Overexpression of microRNAs from the miR-17-92 paralog clusters in AIDS-related non-Hodgkin's lymphomas

Anticancer properties of vincristine is modulated by microRNAs in acute lymphoblastic leukemia Nalm6 cell line

Precursor B-cell acute lymphoblastic leukemia (B-ALL), a highly diverse disease, is the most widespread pediatric malignancy characterized by cytogenetic and molecular abnormalities such as altered microRNA (miR) expression signatures. MiRs are a class of short noncoding RNAs. Dysregulation in the expression of miRs plays a crucial role in different types of cancers. Vincristine is an antineoplastic drug with a broad spectrum of activity against different hematologic malignancies and is the first-line treatment for B-ALL. Previous studies have proposed miR-17 and miR-181/b as oncomirs and miR-34/a as a tumor suppressor in Nalm6 cells, thus in the current study, we investigated the effects of vincristine treatment on the expression of miR-17, miR-34/a and miR-181/b expression levels. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay was conducted to estimate the optimal concentration of vincristine in the Nalm-6 cell line. Expression of miRs was calculated using real-time PCR. Our results showed significant downregulation of miR-17 (FC = 0.226; P < 0.0004) in Nalm6 cells after vincristine treatment. Conversely, miR-34/a (FC = 4.823; P < 0.0001) was significantly upregulated. Also, the expression of miR-181/b (FC = 0.156; P < 0.3465) was not significantly different between the vincristine treated group and the control group. In conclusion, it is proposed that one of the mechanisms by which vincristine improves B-ALL is by modulating the expression of specific miRs. These specific miRs will serve as good diagnostic and prognostic biomarkers.

MiRNA expression profiling in HIV pathogenesis, disease progression and response to treatment: a systematic review

Aim: A systematic review was conducted to identify the association of miRNA expression with HIV pathogenesis, progression and treatment. Methods: A search of articles was conducted in MEDLINE^®, Cochrane Central Register of Controlled Trials and Global Health. Results: 35 articles were included. Due to the heterogeneity of HIV phenotypes, a harmonization based on key progression parameters was proposed. The hsa-miR-29 family, hsa-miR-146b-5p and hsa-miR-150-5p, are the most frequently differentially expressed in HIV. Direct comparison of studies was not possible due to heterogeneity in biological samples and miRNA analysis techniques. Conclusion: This is the first attempt to systematically identify miRNA's different expression in well-defined patient phenotypes and could represent a helpful way to increase general knowledge in this field.

Clinical and Molecular Properties of Human Immunodeficiency Virus-Related Diffuse Large B-Cell Lymphoma

Non-Hodgkin lymphoma is the most common malignancy affecting people living with HIV (PLWH). Among its several subtypes, diffuse large B-cell lymphoma (DLBCL) is an important manifestation within the HIV-infected compartment of the population. Since HIV is able to modulate B cells and promote lymphomagenesis through direct and indirect mechanisms, HIV-related DLBCL has specific characteristics. In this review, we address the clinical and molecular properties of DLBCL disease in the context of HIV infection, as well as the mechanisms by which HIV is able to modulate B lymphocytes and induce their transformation into lymphoma.

Non-Coding RNAs in Diffuse Large B-Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma worldwide. The molecular mechanisms underlying DLBCL have not been fully elucidated, and approximately 40% of patients who undergo standard chemoimmunotherapy still present with primary refractory disease or relapse. Non-coding RNAs (ncRNAs), a group of biomolecules functioning at the RNA level, are increasingly recognized as vital components of molecular biology. With the development of RNA-sequencing (RNA-Seq) technology, accumulating evidence shows that ncRNAs are important mediators of diverse biological processes such as cell proliferation, differentiation, and apoptosis. They are also considered promising biomarkers and better candidates than proteins and genes for the early recognition of disease onset, as they are associated with relative stability, specificity, and reproducibility. In this review, we provide the first comprehensive description of the current knowledge regarding three groups of ncRNAs-microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs)-focusing on their characteristics, molecular functions, as well as diagnostic and therapeutic potential in DLBCL. This review provides an exhaustive account for researchers to explore novel biomarkers for the diagnosis and prognosis of DLBCL and therapeutic targets.

