Is miR-29 an oncogene or tumor suppressor in CLL?

B-1 derived anti-Thy-1 B cells in old aged mice develop lymphoma/leukemia with high expression of CD11b and Hamp2 that different from TCL1 transgenic mice

Human old aged unmutated chronic lymphocytic leukemia U-CLL are the TCL1+ZAP70+CD5+ B cells. Since CD5 makes the BCR signaling tolerance, ZAP70 increased in U-CLL not only TCL1+ alone. In mice, TCL1 (TCL1A) is the negative from neonate to old aged, as TC-. VH8-12/Vk21-5 is the anti-thymocyte/Thy-1 autoreactive ATA B cell. When ATA μκTg generation in mice, ATA B cells are the neonate generated CD5+ B cells in B-1, and in the middle age, CD5+ can be down or continuously CD5+, then, old aged CLL/lymphoma generation with increased CD11b in TC-ZAP70-CD5- or TC-ZAP70+CD5+. In this old aged TC-ATA B microarray analysis showed most similar to human CLL and U-CLL, and TC-ZAP70+CD5+ showed certain higher present as U-CLL. Original neonate ATA B cells showed with several genes down or further increase in old aged tumor, and old aged T-bet+CD11c+, CTNNB1hi, HMGBhi, CXCR4hi, DPP4hi and decreased miR181b. These old aged increased genes and down miR181b are similar to human CLL. Also, in old age ATA B cell tumor, high CD38++CD44++, increased Ki67+ AID+, and decreased CD180- miR15Olow are similar to U-CLL. In this old aged ATA B, increased TLR7,9 and Wnt10b. TC+Tg generated with ATAμκTg mice occurred middle age tumor as TC+ZAP70-CD5+ or TC+ZAP70+CD5+, with high NF-kB1, TLR4,6 and Wnt5b,6 without increased CD11b. Since neonatal state to age with TC+Tg continuously, middle age CLL/lymphoma generation is not similar to old aged generated, however, some increased in TC+ZAP70+ are similar to the old age TC- ATA B tumor. Then, TC- ATA B old age tumor showed some difference to human CLL. ATA B cells showed CD11b+CD22++, CD24 down, and hepcidin Hamp2++ with iron down. This mouse V8-12 similar to human V2-5, and V2-5 showed several cancers with macrophages/neutrophils generated hepcidin+ ironlow or some showed hepcidin- iron+ with tumor, and mouse V8-12 with different Vk19-17 generate MZ B cells strongly increased macrophage++ in old aged and generated intestine/colon tumor. Conclusion, neonate generated TC-ATA B1 cells in old aged tumor generation are CD11b+ in the leukemia CLL together with lymphoma cancer with hepcidin-related Hamp2++ in B-1 cell generation to control iron.

Differential microRNAs Expression during Cancer Development, and Chemoprevention by Natural Compounds: A Comprehensive Review

MicroRNAs are short non-coding RNAs that inhibit gene expression at the post-transcriptional level. Abnormal microRNA expression has been associated with different human diseases, including cancer. Epigenetic changes, mutation, transcriptional deregulation, DNA copy number abnormalities, and defects in the biogenesis machinery play an important role in abnormal microRNA expression. Modulation of microRNAs by natural agents has emerged to enhance the efficacy of conventional chemotherapy through combinatorial therapeutic approach. This review summarizes the current understanding of abnormal microRNA expression in cancer, the different cellular mechanisms of microRNA, and their prevention by natural compounds. Understanding microRNA expression patterns during cancer development may help to identify stage-specific molecular markers. Natural compounds that exert regulatory effects by modulating microRNAs can be used in better cancer chemopreventive strategies by directly targeting microRNAs or as a way to increase sensitivity to existing chemotherapy regimens.

MicroRNA based combinatorial therapy against TKIs resistant CML by inactivating the PI3K/Akt/mTOR pathway: a review

Chronic myeloid leukemia (CML) is characterized by presence of Philadelphia chromosome, which harbors BCR-ABL oncogene responsible for encoding BCR-ABL oncoprotein. This oncoprotein interferes with cellular signaling pathways, resulting in tumor progression. Among these pathways, PI3K/Akt/mTOR pathway is significantly upregulated in CML. Tyrosine kinase inhibitors (TKIs) are current standard therapy for CML, and they have shown remarkable efficacy. However, emergence of TKIs drug resistance has necessitated investigation of novel therapeutic approaches. Components of PI3K/Akt/mTOR pathway have emerged as attractive targets in this context, as this pathway is known to be activated in TKIs-resistant CML cells/patients. Inhibiting this pathway may provide a complementary approach to improving TKIs' efficacy and treatment outcomes. Given previous research indicating that miRNAs play an inhibitory role in cancer, current study used computational tools to identify miRNAs that specifically target pathway's core components. A comprehensive analysis was performed, resulting in identification of 111 miRNAs that potentially target PI3K/Akt/mTOR pathway. From this extensive list, 7 miRNAs was selected for further investigation based on their consistent downregulation across leukemia subtypes. Except for hsa-miR-199a-3p, remaining six miRNAs have been extensively studied in acute myeloid leukemia (AML). Given high similarity between AML and CML, it is believed that six miRNAs which are not studied in context of CML may also be advantageous for curing chemoresistance in CML. Building upon this knowledge, it is reasonable to speculate that a combination therapy approach involving use of miRNAs alongside TKIs may offer improved therapy for TKIs-resistant CML compared to TKIs monotherapy alone.

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.

Connecting the dots in the associations between diet, obesity, cancer, and microRNAs

The prevalence of obesity has reached pandemic levels worldwide, leading to a lower quality of life and higher health costs. Obesity is a major risk factor for noncommunicable diseases, including cancer, although obesity is one of the major preventable causes of cancer. Lifestyle factors, such as dietary quality and patterns, are also closely related to the onset and development of obesity and cancer. However, the mechanisms underlying the complex association between diet, obesity, and cancer remain unclear. In the past few decades, microRNAs (miRNAs), a class of small non-coding RNAs, have been demonstrated to play critical roles in biological processes such as cell differentiation, proliferation, and metabolism, highlighting their importance in disease development and suppression and as therapeutic targets. miRNA expression levels can be modulated by diet and are involved in cancer and obesity-related diseases. Circulating miRNAs can also mediate cell-to-cell communications. These multiple aspects of miRNAs present challenges in understanding and integrating their mechanism of action. Here, we introduce a general consideration of the associations between diet, obesity, and cancer and review the current knowledge of the molecular functions of miRNA in each context. A comprehensive understanding of the interplay between diet, obesity, and cancer could be valuable for the development of effective preventive and therapeutic strategies in future.

