microRNA-449a functions as a tumor suppressor in neuroblastoma through inducing cell differentiation and cell cycle arrest

miR-449a: A Promising Biomarker and Therapeutic Target in Cancer and Other Diseases

In the regulation of gene expression, epigenetic factors like non-coding RNAs (ncRNAs) play an equal role in genetics. The role of microRNAs (miRNAs), which are members of the ncRNA family, in post-transcriptional gene regulation is well-documented and has important implications for both normal and abnormal biological processes, such as angiogenesis, proliferation, survival, and apoptosis. The purpose of this study was to synthesize previous research on miR-449a by analyzing published results from various databases, as there have been a number of investigations on miR-449's potential involvement in the development of human disorders. Based on our findings, miR-449 is strongly dysregulated in a wide range of diseases, from various cancers to cardiovascular diseases, cognitive impairments, and respiratory diseases, and it may play a pivotal role in the development of these problems. In addition, miR-449a functions as a crucial regulator of the expression of several well-known genes, including E2F-3, BCL2, NOTCH1, and SOX4. This, in turn, modulates various pathways and processes related to cancer, including Notch, PI3K, and TGF-β, and contributes to the improvement of cancer drug sensitivity. Curiously, abnormalities in the expression of this miRNA may serve as diagnostic or prognostic indicators for distinguishing between healthy people and patients or to evaluate the survival rates for specific disorders. This article provides a synopsis of the current understanding of miR-449a's role in human disease development through its regulation of gene expression and the biological processes related to these genes and their linked processes. In addition, we have covered the topic of miR-449a's potential as a clinical feature (diagnosis and prognosis) indicator for a range of disorders, both neoplastic and non-neoplastic. In general, our goal was to gain a thorough comprehension of the numerous functions of miR-449a in different disorders.

Epigenetic Dysregulation in MYCN-Amplified Neuroblastoma

Neuroblastoma (NB), a childhood cancer arising from the neural crest, poses significant clinical challenges, particularly in cases featuring amplification of the MYCN oncogene. Epigenetic factors play a pivotal role in normal neural crest and NB development, influencing gene expression patterns critical for tumorigenesis. This review delves into the multifaceted interplay between MYCN and known epigenetic modifications during NB genesis, shedding light on the intricate regulatory networks underlying the disease. We provide an extensive survey of known epigenetic mechanisms, encompassing DNA methylation, histone modifications, non-coding RNAs, super-enhancers (SEs), bromodomains (BET), and chromatin modifiers in MYCN-amplified (MNA) NB. These epigenetic changes collectively contribute to the dysregulated gene expression landscape observed in MNA NB. Furthermore, we review emerging therapeutic strategies targeting epigenetic regulators, including histone deacetylase inhibitors (HDACi), histone methyltransferase inhibitors (HMTi), and DNA methyltransferase inhibitors (DNMTi). We also discuss and summarize current drugs in preclinical and clinical trials, offering insights into their potential for improving outcomes for MNA NB patients.

Extirpating the cancer stem cell hydra: Differentiation therapy and Hyperthermia therapy for targeting the cancer stem cell hierarchy

Ever since the discovery of cancer stem cells (CSCs), they have progressively attracted more attention as a therapeutic target. Like the mythical hydra, this subpopulation of cells seems to contribute to cancer immortality, spawning more cells each time that some components of the cancer cell hierarchy are destroyed. Traditional modalities focusing on cancer treatment have emphasized apoptosis as a route to eliminate the tumor burden. A major problem is that cancer cells are often in varying degrees of dedifferentiation contributing to what is known as the CSCs hierarchy and cells which are known to be resistant to conventional therapy. Differentiation therapy is an experimental therapeutic modality aimed at the conversion of malignant phenotype to a more benign one. Hyperthermia therapy (HT) is a modality exploiting the changes induced in cells by the application of heat produced to aid in cancer therapy. While differentiation therapy has been successfully employed in the treatment of acute myeloid leukemia, it has not been hugely successful for other cancer types. Mounting evidence suggests that hyperthermia therapy may greatly augment the effects of differentiation therapy while simultaneously overcoming many of the hard-to-treat facets of recurrent tumors. This review summarizes the progress made so far in integrating hyperthermia therapy with existing modules of differentiation therapy. The focus is on studies related to the successful application of both hyperthermia and differentiation therapy when used alone or in conjunction for hard-to-treat cancer cell niche with emphasis on combined approaches to target the CSCs hierarchy.

Targeting the epigenome of cancer stem cells in pediatric nervous system tumors

Medulloblastoma, neuroblastoma, and pediatric glioma account for almost 30% of all cases of pediatric cancers. Recent evidence indicates that pediatric nervous system tumors originate from stem or progenitor cells and present a subpopulation of cells with highly tumorigenic and stem cell-like features. These cancer stem cells play a role in initiation, progression, and resistance to treatment of pediatric nervous system tumors. Histone modification, DNA methylation, chromatin remodeling, and microRNA regulation display a range of regulatory activities involved in cancer origin and progression, and cellular identity, especially those associated with stem cell features, such as self-renewal and pluripotent differentiation potential. Here, we review the contribution of different epigenetic mechanisms in pediatric nervous system tumor cancer stem cells. The choice between a differentiated and undifferentiated state can be modulated by alterations in the epigenome through the regulation of stemness genes such as CD133, SOX2, and BMI1 and the activation neuronal of differentiation markers, RBFOX3, GFAP, and S100B. Additionally, we highlighted the stage of development of epigenetic drugs and the clinical benefits and efficacy of epigenetic modulators in pediatric nervous system tumors.

MicroRNAs as prospective biomarkers, therapeutic targets and pharmaceuticals in neuroblastoma

Neuroblastomas, the most prevalent malignant solid neoplasms of childhood, originate from progenitor cells of the sympathetic nervous system. Their genetic causation is diverse and involves multiple molecular mechanisms. This review highlights multiple roles of microRNA in neuroblastoma pathogenesis and discusses the prospects of harnessing these important natural regulator molecules as biomarkers, therapeutic targets and pharmaceuticals in neuroblastoma.

Declined plasma microfibrillar-associated protein 4 levels in acute coronary syndrome

BACKGROUND

Microfibrillar-associated protein (MFAP4), initially identified as an extracellular matrix protein, has been demonstrated in multiple human disorders, but it is yet to be discovered following acute coronary syndrome (ACS) in clinical practice. Therefore, this study aimed to investigate the relationship between circulating MFAP4 levels and coronary stenosis in ACS.

