA expression profiles as biomarkers for diagnosis, prognosis, and response to therapy in leukemia. The dysregulation of some miRNAs involved in childhood acute lymphoid leukemia, such as miR-155, miR-200c, miR-100, miR-181a, miR125b, and miR146a is discussed, showing their possible employment as therapeutic targets. In the current review, the capabilities of miRNAs in non-invasive diagnostics and their prognostic potential as biomarkers are presented.

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.

Early Growth Response Factor 1 in Aging Hematopoietic Stem Cells and Leukemia

Aging is associated with various hematological disorders and a higher risk of myeloproliferative disorders. An aged hematopoietic system can be characterized by decreased immune function and increased myeloid cell production. Hematopoietic stem cells (HSCs) regulate the production of blood cells throughout life. The self-renewal and regenerative potential of HSCs determine the quality and quantity of the peripheral blood cells. External signals from the microenvironment under different conditions determine the fate of the HSCs to proliferate, self-renew, differentiate, or remain quiescent. HSCs respond impromptu to a vast array of extracellular signaling cascades such as cytokines, growth factors, or nutrients, which are crucial in the regulation of HSCs. Early growth response factor 1 (EGR1) is one of the key transcription factors controlling HSC proliferation and their localization in the bone marrow (BM) niche. Downregulation of Egr1 activates and recruits HSCs for their proliferation and differentiation to produce mature blood cells. Increased expression of Egr1 is implicated in immuno-aging of HSCs. However, dysregulation of Egr1 is associated with hematological malignancies such as acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), and chronic myelogenous leukemia (CML). Here, we summarize the current understanding of the role of EGR1 in the regulation of HSC functionality and the manifestation of leukemia. We also discuss the alternative strategies to rejuvenate the aged HSCs by targeting EGR1 in different settings.

Fucoidan-Mediated Inhibition of Fibrotic Properties in Oral Submucous Fibrosis via the MEG3/miR-181a/Egr1 Axis

Oral submucous fibrosis (OSF) is a chronic fibrotic remodeling disease that can progress to oral cancer. However, efficient clinical diagnosis and treatment methods for OSF are still lacking. This study investigated the anti-fibrotic effect of fucoidan on oral fibrosis. To evaluate the fibrotic ability (myofibroblast activities), we performed wound-healing, Transwell migration, and collagen contraction assays by using patient-derived normal and fibrotic buccal submucous fibroblasts (BMFs and fBMFs, respectively). RNA-sequencing and dual-luciferase reporter and RNA immunoprecipitation chip assays were performed to identify the clinical significance and molecular mechanism of non-coding RNAs. Fucoidan suppressed the myofibroblast activities and inhibited the MEG3 in fBMFs. MEG3 was overexpressed in the OSF tissue and was positively associated with myofibroblast markers. Knockdown of MEG3 markedly inhibited myofibroblast activities, which were restored by inhibiting miR-181a and overexpressing Egr1. The results from luciferase reporter and RIP assays confirmed that MEG3 functioned as a competing endogenous RNA (ceRNA) and could directly target miR-181a, thereby preventing the miR-181a-mediated translational repression of Egr1. This study demonstrated that MEG3 exerts a profibrotic effect on OSF by targeting miR-181a/Egr1. Therefore, the administration of fucoidan may serve as a potential therapeutic strategy for OSF by targeting the overexpression of MEG3.

Small Non-Coding RNAs in Leukemia

In 2020, more than 60,500 people were diagnosed with leukemia in the USA, and more than 23,000 died. The incidence of leukemia is still rising, and drug resistance development is a serious concern for patients' wellbeing and survival. In the past two decades, small non-coding RNAs have been studied to evaluate their functions and possible role in cancer pathogenesis. Small non-coding RNAs are short RNA molecules involved in several cellular processes by regulating the expression of genes. An increasing body of evidence collected by many independent studies shows that the expression of these molecules is tissue specific, and that their dysregulation alters the expression of genes involved in tumor development, progression and drug response. Indeed, small non-coding RNAs play a pivotal role in the onset, staging, relapse and drug response of hematological malignancies and cancers in general. These findings strongly suggest that small non-coding RNAs could function as biomarkers and possible targets for therapy. Thus, in this review, we summarize the regulatory mechanisms of small non-coding RNA expression in different types of leukemia and assess their potential clinical implications.

Exosomal miR-181a-5p reduce Mycoplasma gallisepticum (HS strain) infection in chicken by targeting PPM1B and activating the TLR2-mediated MyD88/NF-κB signaling pathway

Mycoplasma gallisepticum (MG) is one of the most important pathogens that causes chronic respiratory disease (CRD) in chickens. Exosomes secreted from cells have been well demonstrated to deliver miRNAs to recipient cells to modulate cellular functions. The purpose of this study is to explore the underlying functions and mechanisms of exosomal miR-181a-5p in MG-HS infection. In this study, we found that miR-181a-5p expression in vivo and in vitro was significantly up-regulated after MG-HS infection. It was also upregulated in exosomes, which were derived from MG-HS-infected type-II pneumocytes cells (CP-II). In addition, exosomes secreted by MG-HS-infected CP-II were able to transfer miR-181a-5p to recipient chicken embryo fibroblast cells (DF-1), resulting in a significant upregulation of miR-181a-5p expression in recipient DF-1 cells. We further identified that Mg²⁺/Mn²⁺-dependent protein phosphatase 1B (PPM1B) was the target gene of miR-181a-5p. Overexpression of miR-181a-5p or knockdown of PPM1B activated the nuclear factor-κB (NF-κB) signaling pathway, whereas inhibition of miR-181a-5p and overexpression of PPM1B led to the opposite results. Besides, up-regulation of miR-181a-5p significantly increased the expression of toll-like receptor 2 (TLR2), myeloid differentiation factor 88 (MyD88), tumor necrosis factors alpha (TNF-α) and interleukin-1β (IL-1β), whereas inhibition of miR-181a-5p showed a contrary result. Up-regulation of miR-181a-5p promoted cell proliferation, cell cycle progression and inhibited apoptosis to resist MG-HS infection. Moreover, overexpression of miR-181a-5p significantly negative regulated the expression of Mycoplasma gallisepticum adhesin protein (pMGA1.2) by directly inhibiting PPM1B. Thus, we concluded that exosomal miR-181a-5p from CP-II cells activated the TLR2-mediated MyD88/NF-κB signaling pathways by directly targeting PPM1B to promote the expression of pro-inflammatory cytokines for defending against MG-HS infection in recipient DF-1 cells.