The Role of miR-29s in Human Cancers—An Update

MicroRNAs (miRNAs) are small non-coding RNAs that directly bind to the 3’ untranslated region (3’-UTR) of the target mRNAs to inhibit their expression. The miRNA-29s (miR-29s) are suggested to be either tumor suppressors or oncogenic miRNAs that are strongly dysregulated in various types of cancer. Their dysregulation alters the expression of their target genes, thereby exerting influence on different cellular pathways including cell proliferation, apoptosis, migration, and invasion, thereby contributing to carcinogenesis. In the present review, we aimed to provide an overview of the current knowledge on the miR-29s biological network and its functions in cancer, as well as its current and potential applications as a diagnostic and prognostic biomarker and/or a therapeutic target in major types of human cancer.

TGF-β/SMAD Pathway Is Modulated by miR-26b-5p: Another Piece in the Puzzle of Chronic Lymphocytic Leukemia Progression

Simple Summary

TGF-β is a key immunoregulatory pathway that can limit the proliferation of B-lymphocytes. Chronic lymphocytic leukemia (CLL) has been historically conceptualized as a neoplasm characterized by accumulation of mature B cells escaping programmed cell death and undergoing cell-cycle arrest in the G0/G1 phase. However, new evidence indicates that tumor expansion is in fact a dynamic process in which cell proliferation also plays an important role. In general, cancers progress by the emergence of subclones with genomic aberrations distinct from the initial tumor. Often, these subclones are selected for advantages in cell survival and/or growth. Here, we provide novel evidence to explain, at least in part, the origins of CLL progression in a subgroup of patients with a poor clinical outcome. In this cohort, the immunoregulatory pathway TGF-β/SMAD is modulated by miR-26b-5p and the impairment of this axis bypasses cell cycle arrest in CLL cells facilitating disease progression.

Abstract

Clinical and molecular heterogeneity are hallmarks of chronic lymphocytic leukemia (CLL), a neoplasm characterized by accumulation of mature and clonal long-lived CD5 + B-lymphocytes. Mutational status of the IgHV gene of leukemic clones is a powerful prognostic tool in CLL, and it is well established that unmutated CLLs (U-CLLs) have worse evolution than mutated cases. Nevertheless, progression and treatment requirement of patients can evolve independently from the mutational status. Microenvironment signaling or epigenetic changes partially explain this different behavior. Thus, we think that detailed characterization of the miRNAs landscape from patients with different clinical evolution could facilitate the understanding of this heterogeneity. Since miRNAs are key players in leukemia pathogenesis and evolution, we aim to better characterize different CLL behaviors by comparing the miRNome of clinically progressive U-CLLs vs. stable U-CLLs. Our data show up-regulation of miR-26b-5p, miR-106b-5p, and miR-142-5p in progressive cases and indicate a key role for miR-26b-5p during CLL progression. Specifically, up-regulation of miR-26b-5p in CLL cells blocks TGF-β/SMAD pathway by down-modulation of SMAD-4, resulting in lower expression of p21^−Cip1 kinase inhibitor and higher expression of c-Myc oncogene. This work describes a new molecular mechanism linking CLL progression with TGF-β modulation and proposes an alternative strategy to explore in CLL therapy.

Non-coding RNAs as emerging regulators and biomarkers in colorectal cancer

CRC is the third most common cancer occurring worldwide and the second leading cause of cancer deaths. In the year 2020, 1,931,590 new cases of CRC and 935,173 deaths were reported. The last two decades have witnessed an intensive study of noncoding RNAs and their implications in various pathological conditions including cancer. Noncoding RNAs such as miRNAs, tsRNAs, piRNAs, lncRNAs, pseudogenes, and circRNAs have emerged as promising prognostic and diagnostic biomarkers in preclinical studies of cancer. Some of these noncoding RNAs have also been shown as promising therapeutic targets for cancer treatment. In this review, we have discussed the emerging roles of various types of noncoding RNAs in CRC and their future implications in colorectal cancer management and research.

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.

Regulation of epigenetic homeostasis in uveal melanoma and retinoblastoma

Uveal melanoma (UM) and retinoblastoma (RB), which cause blindness and even death, are the most frequently observed primary intraocular malignancies in adults and children, respectively. Epigenetic studies have shown that changes in the epigenome contribute to the rapid progression of both UM and RB following classic genetic changes. The loss of epigenetic homeostasis plays an important role in oncogenesis by disrupting the normal patterns of gene expression. The targetable nature of epigenetic modifications provides a unique opportunity to optimize treatment paradigms and establish new therapeutic options for both UM and RB with these aberrant epigenetic modifications. We aimed to review the research findings regarding relevant epigenetic changes in UM and RB. Herein, we 1) summarize the literature, with an emphasis on epigenetic alterations, including DNA methylation, histone modifications, RNA modifications, noncoding RNAs and an abnormal chromosomal architecture; 2) elaborate on the regulatory role of epigenetic modifications in biological processes during tumorigenesis; and 3) propose promising therapeutic candidates for epigenetic targets and update the list of epigenetic drugs for the treatment of UM and RB. In summary, we endeavour to depict the epigenetic landscape of primary intraocular malignancy tumorigenesis and provide potential epigenetic targets in the treatment of these tumours.

Calcineurin Gamma Catalytic Subunit PPP3CC Inhibition by miR-200c-3p Affects Apoptosis in Epithelial Ovarian Cancer

Epithelial ovarian cancer (EOC) outpaces all the other forms of the female reproductive system malignancies. MicroRNAs have emerged as promising predictive biomarkers to therapeutic treatments as their expression might characterize the tumor stage or grade. In EOC, miR-200c is considered a master regulator of oncogenes or tumor suppressors. To investigate novel miR-200c-3p target genes involved in EOC tumorigenesis, we evaluated the association between this miRNA and the mRNA expression of several potential target genes by RNA-seq data of both 46 EOC cell lines from Cancer Cell line Encyclopedia (CCLE) and 456 EOC patient bio-specimens from The Cancer Genome Atlas (TCGA). Both analyses showed a significant anticorrelation between miR-200c-3p and the protein phosphatase 3 catalytic subunit γ of calcineurin (PPP3CC) levels involved in the apoptosis pathway. Quantitative mRNA expression analysis in patient biopsies confirmed the inverse correlation between miR-200c-3p and PPP3CC levels. In vitro regulation of PPP3CC expression through miR-200c-3p and RNA interference technology led to a concomitant modulation of BCL2- and p-AKT-related pathways, suggesting the tumor suppressive role of PPP3CC in EOC. Our results suggest that inhibition of high expression of miR-200c-3p in EOC might lead to overexpression of the tumor suppressor PPP3CC and subsequent induction of apoptosis in EOC patients.