METHODS

We performed the study in 148 ACS subjects, including 75 ST-segment elevation myocardial infarction (STEMI), 27 non-ST-segment elevation myocardial infarction (non-STEMI) and 46 unstable angina (UA). Clinical variables were collected and Gensini and Syntax stenosis scoring systems were applied to assess the severity of coronary stenosis. Kaplan-Meier and logistic regression analysis were used to analyze the relationship between MFAP4 and the severity of coronary stenosis or ACS outcomes. Spearman analysis was used to describe the correlation between MFAP4 and clinical parameters.

RESULTS

Circulating MFAP4 levels were significantly decreased in the STEMI group (0.008 ng/ml) compared with the non-STEMI group (0.014 ng/ml) and UA group (0.019 ng/ml) (p < 0.001). After adjusting for confounding factors, we found that MFAP4 was an independent risk factor for STEMI (odds ratio = 0.395, 95% CI 0.174-0.895, p = 0.026). MFAP4 level was negatively correlated with Gensini score and Syntax score (r = - 0.311 and - 0.211, p < 0.001 and 0.01, respectively). Based on the MFAP4 level of 0.117 ng/ml, ACS patients were divided into two groups: the low-MFAP4 group (< 0.117 ng/ml, n = 60) and the high-MFAP4 group (≥ 0.117 ng/ml, n = 88). After the median follow-up of 165 days, Kaplan-Meier survival analysis revealed that the MACE-free rate was significantly lower in ACS patients with lower MFAP4 levels (p = 0.009).

CONCLUSIONS

MFAP4 has a potential as a biomarker for the degree of coronary stenosis in ACS. Confirmation of observations in larger cohorts and longer follow-up periods is warranted.

METTL1 promotes neuroblastoma development through m7G tRNA modification and selective oncogenic gene translation

Background

Neuroblastoma (NBL) is the most common extra-cranial solid tumour in childhood, with prognosis ranging from spontaneous remission to high risk for rapid and fatal progression. Despite existing therapy approaches, the 5-year event-free survival (EFS) for patients with advanced NBL remains below 30%, emphasizing urgent necessary for novel therapeutic strategies. Studies have shown that epigenetic disorders play an essential role in the pathogenesis of NBL. However, the function and mechanism of N7-methylguanosine (m⁷G) methyltransferase in NBL remains unknown.

Methods

The expression levels of m⁷G tRNA methyltransferase Methyltransferase-like 1 (METTL1) were analyzed by querying the Gene Expression Omnibus (GEO) database and further confirmed by immunohistochemistry (IHC) assay. Kaplan-Meier, univariate and multivariate cox hazard analysis were performed to reveal the prognostic role of METTL1. Cell function assays were performed to evaluate how METTL1 works in proliferation, apoptosis and migration in cell lines and xenograft mouse models. The role of METTL1 on mRNA translation activity of NBL cells was measured using puromycin intake assay and polysome profiling assay. The m⁷G modified tRNAs were identified by tRNA reduction and cleavage sequencing (TRAC-seq). Ribosome nascent-chain complex-bound mRNA sequencing (RNC-seq) was utilized to identify the variation of gene translation efficiency (TE). Analyzed the codon frequency decoded by m⁷G tRNA to clarify the translation regulation and mechanism of m⁷G modification in NBL.

Results

This study found that METTL1 were significantly up-regulated in advanced NBL, which acted as an independent risk factor and predicted poor prognosis. Further in NBL cell lines and BALB/c-nu female mice, we found METTL1 played a crucial role in promoting NBL progression. Furthermore, m⁷G profiling and translation analysis revealed downregulation of METTL1 would inhibit puromycin intake efficiency of NBL cells, indicating that METTL1 did count crucially in regulation of NBL cell translation. With all tRNAs with m⁷G modification identified in NBL cells, knockdown of METTL1 would significantly reduce the levels of both m⁷G modification and m⁷G tRNAs expressions. Result of RNC-seq shew there were 339 overlapped genes with impaired translation in NBL cells upon METTL1 knockdown. Further analysis revealed these genes contained higher frequency of codons decoded by m⁷G-modified tRNAs and were enriched in oncogenic pathways.

Conclusion

This study revealed the critical role and mechanism of METTL1-mediated tRNA m⁷G modification in regulating NBL progression, providing new insights for developing therapeutic approaches for NBL patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40364-022-00414-z.

MFAP4-Mediated Effects in Elastic Fiber Homeostasis, Integrin Signaling and Cancer, and Its Role in Teleost Fish

Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix (ECM) protein belonging to the fibrinogen-related domain superfamily. MFAP4 is highly expressed in elastin-rich tissues such as lung, blood vessels and skin. MFAP4 is involved in organization of the ECM, regulating proper elastic fiber assembly. On the other hand, during pathology MFAP4 actively contributes to disease development and progression due to its interactions with RGD-dependent integrin receptors. Both tissue expression and circulating MFAP4 levels are associated with various disorders, including liver fibrosis and cancer. In other experimental models, such as teleost fish, MFAP4 appears to participate in host defense as a macrophage-specific innate immune molecule. The aim of this review is to summarize the accumulating evidence that indicates the importance of MFAP4 in homeostasis as well as pathological conditions, discuss its known biological functions with special focus on elastic fiber assembly, integrin signaling and cancer, as well as describe the reported functions of non-mammalian MFAP4 in fish. Overall, our work provides a comprehensive overview on the role of MFAP4 in health and disease.

A methylation-driven genes prognostic signature and the immune microenvironment in epithelial ovarian cancer

Aberrant gene methylation has been implicated in the development and progression of tumors. In this study, we aimed to identity methylation driven genes involved in epithelial ovarian cancer (EOC) to establish a prognostic signature for patients with EOC. We identified and verified 6 MDGs that are closely related to the prognosis of ovarian cancer. A prognostic risk score model and nomogram for predicting the prognosis of ovarian cancer were constructed based on the six MDGs. It can also effectively reflect the immune environment and immunotherapy response of ovarian cancer. These MDGs have great significance to the implementation of individualized treatment and disease monitoring of ovarian cancer patients.