Extracellular vesicles derived from T-cell acute lymphoblastic leukemia inhibit osteogenic differentiation of bone marrow mesenchymal stem cells via miR-34a-5p

Reduced bone formation in patients with T-cell acute lymphoblastic leukemia (T-ALL) may be related to the interaction between tumour cells and bone marrow stromal cells (BMSCs). The miRNAs in extracellular vesicles derived from leukemia cells play an essential role in regulating the function of BMSCs; however, the regulatory mechanisms remain unclear. The expression of miR-34a-5p in T-ALL patients and cells was measured by quantitative real-time PCR. BMSCs were co-cultured with extracellular vesicles isolated from T-ALL cells in mineralization medium. The osteogenic differentiation of BMSCs was evaluated by Alizarin Red S staining, alkaline phosphatase (ALP) staining, and detection of osteogenic differentiation markers. A dual-luciferase reporter assay was performed to confirm the targeting relationship between miR-34a-5p and Wnt family member 1 (WNT1). MiR-34a-5p expression was upregulated in T-ALL patients and Jurkat cells. After BMSCs were co-cultured with extracellular vesicles derived from T-ALL cells, osteogenic differentiation of BMSCs was inhibited, and bone mineralization and ALP activity were decreased compared to those of control cells. MiR-34a-5p knockdown in T-ALL cells restored osteogenic differentiation of BMSCs co-cultured with extracellular vesicles. In addition, miR-34a-5p targets and negatively regulates WNT1 expression. In conclusion, our results demonstrated that knockdown of miR-34a-5p in extracellular vesicles derived from T-ALL cells promoted osteogenic differentiation of BMSCs by regulating WNT1.

MicroRNAs Patterns as Potential Tools for Diagnostic and Prognostic Follow-Up in Cancer Survivorship

Advances in screening methods and pharmacological treatments are increasing the life expectancy of cancer patients. During recent decades, the community of long-term disease-free cancer survivors (LCS) has grown exponentially, raising the issues related to cancer follow-up. Cancer relapse and other cancer-related diseases, as well as lifestyle, influence cancer survival. Recently, the regulatory role of microRNAs (miRNAs) in gene expression and their involvement in human diseases, including cancer, has been identified. Extracellular circulating miRNAs (ECmiRNAs) have been found in biological fluids and specific ECmiRNAs have been associated with cancer development and progression or with a therapy response. Here, we focus on the pivotal role of ECmiRNAs as biomarkers in cancer diagnosis and prognosis. Then, we discuss the relevance of ECmiRNAs expression in cancer survivors for the identification of specific ECmiRNAs profiles as potential tools to assess cancer outcome and to control LCS follow-up.

MicroRNA-181a/b-1-encapsulated PEG/PLGA nanofibrous scaffold promotes osteogenesis of human mesenchymal stem cells

Bioactive nanofibres play a useful role in increasing the efficiency of tissue engineering scaffolds. MicroRNAs (miRs) alone, and in combination with tissue engineering scaffolds, can be effective in treating bone fractures and osteoporosis by regulating many post‐transcriptional cellular pathways. Herein, miR‐181a/b‐1 was incorporated in the electrospun poly (lactic‐co‐glycolic acid) (PLGA) nanofibres (PLGA‐miR). After characterization scaffolds, the osteoinductive capacity of the nanofibres was investigated when adipose‐derived mesenchymal stem cells (AT‐MSCs) were cultured on the PLGA and PLGA‐miR nanofibres. miR incorporating in the nanofibres has not any significant effect on the size and morphology of the nanofibres, but its biocompatibility was increased significantly compared to the empty nanofibres. Alkaline phosphatase (ALP) activity and calcium measures were evaluated as two important osteogenic markers, and the results revealed that the highest measures were observed in the AT‐MSCs cultured on PLGA‐miR nanofibres. Detected ALP activity and calcium measures in miR‐transduced AT‐MSCs cultured on TCPS were also significantly higher than AT‐MSCs cultured on PLGA and TCPS groups. The highest expression levels of bone‐related genes were observed in the AT‐MSCs cultured on PLGA‐miR nanofibres. This improvement in the osteogenic differentiation potential of the AT‐MSCs was also confirmed by evaluating osteopontin protein in the cells cultured on PLGA‐miR. It can be concluded that miR‐181a/b‐1 has a significant impact on the AT‐MSC osteogenic differentiation, and this impact synergistically increased when incorporated in the PLGA nanofibres.

The pathological growth of the prostate gland in atherogenic contexts

The human prostate is an androgen-dependent gland where an imbalance in cell proliferation can lead to benign prostatic hyperplasia (BPH), which results in voiding lower urinary tract symptoms in the elderly. In the last decades, novel evidence has suggested that BPH might represent an element into the wide spectrum of disorders conforming the Metabolic Syndrome (MS). The dyslipidemic state and the other atherogenic factors of the MS have been shown to induce, maintain and/or aggravate the pathological growth of different organs, with data regarding the prostate being still limited. We here review the available epidemiological and experimental studies about the association of BPH with dyslipidemias. In particular, we have focused on Oxidized Low-Density Lipoproteins (OxLDL) as a potential trigger for vascular disease and cellular proliferation in atherogenic contexts, analyzing their putative molecular mechanisms, including the induction of specific extracellular vesicles (EVs)-derived miRNAs. In addition to the epidemiological evidence, OxLDL is proposed to play a fundamental role in the upregulation of prostatic cell proliferation by activating the Rho/Akt/p27^Kip1 pathway in atherogenic contexts. miR-21, miR-141, miR-143, miR-145, miR-155, and miR-221 would be involved in the transcription of genes related to the proliferative process. Although much remains to be investigated regarding the impact of OxLDL, its receptors, and molecular mechanisms on the prostate, it is clear that EVs and miRNAs represent a promising target for proliferative pathologies of the prostate gland.

Oncogenic role of lncRNA CRNDE in acute promyelocytic leukemia and NPM1-mutant acute myeloid leukemia

The PML/RARα fusion protein acts in concert with cooperative genetic events in the development of acute promyelocytic leukemia (APL). However, oncogenic long non-coding RNAs (lncRNAs) cooperating with PML/RARα remain under-explored. Here, we first identified a set of pathogenesis-related lncRNAs, aberrantly expressed in APL using RNA-seq data from a large cohort of acute myeloid leukemia (AML) patients and normal counterparts. Among the pathogenesis-related lncRNAs, one of the evolutionarily conservative lncRNAs CRNDE (Colorectal Neoplasia Differentially Expressed) drew our attention. We found that CRNDE was highly expressed in the disease state but not in the preleukemic stage of APL, suggesting that CRNDE might be a secondary event coordinating with PML/RARα to promote APL development. Functional analysis showed that CRNDE knockdown induced differentiation and inhibited proliferation of APL cells, and prolonged survival of APL mice. Further mechanistic studies showed that CRNDE elicited its oncogenic effects through binding the miR-181 family and thereby regulating NOTCH2. Finally, we found that high CRNDE expression was also significantly correlated with NPM1 mutations and contributed to the differentiation block in NPM1-mutant AML. Collectively, our findings shed light on the importance of oncogenic lncRNAs in the development of AML and provide a promising target for AML therapy.