Gene Expression: the Key to Understanding HIV-1 Infection?

Gene expression profiling of the host response to HIV infection has promised to fill the gaps in our knowledge and provide new insights toward vaccine and cure. However, despite 20 years of research, the biggest questions remained unanswered. A literature review identified 62 studies examining gene expression dysregulation in samples from individuals living with HIV. Changes in gene expression were dependent on cell/tissue type, stage of infection, viremia, and treatment status. Some cell types, notably CD4+ T cells, exhibit upregulation of cell cycle, interferon-related, and apoptosis genes consistent with depletion. Others, including CD8+ T cells and natural killer cells, exhibit perturbed function in the absence of direct infection with HIV. Dysregulation is greatest during acute infection. Differences in study design and data reporting limit comparability of existing research and do not as yet provide a coherent overview of gene expression in HIV. This review outlines the extraordinarily complex host response to HIV and offers recommendations to realize the full potential of HIV host transcriptomics.

Epstein barr virus IgG and EBER-1 in Burkitt's lymphoma children at a referral hospital in western Kenya

Burkitt's lymphoma (BL) is a frequent childhood B cell non-Hodgkin's lymphoma (NHL) in equatorial Africa associated with infections. Chronic Epstein Barr virus (EBV) infections can lead to host immune stimulation that may trigger genetic translocation(s), neoplastic transformation and proliferation of B cells. We determined EBV immunoglobulin G (IgG) in sera from participants and EBER-1 in tumour sections in confirmed BL cases at Moi Teaching and Referral Hospital (MTRH). A cross sectional study of children with clinical and histology diagnosis of NHL from whom BL status were confirmed by immunohistochemistry (IHC) was carried out. Epstein Barr virus IgG in sera was determine using Enzyme-linked immunosorbant assay, IHC for EBER-1 and MYC protein in tumour sections. Demographic and clinical information were obtained from questionnaires and hospital files respectively. Ninety three percent of sera were EBV IgG positive of which 31.7% were confirmed as BL. All jaw BL tumours and 86.7% of BL tumours carried EBER-1 antigen. Odds ratio of EBER-1 positive was 1.39, 95% CI: 0.16-12.19 in BL tumours regardless of age or gender. EBV infection among the study participants may be associated with BL, however, EBER-1 and MYC negative in BL tumours suggest alternative BL pathogenesis or variant.

Immunoglobulin heavy variable (IgHV) gene mutation and micro-RNA expression in Burkitt's lymphoma at Moi Teaching and Referral Hospital in Western Kenya

INTRODUCTION

Burkitt's lymphoma (BL) is a virus associated childhood B-cell cancer common in Eastern Africa. Continued survival of B-cells in germinal centres depend on expression of high affinity immunoglobulins (Ig) to complementary antigens by somatic hypermutation of Ig genes. Cellular microRNAs, non-coding RNAs have been reported to play role in cell cycle regulation. Both viral antigen dependent mutation and micro-RNA expression maybe involved in BL pathogenesis.

OBJECTIVE

To describe immunoglobulin heavy variable (IgHV) rearrangement and micro-RNA expressions in BL tumours.

METHODS

Genomic DNA were extracted and purified from BL tissue blocks at Moi Teaching and Referral Hospital, before amplification using IgHV consensus primers and sequencing. The sequences were then aligned with germline alleles in IMGT/V-QUEST® database. Total RNA extracted from tissue blocks and cell lines were used to determine relative expression of hsamiR-34a and hsa-miR-127.

RESULTS

In all tumours, allele alignment scores and number of mutations range were 89.2-93.2%, 15-24 respectively. The range of IgHV amino acid changes were higher in EBER-1+ (15-25) than EBER-1- (9-15). In MYC+ tumours, the relative expression were: hsa-miR-127(2.09);hsa-miR-34a (2.8) and MYC- hsa-miR-127 (1.2), hsa-miR-34a (1.0).

CONCLUSION

B-cell in BL contained somatic mutated IgHV gene and upregulated cellular microRNAs with possible pathogenetic role(s).