Silencing of long chain noncoding RNA paternally expressed gene (PEG10) inhibits the progression of neuroblastoma by regulating microRNA-449a (miR-449a)/ribosomal protein S2 (RPS2) axis

To investigate the mechanism of paternally expressed gene (PEG10) in regulating neuroblastoma (NB) progression. PEG10 expression was detected using quantitative real-time reverse transcription polymerase-chain reaction (qRT-PCR). The interaction of miR-449a and PEG10 or ribosomal protein S2 (RPS2) was employed by starBase, and then proved through RIP and dual-luciferase reporter assays. The NB cell viability, proliferation, invasion, and migration were evaluated by Cell Counting Kit-8 (CCK-8), colony formation, and Transwell assay. The mRNA and protein levels were determined by qRT-PCR and Western blotting, respectively. The levels of PEG10 and RPS2 were remarkably increased in NB tissues and cells, nevertheless the expression of miR-449a was conspicuously declined in NB tissues and cells. Silencing of PEG10 inhibited proliferation, migration, and invasion in SK-N-BE (2) cells, while overexpression of PEG10 promoted proliferation, migration, and invasion in SH-SY5Y cells. We affirmed that PEG10 interacted with miR-449a, and miR-449a could target the 3'UTR of RPS2 and negatively regulate its expression in NB cells. The upregulation of miR-449a inhibited proliferation, migration, and invasion in SK-N-BE (2) cells, while downregulation of miR-449a promoted proliferation, migration, and invasion in SH-SY5Y cells. Moreover, miR-449a overexpression weaken the function of PEG10-mediated on promoting proliferation, migration, and invasion in SH-SY5Y cells, while RPS2 overexpression rescued the effects of miR-449a-mediated on inhibiting those behaviors of SH-SY5Y cells. In conclusion, Silencing of PEG10 could inhibit proliferation, migration, and invasion via the miR-449a/RPS2 axis in NB cells.

MiRNAs Expression Profiling in Raw264.7 Macrophages after Nfatc1-Knockdown Elucidates Potential Pathways Involved in Osteoclasts Differentiation

Differentiation of macrophages toward osteoclasts is crucial for bone homeostasis but can be detrimental in disease states, including osteoporosis and cancer. Therefore, understanding the osteoclast differentiation process and the underlying regulatory mechanisms may facilitate the identification of new therapeutic targets. Hereby, we tried to reveal new miRNAs potentially involved in the regulation of early steps of osteoclastogenesis, with a particular focus on those possibly correlated with NFATc1 expression, by studying miRNAs profiling. During the first 24 h of osteoclastogenesis, 38 miRNAs were differentially expressed between undifferentiated and RANKL-stimulated RAW264.7 cells, while 10 miRNAs were differentially expressed between RANKL-stimulated cells transfected with negative control or NFATc1-siRNAs. Among others, the expression levels of miR-411, miR-144 and members of miR-29, miR-30, and miR-23 families changed after RANKL stimulation. Moreover, the potential role of miR-124 during osteoclastogenesis was explored by transient cell transfection with anti-miR-124 or miR-124-mimic. Two relatively unknown miRNAs, miR-880-3p and miR-295-3p, were differentially expressed between RANKL-stimulated/wild-type and RANKL-stimulated/NFATc1-silenced cells, suggesting their possible correlation with NFATc1. KEGG enrichment analyses showed that kinase and phosphatase enzymes were among the predicted targets for many of the studied miRNAs. In conclusion, our study provides new data on the potential role and possible targets of new miRNAs during osteoclastogenesis.

miR-17-3p promotes the proliferation of multiple myeloma cells by downregulating P21 expression through LMLN inhibition

Multiple myeloma (MM), a hematological malignancy, has a poor prognosis and requires an invasive procedure. Reports have implicated miRNAs in the diagnosis, treatment and prognosis of hematological malignancies. In our study, we evaluated the expression profiles of miR-17-3p in plasma and bone marrow mononuclear cells of monoclonal gammopathy of undetermined significance (MGUS) and MM patients and healthy subjects. The results showed that the plasma and mononuclear cell expression levels of miR-17-3p in MM patients were higher than those in MGUS patients and normal controls. In addition, the expression of miR-17-3p was positively correlated with diagnostic indexes, such as marrow plasma cell abundance and serum M protein level, and positively correlated with the International Staging System stage of the disease. Receiver operating characteristic curve analysis suggested that miR-17-3p might be a diagnostic index of MM. Moreover, miR-17-3p regulated cell proliferation, apoptosis and the cell cycle through P21 in MM cell lines and promoted MM tumor growth in vivo. Furthermore, we predicted and verified LMLN as a functional downstream target gene of miR-17-3p. Negatively regulated by miR-17-3p, LMLN inhibits MM cell growth, exerting a tumor suppressive function through P21. Taken together, our data identify miR-17-3p as a promising diagnostic biomarker for MM in the clinic and unveil a new miR-17-3p-LMLN-P21 axis in MM progression.

Flotillin-2 promotes cell proliferation via activating the c-Myc/BCAT1 axis by suppressing miR-33b-5p in nasopharyngeal carcinoma

Previously, we elucidated the function of flotilin-2 (FLOT2) and branched-chain amino acid transaminase 1(BCAT1) in nasopharyngeal carcinoma (NPC). However, the relationship between FLOT2 and BCAT1 in promoting NPC progression remains unknown. Here, we observed that FLOT2 upregulated BCAT1 expression in NPC cells. Ectopic expression of BCAT1 significantly antagonized the inhibitory effects on NPC cell proliferation induced by FLOT2 depletion. Consequently, BCAT1 knockdown markedly inhibited the pro-proliferative effects of FLOT2 overexpression in NPC cells. FLOT2 expression was positively correlated with BCAT1 expression in NPC tissues and was inversely correlated with the prognosis of NPC patients. Mechanistically, FLOT2 maintains the expression level of c-Myc, a positive transcription factor of BCAT1, and subsequently promote BCAT1 transcription. FLOT2 inhibited miR-33b-5p in NPC cells and attenuated its inhibitory effects on c-Myc. Further, experimental validation of the function of the FLOT2/miR-33b-5p/c-Myc/BCAT1 axis in regulating NPC cell proliferation was performed. Our results revealed that FLOT2 promotes NPC cell proliferation by suppressing miR-33b-5p, to maintain proper levels of c-Myc, and upregulate BCAT1trancription. Therefore, the FLOT2/miR-33b-5p/c-Myc/BCAT1 axis is a potential therapeutic target for NPC.

