miR deregulation in CLL

MicroRNAs: Potential prognostic and theranostic biomarkers in chronic lymphocytic leukemia

Small noncoding ribonucleic acids called microRNAs coordinate numerous critical physiological and biological processes such as cell division, proliferation, and death. These regulatory molecules interfere with the function of many genes by binding the 3'-UTR region of target mRNAs to inhibit their translation or even degrade them. Given that a large proportion of miRNAs behave as either tumor suppressors or oncogenes, any genetic or epigenetic aberration changeing their structure and/or function could initiate tumor formation and development. An example of such cancers is chronic lymphocytic leukemia (CLL), the most prevalent adult leukemia in Western nations, which is caused by unregulated growth and buildup of defective cells in the peripheral blood and lymphoid organs. Genetic alterations at cellular and molecular levels play an important role in the occurrence and development of CLL. In this vein, it was noted that the development of this disease is noticeably affected by changes in the expression and function of miRNAs. Many studies on miRNAs have shown that these molecules are pivotal in the prognosis of different cancers, including CLL, and their epigenetic alterations (e.g., methylation) can predict disease progression and response to treatment. Furthermore, miRNAs are involved in the development of drug resistance in CLL, and targeting these molecules can be considered a new therapeutic approach for the treatment of this disease. MiRNA screening can offer important information on the etiology and development of CLL. Considering the importance of miRNAs in gene expression regulation, their application in the diagnosis, prognosis, and treatment of CLL is reviewed in this paper.

Role of microRNAs in Chronic Lymphocytic Leukemia

Chronic Lymphocytic Leukemia (CLL) is the most common form of leukemia in adults, with a highly variable clinical course. Improvement in the knowledge of the molecular pathways behind this disease has led to the development of increasingly specific therapies, such as BCR signaling inhibitors and BCL-2 inhibitors. In this context, the emerging role of microRNAs (miRNAs) in CLL pathophysiology and their possible application in therapy is worth noting. MiRNAs are one of the most important regulatory molecules of gene expression. In CLL, they can act both as oncogenes and tumor suppressor genes, and the deregulation of specific miRNAs has been associated with prognosis, progression, and drug resistance. In this review, we describe the role of the miRNAs that primarily impact the disease, and how these miRNAs could be used as therapeutic tools. Certainly, the use of miRNAs in clinical practice is still limited in CLL. Many issues still need to be solved, particularly regarding their biological and safety profile, even if several studies have suggested their efficacy on the disease, alone or in combination with other drugs.

Deregulated calcium signaling in blood cancer: Underlying mechanisms and therapeutic potential

Intracellular calcium signaling regulates diverse physiological and pathological processes. In solid tumors, changes to calcium channels and effectors via mutations or changes in expression affect all cancer hallmarks. Such changes often disrupt transport of calcium ions (Ca2+) in the endoplasmic reticulum (ER) or mitochondria, impacting apoptosis. Evidence rapidly accumulates that this is similar in blood cancer. Principles of intracellular Ca2+ signaling are outlined in the introduction. We describe different Ca2+-toolkit components and summarize the unique relationship between extracellular Ca2+ in the endosteal niche and hematopoietic stem cells. The foundational data on Ca2+ homeostasis in red blood cells is discussed, with the demonstration of changes in red blood cell disorders. This leads to the role of Ca2+ in neoplastic erythropoiesis. Then we expand onto the neoplastic impact of deregulated plasma membrane Ca2+ channels, ER Ca2+ channels, Ca2+ pumps and exchangers, as well as Ca2+ sensor and effector proteins across all types of hematologic neoplasms. This includes an overview of genetic variants in the Ca2+-toolkit encoding genes in lymphoid and myeloid cancers as recorded in publically available cancer databases. The data we compiled demonstrate that multiple Ca2+ homeostatic mechanisms and Ca2+ responsive pathways are altered in hematologic cancers. Some of these alterations may have genetic basis but this requires further investigation. Most changes in the Ca2+-toolkit do not appear to define/associate with specific disease entities but may influence disease grade, prognosis, treatment response, and certain complications. Further elucidation of the underlying mechanisms may lead to novel treatments, with the aim to tailor drugs to different patterns of deregulation. To our knowledge this is the first review of its type in the published literature. We hope that the evidence we compiled increases awareness of the calcium signaling deregulation in hematologic neoplasms and triggers more clinical studies to help advance this field.