Expression of microRNA-181a and microRNA-196b in Egyptian Pediatric acute Lymphoblastic Leukemia

Background:

Differential expression of miRNA provides important insights into pathogenesis of cancer including leukemia. Deregulation of microRNA may contribute to hematopoietic malignancies. In this study, we aimed to evaluate the role of miR-181a and miR-196b in acute lymphoblastic leukemia (ALL) and correlate their expression with clinical and laboratory data.

Methods:

The study was performed on bone marrow samples of 70 consecutive newly diagnosed pediatric (ALL) patients, of which 56 were evaluated for both miR-181a and miR-196b (all 70 for miR-181a) by real-time quantitative reverse transcriptase polymerase chain reaction (RT-qPCR). In addition, bone marrow from seven age and sex matched healthy controls derived from donors of bone marrow transplantation were assessed.

Results:

miR-181a expression was significantly up-regulated in ALL patients compared with healthy controls (p<0.001). However, miR-196b expression was significantly down-regulated in patients compared with healthy controls (p=0.038).

Conclusion:

Our results suggest that miR-181a has an oncogenic, while miR-196b has a tumor suppressive role in pediatric ALL patients. A finding which demonstrate the potential role of these microRNAs in pathogenesis of pediatric ALL. Also, estimation of their expression level may provide a tool for confirmation of a diagnosis of childhood ALL and could be a possible predictor of early relapse.

Silencing of Exosomal miR-181a Reverses Pediatric Acute Lymphocytic Leukemia Cell Proliferation

Exosomes are cell-generated nano-vesicles found in most biological fluids. Major components of their cargo are lipids, proteins, RNA, DNA, and non-coding RNAs. The miRNAs carried within exosomes reveal real-time information regarding disease status in leukemia and other cancers, and therefore exosomes have been studied as novel biomarkers for cancer. We investigated the impact of exosomes on cell proliferation in pediatric acute lymphocytic leukemia (PALL) and its reversal by silencing of exo-miR-181a. We isolated exosomes from the serum of PALL patients (Exo-PALL) and conditioned medium of leukemic cell lines (Exo-CM). We found that Exo-PALL promotes cell proliferation in leukemic B cell lines by gene regulation. This exosome-induced cell proliferation is a precise event with the up-regulation of proliferative (PCNA, Ki-67) and pro-survival genes (MCL-1, and BCL2) and suppression of pro-apoptotic genes (BAD, BAX). Exo-PALL and Exo-CM both show over expression of miR-181a compared to healthy donor control exosomes (Exo-HD). Specific silencing of exosomal miR-181a using a miR-181a inhibitor confirms that miR-181a inhibitor treatment reverses Exo-PALL/Exo-CM-induced leukemic cell proliferation in vitro. Altogether, this study suggests that exosomal miR-181a inhibition can be a novel target for growth suppression in pediatric lymphatic leukemia.

MicroRNA-181a as novel liquid biopsy marker of central nervous system involvement in pediatric acute lymphoblastic leukemia

Background

Refractory central nervous system (CNS) involvement is among the major causes of therapy failure in childhood acute leukemia. Applying contemporary diagnostic methods, CNS disease is often underdiagnosed. To explore more sensitive and less invasive CNS status indicators, we examined microRNA (miR) expressions and extracellular vesicle (EV) characteristics.

Methods

In an acute lymphoblastic leukemia (ALL) discovery cohort, 47 miRs were screened using Custom TaqMan Advanced Low-Density Array gene expression cards. As a validation step, a candidate miR family was further scrutinized with TaqMan Advanced miRNA Assays on serial cerebrospinal fluid (CSF), bone marrow (BM) and peripheral blood samples with different acute leukemia subtypes. Furthermore, small EV-rich fractions were isolated from CSF and the samples were processed for immunoelectron microscopy with anti-CD63 and anti-CD81 antibodies, simultaneously.

Results

Regarding the discovery study, principal component analysis identified the role of miR-181-family (miR-181a-5p, miR-181b-5p, miR-181c-5p) in clustering CNS-positive (CNS⁺) and CNS-negative (CNS^‒) CSF samples. We were able to validate miR-181a expression differences: it was about 52 times higher in CSF samples of CNS⁺ ALL patients compared to CNS^‒ cases (n = 8 vs. n = 10, ΔFC = 52.30, p = 1.5E−4), and CNS⁺ precursor B cell subgroup also had ninefold higher miR-181a levels in their BM (p = 0.04). The sensitivity of CSF miR-181a measurement in ALL highly exceeded those of conventional cytospin in the initial diagnosis of CNS leukemia (90% vs. 54.5%). Pellet resulting from ultracentrifugation of CNS⁺ CSF samples of ALL patients showed atypical CD63⁻/CD81⁻ small EVs in high density by immunoelectron microscopy.

Conclusions

After validating in extensive cohorts, quantification of miR-181a or a specific EV subtype might provide novel tools to monitor CNS disease course and further adjust CNS-directed therapy in pediatric ALL.

microRNA-181 serves as a dual-role regulator in the development of human cancers

MicroRNAs (miRNAs) as the regulatory short noncoding RNAs are involved in a wide array of cellular and molecular processes. They negatively regulate gene expression and their dysfunction is correlated with cancer development through modulation of multiple signaling pathways. Therefore, these molecules could be considered as novel biomarkers and therapeutic targets for more effective management of human cancers. Recent studies have demonstrated that the miR-181 family is dysregulated in various tumor tissues and plays a pivotal role in carcinogenesis. They have been shown to act as oncomirs or tumor suppressors considering their mRNA targets and to be involved in cell proliferation, apoptosis, autophagy, angiogenesis and drug resistance. Additionally, these miRNAs have been demonstrated to exert their regulatory effects through modulating multiple signaling pathways including PI3K/AKT, MAPK, TGF-b, Wnt, NF-κB, Notch pathways. Given that, in this review, we briefly summarise the recent studies that have focused on the roles of miRNA-181 family as the multifunctional miRNAs in tumorigenesis and cancer development. These miRNAs may serve as diagnostic and prognostic biomarkers or therapeutic targets in human cancer gene therapy.

MiR-181a functions as an oncogene by regulating CCND1 in multiple myeloma

MicroRNA-181a (miR-181a) has been demonstrated to be upregulated in patients with multiple myeloma (MM). In several studies, miR-181a has been demonstrated to be significantly overexpressed in MM; however, its potential role in development and progression of MM remains unknown. In the present study, the functions of miR-181a and the potential underlying molecular mechanisms in the pathogenesis of MM were examined. Increased expression of miR-181a was observed in bone marrow samples from patients with MM and the MM RPMI8226 cell line. The role of miR-181a was examined and it was demonstrated that it participated in the proliferation and migration processes of the MM cell line. Furthermore, it was demonstrated that the downregulation of miR-181a inhibited the expression of CCND1, a cell cycle regulatory gene, and caused cell cycle arrest in MM cells. The results of the present study suggested that miR-181a functions as an onco-miRNA in MM, which serves regulatory roles by upregulating expression of CCND1 and may therefore serve as a potential target in patients with MM.