Non-Coding RNAs Participate in the Pathogenesis of Neuroblastoma

Neuroblastoma is one of the utmost frequent neoplasms during the first year of life. This pediatric cancer is believed to be originated during the embryonic life from the neural crest cells. Previous studies have detected several types of chromosomal aberrations in this tumor. More recent studies have emphasized on expression profiling of neuroblastoma samples to identify the dysregulated genes in this type of cancer. Non-coding RNAs are among the mostly dysregulated genes in this type of cancer. Such dysregulation has been associated with a number of chromosomal aberrations that are frequently detected in neuroblastoma. In this study, we explain the role of non-coding transcripts in the malignant transformation in neuroblastoma and their role as biomarkers for this pediatric cancer.

miR‑449a‑5p suppresses CDK6 expression to inhibit cardiomyocyte proliferation

Induction of cardiomyocyte (CM) proliferation is a promising approach for cardiac regeneration following myocardial injury. MicroRNAs (miRs) have been reported to regulate CM proliferation. In particular, miR‑449a‑5p has been identified to be associated with CM proliferation in previous high throughput functional screening data. However, whether miR‑449a‑5p regulates CM proliferation has not been thoroughly investigated. This study aimed to explore whether miR‑449a‑5p modulates CM proliferation and to identify the molecular mechanism via which miR‑449a‑5p regulates CM proliferation. The current study demonstrated that miR‑449a‑5p expression levels were significantly increased during heart development. Furthermore, the results suggested that miR‑449a‑5p mimic inhibited CM proliferation <em>in vitro</em> as determined via immunofluorescence for ki67 and histone H3 phosphorylated at serine 10 (pH3), as well as the numbers of CMs. However, miR‑449a‑5p knockdown promoted CM proliferation. CDK6 was identified as a direct target gene of miR‑449a‑5p, and CDK6 mRNA and protein expression was suppressed by miR‑449a‑5p. Moreover, CDK6 gain‑of‑function increased CM proliferation. Overexpression of CDK6 also blocked the inhibitory effect of miR‑449a‑5p on CM proliferation, indicating that CDK6 was a functional target of miR‑449a‑5p in CM proliferation. In conclusion, miR‑449a‑5p inhibited CM proliferation by targeting CDK6, which provides a potential molecular target for preventing myocardial injury.

Inhibitory effect of microRNA-608 on lung cancer cell proliferation, migration, and invasion by targeting BRD4 through the JAK2/STAT3 pathway

Lung cancer is the leading cause of cancer-related mortality around the world. This malignancy has a 5-year survival rate of 21%, because most of the patients are diagnosed in the middle or late stage of the disease when local metastasis and tumor invasion have already progressed. Therefore, the investigation of the pathogenesis of lung cancer is an issue of crucial importance. MicroRNAs (miRNAs) seem to be involved in the evolution and development of lung cancer. MicroRNA-608 is likely to be downregulated in lung cancer tissues. Regarding this, the current study involved the determination of the fundamental mechanism of microRNA-608 in the development of lung cancer. Based on the results of quantitative reverse transcription polymerase chain reaction (RT-qPCR), the expression level of microRNA-608 was downregulated in 40 lung cancer tissues, compared to that in the adjacent normal tissues. The results of dual-luciferase reporter assay revealed that bromodomain-containing protein 4 (BRD4) was the direct target of microRNA-608. Accordingly, the lung cancer tissues had an elevated expression level of BRD4, in contrast to the adjacent normal tissues. The results of Cell Counting Kit 8 assay demonstrated that the high expression of microRNA-608 notably restrained lung cancer cell proliferation. The scratch wound and transwell assays showed that the upregulation of microRNA-608 suppressed the migration and invasion of lung cancer cells. Finally, the western blot assay showed that in the microRNA-608 mimics group, the expression levels of BRD4, p-JAK2, p-STATA3, CD44, and MMP9 were significantly decreased, compared with those in the negative control miRNA mimics group. Our results indicate that high expression of microRNA-608 inhibits the proliferation, migration, and invasion of lung cancer cells by targeting BRD4 via the JAK2/STAT3 pathway.

Bioinformatic analysis of the potential molecular mechanism of PAK7 expression in glioblastoma

The present study aimed to determine the potential molecular mechanisms underlying p21 (RAC1)-activated kinase 7 (PAK7) expression in glioblastoma (GBM) and evaluate candidate prognosis biomarkers for GBM. Gene expression data from patients with GBM, including 144 tumor samples and 5 normal brain samples, were downloaded. Long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) were explored via re-annotation. The differentially expressed genes (DEGs), including differentially expressed mRNAs and differentially expressed lncRNAs, were investigated and subjected to pathway analysis via gene set enrichment analysis. The miRNA-lncRNA-mRNA interaction [competing endogenous RNA (ceRNA)] network was investigated and survival analysis, including of overall survival (OS), was performed on lncRNAs/mRNAs to reveal prognostic markers for GBM. A total of 954 upregulated and 1,234 downregulated DEGs were investigated between GBM samples and control samples. These DEGs, including PAK7, were mainly enriched in pathways such as axon guidance. ceRNA network analysis revealed several outstanding ceRNA relationships, including miR-185-5p-LINC00599-PAK7. Moreover, paraneoplastic antigen Ma family member 5 (PNMA5) and somatostatin receptor 1 (SSTR1) were the two outstanding prognostic genes associated with OS. PAK7 may participate in the tumorigenesis of GBM by regulating axon guidance, and miR-185-5p may play an important role in GBM progression by sponging LINC00599 to prevent interactions with PAK7. PNMA5 and SSTR1 may serve as novel prognostic markers for GBM.

Retinoic acid and microRNA

Retinoic acid (RA), the biologically active metabolite of vitamin A, regulates a vast spectrum of biological processes, such as cell differentiation, proliferation, apoptosis, and morphogenesis. microRNAs (miRNAs) play a crucial role in regulating gene expression by binding to messenger RNA (mRNA) which leads to mRNA degradation and/or translational repression. Like RA, miRNAs regulate multiple biological processes, including proliferation, differentiation, apoptosis, neurogenesis, tumorigenesis, and immunity. In fact, RA regulates the expression of many miRNAs to exert its biological functions. miRNA and RA regulatory networks have been studied in recent years. In this manuscript, we summarize literature that highlights the impact of miRNAs in RA-regulated molecular networks included in the PubMed.