The Modulating Mechanisms of miRNA-196 in Malignancies and Its Prognostic Value: A Systematic Review and Meta-Analysis

Accumulating studies have revealed that up- or downregulated miRNA-196 expression correlates with the prognostic value in various malignancies; however, existing single studies lack robust evidence to elucidate the role of miRNA-196 in malignancy. The pooled results showed that the upregulation of miRNA-196 expression was significantly correlated with unfavorable OS [HR 2.14; 95% confidence interval (CI), 1.78-2.57; p < 0.001)] and worse PFS (HR 2.84; 95% CI, 1.29-6.23, P = 0.01) in various malignancies. According to the regulatory mechanisms, studies shown that multiple tumors associated with transcription processes could be modulated by the miRNA-196 family; correspondingly, the miRNA-196 family exerted biological functions that could be regulated by various molecules. The upregulation of miRNA-196a, miRNA-196b and miRNA-196 expression is correlated with significantly unfavorable OS in multiple malignancies; similarly, miRNA-196 overexpression predicts poor PFS in multiple malignancies. Taken together, these findings indicate that miRNA-196a and miRNA-196b may serve as oncogenic molecules and may be potential prognostic biomarkers in multiple malignancies.

The Role of cis- and trans-Acting RNA Regulatory Elements in Leukemia

RNA molecules are a source of phenotypic diversity and an operating system that connects multiple genetic and metabolic processes in the cell. A dysregulated RNA network is a common feature of cancer. Aberrant expression of long non-coding RNA (lncRNA), micro RNA (miRNA), and circular RNA (circRNA) in tumors compared to their normal counterparts, as well as the recurrent mutations in functional regulatory cis-acting RNA motifs have emerged as biomarkers of disease development and progression, opening avenues for the design of novel therapeutic approaches. This review looks at the progress, challenges and future prospects of targeting cis-acting and trans-acting RNA elements for leukemia diagnosis and treatment.

Small RNAs, Big Diseases

The past two decades have seen extensive research done to pinpoint the role of microRNAs (miRNAs) that have led to discovering thousands of miRNAs in humans. It is not, therefore, surprising to see many of them implicated in a number of common as well as rare human diseases. In this review article, we summarize the progress in our understanding of miRNA-related research in conjunction with different types of cancers and neurodegenerative diseases, as well as their potential in generating more reliable diagnostic and therapeutic approaches.

The Role of Non-coding RNAs in Oncology

For decades, research into cancer biology focused on the involvement of protein-coding genes. Only recently was it discovered that an entire class of molecules, termed non-coding RNA (ncRNA), plays key regulatory roles in shaping cellular activity. An explosion of studies into ncRNA biology has since shown that they represent a diverse and prevalent group of RNAs, including both oncogenic molecules and those that work in a tumor suppressive manner. As a result, hundreds of cancer-focused clinical trials involving ncRNAs as novel biomarkers or therapies have begun and these are likely just the beginning.

Role of Non-Coding RNAs in the Development of Targeted Therapy and Immunotherapy Approaches for Chronic Lymphocytic Leukemia

In the past decade, novel targeted therapy approaches, such as BTK inhibitors and Bcl2 blockers, and innovative treatments that regulate the immune response against cancer cells, such as monoclonal antibodies, CAR-T cell therapy, and immunomodulatory molecules, have been established to provide support for the treatment of patients. However, drug resistance development and relapse are still major challenges in CLL treatment. Several studies revealed that non-coding RNAs have a main role in the development and progression of CLL. Specifically, microRNAs (miRs) and tRNA-derived small-RNAs (tsRNAs) were shown to be outstanding biomarkers that can be used to diagnose and monitor the disease and to possibly anticipate drug resistance and relapse, thus supporting physicians in the selection of treatment regimens tailored to the patient needs. In this review, we will summarize the most recent discoveries in the field of targeted therapy and immunotherapy for CLL and discuss the role of ncRNAs in the development of novel drugs and combination regimens for CLL patients.

microRNA-29b inhibits cell growth and promotes sensitivity to oxaliplatin in colon cancer by targeting FOLR1

The present study was aimed to explore the functional role of microRNA (miR)-29b in colon cancer, as well as underlying mechanisms. Expressions of miR-29b and folate receptor 1 (FOLR1) were measured in both human colon tumor samples and cell lines. Colon cancer cell lines SW480 and SW620 were transfected with miR-29b mimic, antisense oligonucleotides (ASO)-miR-29b, small interfering (siRNA) against FOLR1 (si-FOLR1), or corresponding negative controls (NCs), and then were incubated with or without oxaliplatin (L-OHP). Thereafter, cell viability, cytotoxicity, cell apoptosis, and expression of FOLR1, ATP Binding Cassette Subfamily G Member 2 (ABCG2) and p-glycoprotein (p-gp) were analyzed. We found that miR-29b was significantly decreased, while FOLR1 was statistically elevated in colon cancer samples and cell lines compared to the nontumor samples and nontumourigenic immortalized human colon epithelial cell line FHC. Overexpression of miR-29b markedly inhibited cell viability, promoted sensitivity to L-OHP, stimulated cell apoptosis (all p < .05), and decreased the levels of ABCG2 and p-gp in cancer cells, whereas suppression of miR-29b showed contrary results. Moreover, we observed that FOLR1 was a direct target of miR-29b and was negatively regulated by miR-29b. In addition, the findings revealed that the effects of FOLR1 inhibition on cell viability, sensitivity to L-OHP, cell apoptosis, and the levels of ABCG2 and p-gp were similar to overexpression of miR-29b. Taken together, our study suggests that miR-29b inhibits cell growth and promotes sensitivity to L-OHP in colon cancer by targeting FOLR1.

Multifunctional miR-155 Pathway in Avian Oncogenic Virus-Induced Neoplastic Diseases

MicroRNAs (miRNAs) are small noncoding RNAs that fine-tune the responses of the cell by modulating the cell transcriptome and gene expression. MicroRNA 155 (miR-155) is a conserved multifunctional miRNA involved in multiple roles including the modulation of the immune responses. When deregulated, miR-155 can also contribute to cancer as has been demonstrated in several human malignancies such as diffuse large B cell lymphoma, chronic lymphocytic leukemia, as well as in Epstein⁻Barr virus (EBV)-induced B cell transformation. Avian oncogenic viruses such as Marek's disease virus (MDV), avian leukosis virus (ALV), and reticuloendotheliosis virus (REV) that account for more than 90% of cancers in avian species, also make use of the miR-155 pathway during oncogenesis. While oncogenic retroviruses, such as ALV, activate miR-155 by insertional activation, acutely transforming retroviruses use transduced oncogenes such as v-rel to upregulate miR-155 expression. MDV on the other hand, encodes a functional miR-155 ortholog mdv1-miR-M4, similar to the miR-155 ortholog kshv-miR-K11 present in Kaposi's sarcoma-associated herpesvirus (KSHV). We have shown that mdv1-miR-M4 is critical for the induction of MDV-induced lymphomas further demonstrating the oncogenic potential of miR-155 pathway in cancers irrespective of the diverse etiology. In this review, we discuss on our current understanding of miR-155 function in virus-induced lymphomas focusing primarily on avian oncogenic viruses.