MicroRNA profiles in B-cell non-Hodgkin lymphoma

B-cell non-Hodgkin's lymphomas are tumors of B-cells that arise following clonal expansion and consequent invasion of immune organs by B-cells blocked at a certain step of the differentiation process. Genetic abnormalities with altered gene expression are common in the transformed state of B-cells at any stage of B-cell development. These stages are regulated by a combination of transcription factors, epigenetic modifications, microRNAs, and extrinsic signals. MicroRNAs are a class of short non-coding single-stranded RNAs implicated in the regulation of mRNA function and translation. Each microRNA can regulate multiple transcripts; and a transcript is under potential control by multiple microRNAs. Their dysregulation can contribute to the pathogenesis of B-cell non-Hodgkin lymphomas, and they could be used as a potential target for diagnosis, evaluation of prognosis and therapy monitoring. The mechanisms of microRNA dysregulation range from dysregulation of the DNA sequences encoding the microRNAs to transcriptional regulation of microRNA loci. In this review, we summarized the microRNA profiles of the most common B-cell Non-Hodgkin Lymphomas for the pathogenesis, diagnosis and their potential therapeutic implications.

miR-17∼92 in lymphocyte development and lymphomagenesis

microRNAs (miRNAs) down-modulate the levels of proteins by sequence-specific binding to their respective target mRNAs, causing translational repression or mRNA degradation. The miR-17∼92 cluster encodes for six miRNAs whose target recognition specificities are determined by their distinct sequence. In mice, the four miRNA families generated from the miR-17∼92 cluster coordinate to allow for proper lymphocyte development and effective adaptive immune responses following infection or immunization. Lymphocyte development and homeostasis rely on tight regulation of PI3K signaling to avoid autoimmunity or immunodeficiency, and the miR-17∼92 miRNAs appear as key mediators to appropriately tune PI3K activity. On the other hand, in lymphoid tumors overexpression of the miR-17∼92 miRNAs is a common oncogenic event. In this review, we touch on what we have learned so far about the miR-17∼92 miRNAs, particularly with respect to their role in lymphocyte development, homeostasis and pathology.

Plasma microRNA profiling: Exploring better biomarkers for lymphoma surveillance

Early detection of relapsed lymphoma improves response and survival. Current tools lack power for detection of early relapse, while being cumbersome and expensive. We searched for sensitive biomarkers that precede clinical relapse, and serve for further studies on therapy response and relapse. We recruited 20 healthy adults, 14 diffuse large B-cell lymphoma (DLBCL) patients and 11 Hodgkin lymphoma (HL) patients at diagnosis. Using small-RNA sequencing we identified in DLBCL patients increased plasma levels of miR-124 and miR-532-5p, and decreased levels of miR-425, miR-141, miR-145, miR-197, miR-345, miR-424, miR-128 and miR-122. In the HL group, we identified miR-25, miR-30a/d, miR-26b, miR-182, miR-186, miR-140* and miR-125a to be up-regulated, while miR-23a, miR-122, miR-93 and miR-144 were down-regulated. Pathway analysis of potential mRNAs targets of these miRNA revealed in the DLBCL group potential up-regulation of STAT3, IL8, p13k/AKT and TGF-B signaling, and potential down-regulation of the PTEN and p53 pathways; while in the HL group we have found the cAMP-mediated pathway and p53 pathway to be potentially down-regulated. Survival analyses revealed that plasma levels of miR-20a/b, miR-93 and miR-106a/b were associated with higher mortality. In conclusion, we identified sets of dysregulated circulating miRNA that might serve as reliable biomarkers for relapsed lymphoma.

Primary mediastinal large B-cell lymphoma: transcriptional regulation by miR-92a through FOXP1 targeting

Background

Primary mediastinal large B-cell lymphoma (PMBL) shares pathological features with diffuse large B-cell lymphoma (DLBCL), and molecular features with classical Hodgkin lymphoma (cHL). The miR-17∼92 oncogenic cluster, located at chromosome 13q31, is a region that is amplified in DLBCL.

Methods

Here we compared the expression of each member of the miR-17∼92 oncogenic cluster in samples from 40 PMBL patients versus 20 DLBCL and 20 cHL patients, and studied the target genes linked to deregulated miRNA in PMBL.