MicroRNA dysregulation interplay with childhood abdominal tumors

Abdominal tumors (AT) in children account for approximately 17% of all pediatric solid tumor cases, and frequently exhibit embryonal histological features that differentiate them from adult cancers. Current molecular approaches have greatly improved the understanding of the distinctive pathology of each tumor type and enabled the characterization of novel tumor biomarkers. As seen in abdominal adult tumors, microRNAs (miRNAs) have been increasingly implicated in either the initiation or progression of childhood cancer. Moreover, besides predicting patient prognosis, they represent valuable diagnostic tools that may also assist the surveillance of tumor behavior and treatment response, as well as the identification of the primary metastatic sites. Thus, the present study was undertaken to compile up-to-date information regarding the role of dysregulated miRNAs in the most common histological variants of AT, including neuroblastoma, nephroblastoma, hepatoblastoma, hepatocarcinoma, and adrenal tumors. Additionally, the clinical implications of dysregulated miRNAs as potential diagnostic tools or indicators of prognosis were evaluated.

The PLAGL2/MYCN/miR-506-3p interplay regulates neuroblastoma cell fate and associates with neuroblastoma progression

Background

The oncogene MYCN is critical for tumorigenesis of several types of cancers including neuroblastoma. We previously reported that miR-506-3p repressed MYCN expression in neuroblastoma cells. However, the mechanism underlying such regulation was undetermined since there is no miR-506-3p target site in MYCN 3’UTR.

Methods

By a systematic investigation combining microarray, informatics and luciferase reporter assay, we identified that the transcriptional factor pleiomorphic adenoma gene-like 2 (PLAGL2) is a direct target of miR-506-3p that mediates its regulation on MYCN expression. Using CHIP-PCR and luciferase reporter assay, we validated the transcriptional regulation of MYCN by PLAGL2 and we further demonstrated the transcriptional regulation of PLAGL2 by MYCN. We examined the function of PLAGL2 in regulating neuroblastoma cell fate by cell viability assay, colony formation and Western blotting of differentiation markers. We examined the effect of retinoic acid, the differentiation agent used in neuroblastoma therapy, on miR-506-3p, PLAGL2 and MYCN expressions by quantitative PCR and Western blots. We investigated the clinical relevance of PLAGL2 expression by examining the correlation of tumor PLAGL2 mRNA levels with MYCN mRNA expression and patient survival using public neuroblastoma patient datasets.

Results

We found that miR-506-3p directly down-regulated PLAGL2 expression, and we validated a PLAGL2 binding site in the MYCN promoter region responsible for promoting MYCN transcription, thereby establishing a mechanism through which miR-506-3p regulates MYCN expression. Conversely, we discovered that MYCN regulated PLAGL2 transcription through five N-Myc-binding E-boxes in the PLAGL2 promoter region. We further confirmed the reciprocal regulation between endogenous PLAGL2 and MYCN in multiple neuroblastoma cell lines. Moreover, we found that PLAGL2 knockdown induced neuroblastoma cell differentiation and reduced cell proliferation, and combined knockdown of PLAGL2 and MYCN showed a synergistic effect. More strikingly, we found that high tumor PLAGL2 mRNA levels were significantly correlated with high MYCN mRNA levels and poor patient survival in neuroblastoma patients. Furthermore, we found that retinoic acid increased expression of miR-506-3p and repressed expression of MYCN and PLAGL2.

Conclusions

Our findings altogether suggest that the interplay network formed by PLAGL2, MYCN and miR-506-3p is an important mechanism in regulating neuroblastoma cell fate, determining neuroblastoma prognosis, and mediating the therapeutic function of retinoic acid.

MicroRNAs in neuroblastoma tumorigenesis, therapy resistance, and disease evolution

Neuroblastoma (NB) deriving from neural crest cells is the most common extra-cranial solid cancer at infancy. NB originates within the peripheral sympathetic ganglia in adrenal medulla and along the midline of the body. Clinically, NB exhibits significant heterogeneity stretching from spontaneous regression to rapid progression to therapy resistance. MicroRNAs (miRNAs, miRs) are small (19-22 nt in length) non-coding RNAs that regulate human gene expression at the post-transcriptional level and are known to regulate cellular signaling, growth, differentiation, death, stemness, and maintenance. Consequently, the function of miRs in tumorigenesis, progression and resistance is of utmost importance for the understanding of dysfunctional cellular pathways that lead to disease evolution, therapy resistance, and poor clinical outcomes. Over the last two decades, much attention has been devoted to understanding the functional roles of miRs in NB biology. This review focuses on highlighting the important implications of miRs within the context of NB disease progression, particularly miRs’ influences on NB disease evolution and therapy resistance. In this review, we discuss the functions of both the “oncomiRs” and “tumor suppressor miRs” in NB progression/therapy resistance. These are the critical components to be considered during the development of novel miR-based therapeutic strategies to counter therapy resistance.

Response of breast cancer cells to IFNα-2b in 2D and 3D cell cultures

The effect of IFNα-2b on the migration, proliferation, and expression of epithelial and mesenchymal markers of MCF-7 tumor adenocarcinoma cells in 2D and 3D cell cultures was examined. A significant cytostatic effect of IFNα-2b on the tumor population was detected. It was found that changes in the expression of epithelial (CKs and EpCAM) and mesenchymal markers were caused by changing the growth type of the tumor population. IFNα-2b inhibited migration of tumor cells to the suspension fraction and promoted an increase in expression of CK and EpCAM in 2D and 3D cell cultures, but only in the 3D culture was expression of vimentin increased. IFNα-2b caused an increase in CK and EpCAM expression by 50.5% and 47.8%, respectively, compared with the control in the 2D cell culture. In the 3D cell culture this increase was 33% and 34%, respectively, compared with the control. IFNα-2b stimulated the differentiation and inhibited the migrational ability of tumor cells in the early stages of breast cancer development.

The microRNAs miR-449a and miR-424 suppress osteosarcoma by targeting cyclin A2 expression

MicroRNAs of the miR-16 and miR-34 families have been reported to inhibit cell cycle progression, and their loss has been linked to oncogenic transformation. Utilizing a high-throughput, genome-wide screen for miRNAs and mRNAs that are differentially regulated in osteosarcoma (OS) cell lines, we report that miR-449a and miR-424, belonging to the miR-34 and miR-16 families, respectively, target the major S/G₂ phase cyclin, cyclin A2 (CCNA2), in a bipartite manner. We found that the 3'-UTR of CCNA2 is recognized by miR-449a, whereas the CCNA2 coding region is targeted by miR-424. Of note, we observed loss of both miR-449a and miR-424 in OS, resulting in derepression of CCNA2 and appearance of aggressive cancer phenotypes. Ectopic expression of miR-449a and miR-424 significantly decreased cyclin A2 levels and inhibited proliferation rate, migratory potential, and colony-forming ability of OS cells. To further probe the roles of miR-449a and miR-424 in OS, we developed an OS mouse model by intraosseous injection of U2OS cells into the tibia bone of NOD-scid mice, which indicated that miR-449a and miR-424 co-expression suppresses tumor growth. On the basis of this discovery, we analyzed the gene expression of human OS biopsy samples, revealing that miR-449a and miR-424 are both down-regulated, whereas cyclin A2 is significantly up-regulated in these OS samples. In summary, the findings in our study highlight that cyclin A2 repression by miRNAs of the miR-16 and miR-34 families is lost in aggressive OS.

