MicroRNA 29b functions in acute myeloid leukemia

A miR-29b Byproduct Sequence Exhibits Potent Tumor-Suppressive Activities via Inhibition of NF-κB Signaling in KRAS-Mutant Colon Cancer Cells

We previously demonstrated that miR-29b-3p is a hopeful miRNA-based therapy against colorectal cancer. In this study, we aimed to clarify a value of miR-29b-1-5p as a next-generation treatment, especially for KRAS-mutant colorectal cancer. RT-PCR assay showed that the expression of miR-29b-3p was high, and its partner strand, miR-29b-1-5p, level was only negligible in clinical colorectal cancer samples. Mimic-miR-29b-1-5p significantly inhibited proliferation of KRAS-mutant colorectal cancer cell lines DLD1 and SW480 and KRAS wild-type HT29 cells. Proliferative activity was further examined by either miR-29b-1-5p strand or its opposite complementary sequence because miR-29b-1-5p is a passenger miRNA and may have no physiologic function. We found that completely opposite complementary strand to miR-29b-1-5p, but not miR-29b-1-5p, possessed a potent antitumor effect and named this byproduct miRNA sequence "MIRTX." MIRTX directly targeted the 3'-UTR of CXCR2 and PIK3R1 mRNA and suppressed the NF-κB signaling pathway in KRAS-mutated colorectal cancer cells. MIRTX induced apoptosis in DLD1 with downregulation of antiapoptotic BCL2, BCL-xL, and MCL1 and upregulation of cleaved caspase-3 and cleaved PARP. In mouse xenograft models, systemic administration of MIRTX using a super carbonate apatite as a delivery vehicle significantly inhibited tumor growth of DLD1 and HT29 cells without any particular toxicities. In conclusion, these findings indicate that inhibition of NF-κB signaling by this novel miRNA-based therapeutic could be a promising treatment against refractory KRAS-mutant colorectal cancer and KRAS wild-type colorectal cancer. Mol Cancer Ther; 17(5); 977-87. ©2018 AACR.

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.

miR-188-5p Suppresses Gastric Cancer Cell Proliferation and Invasion via Targeting ZFP91

MicroRNAs (miRNAs) have been demonstrated to be essential regulators in the development and progression of various cancers. The role of miR-188-5p in gastric cancer (GC) has not been determined. In this study, we found that the expression of miR-188-5p was downregulated in GC tissues compared with adjacent normal tissues. The lowly expressed miR-188-5p was significantly associated with lymph node metastasis and advanced TNM stage. Moreover, overexpression of miR-188-5p significantly inhibited GC cell proliferation, migration, and invasion but promoted cellular apoptosis. Mechanistically, we identified transcription factor ZFP91 as a target gene of miR-188-5p in GC. We found that miR-188-5p overexpression significantly inhibited the expression of ZFP91 in GC cell lines. There was an inverse correlation between the expression of miR-188-5p and ZFP91 in GC tissues. We found that restoration of ZFP91 in miR-188-5p-overexpressed MGC-803 and SGC-7901 cells promoted cell proliferation, migration, and invasion. Finally, we also showed that overexpression of miR-188-5p inhibited tumor growth in vivo. Taken together, our findings indicated that miR-188-5p serves as a tumor suppressor in human GC by targeting ZFP91, suggesting that miR-188-5p might be a promising therapeutic target for GC treatment.

miR-29 regulates Tet1 expression and contributes to early differentiation of mouse ESCs

The ten-eleven translocation-1 (Tet1), which converts 5-methylcytosine (5mC) to 5-hydroxymethycytosine (5hmC), plays important roles in many important biological processes, such as mouse embryonic stem cells (ESCs) maintenance. However, the mechanisms for Tet-1 regulation remain largely unknown. Here we showed that miR-29 family (miR-29a, miR-29b and miR-29c) can directly repress Tet1 expression. We found that Tet1 was highly expressed and 5hmC was presented at relatively high levels in mouse ESCs, but the levels of both Tet1 and 5hmC were reduced during the early differentiation of ESCs. On the contrary, miR-29 level was increased in this process. ESCs stably transfecting with miR-29 precursors showed lower levels of Tet1 protein and 5hmC. Furthermore, we demonstrated that miR-29 overexpression selectively affected cell lineage markers and skewed ESC differentiation, which was similar in Tet1 knockdown ESCs. Our results indicate that miR-29 is a direct regulator of Tet1 in mouse ESCs.

MicroRNA-155 increases colon cancer chemoresistance to cisplatin by targeting forkhead box O3

To investigate the effect of microRNA (miR)-155 on colon cancer chemoresistance to cisplatine and its mechanism. Reverse transcription quantitative polymerase chain reaction was used to measure the levels of miR-155 and forkhead box O3 (FOXO3) in colon cancer specimens and cell lines. Overexpression of miR-155 and miR-155 inhibitor were transfected into colon cancer cell lines to investigate its role of chemoresistance to cisplatin in colon cancer. MTS assays were used to analyse cell viability in vitro. In vivo tumor formation assays were performed in C57BL/6 wild type and miR-155 knockout mice (miR-155-/-). A luciferase reporter assay was used to measure the translation of FOXO3. Additionally, the expression of FOXO3 was detected by western blot analysis. It was identified that miR-155 was markedly upregulated in colon cancer tissue and cell lines. Overexpression of miR-155 enhanced colon cancer cell chemoresistance to cisplatin in vitro and tumorigenesis in vivo. In addition, overexpression of miR-155 was associated with decreased levels of FOXO3, primarily through inhibiting the expression of FOXO3 to increase colon cancer resistanec to cisplatin. The present study demonstrated that miR-155 increased colon cancer drug resistance and decreased FOXO3 expression in vivo and in vitro. This may provide a novel method for the treatment of drug-resistant colon cancer.

MicroRNAs as New Biomarkers for Diagnosis and Prognosis, and as Potential Therapeutic Targets in Acute Myeloid Leukemia

Acute myeloid leukemias (AML) are clonal disorders of hematopoietic progenitor cells which are characterized by relevant heterogeneity in terms of phenotypic, genotypic, and clinical features. Among the genetic aberrations that control disease development there are microRNAs (miRNAs). miRNAs are small non-coding RNAs that regulate, at post-transcriptional level, translation and stability of mRNAs. It is now established that deregulated miRNA expression is a prominent feature in AML. Functional studies have shown that miRNAs play an important role in AML pathogenesis and miRNA expression signatures are associated with chemotherapy response and clinical outcome. In this review we summarized miRNA signature in AML with different cytogenetic, molecular and clinical characteristics. Moreover, we reviewed the miRNA regulatory network in AML pathogenesis and we discussed the potential use of cellular and circulating miRNAs as biomarkers for diagnosis and prognosis and as therapeutic targets.

MiR-34a regulates the invasive capacity of canine osteosarcoma cell lines

BACKGROUND

Osteosarcoma (OSA) is the most common bone tumor in children and dogs; however, no substantial improvement in clinical outcome has occurred in either species over the past 30 years. MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and play a fundamental role in cancer. The purpose of this study was to investigate the potential contribution of miR-34a loss to the biology of canine OSA, a well-established spontaneous model of the human disease.