Decreased cell proliferation and induced apoptosis in human B-chronic lymphocytic leukemia following miR-221 inhibition through modulation of p27 expression

Background

This study aimed to investigate the effects of the miR-221 inhibition on the human B-chronic lymphocytic leukemia (B-CLL) cell viability and the p27 gene expression, to introduce a new treatment approach for this type of cancer. In this context, the cyclin-dependent kinase (Cdk) inhibitor 1B (p27Kip1) is considered as an enzyme inhibitor that encodes a protein belonging to the Cip/Kip family of the Cdk inhibitor proteins.

Methods

The affected miR-221 inhibition in the B-CLL cell viability was initially assessed. The inhibition of miR-221 in the B-CLL cell line (183-E95) was thus performed using locked nucleic acid (LNA) as an antagomir. After the LNA-anti-miR-221 transfection, the miR-221 quantification, cell viability, and apoptosis assays were evaluated at different intervals by the reverse transcription-quantitative polymerase chain reaction (RT-qPCR), the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and flow cytometry (FC), respectively. The qRT-PCR was also completed for the p27 gene. The data were subsequently analyzed by independent-samples t-test and one-way analysis of variance (ANOVA).

Results

A gradual reduction was observed in the B-CLL cell viability, and consequently the transfected LNA-anti-miR cell viability reached below 55% of the untreated cells after 72 h of transfection. A statistically significant difference was found in the cell viability between the LNA-anti-miR-treated and control groups (p-value ≤ 0.043). The downregulation of miR-221 in the B-CLL (183-E95) cells was further conducted by LNA-anti-miR-221.

Conclusion

The miR-221 inhibition significantly decreases cell viability through augmenting the p27 gene expression and inducing apoptosis. Moreover, the findings demonstrated that the inhibition of miR-221 might be a new treatment approach for B-CLL, although more confirmation is needed by investigating appropriate animal models.

A Unified Computational Framework for a Robust, Reliable, and Reproducible Identification of Novel miRNAs From the RNA Sequencing Data

In eukaryotic cells, miRNAs regulate a plethora of cellular functionalities ranging from cellular metabolisms, and development to the regulation of biological networks and pathways, both under homeostatic and pathological states like cancer.Despite their immense importance as key regulators of cellular processes, accurate and reliable estimation of miRNAs using Next Generation Sequencing is challenging, largely due to the limited availability of robust computational tools/methods/pipelines. Here, we introduce miRPipe, an end-to-end computational framework for the identification, characterization, and expression estimation of small RNAs, including the known and novel miRNAs and previously annotated pi-RNAs from small-RNA sequencing profiles. Our workflow detects unique novel miRNAs by incorporating the sequence information of seed and non-seed regions, concomitant with clustering analysis. This approach allows reliable and reproducible detection of unique novel miRNAs and functionally same miRNAs (paralogues). We validated the performance of miRPipe with the available state-of-the-art pipelines using both synthetic datasets generated using the newly developed miRSim tool and three cancer datasets (Chronic Lymphocytic Leukemia, Lung cancer, and breast cancer). In the experiment over the synthetic dataset, miRPipe is observed to outperform the existing state-of-the-art pipelines (accuracy: 95.23% and F1-score: 94.17%). Analysis on all the three cancer datasets shows that miRPipe is able to extract more number of known dysregulated miRNAs or piRNAs from the datasets as compared to the existing pipelines.

The role of miRNAs as a big master regulator of signaling pathways involved in lymphoblastic leukemia

MicroRNAs (miRNAs) belong to small noncoding RNAs, which have long attracted researchers' attention because of their potency in acting either as oncogenes or tumor-suppressors in cancers. acute lymphocytic leukemia (ALL) and chronic lymphocytic leukemia (CLL) are two known types of leukemia with high mortality rates in adults and children. On a molecular basis, various signaling pathways are active in both types, making researchers consider the potential role of miRNAs in activating or suppressing these pathways to further hinder cancer development. In this review, we summarized the potential miRNAs, especially circulating ones, involved in essential signaling pathways in the ALL and CLL patients which serve as biomarkers and valuable targets in the treatment fields.