Alteration in Expression of miR-32 and FBXW7 Tumor Suppressor in Plasma Samples of Patients with T-cell Acute Lymphoblastic Leukemia

Background

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive and malignant neoplasm that arises from the hematopoietic T-cell precursors. Inactivation of FBXW7 gene is frequently observed in T-cell acute lymphoblastic leukemia, suggesting a significant tumor-suppressive role for FBXW7 in the pathobiology of this leukemia. Considering the role of microRNAs in cell proliferation and regulation of apoptosis, the aim of this study was to identify novel oncogenic microRNAs that suppress FBXW7 in patients with T-ALL.

Patients and Methods

The expression levels of two bioinformatically predicted microRNAs – miR-32 and miR-107 were compared in patients with T-ALL and a control group. A total of 80 plasma samples were subjected to RNA extraction, and the microRNA expression profiles were assessed by the RT-qPCR. The expression level of miR-103 was used as the endogenous reference for normalization of quantitative data.

Results

The plasma levels of miR-32 and miR-107 in patients with T-ALL were significantly higher (5.65, P < 0.001) and lower (0.432, P = 0.002), respectively. On the other hand, the expression levels of FBXW7 gene were significantly downregulated by –76.9 fold in T-ALL patients (P < 0.001). The results of the ROC curve analysis indicated that overexpression of miR-32 might be used to distinguish T-ALL patients with reasonable sensitivity and specificity.

Conclusion

miR-32 is considered as a novel oncomir that targets FBXW7 and might have a role in the etiology or progression of T-ALL. Furthermore, miR-32 can potentially serve as a non-invasive biomarker for detection of T-ALL.

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.

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.

The Role of MicroRNAs upon Epithelial-to-Mesenchymal Transition in Inflammatory Bowel Disease

Increasing evidence suggest the significance of inflammation in the progression of cancer, for example the development of colorectal cancer in Inflammatory Bowel Disease (IBD) patients. Long-lasting inflammation in the gastrointestinal tract causes serious systemic complications and breaks the homeostasis of the intestine, where the altered expression of regulatory genes and miRNAs trigger malignant transformations. Several steps lead from acute inflammation to malignancies: epithelial-to-mesenchymal transition (EMT) and inhibitory microRNAs (miRNAs) are known factors during multistage carcinogenesis and IBD pathogenesis. In this review, we outline the interactions between EMT components and miRNAs that may affect cancer development during IBD.

Altered expression of miR-181 affects cell fate and targets drug resistance-related mechanisms

MicroRNAs (miRNAs) are non-coding transcripts which regulate genetic and epigenetic events by interfering with mRNA translation. miRNAs are involved in regulation of cell fate due to their ability of interfering with physiological or pathological processes. In this review paper, we evaluate the role of miR-181 family members as prognostic or diagnostic markers or therapeutic targets in malignant pathologies in connection with the main hallmarks of cancer that are modulated by the family. Also, we take over the dual role of this family in dependency with the tumour suppressor and oncogenic features presented in cell and cancer type specific manner. Restoration of the altered expression levels contributes to the activation of cell death pathways or to a reduction in the invasion and migration mechanism; moreover, the mechanism of drug resistance is also modulated by miR-181 sequences with important applications in therapeutic strategies for malignant cells sensitisation. Overall, the main miR-181 family regulatory mechanisms are presented in a cancer specific context, emphasizing the possible clinical application of this family in terms of novel diagnosis and therapy approaches.

Transcriptome analysis identifies key regulators and networks in Acute myeloid leukemia

OBJECTIVES

Acute myeloid leukemia (AML) is a heterogeneous and highly recurrent hematological malignancy. Studies have shown an association between microRNAs and drive genes in AMLs. However, the regulatory roles of miRNAs in AML and how they act on downstream targets and the signaling pathway has been little studied.

METHODS

As to understand the mechanism of mRNA-miRNA interaction in the blood malignancy from a large scale of transcriptomic sequencing studies, we applied a comprehensive miRNA-mRNA association, co-expression gene network and ingenuity pathway analysis using TCGA AML datasets.

RESULTS

Our results showed that his-mir-335 was a critical regulatory of homeobox A gene family. PBX3, KAT6A, MEIS1, and COMMD3-BMI1 were predicted as top transcription regulators in the regulatory network of the HOXA family. The most significantly enriched functions were cell growth, proliferation, and survival in the mRNA-miRNA network.

CONCLUSION

Our work revealed that regulation of the HOXA gene family and its regulation played an important role in the development of AML.

MiR-150-5p retards the progression of myocardial fibrosis by targeting EGR1

To investigate the differential expression of microRNA-150-5p (miR-150-5p) and early growth response 1 (EGR1) in myocardial fibrosis (MF) cells, and determine the effect between miR-150-5p and EGR1 on MF. Human MF cells were generated via Trypanosoma cruzi (T. cruzi) infection, a mouse model of MF was generated via angiotensin II. The expression levels of miR-150-5p and EGR1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assay. The correlation between miR-150-5p and EGR1 was confirmed by a luciferase reporter assay. The viability, proliferation, and apoptotic rate were detected by cell counting kit-8 (CCK-8), colony-formation and flow cytometry assays. Hematoxylin-eosin (HE) staining and Masson staining visualized the degree of MF. Echocardiography was performed to obtain the levels of left ventricle fractional shortening (LVFS) and left ventricle ejection fraction (LVEF), computer algorithms and a videographics program were used to obtain the levels of left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP) and ±left ventricular dp/dt maximum (LV dp/dtmax). We found that the expression of miR-150-5p in MF cells was lower than normal cardiomyocytes, while the expression level of EGR1 in MF cells were higher than normal cardiomyocytes. Cell experiments demonstrated that EGR1 and miR-150-5p could influence the development of MF, and the expression of EGR1 in cardiomyocytes was regulated by miR-150-5p directly. Lastly, we confirmed that sh-Egr1 would decrease the severity of MF, while miR-150-5p antagomir could aggravate MF. Our results illustrate the mechanism of MF development, and provide a potential target for MF treatment.

MicroRNA Dysregulation in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and it can be locally invasive and metastatic to distant sites. MicroRNAs (miRNAs or miRs) are endogenous, small, non-coding RNAs of 19–25 nucleotides in length, that are involved in regulating gene expression at a post-transcriptional level. MicroRNAs have been implicated in diverse biological functions and diseases. In cancer, miRNAs can proceed either as oncogenic miRNAs (onco-miRs) or as tumor suppressor miRNAs (oncosuppressor-miRs), depending on the pathway in which they are involved. Dysregulation of miRNA expression has been shown in most of the tumors evaluated. MiRNA dysregulation is known to be involved in the development of cutaneous squamous cell carcinoma (CSCC). In this review, we focus on the recent evidence about the role of miRNAs in the development of CSCC and in the prognosis of this form of skin cancer.