METHODOLOGY AND PRINCIPAL FINDINGS

RT-qPCR demonstrated that miR-34a expression levels were significantly reduced in primary canine OSA tumors and canine OSA cell lines as compared to normal canine osteoblasts. In canine OSA cell lines stably transduced with empty vector or pre-miR-34a lentiviral constructs, overexpression of miR-34a inhibited cellular invasion and migration but had no effect on cell proliferation or cell cycle distribution. Transcriptional profiling of canine OSA8 cells possessing enforced miR-34a expression demonstrated dysregulation of numerous genes, including significant down-regulation of multiple putative targets of miR-34a. Moreover, gene ontology analysis of down-regulated miR-34a target genes showed enrichment of several biological processes related to cell invasion and motility. Lastly, we validated changes in miR-34a putative target gene expression, including decreased expression of KLF4, SEM3A, and VEGFA transcripts in canine OSA cells overexpressing miR-34a and identified KLF4 and VEGFA as direct target genes of miR-34a. Concordant with these data, primary canine OSA tumor tissues demonstrated increased expression levels of putative miR-34a target genes.

CONCLUSIONS

These data demonstrate that miR-34a contributes to invasion and migration in canine OSA cells and suggest that loss of miR-34a may promote a pattern of gene expression contributing to the metastatic phenotype in canine OSA.

Linc00511 acts as a competing endogenous RNA to regulate VEGFA expression through sponging hsa-miR-29b-3p in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy. Long non-coding RNAs (lncRNAs) are important regulators in pathological processes, yet their potential roles in PDAC are poorly understood. Here, we identify a fundamental role for a novel lincRNA, linc00511, in the progression of PDAC. Linc00511 levels in PDAC tissue specimens and cell lines were examined by quantitative real-time PCR. Corresponding adjacent non-neoplastic tissues were used as controls. The function of linc00511 in PDAC cell lines was determined by RNA interference approach in vitro and in vivo. Fluorescence in situ hybridization (FISH) was used to characterize linc00511 expression in PDAC cells. Insights of the mechanism of competitive endogenous RNAs (ceRNAs) were obtained from bioinformatic analysis, luciferase assays and RIP assays. The association between the linc00511/hsa-miR29b-3p axis and VEGFA was verified by Western blotting assay. Immunohistochemistry was performed to evaluate the expression of VEGFA in PDAC samples. The aberrant up-regulation of linc00511 was detected in PDAC cell lines and patient specimens compared with controls. An increase in linc00511 expression indicates the adverse clinical pathological characteristics and poor prognosis. Functionally, linc00511 depletion in PDAC cells decreased proliferation, migration, invasion and endothelial tube formation. Mechanistically, linc00511 could up-regulate VEGFA via its competing endogenous RNA (ceRNA) activity on hsa-miR-29b-3p. In summary, our results define an important axis controlling proliferation, invasion and tumour angiogenesis in PDAC. Linc00511 is a novel lncRNA that plays a significant regulatory role in the pathogenesis and progression of PDAC. Thus, Linc00511 represents a new prognostic biomarker to predict clinical outcome of PDAC patients after surgery and may serve as a potential therapeutic target for PDAC treatment.

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.

Discovery and functional implications of a miR-29b-1/miR-29a cluster polymorphism in acute myeloid leukemia

We previously reported that microRNA (miR)-29b is down-regulated and has a tumor suppressor role in acute myeloid leukemia (AML). However, little is known about the mechanisms responsible for miR-29b expression downregulation in AML. In this work we screened for mutations that could affect miR-29b expression. Using Sanger sequencing, we identified a germline thymidine (T) base deletion within the miR-29b-1/miR-29a cluster precursor in 16% of AML patients. Remarkably we found a significant enrichment for the presence of the miR-29 polymorphism in core binding factor (CBF) newly diagnosed AML patients (n = 61/303; 20%) with respect to age, sex and race matched controls (n = 43/402:11%, P < 0.01). Mechanistically, this polymorphism affects the expression ratio of mature miR-29b and miR-29a by dampening the processing of miR-29a. RNA immunoprecipitation assays showed reduced DROSHA binding capacity to the polymorphism with respect to the controls. Finally, we showed that this polymorphism negatively impacts the ability of miR-29b-1/miR-29a cluster to target MCL-1 and CDK6, both known miR-29 targets.

MicroRNA-29a inhibits proliferation and motility of schwannoma cells by targeting CDK6

MicroRNA-29 (miR-29) family is involved in various types of cancer regulation. Although miR-29 family was shown to play an inhibitory role in tumorigenesis, the effect of miR-29a expression on schwannoma cells still remains unclear. In this study, we aimed to explore the role of miR-29 family in schwannoma. The expressions of miR-29a, miR-29b, and miR-29c were detected in the Schwann tissues and cell lines using qRT-PCR. The effect of miR-29a, miR-29b, and miR-29c on cell viability, migration, invasion, and apoptosis was tested. Then, the regulatory relationship between miR-29a and CKD6 was detected using qRT-PCR, Western blot, and luciferase assay. Finally, the phosphorylation levels of mainly factors in JNK and p38MAPK/ERK pathways were analyzed by Western blot. The expression of miR-29a, miR-29b, and miR-29c was downregulated in Schwann tissues and cell lines. Cell viability, migration, invasion were decreased, while apoptosis was increased when miR-29a, miR-29b, and miR-29c overexpression. We further found that miR-29a negatively regulated expression of CDK6. Then, knockdown of miR-29a promoted cell viability, migration, invasion, and inhibited apoptosis in schwannoma cells by upregulating CDK6 expression. In addition, the overexpression of miR-29a downregulated CDK6 expression by deactivation of JNK and p38MAPK/ERK pathways. Our data suggested that miR-29a could play an important role in inhibiting proliferation and motility of cancerous Schwann cells, and may suppress tumor growth through upregulation of CDK6.

MiR-29b expression is associated with a dexmedetomidine-mediated protective effect against oxygen-glucose deprivation-induced injury to SK-N-SH cells in vitro

Ischemic cerebral stroke is a leading cause of death and long-term disability world-wide. Neuronal injury following cerebral ischemia initiates a complex series of signaling cascades that lead to neuronal cell death. MicroRNA 29b (miR-29b) has reported involvement in the pathogenic process of ischemic brain injury. Dexmedetomidine (Dex) is a highly selective α₂ adrenergic receptor stimulant that exerts a protective effect on brain tissue. To determine whether Dex might directly influence miR-29b expression after an ischemic injury, human neuroblastoma SK-N-SH cells were subjected to oxygen-glucose deprivation (OGD) for the purpose of creating a neuronal injury model that mimics the effects of brain ischemia in vitro. Next, the association of miR-29b with the protective effect of Dex against ischemic brain injury was studied through the enhancement or inhibition of miR-29b expression by transfection with an miR-29b mimic or inhibitor. We demonstrated that Dex treatment could reduce miR-29b expression, increase cell viability, and inhibit cell apoptosis in the OGD-induced neuronal injury model in vitro. Furthermore, down-regulation of miR-29b expression produced effects on OGD-induced neuronal injuries that were similar to those produced by Dex treatment. Moreover, up-regulation of miR-29b reversed the protective effect of Dex treatment against OGD-induced neuronal injury. Therefore, down-regulation of miR-29b expression might play a role in anti-apoptotic signaling similar to that played by Dex. Elucidation of the role played by miR-29b in ischemia, and identification of a definite association between Dex and miR-29b may lead to the development of new strategies for treating ischemic brain injuries.