Inside the chronic lymphocytic leukemia cell: miRNA and chromosomal aberrations

Alterations in microRNA (miRNA/miRs) expression are associated with the occurrence and course of human diseases, including chronic lymphocytic leukemia (CLL). Expression of miRNAs may vary among patients with CLL in different cytogenetic risk groups. The present study assessed the expression levels of the following miRNAs in 35 patients with CLL: hsa‑miR‑15a, ‑16‑1, ‑29a, ‑29c, ‑34a, ‑34b, ‑155, ‑181a, ‑181b, ‑221, ‑222 and ‑223. Fluorescent in situ hybridization (FISH) analysis was performed for 13q14d, 17p13 and 11q22 deletions and chromosome 12 trisomy. Significantly higher expression levels of miR‑181a, ‑221 and ‑223 were observed in the group at low risk of disease progression (stage 0) compared with the group with high risk of CLL progression (P=0.036, P=0.019 and P=0.038, respectively). The present study revealed that the expression levels of miRNA‑181b and miRNA‑223 were significantly higher in the group of patients without D13S319 deletion (P=0.039 and P=0.037, respectively). Moreover, the expression levels of miR‑15a and miRNA‑29c were demonstrated to be significantly higher in the group of patients with CLL who had a tumor protein p53 deletion, identified by FISH, compared with patients without this lesion (P=0.047, P=0.03 respectively). Based on receiver operating characteristic curve analysis, the present study revealed that miR‑181a, ‑221 and ‑223 expression was able to distinguish low and high risk of CLL progression in patients. Among the tested miRNAs, miRNA‑181a, ‑221 and ‑223 were indicated to have the greatest diagnostic potential in CLL.

Alterations in The Plasma Expression of mir-15b, mir-195 and the Tumor-Suppressor Gene DLEU7 in Patients with B-Cell Chronic Lymphocytic Leukemia

Background

Chronic lymphocytic leukemia (CLL) is one of the most prevalent forms of leukemia in adults. Inactivation of the DLEU7 gene is frequently observed in patients with CLL. Furthermore, microRNAs (miRNAs) have been observed to have a critical role in the pathogenesis of several cancers, including leukemia. Considering the tumor-suppressive role of DLEU7, as well as the tumor suppressor or oncogenic role of microRNAs (miRNAs), the aim of the present study was to evaluate the potential miRNAs targeting the DLEU7 gene in B-cells and explore expression changes these genes in the plasma of B-CLL patients.

Methods

The miRNAs interacting with the DLEU7 gene were predicted and selected using bioinformatics tools. A total of 80 plasma samples were collected from 40 patients with B-cells and 40 healthy individuals, then subjected to RNA extraction and cDNA synthesis. The expression profiles of the predicted miRNAs and the DLEU7 gene in the plasma of B-CLL patients and healthy individuals were determined by RT-qPCR analysis.

Results

The bioinformatics prediction indicated that miR-15b and miR-195 target the DLEU7 gene. The expression levels of miR-15b and miR-195 were significantly higher in the plasma of patients with B-CLL compared to the healthy individuals (91.6, p= 0.001) (169, p= 0.001). However, the expression level of the DLEU7 gene was found to be significantly lower in the patient group compared to healthy controls (0.304, p= 0.001).

Conclusion

Both miR-15b and miR-195, have the potential to function as novel and non-invasive biomarkers in the diagnosis and prognosis of patients with B-CLL.

Therapeutic potential of antagomiRs in haematological and oncological neoplasms

BACKGROUND

The importance of the role of MicroRNAs (or miRNAs) has been emphasised by the large number of studies in human tumour cells, underlining the high impact of post-transcriptional processes in cancer onset, progression, invasion and metastatisation. Currently known as oncomiR, real databases are collecting all the smaller fragments of RNA capable of participating in the oncogenesis.

AIMS

With the aim to collect for the first time the most important acquisitions in literature about antagomiRs in oncology, our narrative review is born with the purpose of showing that specific antisense oligonucleotides, capable to bind and antagonise single or multiple miRNAs, are effective as therapeutic compounds.

RESULTS

Peptide or locked nucleic acids, miRNA sponges or antagomiRs attached to plasmid or lentiviral vectors carrying miRNA sequences to its target are objects of our analysis, demonstrating their effectiveness in a large number and types of tumours. We have also tried how to overcome their high immunogenicity, which remains its greatest limit for clinical use.

CONCLUSIONS

They are ambitious but fascinating promise to alter the promotion of the tumour growth by binding specific molecular targets, with high precision and low toxicity, leaving the scientists the chance of development as anti-cancer drugs and not just.