Abnormal microRNA expression in the course of hematological malignancies

Research on the carcinogenesis process is currently focused primarily on understanding its genetic basis and molecular abnormalities that may be predictive factors and therapeutic targets. It was clearly confirmed recently that microRNAs are involved in the mechanisms of leukocyte development, differentiation, and apoptosis, as well as in the pathogenesis of proliferative diseases of the hematopoietic system. Currently, research strategies allow determination of the deregulation of microRNA profiles in relation to other cytogenetic aberrations, as well as prognostic factors and primary end points. The problem of the possibility of their use as therapeutic targets is also increasingly discussed. In this article, we analyze literature data on abnormalities in microRNA expression in proliferative diseases of the hematopoietic system in the context of classic cytogenetic and molecular aberrations.

Suppressive role exerted by microRNA-29b-1-5p in triple negative breast cancer through SPIN1 regulation

MiR-29 family dysregulation occurs in various cancers including breast cancers. We investigated miR-29b-1 functional role in human triple negative breast cancer (TNBC) the most aggressive breast cancer subtype. We found that miR-29b-1-5p was downregulated in human TNBC tissues and cell lines. To assess whether miR-29b-1-5p correlated with TNBC regenerative potential, we evaluated cancer stem cell enrichment in our TNBC cell lines, and found that only MDA-MB-231 and BT-20 produced primary, secondary and tertiary mammospheres, which were progressively enriched in OCT4, NANOG and SOX2 stemness genes. MiR-29b-1-5p expression inversely correlated with mammosphere stemness potential, and miR-29b-1 ectopic overexpression decreased TNBC cell growth, self-renewal, migration, invasiveness and paclitaxel resistance repressing WNT/βcatenin and AKT signaling pathways and stemness regulators. We identified SPINDLIN1 (SPIN1) among predicted miR-29b-1-5p targets. Consistently, SPIN1 was overexpressed in most TNBC tissues and cell lines and negatively correlated with miR-29b-1-5p. Target site inhibition showed that SPIN1 seems to be directly controlled by miR-29b-1-5p. Silencing SPIN1 mirrored the effects triggered by miR-29b-1 overexpression, whereas SPIN1 rescue by SPIN1miScript protector, determined the reversal of the molecular effects produced by the mimic-miR-29b-1-5p. Overall, we show that miR-29b-1 deregulation impacts on multiple oncogenic features of TNBC cells and their renewal potential, acting, at least partly, through SPIN1, and suggest that both these factors should be evaluated as new possible therapeutic targets against TNBC.

Non-coding RNA networks in cancer

Thousands of unique non-coding RNA (ncRNA) sequences exist within cells. Work from the past decade has altered our perception of ncRNAs from 'junk' transcriptional products to functional regulatory molecules that mediate cellular processes including chromatin remodelling, transcription, post-transcriptional modifications and signal transduction. The networks in which ncRNAs engage can influence numerous molecular targets to drive specific cell biological responses and fates. Consequently, ncRNAs act as key regulators of physiological programmes in developmental and disease contexts. Particularly relevant in cancer, ncRNAs have been identified as oncogenic drivers and tumour suppressors in every major cancer type. Thus, a deeper understanding of the complex networks of interactions that ncRNAs coordinate would provide a unique opportunity to design better therapeutic interventions.

Therapeutic targeting of non-coding RNAs in cancer

The majority of the human genome encodes RNAs that do not code for proteins. These non-coding RNAs (ncRNAs) affect normal expression of the genes, including oncogenes and tumour suppressive genes, which make them a new class of targets for drug development in cancer. Although microRNAs (miRNAs) are the most studied regulatory ncRNAs to date, and miRNA-targeted therapeutics have already reached clinical development, including the mimics of the tumour suppressive miRNAs miR-34 and miR-16, which reached phase I clinical trials for the treatment of liver cancer and mesothelioma, the importance of long non-coding RNAs (lncRNAs) is increasingly being recognised. Here, we describe obstacles and advances in the development of ncRNA therapeutics and provide the comprehensive overview of the ncRNA chemistry and delivery technologies. Furthermore, we summarise recent knowledge on the biological functions of miRNAs and their involvement in carcinogenesis, and discuss the strategies of their therapeutic manipulation in cancer. We review also the emerging insights into the role of lncRNAs and their potential as targets for novel treatment paradigms. Finally, we provide the up-to-date summary of clinical trials involving miRNAs and future directions in the development of ncRNA therapeutics.

MMTV does not encode viral microRNAs but alters the levels of cancer-associated host microRNAs

Mouse mammary tumor virus (MMTV) induces breast cancer in mice in the absence of known virally-encoded oncogenes. Tumorigenesis by MMTV is thought to occur primarily through insertional mutagenesis, leading to the activation of cellular proto-oncogenes and outgrowth of selected cells. Here we investigated whether MMTV encodes microRNAs (miRNAs) and/or modulates host miRNAs that could contribute to tumorigenesis. High throughput small RNA sequencing analysis of MMTV-infected cells and MMTV-induced mammary tumors demonstrates that MMTV does not encode miRNAs. However, infected tissues have altered levels of several host miRNAs, including increased expression of members of the oncogenic miRNA cluster, miR-17-92. Notably, similar changes in miRNA levels have been previously reported in human breast cancers. Combined, our results demonstrate that virally encoded miRNAs do not contribute to MMTV-mediated tumorigenesis, but that changes in specific host miRNAs in infected cells may contribute to virus replication and tumor biology.