Results

We found a higher level of miR-92a in PMBL than in DLBCL, but not in cHL. A combination of in silico prediction and transcriptomic analyses enabled us to identify FOXP1 as a main miR-92a target gene in PMBL, a result so far not established. This was confirmed by 3UTR, and RNA and protein expressions in transduced cell lines. In vivo studies using the transduced cell lines in mice enabled us to demonstrate a tumor suppressor effect of miR-92a and an oncogenic effect of FOXP1.

A higher expression of miR-92a and the down-regulation of FOXP1 mRNA and protein expression were also found in human samples of PMBL, while miR-92a expression was low and FOXP1 was high in DLBCL.

Conclusions

We concluded to a post-transcriptional regulation by miR-92a through FOXP1 targeting in PMBL, with a clinico-pathological relevance for better characterisation of PMBL.

Changes in circulating microRNA levels can be identified as early as day 8 of pregnancy in cattle

Poor reproductive performance remains a major issue in the dairy industry, with low conception rates having a significant impact on milk production through extended calving intervals. A major limiting factor is the lack of reliable methods for early pregnancy diagnosis. Identification of animals within a herd that fail to conceive within 3 weeks after insemination would allow early re-insemination and shorten calving intervals. In a previous study, we found an increase in plasma miR-26a levels in Day 16-pregnant relative to non-pregnant heifers, however changes in miRNA levels that early during pregnancy were very small which likely prevented the identification of robust biomarkers. In this study, we extended our analyses to a wider interval during pregnancy (Days 8 to 60, n = 11 heifers) with the rationale that this may facilitate the identification of additional early pregnancy miRNA biomarkers. Using small RNA sequencing we identified a total of 77 miRNAs that were differentially expressed on Day 60 relative to Day 0 of pregnancy. We selected 14 miRNAs for validation by RT-qPCR and confirmed significant differences in the expression of let-7f, let-7c, miR-30c, miR-101, miR-26a, miR-205 and miR-143 between Days 0 and 60. RT-qPCR profiling throughout Days 0, 8, 16 and 60 of pregnancy showed a distinct increase in circulating levels of miR-26a (3.1-fold, P = 0.046) as early as Day 8 of pregnancy. In summary, in contrast to earlier stages of pregnancy (≤ Day 24), marked differences in the levels of multiple miRNAs can be detected in circulation by Day 60 in cattle. Retrospective analyses showed miR-26a levels to be increased in circulation as early as Day 8, sooner than previously reported in any species, suggesting a biological role for this miRNA in the very early events of pregnancy.

MicroRNA-related polymorphisms and non-Hodgkin lymphoma susceptibility in the Multicenter AIDS Cohort Study

BACKGROUND

MicroRNAs, small non-coding RNAs involved in gene regulation, are implicated in lymphomagenesis. We evaluated whether genetic variations in microRNA coding regions, binding sites, or biogenesis genes (collectively referred to as miRNA-SNPs) were associated with risk of AIDS-associated non-Hodgkin lymphoma (AIDS-NHL), and serum levels of four lymphoma-related microRNAs.

METHODS

Twenty-five miRNA-SNPs were genotyped in 180 AIDS-NHL cases and 529 HIV-infected matched controls from the Multicenter AIDS Cohort Study (MACS), and real-time polymerase chain reaction was used to quantify serum microRNA levels. Adjusted odds ratios (ORs) estimated using conditional logistic regression evaluated associations between miRNA-SNPs and AIDS-NHL risk. A semi-Bayes shrinkage approach was employed to reduce likelihood of false-positive associations. Adjusted mean ratios (MR) calculated using linear regression assessed associations between miRNA-SNPs and serum microRNA levels.

RESULTS

DDX20 rs197412, a non-synonymous miRNA biogenesis gene SNP, was associated with AIDS-NHL risk (OR=1.34 per minor allele; 95% CI: 1.02-1.75), and higher miRNA-222 serum levels nearing statistical significance (MR=1.21 per minor allele; 95% CI: 0.98-1.49). MiRNA-196a2 rs11614913 was associated with decreased central nervous system (CNS) AIDS-NHL (CT vs. CC OR=0.52; 95% CI: 0.27-0.99). The minor allele of HIF1A rs2057482, which creates a miRNA-196a2 binding site, was associated with systemic AIDS-NHL risk (OR=1.73 per minor allele; 95% CI: 1.12-2.67), and decreased CNS AIDS-NHL risk (OR=0.49 per minor allele; 95% CI: 0.25-0.94).