miR-29a-3p suppresses cell proliferation and migration by downregulating IGF1R in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common primary tumor of the liver, has a poor prognosis and rapid progression. MicroRNAs (miRNAs) play important roles in carcinogenesis and tumor progression. Insulin-like growth factor 1 receptor (IGF1R) is a transmembrane heterotetrameric protein that has been reported to promote transformation to malignancy and cancer cell proliferation and survival. In this study, we found that the expression of miR-29a-3p was downregulated in HCC patients, resulting in poor survival rates. Contrastingly, the overexpression of miR-29a-3p significantly inhibited proliferation and migration in HepG2 cells. miR-29a-3p directly targeted IGF1R and down-regulated its expression. Moreover, knockdown of IGF1R led to the increased production of chemokine ligand 5 (CCL5). In tumor lesions, the local expression of CCL5 negatively affected the expression of IGF1R. Transwell analysis showed that CCL5 was important for the chemotactic movement of CD8+ T lymphocytes. The expression of CCL5 in HCC tissues positively correlated with the expression of CD8+ T lymphocyte surface marker, CD8. Patients with high CCL5 expression exhibited better survival. Our results revealed that miR-29a-3p is a tumor suppressor gene that acts by directly repressing the oncogene IGF1R, which takes part in immunoregulation in tumor microenvironments in HCC, implying that miR-29a-3p could be a potential target for HCC treatment.

Regulating the regulators: Epigenetic, transcriptional, and post-translational regulation of RGS proteins

Regulators of G protein signaling (RGS) are a family of proteins classically known to accelerate the intrinsic GTPase activity of G proteins, which results in accelerated inactivation of heterotrimeric G proteins and inhibition of G protein coupled receptor signaling. RGS proteins play major roles in essential cellular processes, and dysregulation of RGS protein expression is implicated in multiple diseases, including cancer, cardiovascular and neurodegenerative diseases. The expression of RGS proteins is highly dynamic and is regulated by epigenetic, transcriptional and post-translational mechanisms. This review summarizes studies that report dysregulation of RGS protein expression in disease states, and presents examples of drugs that regulate RGS protein expression. Additionally, this review discusses, in detail, the transcriptional and post-transcriptional mechanisms regulating RGS protein expression, and further assesses the therapeutic potential of targeting these mechanisms. Understanding the molecular mechanisms controlling the expression of RGS proteins is essential for the development of therapeutics that indirectly modulate G protein signaling by regulating expression of RGS proteins.

Epigenetic regulation of miR-200 as the potential strategy for the therapy against triple-negative breast cancer

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that are involved in the regulation of gene expression at the post-transcriptional level. MicroRNAs play an important role in cancer cell proliferation, survival and apoptosis. Epigenetic modifiers regulate the microRNA expression. Among the epigenetic players, histone deacetylases (HDACs) function as the key regulators of microRNA expression. Epigenetic machineries such as DNA and histone modifying enzymes and various microRNAs have been identified as the important contributors in cancer initiation and progression. Recent studies have shown that developing innovative microRNA-targeting therapies might improve the human health, specifically against the disease areas of high unmet medical need. Thus microRNA based therapeutics are gaining importance for anti-cancer therapy. Studies on Triple negative breast cancer (TNBC) have revealed the early relapse and poor overall survival of patients which needs immediate therapeutic attention. In this report, we focus the effect of HDAC inhibitors on TNBC cell proliferation, regulation of microRNA gene expression by a series of HDAC genes, chromatin epigenetics, epigenetic remodelling at miR-200 promoter and its modulation by various HDACs. We also discuss the need for identifying novel HDAC inhibitors for modulation of miR-200 in triple negative breast cancer.

The heterogeneous landscape of ALK negative ALCL

Anaplastic Large Cell Lymphoma (ALCL) is a clinical and biological heterogeneous disease including systemic ALK positive and ALK negative entities. Whereas ALK positive ALCLs are molecularly characterized and readily diagnosed, specific immunophenotypic or genetic features to define ALK negative ALCL are missing, and their distinction from other T-cell non-Hodgkin lymphomas (T-NHLs) can be controversial. In recent years, great advances have been made in dissecting the heterogeneity of ALK negative ALCLs and in providing new diagnostic and treatment options for these patients. A new revision of the World Health Organization (WHO) classification promoted ALK negative ALCL to a definite entity that includes cytogenetic subsets with prognostic implications. However, a further understanding of the genetic landscape of ALK negative ALCL is required to dictate more effective therapeutic strategies specifically tailored for each subgroup of patients.

Dysfunctional diversity of p53 proteins in adult acute myeloid leukemia: projections on diagnostic workup and therapy

The heterogeneous nature of acute myeloid leukemia (AML) and its poor prognosis necessitate therapeutic improvement. Current advances in AML research yield important insights regarding AML genetic, epigenetic, evolutional, and clinical diversity, all in which dysfunctional p53 plays a key role. As p53 is central to hematopoietic stem cell functions, its aberrations affect AML evolution, biology, and therapy response and usually predict poor prognosis. While in human solid tumors TP53 is mutated in more than half of cases, TP53 mutations occur in less than one tenth of de novo AML cases. Nevertheless, wild-type (wt) p53 dysfunction due to nonmutational p53 abnormalities appears to be rather frequent in various AML entities, bearing, presumably, a greater impact than is currently appreciated. Hereby, we advocate assessment of adult AML with respect to coexisting p53 alterations. Accordingly, we focus not only on the effects of mutant p53 oncogenic gain of function but also on the mechanisms underlying nonmutational wtp53 inactivation, which might be of therapeutic relevance. Patient-specific TP53 genotyping with functional evaluation of p53 protein may contribute significantly to the precise assessment of p53 status in AML, thus leading to the tailoring of a rationalized and precision p53-based therapy. The resolution of the mechanisms underlying p53 dysfunction will better address the p53-targeted therapies that are currently considered for AML. Additionally, a suggested novel algorithm for p53-based diagnostic workup in AML is presented, aiming at facilitating the p53-based therapeutic choices.

miR-29a/b/c function as invasion suppressors for gliomas by targeting CDC42 and predict the prognosis of patients

Background:

The lethality and poor outcome of high-grade gliomas result from the tumour relentless invasion. miR-29a/b/c downexpressions contribute to several human tumourigenesis. However, their relevance to prognosis and invasion in gliomas remains unclear.

Methods:

Relationships of miR-29a/b/c and CDC42 expressions to grade and survival-time in 147 human gliomas were analysed by in situ hybridisation and immunohistochemistry. Dual-luciferase reporter assay was used to identify CDC42 as a target of miR-29a/b/c. Underlining mechanisms by which miR-29a/b/c inhibited glioma cell migration and invasion were studied by in vitro and in vivo assays.

Results:

miR-29a/b/c expressions were inversely correlated with glioma grades, but positively correlated with patients’ survival. Two distinct subgroups of grade I–IV glioma patients with different prognoses were identified according to miR-29a/b/c expressions. miR-29a/b/c overexpressions suppressed glioma cell migration and invasion through targeting CDC42 and subsequently decreasing phosphorylated PAK1/2/3, LIMK1/2 and cofilin, the pivotal downstream effectors of CDC42. Moreover, CDC42 expression was positively correlated with glioma grades, but inversely correlated with miR-29a/b/c expressions and patients’ survival. In glioblastoma cell lines, CDC42-knockdown could mimic the anti-tumour effects of miR-29a/b/c.

Conclusions:

miR-29a/b/c are important tumour suppressors and novel prognostic biomarkers of gliomas, and miR-29a/b/c and CDC42 are potential therapeutic candidates for malignant gliomas.