MicroRNA-29b alleviates oxygen and glucose deprivation/reperfusion-induced injury via inhibition of the p53-dependent apoptosis pathway in N2a neuroblastoma cells

Cerebral ischemic injury causes severe brain damage and remains one of the leading causes of morbidity and mortality worldwide. Members of the microRNA-29 (miR-29) family are involved in regulating the process of ischemia and may be developed as biomarkers to diagnose and treat cerebral ischemia. The role of miR-29b in cerebral ischemia injury remains poorly understood. The purpose of the present study was to investigate whether miR-29b overexpression suppressed cerebral ischemic injury and to explore its underlying mechanism of action. The results demonstrated that levels of miR-29b in N2a neuroblastoma cells decreased following oxygen and glucose deprivation/reperfusion (OGD/R) treatment. Transfection with miR-29b mimics significantly increased cell viability, decreased lactate dehydrogenase (LDH) leakage, inhibited apoptosis by decreasing morphological changes occurring in the nuclei and reduced caspase-3 activity in OGD/R-treated N2a cells. Conversely, miR-29b inhibitors enhanced OGD/R-induced cytotoxicity and apoptosis. In addition, the miR-29b mimics blocked the increase in Bax and p53 expression and decreased Bcl-2 expression in OGD/R-treated N2a cells, whereas miR-29b inhibitors exacerbated the changes in the expression of these apoptosis-associated proteins caused by OGD/R. p53 knockdown using p53 small interfering RNA decreased cell viability and increased LDH leakage, reversing the improvements that the miR-29b mimics induced in damaged cells. Taken together, the results of the present study demonstrated that miR-29b attenuates ischemic injury by negatively regulating the p53-dependent apoptosis pathway and may therefore be a novel potential therapeutic target for treating ischemic stroke.

Cell-free microRNAs in blood and other body fluids, as cancer biomarkers

The discovery of cell-free microRNAs (miRNAs) in serum, plasma and other body fluids has yielded an invaluable potential source of non-invasive biomarkers for cancer and other non-malignant diseases. miRNAs in the blood and other body fluids are highly stable in biological samples and are resistant to environmental conditions, such as freezing, thawing or enzymatic degradation, which makes them convenient as potential biomarkers. In addition, they are more easily sampled than tissue miRNAs. Altered levels of cell-free miRNAs have been found in every type of cancer analysed, and increasing evidence indicates that they may participate in carcinogenesis by acting as cell-to-cell signalling molecules. This review summarizes the biological characteristics and mechanisms of release of cell-free miRNAs that make them promising candidates as non-invasive biomarkers of cancer.

PPAR-delta promotes survival of chronic lymphocytic leukemia cells in energetically unfavorable conditions

Targeting the mechanisms that allow chronic lymphocytic leukemia (CLL) cells to survive in harsh cancer microenvironments should improve patient outcomes. The nuclear receptor peroxisome proliferator activated receptor delta (PPARδ) sustains other cancers, and in silico analysis showed higher PPARD expression in CLL cells than normal lymphocytes and other hematologic cancers. A direct association was found between PPARδ protein levels in CLL cells and clinical score. Transgenic expression of PPARδ increased the growth and survival of CD5⁺ Daudi cells and primary CLL cells in stressful conditions including exhausted tissue culture media, low extracellular glucose, hypoxia and exposure to cytotoxic drugs. Glucocorticoids and synthetic PPARδ agonists up-regulated PPARD expression and also protected Daudi and primary CLL cells from metabolic stressors. Survival in low glucose was related to increased antioxidant expression, substrate utilization and mitochondrial performance, and was reversed by genetic deletion and synthetic PPARδ antagonists. These findings suggest PPARδ conditions CLL cells to survive in harsh microenvironmental conditions by reducing oxidative stress and increasing metabolic efficiency. Targeting PPARδ may be beneficial in the treatment of CLL.

MicroRNA: Defining a new niche in Leukemia

MicroRNAs (miRNAs) are endogenous short non-coding RNAs found to play key roles in the pathogenesis of leukemia. Apart from being traditionally identified as modulators of oncogenes, the potential roles of miRNAs seems to be growing with novel and recent findings among different subtypes of hematological malignancies. Leukemia is one of the earliest malignancies to be linked to abnormal expression of miRNAs. However, a clear understanding of the involvement of miRNAs in intricate mechanisms of leukemogenesis is still a necessity. This review summarizes the multiple roles of miRNAs in the pathogenesis of leukemia and highlights major research findings contributing to these aspects.

MicroRNA-29a promotes smooth muscle cell differentiation from stem cells by targeting YY1

MicroRNA-29a (miR-29a) has been extensively studied in tumor biology and fibrotic diseases, but little is known about its functional roles in vascular smooth muscle cell (VSMC) differentiation from embryonic stem cells (ESCs). Using well-established VSMC differentiation models, we have observed that miR-29a induces VSMC differentiation from mouse ESCs by negatively regulating YY1, a transcription factor that inhibits muscle cell differentiation and muscle-specific gene expression. Moreover, gene expression levels of three VSMC specific transcriptional factors were up-regulated by miR-29a over-expression, but down-regulated by miR-29a inhibition or YY1 over-expression. Taken together, our data demonstrate that miR-29a and its target gene, YY1, play a regulatory role in VSMC differentiation from ESCs in vitro and in vivo.

miR-29b attenuates tumorigenicity and stemness maintenance in human glioblastoma multiforme by directly targeting BCL2L2

Glioblastoma multiforme (GBM) is the most common malignant brain tumor and exhibits aggressive and invasive behavior. We previously identified four miRNAs—miR-29b, 494, 193a-3p, and 30e—with enhanced expression in GBM following treatment of ionizing radiation by miRNA microarray analysis. In this study, we found that only miR-29b inhibited tumor cell migration and invasion by reducing MMP-2 activity via phospho-AKT/β-catenin signaling, and stimulated a more epithelial-like morphology. Moreover, miR-29b inhibits angiogenesis by attenuating tube formation and the expression of VEGF and Ang-2, and stemness maintenance in GBM cells, as demonstrated by decreasing neurosphere formation and cancer stem cell marker protein expression. These findings support the anti-tumor properties of miR-29b in human GBM cells. Furthermore, miR-29b expression was inversely proportional to that of BCL2L2 mRNA or protein in various cancer cell types. Interestingly, BCL2L2 mRNA is highly expressed in the mesenchymal type of GBM. To further elucidate the relationship between miR-29b and BCL2L2 in GBM, we performed co-transfection reporter assays and determined that miR-29b downregulates BCL2L2 expression by directly binding its 3′UTR. Finally, we confirmed that BCL2L2 repression is of central importance to miR-29b anti-tumor activity using functional assays to examine cell migration, invasion, angiogenesis, and stemness. From these data, we propose that miR-29b may be a useful therapeutic agent in GBM.