CONCLUSIONS

This study suggests that a few miRNA-SNPs are associated with AIDS-NHL risk and may modulate miRNA expression. These results support a role for miRNA in AIDS-NHL and may highlight pathways to be targeted for risk stratification or therapeutics.

The MYC/miR-17-92 axis in lymphoproliferative disorders: A common pathway with therapeutic potential

MicroRNAs (miRNAs) represent a class of small non-coding single-stranded RNA molecules acting as master regulators of gene expression post transcriptionally by inhibiting the translation or inducing the degradation of target messenger RNAs (mRNAs). In particular, the miR-17-92 cluster is widely expressed in many different cell types and is essential for many developmental and pathogenic processes. As a strong oncogene, miR-17-92 can regulate multiple cellular processes that favor malignant transformation, promoting cell survival, rapid cell proliferation, and increased angiogenesis. The miR-17-92 cluster has been reported to be involved in hematopoietic malignancies including diffuse large B-cell lymphoma, mantle cell lymphoma, Burkitt's lymphoma, and chronic lymphocytic leukemia. Given the multiple and potent effects on cellular proliferation and apoptosis exerted by the miR-17-92 cluster, miRNAs belonging to the cluster surely represent attractive targets for cancer therapy also in the context of lymphoproliferative disorders. In the present review, we focus on the role of the miR-17-92 cluster in lymphoproliferative disorders, including diagnostic/prognostic implications, and on the potential applications of anti-miRNAs based therapies targeting miRNAs belonging to the cluster.

Role of microRNAs in primary central nervous system lymphomas

Primary central nervous system lymphomas (PCNSL) are extranodal non-Hodgkin lymphomas arising exclusively inside the CNS, and account for about 3% of primary intracranial tumours. This tumour lacks systemic manifestations and prognosis of patients with PCNSL remains poor despite recent advancement of chemoradiotherapy. MicroRNAs are small non-coding RNAs that post-transcriptionally downregulate gene expression by binding to target mRNAs, inducing their degradation or translational repression. MicroRNAs play significant roles in almost all malignancy-related biological processes, including cell proliferation, differentiation, apoptosis and metabolism. Many deregulated miRNAs has been identified in PCNSL but their biological significance remains to be fully elucidated. In this review, we summarize current evidence regarding the pathogenic role of PCNSL-associated microRNAs and their potential applications for diagnosis and prognostication of this deadly disease.

The Three Paralogous MicroRNA Clusters in Development and Disease, miR-17-92, miR-106a-363, and miR-106b-25

MicroRNAs (miRNAs) form a class of noncoding RNA genes whose products are small single-stranded RNAs that are involved in the regulation of translation and degradation of mRNAs. There is a fine balance between deregulation of normal developmental programs and tumor genesis. An increasing body of evidence suggests that altered expression of miRNAs is entailed in the pathogenesis of human cancers. Studies in mouse and human cells have identified the miR-17-92 cluster as a potential oncogene. The miR-17-92 cluster is often amplified or overexpressed in human cancers and has recently emerged as the prototypical oncogenic polycistron miRNA. The functional analysis of miR-17-92 is intricate by the existence of two paralogues: miR-106a-363 and miR-106b-25. During early evolution of vertebrates, it is likely that the three clusters commenced via a series of duplication and deletion occurrences. As miR-106a-363 and miR-106b-25 contain miRNAs that are very similar, and in some cases identical, to those encoded by miR-17-92, it is feasible that they regulate a similar set of genes and have overlapping functions. Further understanding of these three clusters and their functions will increase our knowledge about cancer progression. The present review discusses the characteristics and functions of these three miRNA clusters.

MicroRNAs in diffuse large B-cell lymphoma

The aberrant expression of microRNAs (miRs) has a significant impact on the biological characteristics of lymphocytes, and is important in the pathogenesis of diffuse large B-cell lymphoma (DLBCL). It has been demonstrated, using miR profiling and detecting distinct miR signatures, that certain miRs may accurately distinguish different subtypes and prognostic classifications of DLBCL, as well as distinguish DLBCL from other more indolent lymphomas, including follicular lymphoma. miRs are excellent biomarkers for cancer diagnosis and prognosis. In DLBCL, specific miR expression profiles in the tissues of patients are associated with prognosis and clinical outcome. Over the past decade, there has been substantial investigation concerning the pathogenetic, diagnostic and prognostic roles of miRs in DLBCL. The aim of the present review is to describe the aberrant expression of miRs in DLBCL, and the functions, potential clinical use and possible therapeutic targets of miRs in this disease.