MicroRNAs and acute myeloid leukemia: therapeutic implications and emerging concepts

Acute myeloid leukemia (AML) is a deadly hematologic malignancy characterized by the uncontrolled growth of immature myeloid cells. Over the past several decades, we have learned a tremendous amount regarding the genetic aberrations that govern disease development in AML. Among these are genes that encode noncoding RNAs, including the microRNA (miRNA) family. miRNAs are evolutionarily conserved small noncoding RNAs that display important physiological effects through their posttranscriptional regulation of messenger RNA targets. Over the past decade, studies have identified miRNAs as playing a role in nearly all aspects of AML disease development, including cellular proliferation, survival, and differentiation. These observations have led to the study of miRNAs as biomarkers of disease, and efforts to therapeutically manipulate miRNAs to improve disease outcome in AML are ongoing. Although much has been learned regarding the importance of miRNAs in AML disease initiation and progression, there are many unanswered questions and emerging facets of miRNA biology that add complexity to their roles in AML. Moving forward, answers to these questions will provide a greater level of understanding of miRNA biology and critical insights into the many translational applications for these small regulatory RNAs in AML.

Prognostic value of the MicroRNA-29 family in multiple human cancers: A meta-analysis and systematic review

MicroRNAs (miRNAs) in cancer development have attracted much attention in recent years. miR-29 is known to critically affect cancer progression by functioning as a tumor suppressor. However, it may also act as an oncogene under certain situations. The prognostic value of the miR-29 family in cancer progression is still under debate and reported results are inconsistent. Therefore, we reported here a meta-analysis and systematic review to analyze the prognostic role of the miR-29 family in cancer. We screened 20 published studies and calculated pooled hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for overall survival (OS) or disease-free survival/recurrence-free survival (DFS/RFS). Our results showed that a low or absent expression of miR-29 family was significantly associated with poor OS (HR, 1.57; 95%CI, 1.18-2.08), and inferior to 5-year DFS/RFS (HR, 1.89; 95%CI, 1.47-2.44). Analysis of individual miR-29 subtypes indicated that the low expression of miR-29a/b/c subtypes correlated with poor 5-year OS (miR-29a: HR, 1.99; 95%CI, 1.41-2.80; miR-29b: HR, 1.60; 95%CI, 1.18-2.17; miR-29c: HR, 1.69; 95%CI, 1.00-2.86), as well as poor 5-year DFS/RFS (miR-29b: HR, 1.70; 95%CI, 1.27-2.27). Ethnicity analysis demonstrated Asian patients with low expression of miR-29 were significantly correlated with poor OS (HR, 1.61; 95%CI, 1.16-2.23) and 5-year DFS/RFS (HR, 2.03; 95%CI, 1.50-2.74). Taken together, our analysis indicates that the low expression of miR-29 is associated with aggressiveness and poor prognosis of malignant neoplasms. More importantly, miR-29 might serve as a key biomarker for predicting the recurrence and progression of human cancers.

Endothelial growth medium suppresses apoptosis of mesenchymal stem cells in vitro via decrease of miR‑29a

The administration of mesenchymal stem cells (MSCs) in cases of cardiac ischemia/reperfusion injury (IRI) has been associated with a significant reduction of myocardial cell death and an effective improvement in cardiac function. However, one major limiting factor in MSCs transplantation therapy is the low survival rate of the transplanted cells. The present study aimed to demonstrate that human amnion‑derived mesenchymal stem cells (hAMSCs) cultured with endothelial growth medium (EGM‑2) exhibited reduced apoptosis when exposed to serum‑free and hypoxic conditions; and that the expression of microRNA (miR)‑29a decreased significantly. Furthermore, miR‑29a knockdown resulted in decreased apoptosis of hAMSCs and increased myeloid cell leukemia (MCL)‑1 at the mRNA and protein levels. These results suggested that EGM‑2 promoted survival of hAMSCs partly through the regulation of miR‑29a and MCL‑1 expression levels. These findings may provide a novel understanding of a potential effective therapeutic strategy for cardiac IRI.

MicroRNA-29 family functions as a tumor suppressor by targeting RPS15A and regulating cell cycle in hepatocellular carcinoma

Growing evidence shows that miRNA plays an important role in the development and progression of cancer. In this study, we found that the expression levels of miR-29 family were dramatically decreased in hepatocellular carcinoma (HCC) cell lines and clinical tissues. Then, we demonstrated that ectopic expression of miR-29 family could significantly suppress cell proliferation and induce apoptosis in HCC cells. Luciferase assay together with western blot assay confirmed that miR-29 family bound directly to the 3'-untranslated region (3'-UTR) of RPS15A and reduced the expression of RPS15A. In addition, the cell cycle related gene including cyclinA, cyclin D1 and p21 were also down-regulated when increased the expression of miR-29 family, which is similar as silencing RPS15A expression. Moreover, co-transfection of miR-29 mimics with 3'UTR-deleted RPS15A could rescue the expressions of cyclin A and cyclin D1 while down-regulate the p21 expression. In conclusion, miR-29 family functions as a novel tumor suppressor in HCC by regulate cell growth and cell cycle through binding to RPS15A 3'UTR. These findings may be utilized in developing novel therapeutic tools for HCC.

Deciphering the Role of microRNAs in BRD4-NUT Fusion Gene Induced NUT Midline Carcinoma

NUT midline carcinoma (NMC) is a very aggressive and lethal type of squamous epithelial cell cancer caused due to fusion of BRD4 and NUT genes. The gene fusion results into a new fusion protein that promotes oncogenesis. The detailed molecular mechanisms underlying the NMC are still not clear and new findings are urgently required to complement the current efforts. Abnormal microRNAs (miRNA) expression promotes tumour formation by modulating the functional expression of critical genes other than the parent genes involved in tumour cell proliferation or survival. Here, using Insilco methods, miRNA targeting the transcripts of parent genes (BRD4 and NUT) and the BRD4-NUT fusion gene were predicted. We investigated a situation, wherein abnormal miRNA expression in malignant cells could arise due to deletion and fusion of genomic regions encompassing the target site of miRNA genes. A set of 48 dysregulated miRNAs targeting the critical genes other than the parent genes (BRD4 and NUT) was identified. Functional enrichment analysis of KEGG pathways of target genes of these Ex-miRNAs implicates their role in cancer pathways. Amplification in the expression level of these miRNAs can be used for NMC diagnosis and prognosis.

Specific Depletion of Leukemic Stem Cells: Can MicroRNAs Make the Difference?

For over 40 years the standard treatment for acute myeloid leukemia (AML) patients has been a combination of chemotherapy consisting of cytarabine and an anthracycline such as daunorubicin. This standard treatment results in complete remission (CR) in the majority of AML patients. However, despite these high CR rates, only 30–40% (<60 years) and 10–20% (>60 years) of patients survive five years after diagnosis. The main cause of this treatment failure is insufficient eradication of a subpopulation of chemotherapy resistant leukemic cells with stem cell-like properties, often referred to as “leukemic stem cells” (LSCs). LSCs co-exist in the bone marrow of the AML patient with residual healthy hematopoietic stem cells (HSCs), which are needed to reconstitute the blood after therapy. To prevent relapse, development of additional therapies targeting LSCs, while sparing HSCs, is essential. As LSCs are rare, heterogeneous and dynamic, these cells are extremely difficult to target by single gene therapies. Modulation of miRNAs and consequently the regulation of hundreds of their targets may be the key to successful elimination of resistant LSCs, either by inducing apoptosis or by sensitizing them for chemotherapy. To address the need for specific targeting of LSCs, miRNA expression patterns in highly enriched HSCs, LSCs, and leukemic progenitors, all derived from the same patients’ bone marrow, were determined and differentially expressed miRNAs between LSCs and HSCs and between LSCs and leukemic progenitors were identified. Several of these miRNAs are specifically expressed in LSCs and/or HSCs and associated with AML prognosis and treatment outcome. In this review, we will focus on the expression and function of miRNAs expressed in normal and leukemic stem cells that are residing within the AML bone marrow. Moreover, we will review their possible prospective as specific targets for anti-LSC therapy.