Targeting MicroRNA in Cancer Using Plant-Based Proanthocyanidins

Proanthocyanidins are oligomeric flavonoids found in plant sources, most notably in apples, cinnamon, grape skin and cocoa beans. They have been also found in substantial amounts in cranberry, black currant, green tea, black tea and peanut skins. These compounds have been recently investigated for their health benefits. Proanthocyanidins have been demonstrated to have positive effects on various metabolic disorders such as inflammation, obesity, diabetes and insulin resistance. Another upcoming area of research that has gained widespread interest is microRNA (miRNA)-based anticancer therapies. MicroRNAs are short non-coding RNA segments, which plays a crucial role in RNA silencing and post-transcriptional regulation of gene expression. Currently, miRNA based anticancer therapies are being investigated either alone or in combination with current treatment methods. In this review, we summarize the current knowledge and investigate the potential of naturally occurring proanthocyanidins in modulating miRNA expression. We will also assess the strategies and challenges of using this approach as potential cancer therapeutics.

miR-29s: a family of epi-miRNAs with therapeutic implications in hematologic malignancies

A wealth of studies has highlighted the biological complexity of hematologic malignancies and the role of dysregulated signal transduction pathways. Along with the crucial role of genetic abnormalities, epigenetic aberrations are nowadays emerging as relevant players in cancer development, and significant research efforts are currently focusing on mechanisms by which histone post-translational modifications, DNA methylation and noncoding RNAs contribute to the pathobiology of cancer. As a consequence, these studies have provided the rationale for the development of epigenetic drugs, such as histone deacetylase inhibitors and demethylating compounds, some of which are currently in advanced phase of pre-clinical investigation or in clinical trials. In addition, a more recent body of evidence indicates that microRNAs (miRNAs) might target effectors of the epigenetic machinery, which are aberrantly expressed or active in cancers, thus reverting those epigenetic abnormalities driving tumor initiation and progression. This review will focus on the broad epigenetic activity triggered by members of the miR-29 family, which underlines the potential of miR-29s as candidate epi-therapeutics for the treatment of hematologic malignancies.

Novel mechanisms of regulation of miRNAs in CLL

B-cell chronic lymphocytic leukemia (CLL) is the most common adult human leukemia. Although, the molecular alterations leading to CLL onset and progression are still under investigation (specifically, the interplay and exact role of oncogenes and tumor suppressors in CLL pathogenesis). MicroRNAs are small non-coding RNAs that regulate gene expression and are expressed in a tissue specific manner. Deregulation of microRNAs can alter expression levels of genes involved in the development and/or progression of tumors. In CLL, microRNAs can function as oncogenes or tumor suppressors. Here, we review the most recent findings on the role of microRNAs in the onset/progression of CLL, and how this knowledge can be used to identify new biomarkers and targets to treat this leukemia.

MicroRNA as Biomarkers and Diagnostics

MicroRNAs (miRNAs) are a group of small non-coding RNAs that are involved in regulating a range of developmental and physiological processes; their dysregulation has been associated with development of diseases including cancer. Circulating miRNAs and exosomal miRNAs have also been proposed as being useful in diagnostics as biomarkers for diseases and different types of cancer. In this review, miRNAs are discussed as biomarkers for cancer and other diseases, including viral infections, nervous system disorders, cardiovascular disorders, and diabetes. We summarize some of the clinical evidence for the use of miRNAs as biomarkers in diagnostics and provide some general perspectives on their use in clinical situations. The analytical challenges in using miRNAs in cancer and disease diagnostics are evaluated and discussed. Validation of specific miRNA signatures as biomarkers is a critical milestone in diagnostics.

EBV Noncoding RNAs

EBV expresses a number of viral noncoding RNAs (ncRNAs) during latent infection, many of which have known regulatory functions and can post-transcriptionally regulate viral and/or cellular gene expression. With recent advances in RNA sequencing technologies, the list of identified EBV ncRNAs continues to grow. EBV-encoded RNAs (EBERs) , the BamHI-A rightward transcripts (BARTs) , a small nucleolar RNA (snoRNA) , and viral microRNAs (miRNAs) are all expressed during EBV infection in a variety of cell types and tumors. Recently, additional novel EBV ncRNAs have been identified. Viral miRNAs, in particular, have been under extensive investigation since their initial identification over ten years ago. High-throughput studies to capture miRNA targets have revealed a number of miRNA-regulated viral and cellular transcripts that tie into important biological networks. Functions for many EBV ncRNAs are still unknown; however, roles for many EBV miRNAs in latency and in tumorigenesis have begun to emerge. Ongoing mechanistic studies to elucidate the functions of EBV ncRNAs should unravel additional roles for ncRNAs in the viral life cycle. In this chapter, we will discuss our current knowledge of the types of ncRNAs expressed by EBV, their potential roles in viral latency, and their potential involvement in viral pathogenesis.

MicroRNA-29b is a therapeutic target in cerebral ischemia associated with aquaporin 4

MicroRNA-29b (miR-29b) is involved in regulating ischemia process, but the molecular mechanism is unclear. In this work, we explored the function of miR-29b in cerebral ischemia. The level of miR-29b in white blood cells was evaluated in patients and mice after ischemic stroke. Brain infarct volume and National Institute of Health stroke scale (NIHSS) scores were analyzed to determine the relationship between miR-29b expression and the severity of stroke. The relationship of miR-29b and aquaporin-4 (AQP4) was further studied in mice. We found that miR-29b was significantly downregulated in stroke patients (P<0.05). MiR-29b level negatively associated with NIHSS scores (r=-0.349, P<0.01) and brain infarct volume (r=-0.321, P<0.05). In ischemic mice, miR-29b in the brain and blood were both downregulated (r=0.723, P<0.05). MiR-29b overexpression reduced infarct volume (49.50±6.55 versus 35.48±2.28 mm(3), P<0.05), edema (164±4% versus 108±4%, P<0.05), and blood-brain barrier (BBB) disruption compared with controls (15±9% versus 7±3%, P<0.05). Aquaporin-4 expression greatly decreased after miR-29b overexpression (28±7% versus 11±3%, P<0.05). Dual-luciferase reporter system showed that AQP-4 was the direct target of miR-29b (P<0.05). We concluded that miR-29b could potentially predict stroke outcomes as a novel circulating biomarker, and miR-29b overexpression reduced BBB disruption after ischemic stroke via downregulating AQP-4.

Potential roles of microRNA-29a in the molecular pathophysiology of T-cell acute lymphoblastic leukemia

Recent evidence has shown that deregulated expression of members of the microRNA-29 (miR-29) family may play a critical role in human cancer, including hematological malignancies. However, the roles of miR-29 in the molecular pathophysiology of T-cell acute lymphoblastic leukemia (T-ALL) has not been investigated. Here, we show that lower levels of miR-29a were significantly associated with higher blast counts in the bone marrow and with increased disease-free survival in T-ALL patients. Furthermore, miR-29a levels are extremely reduced in T-ALL cells compared to normal T cells. Microarray analysis following introduction of synthetic miR-29a mimics into Jurkat cells revealed the downregulation of several predicted targets (CDK6, PXDN, MCL1, PIK3R1, and CXXC6), including targets with roles in active and passive DNA demethylation (such as DNMT3a, DNMT3b, and members of the TET family and TDG). Restoring miR-29a levels in Jurkat and Molt-4 T-ALL cells led to the demethylation of many genes commonly methylated in T-ALL. Overall, our results suggest that reduced miR-29a levels may contribute to the altered epigenetic status of T-ALL, highlighting its relevance in the physiopathology of this disease.