Diagnostic biomarker and therapeutic target applications of miR-326 in cancers: A systematic review

MicroRNAs (miRNAs) are endogenous mediators of RNA interference and have key roles in the modulation of gene expression under healthy, inflamed, stimulated, carcinogenic, or other cells, and tissues of a pathological state. Many studies have proved the association between miRNAs and cancer. The role of miR-326 as a tumor suppressor miRNA in much human cancer confirmed. We will explain the history and the role of miRNAs changes, especially miR-326 in cancers and other pathological conditions. Attuned with these facts, this review highlights recent preclinical and clinical research performed on miRNAs as novel promising diagnostic biomarkers of patients at early stages, prediction of prognosis, and monitoring of the patients in response to treatment. All related publications retrieved from the PubMed database, with keywords such as epigenetic, miRNA, microRNA, miR-326, cancer, diagnostic biomarker, and therapeutic target similar terms from 1899 to 2018 with limitations in the English language. Recently, researchers have focused on the impacts of miRNAs and their association in inflammatory, autoinflammatory, and cancerous conditions. Recent studies have suggested a major pathogenic role in cancers and autoinflammatory diseases. Investigations have explained the role of miRNAs in cancers, autoimmunity, and autoinflammatory diseases, and so on. The miRNA-326 expression has an important role in cancer conditions and other diseases.

Computational Methods to Investigate the Impact of miRNAs on Pathways

Pathway analysis is a wide class of methods allowing to determine the alteration of functional processes in complex diseases. However, biological pathways are still partial, and knowledge coming from posttranscriptional regulators has started to be considered in a systematic way only recently. Here we will give a global and updated view of the main pathway and subpathway analysis methodologies, focusing on the improvements obtained through the recent introduction of microRNAs as regulatory elements in these frameworks.

Altered expression of MALAT1 lncRNA in chronic lymphocytic leukemia patients, correlation with cytogenetic findings

Background

Recent studies have devoted much attention to non-protein-coding transcripts in relation to a wide range of malignancies. MALAT1, a long non-coding RNA, has been reported to be associated with cancer progression and prognosis. Thus, we here determined MALAT1 gene expression in chronic lymphocytic leukemia (CLL), a genetically heterogeneous disease, and explored its possible relationships with cytogenetic abnormalities.

Methods

MALAT1 expression level was evaluated using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) on blood mononuclear cells from 30 non-treated CLL patients and 30 matched healthy controls. Cytogenetic abnormalities were determined in patients by fluorescence in situ hybridization (FISH).

Results

MALAT1 expression level was up-regulated in the CLL group compared to healthy controls (P=0.008). Del13q14, followed by Del11q22, were the most prevalent cytogenetic abnormalities. We found no association between the FISH results and MALAT1 expression in patients.

Conclusion

Altered expression of MALAT1 is associated with CLL development. Further investigations are required to assess the relationship between this long non-coding RNA and CLL patient survival and prognosis.

6mer seed toxicity in tumor suppressive microRNAs

Many small-interfering (si)RNAs are toxic to cancer cells through a 6mer seed sequence (positions 2–7 of the guide strand). Here we performed an siRNA screen with all 4096 6mer seeds revealing a preference for guanine in positions 1 and 2 and a high overall G or C content in the seed of the most toxic siRNAs for four tested human and mouse cell lines. Toxicity of these siRNAs stems from targeting survival genes with C-rich 3′UTRs. The master tumor suppressor miRNA miR-34a-5p is toxic through such a G-rich 6mer seed and is upregulated in cells subjected to genotoxic stress. An analysis of all mature miRNAs suggests that during evolution most miRNAs evolved to avoid guanine at the 5′ end of the 6mer seed sequence of the guide strand. In contrast, for certain tumor-suppressive miRNAs the guide strand contains a G-rich toxic 6mer seed, presumably to eliminate cancer cells.

Small interfering (siRNAs) can be toxic to cancer cells. Here the authors investigate the toxicity of microRNA in cancer cells by performing a siRNA screen that tests the miRNA activities of an extensive list of miRNAs with different 6mer seed sequences.

Role of Mitochondria-Associated ER Membranes in Calcium Regulation in Cancer-Specific Settings

Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) are highly specialized subcellular compartments that are shaped by ER subdomains juxtaposed to mitochondria but are biochemically distinct from pure ER and pure mitochondria. MAMs are enriched in enzymes involved in lipid synthesis and transport, channels for calcium transfer, and proteins with oncogenic/oncosuppressive functions that modulate cell signaling pathways involved in physiological and pathophysiological processes. The term "cancer" denotes a group of disorders that result from uncontrolled cell growth driven by a mixture of genetic and environmental components. Alterations in MAMs are thought to account for the onset as well as the progression and metastasis of cancer and have been a focus of investigation in recent years. In this review, we present the current state of the art regarding MAM-resident proteins and their relevance, alterations, and deregulating functions in different types of cancer from a cell biology and clinical perspective.