MicroRNA-29 Family Suppresses the Invasion of HT1080 Human Fibrosarcoma Cells by Regulating Matrix Metalloproteinase 2 Expression

Matrix metalloproteinase 2 (MMP2) is a potent protumorigenic, proangiogenic, and prometastatic enzyme that is overexpressed in metastatic cancer. Although there have been various studies on the MMP2 gene, further studies of regulatory factors are required to achieve inhibition of MMP2 enzyme activities. MicroRNAs (miRNAs) play key roles in tumor metastasis. However, the specific functions of miRNAs in metastasis are unclear. In this study, we assessed the function of the microRNA-29 family (miR-29s) in HT1080 human fibrosarcoma cells and examined the regulatory mechanisms of these miRNAs on MMP2 activation. Using miRanda, TargetScan, and PicTar databases, miR-29s were identified as candidate miRNAs targeting MMP2. Gain-of-function studies showed that overexpression of miR-29s could inhibit the invasion of HT1080 cells, suggesting their tumor-suppressive roles in HT1080 cells. In addition, dual luciferase reporter assays indicated that miR-29s could inhibit the expression of the luciferase gene containing the 3'-untranslated region of MMP2 mRNA. Ectopic expression of miR-29s down-regulated the expression of MMP2. Moreover, ectopic expression of miR-29s reduced MMP2 enzyme activity. These results suggested that miR-29s could decrease the invasiveness of HT1080 cells by modulating MMP2 signaling. Taken together, our results demonstrated that miR-29s may serve as therapeutic targets to control tumor metastasis.

Regulation of miR-29b-1/a transcription and identification of target mRNAs in CHO-K1 cells

miR-29b and miR-29a transcript levels were reported to increase in exponentially growing CHO-K1 cells. Here, we examine the regulation of miR-29b-1/a in CHO-K1 cells. We observed that 4-hydroxytamoxifen (4-OHT) increased pri-miR-29b-1 and pri-miR-29a transcription in CHO-K1 cells by activating endogenous estrogen receptor α (ERα). DICER, an established, bona fide target of miR-29b-1/a, was shown to be regulated by 4-OHT in CHO-K1 cells. We showed that miR-29b-1 and miR-29a serve a repressive role in cell proliferation, migration, invasion, and colony formation in CHO-K1 cells. To identify other targets of miR-29b-1 and miR-29a, RNA sequencing was performed by transfecting cells with anti-miR-29a, which inhibits both miR-29a and miR-29b-1, pre-miR-29b-1, and/or pre-miR-29a. In silico network analysis in MetaCore™ identified common and unique putative gene targets of miR-29b-1 and miR-29a. Pathway analysis of identified putative miR-29 targets were related to cell adhesion, cytoskeletal remodeling, and development. Further inquiry revealed regulation of pathways mediating responses to growth factor stimulus and cell cycle regulation.

MicroRNA-29b Inhibits Angiogenesis by Targeting VEGFA through the MAPK/ERK and PI3K/Akt Signaling Pathways in Endometrial Carcinoma

OBJECTIVE

The purpose of this study is to explore the effects of microRNA-29b (miR-29b) regulating MAPK/ERK and PI3K/Akt signaling pathways on angiogenesis in endometrial carcinoma (EC) by targeting VEGFA.

METHODS

Between February 2013 and April 2015, 126 EC patients admitted to the Second Affiliated Hospital of Nanchang University were randomly selected, with 126 EC tissues and the corresponding adjacent normal tissues collected after surgery. The human EC cell lines RL-95-2 and HEC-1-B and human endometrial cells were assigned to the normal group (human endometrial cells), the blank group (untransfected RL-95-2 or HEC-1-B cells), the pMIR-control group (RL-95-2 or HEC-1-B cells transfected with an empty vector), the pMIR-miR-29b group (RL-95-2 or HEC-1-B cells transfected with the miR-29b plasmid), LNA-control group (RL-95-2 or HEC-1-B cells transfected with an oligonucleotide inhibitors control), the LNA-miR-29b inhibitors group (RL-95-2 or HEC-1-B cells transfected with miRCURY LNATM miR-29b inhibitors), the LNA-miR-29b inhibitors + PD98059 group (RL-95-2 or HEC-1-B cells transfected with miRCURY LNATM miR-29b inhibitors and PD98059, an inhibitor of the MAPK/ERK signaling pathway) and the LNA-miR-29b inhibitors + wortmannin group (RL-95-2 or HEC-1-B cells transfected with miRCURY LNATM miR-29b inhibitors and wortmannin, an inhibitor of the PI3K/Akt signaling pathway). qRT-PCR and Western blotting were conducted to detect the miR-29b expression and the mRNA and protein expressions of VEGFA, ERK, Akt, mTOR and Bcl-2. Immunohistochemistry (IHC) was performed to determine the microvessel density (MVD) expression in the EC tissues, adjacent normal tissues and nude-mice.

RESULTS

Compared with the adjacent normal tissues, miR-29b expression was down-regulated, the mRNA and protein expressions of VEGFA, ERK, Akt, mTOR and Bcl-2 were up-regulated, and MVD expression was increased in the EC tissues. Compared with the normal group, miR-29b expression was down-regulated, while the mRNA and protein expressions of VEGFA, ERK, Akt, mTOR and Bcl-2 were up-regulated in the other groups. Compared with the blank, pMIR-control and LNA-control groups, miR-29b expression was increased, while mRNA and protein expressions of VEGFA, ERK, Akt, mTOR and Bcl-2 were decreased in the pMIR-miR-29b group. The LNA-miR-29b inhibitors group exhibited elevated miR-29b expression and decreased mRNA and protein expressions of VEGFA, ERK, Akt, mTOR and Bcl-2 (All P < 0.05). Additionally, miR-29b expression was reduced in the LNA-miR-29b inhibitors + PD98059 and LNA-miR-29b inhibitors + wortmannin groups. In comparison to the normal group, MVD expression was elevated in the other groups. Compared with the blank, pMIR-control, LNA-control, LNA-miR-29b inhibitors + PD98059 and LNA-miR-29b inhibitors + wortmannin groups, MVD expression was decreased in the pMIR-miR-29b group but increased in the LNA-miR-29b inhibitors group.

CONCLUSION

Our results indicate that miR-29b negatively modulates the MAPK/ERK and PI3K/Akt signaling pathways to inhibit angiogenesis in EC by targeting VEGFA.