Geroconversion: irreversible step to cellular senescence

Cellular senescence happens in 2 steps: cell cycle arrest followed, or sometimes preceded, by gerogenic conversion (geroconversion). Geroconvesrion is a form of growth, a futile growth during cell cycle arrest. It converts reversible arrest to irreversible senescence. Geroconversion is driven by growth-promoting, mitogen-/nutrient-sensing pathways such as mTOR. Geroconversion leads to hyper-secretory, hypertrophic and pro-inflammatory cellular phenotypes, hyperfunctions and malfunctions. On organismal level, geroconversion leads to age-related diseases and death. Rapamycin, a gerosuppressant, extends life span in diverse species from yeast to mammals. Stress-and oncogene-induced accelerated senescence, replicative senescence in vitro and life-long cellular aging in vivo all can be described by 2-step model.

MicroRNA-29b attenuates non-small cell lung cancer metastasis by targeting matrix metalloproteinase 2 and PTEN

BACKGROUND

Our pilot study using miRNA PCR array found that miRNA-29b (miR-29b) is differentially expressed in primary cultured CD133-positive A549 cells compared with CD133-negative A549 cells.

METHODS

Ten human non-small cell lung cancer (NSCLC) cell lines and samples from thirty patients with NSCLC were analyzed for the expression of miR-29b by quantitative RT-PCR. Bioinformatics analysis combined with tumor metastasis PCR array showed the potential target genes for miR-29b. miR-29b lentivirus and inhibitors were transfected into NSCLC cells to investigate its role on regulating cell proliferation which was measured by CCK-8 assay in vitro and nude mice xenograft tumor assay in vivo. Cell motility ability was evaluated by transwell assay. The target genes of miR-29b were determined by luciferase assay, quantitative RT-PCR and western blot.

RESULTS

Bioinformatics analysis combined with tumor metastasis PCR array showed that matrix metalloproteinase 2 (MMP2) and PTEN could be important target genes of miR-29b. The expression of miR-29b was down regulated in NSCLC tissues compared to the normal tissues. Clinicopathological analysis demonstrated that miR-29b had significant negative correlation with lymphatic metastasis. The gain-of-function studies revealed that ectopic expression of miR-29b decreased cell proliferation, migration and invasion abilities of NSCLC cells. In contrasts, loss-of-function studies showed that inhibition of miR-29b promoted cell proliferation, migration and invasion of NSCLC cells in vitro. Nude mice xenograft tumor assay confirmed that miR-29b inhibited lung cancer growth in vivo. High-invasion (A549-H) and low-invasion (A549-L) NSCLC cell sublines from A549 cells were created by using the repeated transwell assay aimed to confirm the effect of miR-29b on migration and invasion of NSCLC. Furthermore, the dual-luciferase reporter assay demonstrated that miR-29b inhibited the expression of the luciferase gene containing the 3'-UTRs of MMP2 and PTEN mRNA. Western blotting and quantitative RT-PCR indicated that miR-29b down-regulated the expression of MMP2 at the protein and mRNA levels.

CONCLUSION

Taken together, our results demonstrate that miR-29b serves as a tumor metastasis suppressor, which suppresses NSCLC cell metastasis by directly inhibiting MMP2 expression. The results show that miR-29b may be a novel therapeutic candidate target to slow NSCLC metastasis.

Genetic alteration regulated by microRNAs in biliary tract cancers

Biliary tract cancers (BTCs) constitute a relatively rare but highly malignant class of tumors with poor prognosis including gallbladder cancer, intra- and extra-hepatic cholangiocarcinoma. Recently, accumulated evidences have demonstrated that deregulated expression of microRNAs (miRNAs) is closely associated with the development, invasion, metastasis and prognosis of different cancers including BTCs. MiRNAs comprise an endogenously expressed and highly evolutionarily conserved group of small, non-coding, single-stranded RNAs which negatively regulate target genes expression by means of combining with 3' untranslated region (UTR) of corresponding mRNAs at the post-transcriptional level with significant roles in various fundamental cellular procedures including cell proliferation, differentiation, migration, cell cycle control and apoptosis. Recent studies have indicated that miRNAs could function as novel tumor-promoting genes or tumor suppressor genes to act as potential therapeutic targets in anticancer treatment because the genetic alteration regulated by miRNAs could result in tumorigenesis and tumor inhibition. Anomalous miRNAs expression patterns, acting as phenotypic signatures of distinct cancers, are promising to be used as diagnostic, prognostic, predictive biomarkers. In this review, we summarize the current findings from the studies about potential genetic alteration regulated by miRNAs and their roles in BTCs.

Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature

Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype specifically associated with distal lung vasculature, at least partially due to the derepression of KLF4, components of the PDGF pathway and ECM-related genes associated with synthetic phenotype. Moreover, we found that expression of FBXO32 in vSMCs is significantly upregulated in the distal vasculature of miR-29 null lungs. This indicates a potential important role of miR-29 in smooth muscle cell function by regulating FBXO32 and SMC protein degradation. These results are strongly supported by findings of a cell autonomous role of endogenous miR-29 in promoting SMC differentiation in vitro. Together, our findings suggested a vessel specific role of miR-29 in vSMC differentiation and function by targeting several key negative regulators.

The pathogenesis of some vascular diseases, such as PAH is selectively associated with aberrant differentiation and proliferation of vSMCs of distal arteries. While significant progresses have been made in understanding the core mechanism of differentiation and proliferation of vSMCs, little is known regarding vessel specific regulations. By investigating the expression and function of miR-29 in vivo, we found a vessel selective enriched expression and function of miR-29 during mouse lung development. Interestingly, disruption of miR-29 results in defects in vSMCs differentiation of distal vessels, reminiscent of vSMC phenotype observed in the early stage of PAH in which immature/synthetic vSMCs of distal arteries failed to differentiate and were unable to tune down the expression of collagens and other extracellular-related genes. This is the first evidence that miR-29 selectively regulates vSMCs differentiation and vessel wall formation. Future implications are to study the expression and function of miR-29 in human pulmonary vascular diseases, which might lead to establishing miR-29 as a therapeutic target for disease intervention.