Therapeutic inhibition of USP7-PTEN network in chronic lymphocytic leukemia: a strategy to overcome TP53 mutated/deleted clones

Chronic Lymphocytic Leukemia (CLL) is a lymphoproliferative disorder with either indolent or aggressive clinical course. Current treatment regiments have significantly improved the overall outcomes even if higher risk subgroups - those harboring TP53 mutations or deletions of the short arm of chromosome 17 (del17p) - remain highly challenging. In the present work, we identified USP7, a known de-ubiquitinase with multiple roles in cellular homeostasis, as a potential therapeutic target in CLL. We demonstrated that in primary CLL samples and in CLL cell lines USP7 is: i) over-expressed through a mechanism involving miR-338-3p and miR-181b deregulation; ii) functionally activated by Casein Kinase 2 (CK2), an upstream interactor known to be deregulated in CLL; iii) effectively targeted by the USP7 inhibitor P5091. Treatment of primary CLL samples and cell lines with P5091 induces cell growth arrest and apoptosis, through the restoration of PTEN nuclear pool, both in TP53-wild type and -null environment. Importantly, PTEN acts as the main tumor suppressive mediator along the USP7-PTEN axis in a p53 dispensable manner. In conclusion, we propose USP7 as a new druggable target in CLL.

Investigation of AID, Dicer, and Drosha Expressions in Patients with Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is the most common leukemia in Western countries. Cytogenetic lesions such as del13q14, del11q22.3, and del17p13 are identified in 50-60% of patients. Activation-induced cytidine deaminase (AID) plays a central role in somatic hyper mutation (SHM) and class switch recombination (CSR) and functions on Ig genes, but also target non-Ig genes, and over-expression of AID can lead to point mutations or translocations in non-Ig genes such as IgH/Myc translocation. Dicer and Drosha, which have a role in activation process of miRNA, also act in a double-strand DNA break (DSB) repair mechanism. In this study, whether the changes of AID, Dicer and Drosha expressions may be associated with both deletions and clinical outcomes in patients with CLL were investigated. AID expressions were increased in patients with CLL. However, cell lysate AID protein levels were only increased in patients with del17p or del11q who have poor prognosis. Decreased Dicer expressions were found in patients with deletion, whereas increased Drosha expressions were found in patients without deletion and with del13q. According to Rai and Binet staging systems, advanced-stage patients showed increased AID protein levels, decreased Dicer and Drosha expressions. Our findings may suggest that high AID expression and lower Dicer expression were observed in patients with CLL especially del17p and del11q and might associated with deletions such as del17p and del11q. AID, Dicer, and Drosha expressions might be used as an indicator of prognosis for CLL.

Inhibition of MicroRNA miR-222 with LNA Inhibitor Can Reduce Cell Proliferation in B Chronic Lymphoblastic Leukemia

MicroRNAs (miRNAs) are small regulatory molecules that negatively regulate gene expression by base-pairing with their target mRNAs. miRNAs have contribute significantly to cancer biology and recent studies have demonstrated the oncogenic or tumor-suppressing role in cancer cells. In many tumors up-regulation miRNAs has been reported especially miR-222 has been shown to be up-regulated in B chronic lymphocytic leukemia (B-CLL). In this study we assessed the effected inhibition of miR-222 in cell viability of B-CLL. We performed inhibition of mir-222 in B-CLL cell line (183-E95) using locked nucleic acid (LNA) antagomir. At different time points after LNA-anti-mir-222 transfection, miR-222 quantitation and cell viability were assessed by qRT-real time polymerase chain reaction and MTT assays. The data were analyzed by independent t test and one way ANOVA. Down-regulation of miR-222 in B-CLL cell line (183-E95) with LNA antagomir decreased cell viability in B-CLL. Cell viability gradually decreased over time as the viability of LNA-anti-mir transfected cells was <47 % of untreated cells at 72 h post-transfection. The difference in cell viability between LNA-anti-miR and control groups was statistically significant (p < 0.042). Based on our findings, the inhibition of miR-222 speculate represent a potential novel therapeutic approach for treatment of B-CLL.