MCL-1 is modulated in Crohn's disease fibrosis by miR-29b via IL-6 and IL-8

The miR-29 family is involved in fibrosis in multiple organs, including the intestine where miR-29b facilitates TGF-β-mediated up-regulation of collagen in mucosal fibroblasts from Crohn’s disease (CD) patients. Myeloid cell leukemia-1 (MCL-1), a member of the B-cell CLL/Lymphoma 2 (BCL-2) apoptosis family, is involved in liver fibrosis and is targeted by miR-29b via its 3’-UTR in cultured cell lines. We investigate the role of MCL-1 and miR-29b in primary intestinal fibroblasts and tissue from stricturing CD patients. Transfection of CD intestinal fibroblasts with pre-miR-29b resulted in a significant increase in the mRNA expression of MCL-1 isoforms [MCL-1Long (L)/Extra Short (ES) and MCL-1Short (S)], although MCL-1S was expressed at significantly lower levels. Western blotting predominantly detected the anti-apoptotic MCL-1L isoform, and immunofluorescence showed that staining was localised in discrete nuclear foci. Transfection with pre-miR-29b or anti-miR-29b resulted in a significant increase or decrease, respectively, in MCL-1L foci. CD fibroblasts treated with IL-6 and IL-8, inflammatory cytokines upstream of MCL-1, increased the total mass of MCL-1L-positive foci. Furthermore, transfection of intestinal fibroblasts with pre-miR-29b resulted in an increase in mRNA and protein levels of IL-6 and IL-8. Finally, immunohistochemistry showed reduced MCL-1 protein expression in fibrotic CD samples compared to non-stricturing controls. Together, our findings suggest that induction of MCL-1 by IL-6/IL-8 may surmount any direct down-regulation by miR-29b via its 3’-UTR. We propose that an anti-fibrotic miR-29b/IL-6 IL-8/MCL-1L axis may influence intestinal fibrosis in CD. In the future, therapeutic modulation of this pathway might contribute to the management of fibrosis in CD.

DNA Methylation Targeting: The DNMT/HMT Crosstalk Challenge

Chromatin can adopt a decondensed state linked to gene transcription (euchromatin) and a condensed state linked to transcriptional repression (heterochromatin). These states are controlled by epigenetic modulators that are active on either the DNA or the histones and are tightly associated to each other. Methylation of both DNA and histones is involved in either the activation or silencing of genes and their crosstalk. Since DNA/histone methylation patterns are altered in cancers, molecules that target these modifications are interesting therapeutic tools. We present herein a vast panel of DNA methyltransferase inhibitors classified according to their mechanism, as well as selected histone methyltransferase inhibitors sharing a common mode of action.

MicroRNA in Immune Regulation

The immune system protects us from enormously diverse microbial pathogens but needs to be tightly regulated to avoid deleterious immune-mediated inflammation and tissue damage. A wide range of molecular determinants and cellular components work in concert to control the magnitude and duration of a given immune response. In the past decade, microRNAs (miRNAs), a major class of small non-coding RNA species, have been extensively studied as key molecular players in immune regulation. In this chapter, we will discuss how miRNAs function as negative regulators to restrict innate and adaptive immune responses. Moreover, we will review the current reports regarding miRNAs in human immunological diseases. Finally, we will also address the emerging roles of other non-coding RNAs, long non-coding RNAs (lncRNAs) in particular, in the regulation of the immune system.

MiR-29 modulates multidrug resistance of gastric cancer cells by targeting Mcl-1

AIM

To investigate the differential expression of miR-29 in SGC7901/vincristine (VCR), SGC7901/adriamycin (ADR) and SGC7901 gastric cancer cell lines, and to explore its role in multidrug resistance of gastric cancer cells and the possible mechanism involved.

METHODS

qRT-PCR was used to detect the expression of miR-29 in different gastric cancer cell lines. After up- or down-regulation of miR-29 expression, MTT assay was applied to detect the changes in drug sensitivity (IC₅₀) of different gastric cancer cell lines. Apoptosis and cell cycle arrest were analyzed by flow cytometry. Western blot analysis and luciferase assay were performed to investigate the possible mechanism involved.

RESULTS

The expression levels of the miR-29 family members (miR-29a/b/c) in SGC7901/VCR and SGC7901/ADR cell lines were significantly lower than those in parental SGC7901 cells (P < 0.05). MTT assay showed that down-regulation of miR-29 led to a significant increase in the drug sensitivity (IC₅₀) of SGC7901 cells, while up-regulation of miR-29 induced a significant decrease in the drug sensitivity (IC₅₀) of SGC7901/VCR and SGC7901/ADR cells (P < 0.05). Flow cytometry analysis indicated that altered miR-29 expression caused significant changes in 5-fluorouridine induced apoptosis (P < 0.05). Western blot analysis and luciferase assay demonstrated that in gastric cancer cells myeloid cell leukemia-1 (Mcl-1) is the direct functional target of miR-29.

CONCLUSION

MiR-29 modulates multidrug resistance of gastric cancer cells by directly targeting the expression of anti-apoptotic Mcl-1.

MicroRNA-29 impairs the early phase of reprogramming process by targeting active DNA demethylation enzymes and Wnt signaling

Somatic cell reprogramming by transcription factors and other modifiers such as microRNAs has opened broad avenues for the study of developmental processes, cell fate determination, and interplay of molecular mechanisms in signaling pathways. However, many of the mechanisms that drive nuclear reprogramming itself remain yet to be elucidated. Here, we analyzed the role of miR-29 during reprogramming in more detail. Therefore, we evaluated miR-29 expression during reprogramming of fibroblasts transduced with lentiviral OKS and OKSM vectors and we show that addition of c-MYC to the reprogramming factor cocktail decreases miR-29 expression levels. Moreover, we found that transfection of pre-miR-29a strongly decreased OKS-induced formation of GFP⁺-colonies in MEF-cells from Oct4-eGFP reporter mouse, whereas anti-miR-29a showed the opposite effect. Furthermore, we studied components of two pathways which are important for reprogramming and which involve miR-29 targets: active DNA-demethylation and Wnt-signaling. We show that inhibition of Tet1, Tet2 and Tet3 as well as activation of Wnt-signaling leads to decreased reprogramming efficiency. Moreover, transfection of pre-miR-29 resulted in elevated expression of β-Catenin transcriptional target sFRP2 and increased TCF/LEF-promoter activity. Finally, we report that Gsk3-β is a direct target of miR-29 in MEF-cells. Together, our findings contribute to the understanding of the molecular mechanisms by which miR-29 influences reprogramming.

Therapeutic Resistance in Acute Myeloid Leukemia: The Role of Non-Coding RNAs

Acute myeloid leukemia (AML) is caused by malignant transformation of hematopoietic stem or progenitor cells and displays the most frequent acute leukemia in adults. Although some patients can be cured with high dose chemotherapy and allogeneic hematopoietic stem cell transplantation, the majority still succumbs to chemoresistant disease. Micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) are non-coding RNA fragments and act as key players in the regulation of both physiologic and pathologic gene expression profiles. Aberrant expression of various non-coding RNAs proved to be of seminal importance in the pathogenesis of AML, as well in the development of resistance to chemotherapy. In this review, we discuss the role of miRNAs and lncRNAs with respect to sensitivity and resistance to treatment regimens currently used in AML and provide an outlook on potential therapeutic targets emerging thereof.