The High Expression of the microRNA 17-92 Cluster and its Paralogs, and the Downregulation of the Target Gene PTEN, Is Associated with Primary Cutaneous B-Cell Lymphoma Progression

The oncogenic microRNA (miR) 17-92 cluster has a causative role in the lymphomagenesis of nodal B-cell lymphomas, by activating proliferation and inhibiting apoptosis. Here we analyzed primary cutaneous B-cell lymphomas for the miR-17-92 cluster and its paralogs miR-106a-363 and miR-106b-25. In 22 primary cutaneous diffuse large B-cell lymphomas, leg type (PCLBCL-LT) compared with 22 primary cutaneous follicle center lymphomas (PCFCLs), we found that miR-20a and miR-106a were overexpressed. Multivariate Cox analysis showed that higher miR-20a and miR-20b expression levels were associated with shorter disease-free and overall survival, independently from histological type. Gene expression profiling also showed a downregulation of 8 candidate target genes of miR-20a, miR-20b, and miR-106a in PCLBCL-LT compared with PCFCL. Among the candidate target genes, PTEN, NCOA3, and CAPRIN2 were confirmed to be underexpressed in PCLBCL-LT using quantitative reverse transcriptase-PCR on CD20-positive laser-microdissected tumor cells. In multivariate Cox analysis, lower PTEN mRNA expression level was associated with shorter disease-free survival (DFS), independently from the histological type. Altogether, this molecular and bioinformatic study of 44 patient skin biopsy samples showed that the oncogenic miR-17-92 cluster and its paralogs were involved in cutaneous B-cell lymphoma progression, and that the downregulation of the target gene PTEN was associated with shorter DFS.

5-lipoxygenase is a direct target of miR-19a-3p and miR-125b-5p

5-Lipoxygenase (5-LO) is the key enzyme in leukotriene biosynthesis. Leukotrienes are mediators of the innate immune system and inflammatory processes, and they might also be involved in cancer development. MicroRNAs (miRNAs) are important translational regulators and have been shown to be involved in development, differentiation, and cancer. Unraveling the miRNA network is important for understanding the cellular regulation processes. We identified two new miRNAs, miR-19a-3p and miR-125b-5p, regulating 5-LO and confirmed direct interaction by reporter gene assays. Furthermore, we investigated the regulation of 5-LO by these two miRNAs in several cell types. Inhibition of both miRNAs by antagomirs during differentiation of the myeloid cell line Mono Mac 6 led to a significant increase in 5-LO protein expression. Stimulation of human T lymphocytes with PHA resulted in a strong downregulation of 5-LO mRNA expression and in the induction of miR-19a-3p. The inhibition of miR-19a-3p with an antagomir led to a significant increase in 5-LO mRNA expression in T lymphocytes. Taken together, our data reveal that miR-19a-3p and miR-125b-5p target 5-LO in a cell type- and stimulus-specific manner.

MicroRNAs in B-cells: from normal differentiation to treatment of malignancies

MicroRNAs (miRNAs) are small non-coding RNAs that play important post-transcriptional regulatory roles in a wide range of biological processes. They are fundamental to the normal development of cells, and evidence suggests that the deregulation of specific miRNAs is involved in malignant transformation due to their function as oncogenes or tumor suppressors. We know that miRNAs are involved in the development of normal B-cells and that different B-cell subsets express specific miRNA profiles according to their degree of differentiation. B-cell-derived malignancies contain transcription signatures reminiscent of their cell of origin. Therefore, we believe that normal and malignant B-cells share features of regulatory networks controlling differentiation and the ability to respond to treatment. The involvement of miRNAs in these processes makes them good biomarker candidates. B-cell malignancies are highly prevalent, and the poor overall survival of patients with these malignancies demands an improvement in stratification according to prognosis and therapy response, wherein we believe miRNAs may be of great importance. We have critically reviewed the literature, and here we sum up the findings of miRNA studies in hematological cancers, from the development and progression of the disease to the response to treatment, with a particular emphasis on B-cell malignancies.