MicroRNA replacement therapy in cancer

Despite the recent progress in cancer management approaches, the mortality rate of cancer is still growing and there are lots of challenges in the clinics in terms of novel therapeutics. MicroRNAs (miRNA) are regulatory small noncoding RNAs and are already confirmed to have a great role in regulating gene expression level by targeting multiple molecules that affect cell physiology and disease development. Recently, miRNAs have been introduced as promising therapeutic targets for cancer treatment. Regulatory potential of tumor suppressor miRNAs, which enables regulation of entire signaling networks within the cells, makes them an interesting option for developing cancer therapeutics. In this regard, over recent decades, scientists have aimed at developing powerful and safe targeting approaches to restore these suppressive miRNAs in cancerous cells. The present review summarizes the function of miRNAs in tumor development and presents recent findings on how miRNAs have served as therapeutic agents against cancer, with a special focus on tumor suppressor miRNAs (mimics). Moreover, the latest investigations on the therapeutic strategies of miRNA delivery have been presented.

High Expression Levels of AGGF1 and MFAP4 Predict Primary Platinum-Based Chemoresistance and are Associated with Adverse Prognosis in Patients with Serous Ovarian Cancer

Primary platinum-based chemoresistance occurs in approximately one-third of patients with serous ovarian cancer (SOC); however, traditional clinical indicators are poor predictors of chemoresistance. So we aimed to identify novel genes as predictors of primary platinum-based chemoresistance. Gene expression microarray analyses were performed to identify the genes related to primary platinum resistance in SOC on two discovery datasets (GSE51373, GSE63885) and one validation dataset (TCGA). Univariate and multivariate analyses with logistic regression were performed to evaluate the predictive values of the genes for platinum resistance. Machine learning algorithms (linear kernel support vector machine and artificial neural network) were applied to build prediction models. Univariate and multivariate analyses with Cox proportional hazards regression and log-rank tests were used to assess the effects of these gene signatures for platinum resistance on prognosis in two independent datasets (GSE9891, GSE32062). AGGF1 and MFAP4 were found highly expressed in patients with platinum-resistant SOC and independently predicted platinum resistance. Platinum resistance prediction models based on these targets had robust predictive power (highest AUC: 0.8056, 95% CI: 0.6338-0.9773; lowest AUC: 0.7245, 95% CI: 0.6052-0.8438). An AGGF1- and MFAP4-centered protein interaction network was built, and hypothetical regulatory pathways were identified. Enrichment analysis indicated that aberrations of extracellular matrix may play important roles in platinum resistance in SOC. High AGGF1 and MFAP4 expression levels were also related to shorter recurrence-free and overall survival in patients with SOC after adjustment for other clinical variables. Therefore, AGGF1 and MFAP4 are potential predictive biomarkers for response to platinum-based chemotherapy and survival outcomes in SOC.

Integrated analysis of microfibrillar-associated proteins reveals MFAP4 as a novel biomarker in human cancers

Aim: The potential functions and underlying mechanism of microfibrillar-associated proteins (MFAPs) are explored in human cancers. Materials & methods: Here, we examined the expression profiles, prognostic values, epigenetic and genetic alterations of MFAPs in human cancers from public omics repository. Results: Among MFAPs family, MFAP4 was frequently downregulated in the most human cancers and high mRNA expression of MFAP4 significantly correlated with better overall survival in breast cancer. DNA hypermethylation in the promoter of MFAP4 decreased its mRNA expression. MFAP4 strongly associated with pathway in impairment and alteration of the elastic fibers. Conclusion: This integrated analysis provides new insights into MFAPs in human cancers and indicates that MFAP4 could be used as novel biomarker for developing therapies against human cancers.

Cancer Stem Cells and Neuroblastoma: Characteristics and Therapeutic Targeting Options

The majority of embryonal tumors or childhood blastomas derive from pluripotent progenitors or fetal stem cells that acquire cancer stem cell (CSC) properties: multipotency, self-renewal ability, metastatic potential, chemoresistance, more pronounced levels of drug transporters, enhanced DNA-damage repair mechanisms, and a quiescent state. Neuroblastoma (NB) is considered a neuroendocrine tumor and is the most common extracranial neoplasm in children. NB pathogenesis has frequently been associated with epigenetic dysregulation and a failure to implement a differentiation program. The origin, characteristics, and isolation of the CSC subpopulation in NB are still incompletely understood, despite the evidence that this cell subset contributes to disease recurrence and acquired resistance to standard therapies. Here, we summarize the literature regarding the isolation and characterization of CSCs in NB over the past decades, from the early recognition of the expression of stem cell factor (SCF) or its receptor c-KIT to more recent studies identifying the ability of G-CSF and STAT3 to support stem cell-like properties in NB cells. Additionally, we review the morphological variants of NB tumors whose recent epigenetic analyses have shed light on the tumor heterogeneity so common in NB. NB-derived mesenchymal stem cells have recently been isolated from primary tumors of NB patients and associated with a pro-tumorigenic role in the tumor microenvironment, enabling immune escape by tumors, and contributing to their invasive and metastatic capabilities. In particular, we will focus on epigenetic reprogramming in the CSC subpopulation in NB and strategies to target CSCs in NB.

microRNA-2110 functions as an onco-suppressor in neuroblastoma by directly targeting Tsukushi

microRNA-2110 (miR-2110) was previously identified as inducing neurite outgrowth in a neuroblastoma cell lines BE(2)-C, suggesting its differentiation-inducing and oncosuppressive function in neuroblastoma. In this study, we demonstrated that synthetic miR-2110 mimic had a generic effect on reducing cell survival in neuroblastoma cell lines with distinct genetic backgrounds, although the induction of cell differentiation traits varied between cell lines. In investigating the mechanisms underlying such functions of miR-2110, we identified that among its predicted target genes down-regulated by miR-2110, knockdown of Tsukushi (TSKU) expression showed the most potent effect in inducing cell differentiation and reducing cell survival, suggesting that TSKU protein plays a key role in mediating the functions of miR-2110. In investigating the clinical relevance of miR-2110 and TSKU expression in neuroblastoma patients, we found that low tumor miR-2110 levels were significantly correlated with high tumor TSKU mRNA levels, and that both low miR-2110 and high TSKU mRNA levels were significantly correlated with poor patient survival. These findings altogether support the oncosuppressive function of miR-2110 and suggest an important role for miR-2110 and its target TSKU in neuroblastoma tumorigenesis and in determining patient prognosis.