Comprehensive Investigation of miRNome Identifies Novel Candidate miRNA-mRNA Interactions Implicated in T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy originating from T-cell precursors. The genetic landscape of T-ALL has been largely characterized by next-generation sequencing. Yet, the transcriptome of miRNAs (miRNome) of T-ALL has been less extensively studied. Using small RNA sequencing, we characterized the miRNome of 34 pediatric T-ALL samples, including the expression of isomiRs and the identification of candidate novel miRNAs (not previously annotated in miRBase). For the first time, we show that immunophenotypic subtypes of T-ALL present different miRNA expression profiles. To extend miRNome characteristics in T-ALL (to 82 T-ALL cases), we combined our small RNA-seq results with data available in Gene Expression Omnibus. We report on miRNAs most abundantly expressed in pediatric T-ALL and miRNAs differentially expressed in T-ALL versus normal mature T-lymphocytes and thymocytes, representing candidate oncogenic and tumor suppressor miRNAs. Using eight target prediction algorithms and pathway enrichment analysis, we identified differentially expressed miRNAs and their predicted targets implicated in processes (defined in Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) of potential importance in pathogenesis of T-ALL, including interleukin-6-mediated signaling, mTOR signaling, and regulation of apoptosis. We finally focused on hsa-mir-106a-363 cluster and functionally validated direct interactions of hsa-miR-20b-5p and hsa-miR-363-3p with 3' untranslated regions of their predicted targets (PTEN, SOS1, LATS2), overrepresented in regulation of apoptosis. hsa-mir-106a-363 is a paralogue of prototypic oncogenic hsa-mir-17-92 cluster with yet unestablished role in the pathogenesis of T-ALL. Our study provides a firm basis and data resource for functional analyses on the role of miRNA-mRNA interactions in T-ALL.

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.

MicroRNA-181a-5p suppresses cell proliferation by targeting Egr1 and inhibiting Egr1/TGF-β/Smad pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the leading cause of cancer mortality worldwide. Early growth response factor 1 (Egr1) plays a crucial role in cancer progression. However, its precise role in HCC has not been clear. Here, we identified the aggravating role of Egr1 in cell proliferation of HCC firstly. The expression of Egr1 was significantly increased in HCC tissues. Functionally, overexpression of Egr1 enhanced, whereas silenced Egr1 expression attenuated HCC cells proliferation in vitro. Mechanistically, up-regulated Egr1 induced cell proliferation through activating Transforming growth factor (TGF)-β1/Smad signaling pathway concomitantly with upregulation of p-Smad2 and p-Smad3. Secondly, miR-181a-5p was down-regulated in clinical HCC specimens and its expression was inversely correlated with Egr1 expression. Functionally, overexpression of miR-181a-5p inhibited, whereas decreased expression of miR-181a-5p promoted HCC cells proliferation in vitro. Furthermore, we demonstrated that miR-181a-5p overexpression directly suppressed Egr1, resulting in a down-regulated TGF-β1/Smad pathway. Besides, the silenced Egr1 expression could rescue the enhanced cell proliferation induced by miR-181a-5p inhibitor. Thus, we concluded that miR-181a-5p is a negative regulator of Egr1 that can suppress tumor proliferation in HCC through targeting Egr1/TGF-β1/Smad pathway, which may be a potential therapeutic approach of HCC.

Tumor suppression by the EGR1, DMP1, ARF, p53, and PTEN Network

Recent studies have indicated that EGR1 is a direct regulator of tumor suppressors including TGFβ1, PTEN, and p53. The Myb-like transcription factor Dmp1 is a physiological regulator of the Arf-p53 pathway through transactivation of the Arf promoter and physical interaction of p53. The Dmp1 promoter has binding sites for Egr proteins, and Egr1 is a target for Dmp1. Crosstalks between p53 and PTEN have been reported. The Egr1-Dmp1-Arf-p53-Pten pathway displays multiple modes of interaction with each other, suggesting the existence of a functional network of tumor suppressors that maintain normal cell growth and prevent the emergence of incipient cancer cells.

FMRP regulates endothelial cell proliferation and angiogenesis via the miR-181a-CaM-CaMKII pathway

RNA binding proteins (RBPs) and microRNAs have emerged as crucial post-transcriptional regulators of gene expression. Although the role of Fragile X mental retardation protein (FMRP) has been well studied in the brain, the function of FMRP in endothelial cells remains unknown. In our study, we showed that FMRP controlled human umbilical vein endothelial cells (HUVECs) proliferation and angiogenesis via the miR-181a-mediated calmodulin (CaM)/CaMKII pathway. The knockdown of FMRP induced miR-181a expression and contributed to endothelial cell proliferation and angiogenesis. Furthermore, we identified CaM as a downstream target of miR-181a in endothelial cells. Additionally, tumor necrosis factor-ɑ (TNF-ɑ) treatment specifically decreased the activity of the CaM/CaMKII pathway through the dephosphorylation of FMRP and upregulation of miR-181a. Finally, the overexpression of constitutively phosphorylated FMRP rescued the TNF-ɑ-impaired endothelial cell proliferation and angiogenesis by activating the CaM/CaMKII pathway and downregulating miR-181a, which suggested there was a pivotal role of FMRP in vascular integrity in response to inflammatory stimuli. Thus, our study supports a novel function and mechanism involving FMRP and the miR-181a-CaM-CaMKII pathway may be a therapeutic target for protecting against inflammation-induced vascular diseases.

The expression and role of miR-181a in multiple myeloma

This study aims to investigate the role of miR-181a in multiple myeloma (MM). Fresh peripheral blood and bone marrows were collected. Expression of miR-181a, BCL-2 mRNA, and NOVA1 mRNA was detected by RT-qPCR. The correlation between miR-181a and clinical features of MM was further analyzed. miR-181a in serum and bone marrow mononuclear cells of MM patients were significantly higher. And, miR-181a level was significantly higher in MM Durie-Salmon stage III than that in stage I+II. miR-181a was positively correlated to Durie-Salmon staging, age, kidney injury, bone injury, β2-MG whereas negatively related to red blood cell, hemoglobin, and albumin. Additionally, BCL-2 and NOVA1 were predicted to be downstream targets of miR-181a. BCL-2 mRNA was significantly higher in the bone marrow mononuclear cells from MM patients. To sum up, the miR-181a expression is increased in peripheral blood and bone marrow of MM patients and is closely related to the clinical pathological indicators of MM.