Integrated Analysis of Dysregulated miRNA-gene Expression in HMGA2-silenced Retinoblastoma Cells

Retinoblastoma (RB) is a primary childhood eye cancer. HMGA2 shows promise as a molecule for targeted therapy. The involvement of miRNAs in genome-level molecular dys-regulation in HMGA2-silenced RB cells is poorly understood. Through miRNA expression microarray profiling, and an integrated array analysis of the HMGA2-silenced RB cells, the dysregulated miRNAs and the miRNA-target relationships were modelled. Loop network analysis revealed a regulatory association between the transcription factor (SOX5) and the deregulated miRNAs (miR-29a, miR-9*, miR-9-3). Silencing of HMGA2 deregulated the vital oncomirs (miR-7, miR-331, miR-26a, miR-221, miR-17~92 and miR-106b∼25) in RB cells. From this list, the role of the miR-106b∼25 cluster was examined further for its expression in primary RB tumor tissues (n = 20). The regulatory targets of miR-106b∼25 cluster namely p21 (cyclin-dependent kinase inhibitor) and BIM (pro-apoptotic gene) were elevated, and apoptotic cell death was observed, in RB tumor cells treated with the specific antagomirs of the miR-106b∼25 cluster. Thus, suppression of miR-106b∼25 cluster controls RB tumor growth. Taken together, HMGA2 mediated anti-tumor effect present in RB is, in part, mediated through the miR-106b∼25 cluster.

Serum microRNAs in HIV-infected individuals as pre-diagnosis biomarkers for AIDS-NHL

OBJECTIVE

To determine if changes in levels of serum microRNAs (miRNAs) were seen preceding the diagnosis of AIDS-related non-Hodgkin lymphoma (AIDS-NHL).

DESIGN

Serum miRNA levels were compared in 3 subject groups from the Multicenter AIDS Cohort Study: HIV-negative men (n = 43), HIV-positive men who did not develop NHL (n = 45), and HIV-positive men before AIDS-NHL diagnosis (n = 62, median time before diagnosis, 8.8 months).

METHODS

A total of 175 serum-enriched miRNAs were initially screened to identify differentially expressed miRNAs among these groups and the results validated by quantitative polymerase chain reaction. Receiver-operating characteristic analysis was then performed to assess biomarker utility.

RESULTS

Higher levels of miR-21 and miR-122, and a lower level of miR-223, were able to discriminate HIV-infected from the HIV-uninfected groups, suggesting that these miRNAs are biomarkers for HIV infection but are not AIDS-NHL specific. Among the HIV-infected groups, a higher level of miR-222 was able to discriminate diffuse large B-cell lymphoma (DLBCL) and primary central nervous system lymphoma (PCNSL) subjects from HIV-infected subjects who did not develop NHL, with area under the receiver-operating characteristic curve of 0.777 and 0.792, respectively. At miR-222 cutoff values of 0.105 for DLBCL and 0.109 for PCNSL, the sensitivity and specificity were 75% and 77%, and 80% and 82%, respectively.

CONCLUSIONS

Altered serum levels of miR-21, miR-122, and miR-223 are seen in HIV-infected individuals. Higher serum level of miR-222 has clear potential as a serum biomarker for earlier detection of DLBCL and PCNSL among HIV-infected individuals.