Evaluation of miR-29c inhibits endotheliocyte migration and angiogenesis of human endothelial cells by suppressing the insulin like growth factor 1

MicroRNAs, a class of 22-nucleotide non-coding RNAs, modulate gene expression by associating with the 3'-untranslated regions (3'- UTRs) of messenger RNAs (mRNAs). Although multiple miRNAs are known to be regulated during angiogenesis, their individual roles in blood vessel development are still not fully understood. Herein, we investigate the role of miR-29c in regulating cell cycle and angiogenic phenotype of endothelial cells. The results showed that IGF-1 is highly expressed and down-regulated by miR-29c in human umbilical vein endothelial cells (HUVEC). Consistent with this preliminary finding, introduction of exogenous miR-29c or miR-29c inhibitor alters cell cycle progression, proliferation and tube formation of HUVEC, respectively. Furthermore, by using luciferase reporter assay, we find that the expression of IGF-1, a suppressor transcription factor, is directly regulated by miR-29c through 3'-UTR. In addition, we show that the selective inhibition of PI3K/AKT pathway prior to miR-29c stimulation prevents the expression of angiogenesis suppressor miRNAs that are family and cluster specific. As a conclusion, we find that miR-29c plays a significant role in regulating cell cycle, proliferation and angiogenic properties of HUVECs. This function is likely mediated through IGF-1 proteins at the post-transcriptional level. As a novel molecular target, miR-29c may have a potential value in the treatment of angiogenesis-associated diseases, such as cardiovascular diseases and cancers.

Evaluation of miR-29c inhibits endotheliocyte migration and angiogenesis of human endothelial cells by suppressing the insulin like growth factor 1

MicroRNAs, a class of 22-nucleotide non-coding RNAs, modulate gene expression by associating with the 3'-untranslated regions (3'-UTRs) of messenger RNAs (mRNAs). Although multiple miRNAs are known to be regulated during angiogenesis, their individual roles in blood vessel development are still not fully understood. Herein, we investigate the role of miR-29c in regulating cell cycle and angiogenic phenotype of endothelial cells. The results showed that IGF-1 is highly expressed and down-regulated by miR-29c in human umbilical vein endothelial cells (HUVEC). Consistent with this preliminary finding, introduction of exogenous miR-29c or miR-29c inhibitor alters cell cycle progression, proliferation and tube formation of HUVEC, respectively. Furthermore, by using luciferase reporter assay, we find that the expression of IGF-1, a suppressor transcription factor, is directly regulated by miR-29c through 3'-UTR. In addition, we show that the selective inhibition of PI3K/AKT pathway prior to miR-29c stimulation prevents the expression of angiogenesis suppressor miRNAs that are family and cluster specific. As a conclusion, we find that miR-29c plays a significant role in regulating cell cycle, proliferation and angiogenic properties of HUVECs. This function is likely mediated through IGF-1 proteins at the post-transcriptional level. As a novel molecular target, miR-29c may have a potential value in the treatment of angiogenesis-associated diseases, such as cardiovascular diseases and cancers.

Role of microRNA in chronic lymphocytic leukemia onset and progression

B-cell chronic lymphocytic leukemia (CLL) is the most common human leukemia occurring as indolent or aggressive form. CLL clinical features and genetic abnormalities are well documented, but molecular details are still under investigation. MicroRNAs are small non-coding RNAs involved in several cellular processes and expressed in a tissue-specific manner. MicroRNAs regulate gene expression, and their deregulation can alter expression levels of genes involved in development/progression of tumors. In CLL, microRNAs can function as oncogenes or tumor suppressors and can also serve as markers for CLL onset/progression. Here, we discuss the most recent findings about the role of microRNAs in CLL and how this knowledge can be used to identify new biomarkers and treatment approaches.

Heroin use promotes HCV infection and dysregulates HCV-related circulating microRNAs

Hepatitis C virus (HCV) infection is common among injection drug users (IDUs). There is accumulating evidence that circulating microRNAs (miRNAs) are associated with HCV infection and disease progression. The present study was undertaken to determine the in vivo impact of heroin use on HCV infection and HCV-related circulating miRNA expression. Using the blood specimens from four groups of the study subjects (HCV-infected individuals, heroin users with/without HCV infection, and healthy volunteers), we found that HCV-infected heroin users had significantly higher viral load than HCV-infected non-heroin users (p = 0.0004). Measurement of HCV-related circulating miRNAs in plasma showed that miRs-122, 141, 29a, 29b, and 29c were significantly increased in the heroin users with HCV infection, whereas miR-351, an HCV inhibitory miRNA, was significantly decreased in heroin users as compared to control subjects. Further investigation identified a negative correlation between the plasma levels of miR-29 family members and severity of HCV infection based on aspartate aminotransferase to platelet ratio index (APRI). In addition, heroin use and/or HCV infection also dysregulated a panel of plasma miRNAs. Taken together, these data for the first time revealed in vivo evidence that heroin use and/or HCV infection alter circulating miRNAs, which provides a novel mechanism for the impaired innate anti-HCV immunity among IDUs.

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.

Modulation of miR-29 expression by α-fetoprotein is linked to the hepatocellular carcinoma epigenome

Globally, hepatocellular carcinoma (HCC) accounts for 70%-85% of primary liver cancers and ranks as the second leading cause of male cancer death. Serum alpha-fetoprotein (AFP), normally highly expressed in the liver only during fetal development, is reactivated in 60% of HCC tumors and associated with poor patient outcome. We hypothesize that AFP+ and AFP- tumors differ biologically. Multivariable analysis in 237 HCC cases demonstrates that AFP level predicts poor survival independent of tumor stage (P<0.043). Using microarray-based global microRNA (miRNA) profiling, we found that miRNA-29 (miR-29) family members were the most significantly (P<0.001) down-regulated miRNAs in AFP+ tumors. Consistent with miR-29's role in targeting DNA methyltransferase 3A (DNMT3A), a key enzyme regulating DNA methylation, we found a significant inverse correlation (P<0.001) between miR-29 and DNMT3A gene expression, suggesting that they might be functionally antagonistic. Moreover, global DNA methylation profiling reveals that AFP+ and AFP- HCC tumors have distinct global DNA methylation patterns and that increased DNA methylation is associated with AFP+ HCC. Experimentally, we found that AFP expression in AFP- HCC cells induces cell proliferation, migration, and invasion. Overexpression of AFP, or conditioned media from AFP+ cells, inhibits miR-29a expression and induces DNMT3A expression in AFP- HCC cells. AFP also inhibited transcription of the miR-29a/b-1 locus, and this effect is mediated through c-MYC binding to the transcript of miR-29a/b-1. Furthermore, AFP expression promotes tumor growth of AFP- HCC cells in nude mice.

CONCLUSION

Tumor biology differs considerably between AFP+ HCC and AFP- HCC; AFP is a functional antagonist of miR-29, which may contribute to global epigenetic alterations and poor prognosis in HCC.