PTPN22 Silencing in Human Acute T-Cell Leukemia Cell Line (Jurkat Cell) and its Effect on the Expression of miR-181a and miR-181b

Purpose: T-cell acute lymphoblastic leukemia (T-ALL) is one of the most common malignancies associated with T-lymphocytes, accounting for 10 to 15 percent of ALL cases in children and 25 percent in adults. Innovative therapeutic approaches that overcome ineffective treatments on tumor cells may be a potential source of improvement in therapeutic approaches. Suppression of gene expression at transfusion level is one of the important strategies in gene therapy. The expression of PTPN22 and miR-181 genes in all types of hematologic malignancies increases and is likely to contribute to the survival and death of cells by affecting a variety of signaling pathways. The purpose of this study was to determine the role of PTPN22 inhibition by siRNA, and alteration in miR-181a and miR-181b in Jurkat cell line.

Methods: Jurkat cells were transfected with 80 pmol of siRNA to inhibit PTPN22. After that, expression of PTPN22 mRNA and transcript levels of miR-181a and miR-181b were measured with Real-time PCR after 48hrs.

Results: Experiments demonstrated that siRNA transfection resulted in significant downregulation of PTPN22 mRNA after 48 hrs in 80 pmol dose of siRNA. Moreover, transcript levels of both miR-181a and miR-181b was decreased after transfection.

Conclusion: PTPN22, miR-181a and miR-181b might be involved in progression of Jurkat cells and targeting these molecules by RNAi might confer promising tool in treatment of T-ALL.

MicroRNAs as modulators of T cell functions in cancer

MicroRNAs (miRNAs) are short RNA molecules that regulate gene expression post-transcriptionally. They have emerged as important modulators of T lymphocyte biology, influencing cell activation, differentiation and proliferation in response to environmental signals. Here, we will discuss how miRNAs expressed by T cells can influence two key aspects of tumorigenesis, namely the direct, cell-intrinsic oncogenic transformation of T lymphocytes, as well as the indirect effects on tumor growth mediated by altered immune surveillance. We will specifically focus on three miRNAs that have been shown to regulate different aspects of T cell biology in both physiological and pathological conditions, namely miR-155, miR-146a and miR-181a. We aim at providing examples of the fundamental importance of miRNA-regulated networks in determining the fate of T lymphocytes during oncogenic transformation and in the control of tumor growth.

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.

T-cell acute lymphoblastic leukemia from miRNA perspective: Basic concepts, experimental approaches, and potential biomarkers

T-cell acute lymphoblastic leukemia (T-ALL) is a rare, aggressive and heterogeneous malignancy originating from T-cell precursors. The mechanisms of T-ALL pathogenesis related to non-protein coding part of the genome are currently intensively studied. miRNAs are short, non-coding molecules acting as negative regulators of gene expression which shape phenotype of cells in a complex and context-specific manner. miRNAs may act as oncogenes or tumor suppressors; several miRNAs have been related to drug resistance and treatment response in various malignancies. Here we present the review of the state-of-the-art knowledge on the role of miRNAs in T-ALL pathogenesis, with detailed overview of the studies reporting on miRNAs with oncogenic and tumor suppressor potential. We discuss whether miRNAs might be considered candidate biomarkers of prognosis in T-ALL and leukemia subtype-specific markers. We also describe experimental approaches and a typical workflow applied in research on the involvement of miRNAs in oncogenesis.

MicroRNA expression and activity in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a lymphoid malignancy caused by the oncogenic transformation of immature T-cell progenitors. Many biologically relevant genetic and epigenetic alterations have been identified as driving factors for this transformation. Recently, microRNAs (miRNAs) have been shown to influence various leukemias, including T-ALL. Aberrant expression of miRNAs can function as either oncogenes or tumor suppressors in T-ALL through the regulation of cell migration, invasion, proliferation, apoptosis, and chemoresistance. This occurs by targeting key signaling pathways or transcriptional factors that play a critical role in T-ALL pathology and progression. Different miRNA expression profiles have been linked to specific genetic subtypes of human T-ALL. Furthermore, miRNAs can also act as independent prognostic factors to predict clinical outcomes for T-ALL patients. In the current review, we will focus on the role of miRNAs in the development and progression of T-ALL.

Up-regulation of miR-181a in clear cell renal cell carcinoma is associated with lower KLF6 expression, enhanced cell proliferation, accelerated cell cycle transition, and diminished apoptosis

OBJECTIVES

Dysregulated expression of miR-181a accompanies tumorigenesis in many human cancers. However, in clear cell renal cell carcinoma (ccRCC), the role of miR-181a remains unclear. The aim of this study was to investigate biological functions of miR-181a and its expression levels in ccRCC tissues and cancer cell lines.

MATERIAL AND METHODS

Expression levels of miR-181a in samples of ccRCC tumors and adjacent nontumor tissues from 42 patients as well as in 786-O, 769-P, A498, and CAKI-1 ccRCC cell lines were determined by quantitative real-time polymerase chain reaction. Potential targets of miR-181a were predicted using bioinformatic approaches and then verified by using the luciferase reporter assay. The effects of miR-181a on cell proliferation, colony formation, cell cycle progression, and apoptosis were investigated in ccRCC cell lines transfected with specific miR-181a mimic and inhibitor.

RESULTS

We found that miR-181a expression was up-regulated in ccRCC tissues and cell lines. The expression level of miR-181a significantly correlated with the tumor size, tumor/node/metastasis staging, and Fuhrman grade. Luciferase assays showed that KLF6 was a target of miR-181a. KLF6 expression was inversely correlated with the level of miR-181a. Overexpression of miR-181a led to reduced KLF6 mRNA and protein levels, whereas mutations of the potential miR-181a binding sites in the KLF6 gene abrogated this inhibitory effect. Furthermore, overexpression of miR-181a promoted proliferation and G1/S cell cycle transition, as well as inhibited apoptosis by down-regulating KLF6 in ccRCC cells.

CONCLUSIONS

miR-181a is up-regulated in ccRCC and may act as a tumor promoting factor by targeting KLF6 expression. Manipulating miR-181a may provide a beneficial effect in the treatment of ccRCC.

MiR-301b promotes the proliferation, mobility, and epithelial-to-mesenchymal transition of bladder cancer cells by targeting EGR1

We investigated the role of miR-301b in the modulation of the proliferation, migration, and invasion of bladder cancer (BLCA) cells. The expression of miR-301b and EGR1 (early growth response gene 1) mRNA were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). A dual-luciferase reporter gene system was used to identify the target relationship between miR-301b and EGR1. Cell proliferation, cell cycle, and apoptosis were analyzed by MTT assay, colony-forming assay, and flow cytometry, respectively. Cell motility and invasiveness were assessed by wound healing and Transwell assays. The expression of proteins involved in epithelial-to-mesenchymal transition (EMT) and EGR1 were determined by Western blot. Our results showed that miR-301b was up-regulated while EGR1 was down-regulated in BLCA tissues compared with adjacent normal tissues. The proliferation, migration, and invasiveness of T24 cells (a kind of human BLCA cell) were suppressed by decreasing miR-301b expression or increasing EGR1 expression. In addition, miR-301b promoted EMT signaling by influencing the expression of related proteins. In conclusion, miR-301b promotes the proliferation, migration, and aggressiveness of human BLCA cells by inhibiting the expression of EGR1.