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.

c-Myc suppresses miR-451⊣YWTAZ/AKT axis via recruiting HDAC3 in acute myeloid leukemia

Aberrant activation of c-Myc plays an important oncogenic role via regulating a series of coding and non-coding genes in acute myeloid leukemia (AML). Histone deacetylases (HDACs) can remove acetyl group from histone and regulate gene expression via changing chromatin structure. Here, we found miR-451 is abnormally down-regulated in AML patient samples; c-Myc recruits HDAC3 to form a transcriptional suppressor complex, co-localizes on the miR-451 promoter, epigenetically inhibits its transcription and finally induces its downregulation in AML. Furthermore, our in vitro and in vivo results suggest that miR-451 functions as a tumor suppressor via promoting apoptosis and suppressing malignant cell proliferation. The mechanistic study demonstrated that miR-451 directly targets YWHAZ mRNA and suppresses YWHAZ/AKT signaling in AML. Knockdown of c-Myc results in restoration of miR-451 and inhibition of YWHAZ/AKT signaling. In AML patients, low level of miR-451 is negatively correlated with high levels of c-Myc and YWHAZ, while c-Myc level is positively related to YWHAZ expression. These results suggested that c-Myc⊣miR-451⊣YWHAZ/AKT cascade might play a crucial role during leukemogenesis, and reintroduction of miR-451 could be as a potential strategy for AML therapy.

MicroRNA-29b mediates altered innate immune development in acute leukemia

Natural killer (NK) cells can have potent antileukemic activity following haplo-mismatched, T cell-depleted stem cell transplantations for the treatment of acute myeloid leukemia (AML), but they are not successful in eradicating de novo AML. Here, we have used a mouse model of de novo AML to elucidate the mechanisms by which AML evades NK cell surveillance. NK cells in leukemic mice displayed a marked reduction in the cytolytic granules perforin and granzyme B. Further, as AML progressed, we noted the selective loss of an immature subset of NK cells in leukemic mice and in AML patients. This absence was not due to elimination by cell death or selective reduction in proliferation, but rather to the result of a block in NK cell differentiation. Indeed, NK cells from leukemic mice and humans with AML showed lower levels of TBET and EOMES, transcription factors that are critical for terminal NK cell differentiation. Further, the microRNA miR-29b, a regulator of T-bet and EOMES, was elevated in leukemic NK cells. Finally, deletion of miR-29b in NK cells reversed the depletion of this NK cell subset in leukemic mice. These results indicate that leukemic evasion of NK cell surveillance occurs through miR-mediated dysregulation of lymphocyte development, representing an additional mechanism of immune escape in cancer.

miRNA29 Promotes Viral Replication During Early Stage of PRRSV Infection In Vitro

miRNAs are involved in various biological processes, such as host-virus interactions and antiviral immunity. In this study, we investigated the role of miR-29 on porcine reproductive and respiratory syndrome virus (PRRSV) replication and its target genes. At first, miR-29a/b-1/c expression was detected when porcine alveolar macrophages (PAMs) were infected with PRRSV at different infective doses by real time-quantitative polymerase chain reaction (RT-qPCR). The result showed that miR-29a/b-1 expression significantly increased after 6 h (p < 0.01), with the peak around 24 h, miR-29c expression in each period of PRRSV infection was very low. Then, pre-miR-29a/b-1 lentiviral vectors were constructed. Absolute RT-qPCR analysis showed that PAMs transfected with pre-miR-29a/b-1 lentiviral vectors significantly promoted PRRSV replication in PAM within 24 h (p < 0.01). The expression of the target genes (AKT3, TP53INP1, and RPS6KB1) of miR-29a significantly reduced (p < 0.01). Western blot analysis showed that AKT3 and TP53INP1 are reduced at miR-29a overexpression. To further validate the interaction between miR-29a and its target gene sites, the luciferase assay results demonstrated that miR-29a interacted with AKT3 3'UTR 1676 and 1261 sites, leading the inhibition of luciferase expression. Our findings support that miR-29a could promote PRRSV replication during early stage of virus infection in vitro and AKT3 could be the target gene of miR-29a.

MicroRNA-29B (mir-29b) regulates the Warburg effect in ovarian cancer by targeting AKT2 and AKT3

Epithelial ovarian cancer (EOC) is the most lethal and aggressive gynecological malignancy, and abnormal cellular metabolism significantly contributes to cancer onset and progression. Here, we report that miR-29b negatively regulates AKT2/AKT3 expression, causing HK2/PKM2 downregulation and leading to a decreased Warburg effect and slowed ovarian cancer progression. Compared to normal ovaries, ovaries with epithelial cancer exhibited lower miR-29b expression at both cellular/histological levels. Glucose consumption and lactate production experiments confirmed miR-29b's regulation of EOC metabolism. A luciferase reporter assay confirmed the direct binding of miR-29b to AKT2/AKT3 3′ UTRs. miR-29b silencing correlated with increased expression of AKT2/3, pAKT2/3, HK2, and PKM2. Pyruvic acid and NAD+/NADH levels also changed when miR-29b expression was suppressed; this effect could be blocked by specific AKT inhibitors, suggesting the miR-29b-AKT axis regulates the Warburg effect in ovarian cancer. In xenograft mouse models, miR-29b inhibited tumor formation in vivo. In vivo imaging also demonstrated that miR-29b agomir inhibited the relative uptake of ¹⁸F-FDG in the xenograft tumors, suggesting that miR-29b over-expression could negatively modulate tumor glucose metabolism in vivo. Taken together, our study suggests that miR-29b regulates the Warburg effect in EOC via AKT2/AKT3 and may provide novel options for future treatments for EOC.

MicroRNAs in Control of Stem Cells in Normal and Malignant Hematopoiesis

Studies on hematopoietic stem cells (HSCs) and leukemia stem cells (LSCs) have helped to establish the paradigms of normal and cancer stem cell concepts. For both HSCs and LSCs, specific gene expression programs endowed by their epigenome functionally distinguish them from their differentiated progenies. MicroRNAs (miRNAs), as a class of small non-coding RNAs, act to control post-transcriptional gene expression. Research in the past decade has yielded exciting findings elucidating the roles of miRNAs in control of multiple facets of HSC and LSC biology. Here we review recent progresses on the functions of miRNAs in HSC emergence during development, HSC switch from a fetal/neonatal program to an adult program, HSC self-renewal and quiescence, HSC aging, HSC niche, and malignant stem cells. While multiple different miRNAs regulate a diverse array of targets, two common themes emerge in HSC and LSC biology: miRNA mediated regulation of epigenetic machinery and cell signaling pathways. In addition, we propose that miRNAs themselves behave like epigenetic regulators, as they possess key biochemical and biological properties that can provide both stability and alterability to the epigenetic program. Overall, the studies of miRNAs in stem cells in the hematologic contexts not only provide key understandings to post-transcriptional gene regulation mechanisms in HSCs and LSCs, but also will lend key insights for other stem cell fields.

Aptamer-hybrid nanoparticle bioconjugate efficiently delivers miRNA-29b to non-small-cell lung cancer cells and inhibits growth by downregulating essential oncoproteins

MicroRNAs (miRNAs) are potentially attractive candidates for cancer therapy. However, their therapeutic application is limited by lack of availability of an efficient delivery system to stably deliver these potent molecules intracellularly to cancer cells while avoiding healthy cells. We developed a novel aptamer-hybrid nanoparticle bioconjugate delivery system to selectively deliver miRNA-29b to MUC1-expressing cancer cells. Significant downregulation of oncoproteins DNMT3b and MCL1 was demonstrated by these MUC1 aptamer-functionalized hybrid nanoparticles in A549 cells. Furthermore, downregulation of these oncoproteins led to antiproliferative effect and induction of apoptosis in a superior version when compared with Lipofectamine 2000. This novel aptamer-hybrid nanoparticle bioconjugate delivery system could potentially serve as a platform for intracellular delivery of miRNAs to cancer cells, hence improving the therapeutic outcome of lung cancer.