Inhibition of GPR158 by microRNA-449a suppresses neural lineage of glioma stem/progenitor cells and correlates with higher glioma grades

To identify biomarkers for glioma growth, invasion and progression, we used a candidate gene approach in mouse models with two complementary brain tumour phenotypes, developing either slow-growing, diffusely infiltrating gliomas or highly proliferative, non-invasive primitive neural tumours. In a microRNA screen we first identified microRNA-449a as most significantly differentially expressed between these two tumour types. miR-449a has a target dependent effect, inhibiting cell growth and migration by downregulation of CCND1 and suppressing neural phenotypes by inhibition of G protein coupled-receptor (GPR) 158. GPR158 promotes glioma stem cell differentiation and induces apoptosis and is highest expressed in the cerebral cortex and in oligodendrogliomas, lower in IDH mutant astrocytomas and lowest in the most malignant form of glioma, IDH wild-type glioblastoma. The correlation of GPR158 expression with molecular subtypes, patient survival and therapy response suggests a possible role of GPR158 as prognostic biomarker in human gliomas.

Tumor suppressor miR-449a inhibits the development of gastric cancer via down-regulation of SGPL1

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors. Numerous studies have demonstrated that miR-449a plays important roles in human carcinogenesis. However, its precise functional and regulatory roles remain unclear. In this study, we mainly explored the functional role of miR-449a in gastric cancer (GC). The expression levels of miR-449a in 98 cases of GC tissues and cell lines were determined by qRT-PCR. The possible mechanisms of miR-449a in GC cells were explored by fluorescence reporter assay. miR-449a expression was significantly lower in GC tissues compared to matched para-carcinoma tissues and was associated with tumor differentiation. Furthermore, in vitro knockdown of miR-449a by siRNA significantly inhibited MKN-28 cell proliferation, migration and invasion as well as tumorigenesis via inducing G0/G1 arrest of GC cells. In addition, we identified SGPL1 as a target of miR-449a and demonstrated that miR-449a regulated SGPL1 expression via binding its 3′-UTR region. The experiments indicated that miR-449a functions as a novel tumor suppressor in GC and its anti-oncogenic activity may involve its inhibition of the target gene SGPL1. These findings suggested that miR-449a may be a promising candidate for the development of antitumor drugs targeting GC.

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors.

Circ-8073 regulates CEP55 by sponging miR-449a to promote caprine endometrial epithelial cells proliferation via the PI3K/AKT/mTOR pathway

Circular RNAs (circRNAs) are a large class of endogenous non-coding RNAs that function as regulators in various cells and tissues. Here, the function and mechanism of circRNA8073 (Circ-8073) on endometrial epithelial cells (EECs) and the development of endometrial receptivity were investigated in dairy goats. Circ-8073 could bind to and inhibit miR-449a activity. Circ-8073 binding to the target site of miR-449a had a negative feedback relationship. Centrosomal protein55 (CEP55) was a direct target gene of miR-449a, and Circ-8073 could increase the expression levels of CEP55 by sponging miR-449a in EECs in vitro. Circ-8073/miR-449a/CEP55 could promote EECs proliferation via the PI3K/AKT/mTOR pathway. In addition, CEP55 could regulate the expression levels of vascular endothelial growth factor (VEGF) and forkhead box M1 (FOXM1) in EECs, which contributed to the development of endometrial receptivity. These findings showed that Circ-8073 regulated CEP55 by sponging miR-449a to promote EEC proliferation via the PI3K/AKT/mTOR pathway, suggesting that it could function as a regulator in the development of endometrial receptivity in dairy goats.

miR-449a: a potential therapeutic agent for cancer

MicroRNAs (miRNAs) have been reported to be associated with cancer progression and carcinogenesis. They are small, highly conserved, noncoding RNA molecules consisting of 19-25 nucleotides. By binding to complementary binding sites within the 3'-untranslated region of target mRNAs, miRNAs inhibit the translation of mRNAs or promote their degradation. miRNAs play critical roles in cancer initiation and development by functioning either as oncogenes or as tumor suppressors. Similarly, several studies have shown that miRNAs are involved in regulating various biological processes, including apoptosis, proliferation, cellular differentiation, signal transduction, and carcinogenesis. Among miRNAs, one that may be of particular interest in cancer biology is miR-449a, which has been reported to inhibit tumor growth, invasion, and metastasis, and to promote apoptosis and differentiation through the transforming growth factor-β activated kinase 1, NOTCH, nuclear factor-κB/P65/vascular endothelial growth factor, retinoblastoma-E2F, mitogen-activated protein kinase signaling pathways, WNT-β-catenin signaling, tumor protein P53, and androgen receptor signaling pathways. The miR-449 cluster is located in the second intron of CDC20B on chromosome 5q11.2, a region that has been identified as a susceptibility locus in cancer, and the abnormal expression of miR-449a may be related to the occurrence and development of tumors. As one example, miR-449a has been reported to be involved in the development of carcinoma and may be a potential prognostic indicator. On the basis of the putative pathogenetic relationships between cancer and miR-449a, we consider that miR-449a has the potential to serve as a therapeutic agent for the treatment of some types of cancer. In this review, the role of miR-449a in tumorigenesis and its mechanism of action are explored. Furthermore, its potential as a therapeutic agent in cancer treatment is considered.