Loss of Egr1, a human del5q gene, accelerates BCR-ABL driven chronic myelogenous leukemia

There is substantial evidence that early growth response-1 (Egr1) gene, a zinc-finger transcription factor, behaves as a tumor suppressor in leukemia. This includes reports from this laboratory that constitutive Egr1 overrides leukemia conferred by deregulated c-Myc or E2F-1 in the M1 myeloid leukemic cell line by promoting differentiation. To investigate the effect of Egr1 on the initiation and progression of Chronic Myelogenous Leukemia (CML), lethally irradiated syngeneic wild type mice were reconstituted with bone marrow (BM) from either wild type or Egr1 null mice transduced with a 210-kD BCR-ABL-expressing MSCV-retrovirus (bone marrow transplantation {BMT}). Loss of Egr1 was observed to accelerate the development of BCR-ABL driven leukemia in recipient mice, resulting in the development of a more aggressive disease, a significantly shortened median survival time, and increased BCR-ABL expressing leukemic stem/progenitor cells (GFP+Lin-cKit+Sca+). Egr1 deficient progenitors expressing BCR-ABL exhibited decreased apoptosis, and increased cell viability and proliferation relative to WT counterparts. Secondary BMT of BCR-ABL BM revealed that loss of Egr1 resulted in enrichment of LSCs, consistent with shorter survival time and more aggressive disease of these mice compared to WT counterparts. Furthermore, serial re-plating colony assays indicated that loss of Egr1 increased self-renewal ability of BCR-ABL expressing BM. These novel findings on the tumor suppressor role of Egr1 in CML provide the impetus to study the effect of altering Egr1 expression in AML, where the overall five year survival rate remains low. The effect of loss of Egr1 in CML could reflect its established functions in normal hematopoiesis, maintaining quiescence of HSCs and driving terminal differentiation to the monocyte/macrophage lineage. Gain of function studies should validate these conclusions and provide further rationale for increased Egr1 as a therapeutic target in AML.

EMT/MET at the Crossroad of Stemness, Regeneration and Oncogenesis: The Ying-Yang Equilibrium Recapitulated in Cell Spheroids

The epithelial-to-mesenchymal transition (EMT) is an essential trans-differentiation process, which plays a critical role in embryonic development, wound healing, tissue regeneration, organ fibrosis, and cancer progression. It is the fundamental mechanism by which epithelial cells lose many of their characteristics while acquiring features typical of mesenchymal cells, such as migratory capacity and invasiveness. Depending on the contest, EMT is complemented and balanced by the reverse process, the mesenchymal-to-epithelial transition (MET). In the saving economy of the living organisms, the same (Ying-Yang) tool is integrated as a physiological strategy in embryonic development, as well as in the course of reparative or disease processes, prominently fibrosis, tumor invasion and metastasis. These mechanisms and their related signaling (e.g., TGF-β and BMPs) have been effectively studied in vitro by tissue-derived cell spheroids models. These three-dimensional (3D) cell culture systems, whose phenotype has been shown to be strongly dependent on TGF-β-regulated EMT/MET processes, present the advantage of recapitulating in vitro the hypoxic in vivo micro-environment of tissue stem cell niches and their formation. These spheroids, therefore, nicely reproduce the finely regulated Ying-Yang equilibrium, which, together with other mechanisms, can be determinant in cell fate decisions in many pathophysiological scenarios, such as differentiation, fibrosis, regeneration, and oncogenesis. In this review, current progress in the knowledge of signaling pathways affecting EMT/MET and stemness regulation will be outlined by comparing data obtained from cellular spheroids systems, as ex vivo niches of stem cells derived from normal and tumoral tissues. The mechanistic correspondence in vivo and the possible pharmacological perspective will be also explored, focusing especially on the TGF-β-related networks, as well as others, such as SNAI1, PTEN, and EGR1. This latter, in particular, for its ability to convey multiple types of stimuli into relevant changes of the cell transcriptional program, can be regarded as a heterogeneous "stress-sensor" for EMT-related inducers (growth factor, hypoxia, mechano-stress), and thus as a therapeutic target.

miR-181a-2 downregulates the E3 ubiquitin ligase CUL4A transcript and promotes cell proliferation

MiR-181a-2 plays a major role in cell proliferation both positively and negatively depending on tissue type by targeting several regulators 3'UTR regions. We have predicted several targets for miR-181a-2 through computational approaches and characterized one its interesting target, CUL4A, an E3 ubiquitin ligase. CUL4A regulates diverse functions in the cells including DNA repair, DNA replication, cell cycle, genomic stability through polyubiquitination of target proteins. Deregulation of both miR-181a-2 and CUL4A are reported in many cancerous cells, but the functional link between them is unknown. We show that miR-181a-5p binds to 3'UTR of CUL4A and regulates its transcripts levels in HEK293 cells through overexpression studies. In addition, by using MTT and Neutral red assays, we showed that miR-181a-2 overexpression increased the proliferation in HEK293 cells. Moreover, cell cycle analysis using flow cytometer revealed that an increase in S-phase cells upon the overexpression of miR-181a-2. Though several miRNAs are known to downregulate the CUL4A levels, here we show that miR-181a-2 also participates in the downregulation of CUL4A. Taken together, our data demonstrated that miR-181a-2 increases the cell proliferation in HEK293 cells possibly through the downregulation of CUL4A.

MicroRNA-181a and its target Smad 7 as potential biomarkers for tracking child acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric hematologic tumor. MiR-181a was expected to have a role in the development of hematological malignancies; it might act as tumor suppressor or oncogene. Smad7 was selected as miR-181a target pair. It is a negative regulator for the TGF-β1 signaling pathway. In this study, relative expression levels of miR-181a by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), both Smad 7 and TGF-β1 proteins levels by enzyme linked immunosorbent assay (ELISA) were all measured in serum of 60 child, 30 with ALL and 30 age and sex matched healthy child as control group. MiR-181a expression showed highly significant decrease; plus a significant increase and decrease of Smad7 and TGF-β1 protein levels respectively, in serum samples of ALL as compared to control group. MiR-181a expression achieved a highly significant positive and a significant negative correlation with TGF-β1 and Smad7 respectively. Furthermore, the levels of Smad7 and TGF-β1 were negatively correlated with each other (p<0.05). Although, positivity rate of both Smad7 and TGF-β1 in ALL group increased with presence of hepatosplenomegaly, still there was no statistical significance. In conclusion, miR-181a could act as a tumor suppressor in pediatric ALL with over expression of its target pair, Smad7. Smad7 regulates TGF-β1 signaling via a negative feedback loop and mediates the interaction between TGF-β1 and other signaling pathways; suggesting that Smad7 over expression may have therapeutic potential in ALL.