Involvement of DNMT 3B promotes epithelial-mesenchymal transition and gene expression profile of invasive head and neck squamous cell carcinomas cell lines

BACKGROUND

The 5-year overall survival rates for head and neck cancer (HNC) relies on distant metastasis. Importantly, the epithelial-mesenchymal transition (EMT) is believed to be an initial step of metastasis. However, the relationship of epigenetic with EMT formation is still unexplored in HNC. This study focuses on invasive subclones of HNC cell lines through the simulation of invasion in vitro; and underlying mechanisms were analyzed including DNA methylation and gene expression profile.

METHODS

Invasive subclones of NHC cell lines were successfully obtained using transwell coated with Matrixgel. Cells invaded through 8 μm pore several times were subcultured and examined with EMT features including morphology, EMT marker genes expression, and invasive ability. Moreover, compared the profile of genes expression in parental and invasive cells was analyzed using mRNA expression array.

RESULTS

DNA methyltransferase 3B (DNMT 3B) was upregulated in invasive subclones and might control the 5' region of E-cadherin (E-cad) methylation and further inhibited E-cad protein expression. Interference of DNMT 3B by siRNA or miRNA 29b could reduce EMT and cell invasion. Expression array analysis revealed the most possible involved pathways in cell invasion including arginine and proline metabolism, TGF-beta, and focal adhesion.

CONCLUSIONS

DNMT 3B might control EMT by DNA methylation manner in invasive HNC cell lines. Moreover, miR-29b mimic downregulated DNMT 3B and inhibited EMT and cell invasion indicated the role of therapeutic agent for invasive HNC. Genes identified from array data and new molecules are involved in metastasis of HNC need further validation.

Targeting epigenetic regulators for cancer therapy: modulation of bromodomain proteins, methyltransferases, demethylases, and microRNAs

INTRODUCTION

Histone deacetylases (HDACs) and DNA methyltransferases (DNMTs) were the first epigenetic targets to be successfully addressed for cancer treatment, but more recently additional families of epigenetic modulators have been the subject of intense research. Potent inhibitors have been identified in several instances and have proven to be invaluable tools for studying these proteins in normal physiology and in disease. Some have now progressed to clinical studies in hematological and solid tumors, and encouraging early results have been reported.

AREAS COVERED

This article reviews recent advances regarding the roles of new epigenetic players beyond HDACs and DNMTs in cancer, and discusses the impact of selective chemical probes on unravelling their function. The emerging field of non-coding RNAs (ncRNAs) and ongoing clinical studies with epigenetic drugs and microRNAs (miRNAs) are also addressed.

EXPERT OPINION

The roles of different epigenetic factors in numerous cancers have been unraveled recently, leading to the initiation of clinical studies. With inhibitors of BET bromodomain proteins, the histone methyltransferases EZH2 and DOT1L, and the histone demethylase LSD1 progressing through clinical trials, and the recognition of the importance of ncRNAs as potential biomarkers and therapeutics, this bears the hope that novel epigenetic therapies will be approved soon.

PTBP1 modulation of MCL1 expression regulates cellular apoptosis induced by antitubulin chemotherapeutics

Myeloid cell leukemia sequence 1 (MCL1), an anti-apoptotic BCL2 family protein, is a key regulator of intrinsic apoptosis. Normal cells require strict control over MCL1 expression with aberrant MCL1 expression linked to the emergence of various diseases and chemoresistance. Previous studies have detailed how MCL1 expression is regulated by multiple mechanisms both transcriptionally and translationally. However, characterization of the post-transcriptional regulators of MCL1 mRNA is limited. Polypyrimidine tract binding protein 1 (PTBP1) is a known regulator of post-transcriptional gene expression that can control mRNA splicing, translation, stability and localization. Here we demonstrate that PTBP1 binds to MCL1 mRNA and that knockdown of PTBP1 upregulates MCL1 expression in cancer cells by stabilizing MCL1 mRNA and increasing MCL1 mRNA accumulation in cytoplasm. Further, we show that depletion of PTBP1 protects cancer cells from antitubulin agent-induced apoptosis in a MCL1-dependent manner. Taken together, our findings suggest that PTBP1 is a novel regulator of MCL1 mRNA by which it controls apoptotic response to antitubulin chemotherapeutics.

MiR-29b suppresses the proliferation and migration of osteosarcoma cells by targeting CDK6

Osteosarcoma is the most common primary sarcoma of bone, and it is a leading cause of cancer death among adolescents and young adults. However, the molecular mechanism underlying osteosarcoma carcinogenesis remains poorly understood. Recently, cyclin-dependent kinase 6 (CDK6) was identified as an important oncogene. We found that CDK6 protein level, rather than CDK6 mRNA level, is much higher in osteosarcoma tissues than in normal adjacent tissues, which indicates a post-transcriptional mechanism involved in CDK6 regulation in osteosarcoma. MiRNAs are small non-coding RNAs that repress gene expression at the post-transcriptional level and have widely been shown to play important roles in many human cancers. In this study, we investigated the role of miR-29b as a novel regulator of CDK6 using bioinformatics methods. We demonstrated that CDK6 can be downregulated by miR-29b via binding to the 3'-UTR region in osteosarcoma cells. Furthermore, we identified an inverse correlation between miR-29b and CDK6 protein levels in osteosarcoma tissues. Finally, we examined the function of miR-29b-driven repression of CDK6 expression in osteosarcoma cells. The results revealed that miR-29b acts as a tumor suppressor of osteosarcoma by targeting CDK6 in the proliferation and migration processes. Taken together, our results highlight an important role for miR-29b in the regulation of CDK6 in osteosarcoma and may open new avenues for future osteosarcoma therapies.

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.

Therapeutic Targeting of miR-29b/HDAC4 Epigenetic Loop in Multiple Myeloma

Epigenetic abnormalities are common in hematologic malignancies, including multiple myeloma, and their effects can be efficiently counteracted by a class of tumor suppressor miRNAs, named epi-miRNAs. Given the oncogenic role of histone deacetylases (HDAC) in multiple myeloma, we investigated whether their activity could be antagonized by miR-29b, a well-established epi-miRNA. We demonstrated here that miR-29b specifically targets HDAC4 and highlighted that both molecules are involved in a functional loop. In fact, silencing of HDAC4 by shRNAs inhibited multiple myeloma cell survival and migration and triggered apoptosis and autophagy, along with the induction of miR-29b expression by promoter hyperacetylation, leading to the downregulation of prosurvival miR-29b targets (SP1, MCL-1). Moreover, treatment with the pan-HDAC inhibitor SAHA upregulated miR-29b, overcoming the negative control exerted by HDAC4. Importantly, overexpression or inhibition of miR-29b, respectively, potentiated or antagonized SAHA activity on multiple myeloma cells, as also shown in vivo by a strong synergism between miR-29b synthetic mimics and SAHA in a murine xenograft model of human multiple myeloma. Altogether, our results shed light on a novel epigenetic circuitry regulating multiple myeloma cell growth and survival and open new avenues for miR-29b-based epi-therapeutic approaches in the treatment of this malignancy. Mol Cancer Ther; 15(6); 1364-75. ©2016 AACR.