Growth-promoting role of the miR-106a~363 cluster in Ewing sarcoma

MicroRNAs (miRs) have been identified as potent regulators of both normal development and the hallmarks of cancer. Targeting of microRNAs has been shown to have preclinical promise, and select miR-based therapies are now in clinical trials. Ewing Sarcoma is a biologically aggressive pediatric cancer with little change in clinical outcomes despite improved chemotherapeutic regimens. There is a substantial need for new therapies to improve Ewing Sarcoma outcomes and to prevent chemotherapy-related secondary sequelae. Most Ewing Sarcoma tumors are driven by the EWS/Fli-1 fusion oncoprotein, acting as a gain-of-function transcription factor causing dysregulation of a variety of targets, including microRNAs. Our previous studies, and those of others, have identified upregulation of miRs belonging to the related miR-17∼92a, miR-106b∼25, and miR-106a∼363 clusters in Ewing Sarcoma. However, the functional consequences of this have not been characterized, nor has miR blockade been explored as an anti-cancer strategy in Ewing Sarcoma. To simulate a potential therapeutic approach, we examined the effects of blockade of these clusters, and their component miRs. Using colony formation as a read-out, we find that blockade of selected individual cluster component miRs, using specific inhibitors, has little or no effect. Combinatorial inhibition using miR “sponge” methodology, on the other hand, is inhibitory to colony formation, with blockade of whole clusters generally more effective than blockade of miR families. We show that a miR-blocking sponge directed against the poorly characterized miR-106a∼363 cluster is a particularly potent inhibitor of clonogenic growth in a subset of Ewing Sarcoma cell lines. We further identify upregulation of miR-15a as a downstream mechanism contributing to the miR-106a∼363 sponge growth-inhibitory effect. Taken together, our studies provide support for a pro-oncogenic role of the miR-106a∼363 cluster in Ewing Sarcoma, and identify miR-106a∼363 blockade, as well as miR-15a replacement, as possible strategies for inhibition of Ewing Sarcoma growth.

MicorRNA 106b ∼ 25 cluster and gastric cancer

Conventional strategies for the early diagnosis and treatment of gastric cancer are not yet satisfactory, and it calls for better diagnosis and treatments based on a deeper understanding of the molecular mechanisms. It has been revealed that the number of verified human microRNA (miRNA) expression contribute to the initiation and progression of cancer. Among them, miR-106b ∼ 25 cluster is of particular interest. The miRNA-106b ∼ 25 cluster is composed of the highly conserved miRNA-106b, miRNA-93 and miRNA-25. The miRNA-106b ∼ 25 polycistron exerted potential proliferative, anti-apoptotic and cell cycle-promoting effects on cancer cells. Over-expression of the miRNA-106b ∼ 25 cluster is known to overcome TGF-beta mediated growth suppression via targeting p21 and Bim. This cluster can additionally target the inhibitory Smad7 protein and increase TGF-beta RI which is sufficient to induce epithelial-to-mesenchymal transition (EMT). MiRNA-93 can promote angiogenesis. The tumor suppressor genes RB and PTEN are the direct targets of miRNA-106b ∼ 25. Especially, miRNA-106b ∼ 25 clusters play an important role in oncogenesis of gastric cancer. Focus on the essential role in tumorgenisis and extremely low expression of miRNA-106b ∼ 25 in normal tissues, it maybe an appropriate target of gastric cancer treatment and a novel biomarkers for detecting gastric cancer.

Apoptosis and microRNA aberrations in cancer

Carcinogenesis arises from the malfunction of genes that control cell growth and division. Therefore, the most effective method of hindering tumourigenesis is to induce the death of immortalized cancer cells. Apoptosis or programmed cell death has shown the most promises in impairing cancer growth. A variety of proteins is involved in the regulation of apoptosis and the malfunction of any these regulators may cause cell proliferation. The microRNAs have been shown to play a central role in the regulation of the cell cycle, including apoptosis. The microRNAs are involved in post-transcriptional gene suppression and have been implicated in the regulation of cell differentiation and development. Aberrations in the microRNA regulation of apoptosis lead to tumourigenesis. The present review assesses the current knowledge of apoptotic regulation in cancer and the effect of microRNA aberrations in tumourigenesis.

B-cell activation induced microRNA-21 is elevated in circulating B cells preceding the diagnosis of AIDS-related non-Hodgkin lymphomas

We show that microRNA-21 is significantly elevated in peripheral B cells of HIV-infected individuals who go on to develop AIDS-related non-Hodgkin lymphoma (n=13, <3 years prior to diagnosis) when compared with HIV-negative (n=18) or HIV-positive controls (n=21) (P<0.01). Moreover, miR-21 is overexpressed in activated B cells and can be induced by interleukin 4 alone, or with CD40 or immunoglobulin M co-stimulation, and lipopolysaccharides, suggesting that miR-21 may help maintain B-cell hyperactivation, contributing to lymphomagenesis.