Universal attenuators and their interactions with feedback loops in gene regulatory networks

Using a combination of mathematical modelling, statistical simulation and large-scale data analysis we study the properties of linear regulatory chains (LRCs) within gene regulatory networks (GRNs). Our modelling indicates that downstream genes embedded within LRCs are highly insulated from the variation in expression of upstream genes, and thus LRCs act as attenuators. This observation implies a progressively weaker functionality of LRCs as their length increases. When analyzing the preponderance of LRCs in the GRNs of Escherichia coli K12 and several other organisms, we find that very long LRCs are essentially absent. In both E. coli and M. tuberculosis we find that four-gene LRCs are intimately linked to identical feedback loops that are involved in potentially chaotic stress response, indicating that the dynamics of these potentially destabilising motifs are strongly restrained under homeostatic conditions. The same relationship is observed in a human cancer cell line (K562), and we postulate that four-gene LRCs act as ‘universal attenuators’. These findings suggest a role for long LRCs in dampening variation in gene expression, thereby protecting cell identity, and in controlling dramatic shifts in cell-wide gene expression through inhibiting chaos-generating motifs.

HTLV-1 Tax upregulates early growth response protein 1 through nuclear factor-κB signaling

Human T cell leukemia virus type 1 (HTLV-1) is a complex retrovirus that causes adult T cell leukemia (ATL) in susceptible individuals. The HTLV-1-encoded oncoprotein Tax induces persistent activation of the nuclear factor-κB (NF-κB) pathway. Early growth response protein 1 (EGR1) is overexpressed in HTLV-1-infected T cell lines and ATL cells. Here, we showed that both Tax expression and HTLV-1 infection promoted EGR1 overexpression. Loss of the NF-κB binding site in the EGR1 promotor or inhibition of NF-κB activation reduced Tax-induced EGR1 upregulation. Tax mutants unable to activate NF-κB induced only slight EGR1 upregulation as compared with wild-type Tax, confirming NF-κB pathway involvement in EGR1 regulation. Tax also directly interacted with the EGR1 protein and increased endogenous EGR1 stability. Elevated EGR1 in turn promoted p65 nuclear translocation and increased NF-κB activation. These results demonstrate a positive feedback loop between EGR1 expression and NF-κB activation in HTLV-1-infected and Tax-expressing cells. Both NF-κB activation and Tax-induced EGR1 stability upregulated EGR1, which in turn enhanced constitutive NF-κB activation and facilitated ATL progression in HTLV-1-infected cells. These findings suggest EGR1 may be an effective anti-ATL therapeutic target.

Regulation of PI3K signaling in T-cell acute lymphoblastic leukemia: a novel PTEN/Ikaros/miR-26b mechanism reveals a critical targetable role for PIK3CD

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy, and T-ALL patients are prone to early disease relapse and suffer from poor outcomes. The PTEN, PI3K/AKT, and Notch pathways are frequently altered in T-ALL. PTEN is a tumor suppressor that inactivates the PI3K pathway. We profiled miRNAs in Pten-deficient mouse T-ALL and identified miR-26b as a potentially dysregulated gene. We validated decreased expression levels of miR-26b in mouse and human T-ALL cells. In addition, expression of exogenous miR-26b reduced proliferation and promoted apoptosis of T-ALL cells in vitro, and hindered progression of T-ALL in vivo. Furthermore, miR-26b inhibited the PI3K/AKT pathway by directly targeting PIK3CD, the gene encoding PI3Kδ, in human T-ALL cell lines. ShRNA for PIK3CD and CAL-101, a PIK3CD inhibitor, reduced the growth and increased apoptosis of T-ALL cells. Finally, we showed that PTEN induced miR-26b expression by regulating the differential expression of Ikaros isoforms that are transcriptional regulators of miR-26b. These results suggest that miR-26b functions as a tumor suppressor in the development of T-ALL. Further characterization of targets and regulators of miR-26b may be promising for the development of novel therapies.

T-ALL and thymocytes: a message of noncoding RNAs

In the last decade, the role for noncoding RNAs in disease was clearly established, starting with microRNAs and later expanded towards long noncoding RNAs. This was also the case for T cell acute lymphoblastic leukemia, which is a malignant blood disorder arising from oncogenic events during normal T cell development in the thymus. By studying the transcriptomic profile of protein-coding genes, several oncogenic events leading to T cell acute lymphoblastic leukemia (T-ALL) could be identified. In recent years, it became apparent that several of these oncogenes function via microRNAs and long noncoding RNAs. In this review, we give a detailed overview of the studies that describe the noncoding RNAome in T-ALL oncogenesis and normal T cell development.

High glucose down-regulates microRNA-181a-5p to increase pro-fibrotic gene expression by targeting early growth response factor 1 in HK-2 cells

Tubulointerstitial fibrosis (TIF) plays an important role in the progression of renal fibrosis in diabetic nephropathy (DN). Accumulating evidence supports a crucial effect of early growth response factor 1 (Egr1) on renal fibrosis in DN, but the underlying mechanisms are not entirely clear. Here, we explored the aggravating role of Egr1 and identified microRNA-181a-5p (miR-181a-5p) as an upstream regulator of Egr1 in TIF of DN. We demonstrated that overexpression of Egr1 enhanced, whereas small interfering RNA targeting Egr1 decreased the expressions of transforming growth factor β1 (TGF-β1) and fibrosis-related genes including fibronectin and collagen I in human proximal tubule cell line (HK-2) cells. We then found that miR-181a-5p expression was down-regulated, accompanied by the corresponding up-regulation of Egr1, TGF-β1, fibronectin and collagen I in renal tissues of type 2 diabetic Otsuka-Long-Evans-Tokushima-Fatty rats with DN, and that the expression of miR-181a-5p was negatively correlated with the level of Egr1 in HK-2 cells treated with high glucose. Furthermore, we identified that miR-181a-5p directly suppressed Egr1 to decrease the expressions of TGF-β1, fibronectin and collagen I in HK-2 cells through targeting the 3' untranslated region of Egr1. The functional relevance of miR-181a-5p-induced Egr1 decrease was supported by inhibition and overexpression of miR-181a-5p in HK-2 cells. Thus, we concluded that aberrant Egr1 expression, which can be suppressed by miR-181a-5p directly, plays a crucial role in the progression of renal TIF in DN. This study indicates that targeting miR-181a-5p may be a novel therapeutic approach of DN.