MicroRNAs in chronic lymphocytic leukemia: miRacle or miRage for prognosis and targeted therapies?

Chronic lymphocytic leukemia (CLL) is a heterogeneous disease and has a highly variable clinical course with survival ranging from a couple of months to several decades. MicroRNAs (miRNAs), small non-coding RNAs that regulate transcription and translation of genes, have been found to be involved in CLL initiation, progression, and resistance to therapy. In addition, they can be used as prognostic biomarkers and as targets for novel therapies. In this review, we describe the association between miRNAs and the cytogenetic aberrations commonly found in CLL, as well as with other prognostic factors. We describe the presence of miRNAs as extracellular entities in the plasma and serum of CLL patients and discuss their role in resistance to therapy. Finally, we will explore the potential of targeted miRNA therapy for the treatment of CLL, with a special emphasis on MRX34, the first miRNA mimic that is currently being evaluated for clinical use.

MicroRNA-155 and Its Role in Malignant Hematopoiesis

MicroRNA-155 (miR-155) is a multifunctional molecule involved in both normal and malignant hematopoiesis. It has been found to be involved in the pathogenesis of many different hematological malignancies with either an oncogenic or a tumor-repressor effect, depending on the nature of the cell and the type of malignancy. In particular, it has been strongly implicated in the causation of diffuse large B-cell lymphomas. This review focuses on the molecular interactions of miR-155, its oncogenic mechanisms, and its potential as an effective therapeutic target for the associated malignancies.

Epigenetic silencing of miR-708 enhances NF-κB signaling in chronic lymphocytic leukemia

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression and their deregulation is involved in tumor development. Epigenetic gene silencing in cancer by DNA methylation contributes to the silencing of tumor-suppressor genes, including miRNAs. We have recently shown that the promoter of miR-708 is aberrantly methylated in chronic lymphocytic leukemia (CLL). To characterize the molecular signaling networks that are influenced by miR-708, we performed a luciferase-based screen evaluating the effects of ectopic miR-708 expression on leukemia-relevant signaling pathways. We found that miR-708 strongly repressed NF-κB signaling, a pathway known to be deregulated in CLL. Among the predicted miR-708 targets was IKKβ (inhibitor of kappa light polypeptide gene enhancer in B cells, kinase-β/IKBKB), a key kinase facilitating NF-κB signaling. We validated the interaction of miR-708 with the 3'-untranslated region of IKKβ and found that miR-708 overexpression represses endogenous IKKβ. Phosphorylation of the IKKβ target IκBα and expression of known NF-κB target genes were impaired by miR-708. Furthermore, we identified an enhancer region downstream of the miR-708 promoter that displays a distinct DNA methylation status in CLL. High enhancer methylation is significantly correlated with lower miR-708 expression and is predominantly found in patients with poor prognosis and shorter time to treatment. These results demonstrate that miR-708 regulates the NF-κB pathway by targeting IKKβ, and that methylation of a key enhancer region contributes to its suppression in CLL.

microRNA and Chronic Lymphocytic Leukemia

Expression profiling of microRNAs identified important differences in microRNA expression between CLL samples and normal CD5+ B-cells. Researchers have first discussed the dual role of miRNAs working as tumor suppressors (inhibiting malignant potential) or as oncogenes (activating malignant potential) in CLL pathogenesis. Understanding the roles of miRNAs in leukemic cells brings information on a new layer of gene regulation and also provides new markers for improved diagnosis and prognosis, as well as novel therapeutic options for CLL patients. Herein we will focus on the roles of miRNAs in CLL, highlighting what is already known about their function, proposing a novel model of CLL predisposition and progression, and describing the challenges for the near future.

The fusion of two worlds: non-coding RNAs and extracellular vesicles--diagnostic and therapeutic implications (Review)

The role of the extracellular non-coding RNAs, particularly microRNAs present in tumor-derived extravesicles, has been intensively exploited in human cancer as a promising tool for diagnostic and prognostic purposes. Current knowledge on exosomes shows an important role not only as vehicles in the intercellular communication, but the transfer of their content can specifically modulate the surrounding microenvironment, leading to tumor development and progression and affecting therapy response. Based on this, much effort has focused on understanding the mechanisms behind the biology of exosomes and their closely interaction with non-coding RNAs as an efficient tool in tumor diagnostic and therapy. Here we summarize the current knowledge on extracellular and exosomes-enclosed non-coding RNAs, and their importance as potential biomarkers and mediators of intercellular communication in tumor biology.