Loss of miR-449a in ERG-associated prostate cancer promotes the invasive phenotype by inducing SIRT1

Epigenetic regulation by SIRT1, a multifaceted NAD⁺-dependent protein deacetylase, is one of the most common factors modulating cellular processes in a broad range of diseases, including prostate cancer (CaP). SIRT1 is over-expressed in CaP cells, however the associated mechanism is not well understood. To identify whether specific microRNAs might mediate this linkage, we have screened a miRNA library for differential expression in ERG-associated CaP tissues. Of 20 differentially and significantly expressed miRNAs that distinguish ERG-positive tumors from ERG-negative tumors, we find miR-449a is highly suppressed in ERG-positive tumors. We establish that SIRT1 is a direct target of miR-449a and is also induced by ERG in ERG-associated CaP. Our data suggest that attenuation of miR-449a promotes the invasive phenotype of the ERG-positive CaP in part by inducing the expression of SIRT1 in prostate cancer cells. Furthermore, we also find that suppression of SIRT1 results in a significant reduction in ERG expression in ERG-positive CaP cells, indicating a feed-back regulatory loop associated with ERG, miR-449a and SIRT1. We also report that ERG suppresses p53 acetylation perhaps through miR-449a-SIRT1 axis in CaP cells. Our findings provide new insight into the function of miRNAs in regulating ERG-associated CaP. Thus, miR-449a activation or SIRT1 suppression may represent new therapeutic opportunity for ERG-associated CaP.

iTRAQ-Based Quantitative Proteomic Analyses of High Grade Esophageal Squamous Intraepithelial Neoplasia

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers worldwide and is the fourth most lethal cancer in China. Little is known about the proteome of high grade esophageal squamous intraepithelial neoplasia (HGN), which is a premalignant lesion of ESCC. A quantitative proteomic analysis using an isobaric tag for relative and absolute quantification (iTRAQ) approach is used to characterize the protein expression profiles in HGN. Among the 3156 identified proteins, a total of 236 proteins are discovered to be differentially expressed. Compared with paired normal esophageal epithelial tissues, 138 proteins are upregulated and 98 proteins are downregulated in HGN. Bioinformatics analyses are performed according to gene ontology, clusters of orthologous groups, and kyoto encyclopedia of genes and genomes enrichment analyses. Six differentially expressed proteins are chosen and validated by Western blotting. The results of the study increase our understanding of early tumorigenesis during ESCC, and provide insights into the proteome at the initial stages of the disease that can be used to identify potential biomarkers for early diagnosis and for therapeutic targets.

Knockdown of Long Non-Coding RNA KCNQ1OT1 Restrained Glioma Cells' Malignancy by Activating miR-370/CCNE2 Axis

Accumulating evidence has highlighted the potential role of long non-coding RNAs (lncRNAs) as biomarkers and therapeutic targets in solid tumors. Here, we elucidated the function and possible molecular mechanisms of lncRNA KCNQ1OT1 in human glioma U87 and U251 cells. Quantitative Real-Time polymerase chain reaction (qRT-PCR) demonstrated that KCNQ1OT1 expression was up-regulated in glioma tissues and cells. Knockdown of KCNQ1OT1 exerted tumor-suppressive function in glioma cells. Moreover, a binding region was confirmed between KCNQ1OT1 and miR-370 by dual-luciferase assays. qRT-PCR showed that miR-370 was down-regulated in human glioma tissue and cells. In addition, restoration of miR-370 exerted tumor-suppressive function via inhibiting cell proliferation, migration and invasion, while promoting the apoptosis of human glioma cells. Knockdown of KCNQ1OT1 decreased the expression level of Cyclin E2 (CCNE2) by binding to miR-370. Further, miR-370 bound to CCNE2 3′UTR region and decreased the expression of CCNE2. These results provided a comprehensive analysis of KCNQ1OT1-miR-370-CCNE2 axis in human glioma cells and might provide a novel strategy for glioma treatment.

Identification of four potential predicting miRNA biomarkers for multiple myeloma from published datasets

Background

Multiple myeloma is a cancer which has a high occurrence rate and causes great injury to people worldwide. In recent years, many studies reported the effects of miRNA on the appearance of multiple myeloma. However, due to the differences of samples and sequencing platforms, a large number of inconsistent results have been generated among these studies, which limited the cure of multiple myeloma at the miRNA level.

Methods

We performed meta-analyses to identify the key miRNA biomarkers which could be applied on the treatment of multiple myeloma. The key miRNAs were determined by overlap comparisons of seven datasets in multiple myeloma. Then, the target genes for key miRNAs were predicted by the software TargetScan. Additionally, functional enrichments and binding TFs were investigated by DAVID database and Tfacts database, respectively.

Results

Firstly, comparing the normal tissues, 13 miRNAs were differently expressed miRNAs (DEMs) for at least three datasets. They were considered as key miRNAs, with 12 up-regulated (hsa-miR-106b, hsa-miR-125b, hsa-miR-130b, hsa-miR-138, hsa-miR-15b, hsa-miR-181a, hsa-miR-183, hsa-miR-191, hsa-miR-19a, hsa-miR-20a, hsa-miR-221 and hsa-miR-25) and one down-regulated (hsa-miR-223). Secondly, functional enrichment analyses indicated that target genes of the upregulated miRNAs were mainly transcript factors and enriched in transcription regulation. Besides, these genes were enriched in multiple pathways: the cancer signal pathway, insulin signal metabolic pathway, cell binding molecules, melanin generation, long-term regression and P53 signaling pathway. However, no significant enrichment was found for target genes of the down-regulated genes. Due to the distinct regulation function, four miRNAs (hsa-miR-19a has-miR-221 has-miR25 and has-miR223) were ascertained as the potential prognostic and diagnostic markers in MM. Thirdly, transcript factors analysis unveiled that there were 148 TFs and 60 TFs which bind target genes of the up-regulated miRNAs and target genes of the down-regulated miRNAs, respectively. They respectively generated 652 and 139 reactions of TFs and target genes. Additionally, 50 (31.6%) TFs were shared, while higher specificity was found in TFs of target genes for the upregulated miRNAs.

Discussions

Together, our findings provided the key miRNAs which affected occurrence of multiple myeloma and regulation function of these miRNAs. It is valuable for the prognosis and diagnosis of multiple myeloma.

Mir-449a, a potential diagnostic biomarker for WNT group of medulloblastoma

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. The 5 year disease-free survival rate is rather low. There is a consensus that MB can be divided into at least four clinically, transcriptionally, and genetically distinct molecular variants, being designated as wingless (WNT), sonic hedgehog (SHH), Group 3 and Group 4. It poses a great challenge to the design of therapeutic strategy for MB patients. Intensive clinical intervention, including high dose radiotherapy, is commonly used in treatment of high risk MB, most of which are considered to be Group 3 patients. But such intensive therapy should be avoided to protect neurologic function of patients in the lower risk WNT group. In present study, MB subgroup assignment in formalin-fixed paraffin embedded (FFPE) specimens from 45 Chinese patients were performed by Nanostring platform using 22 well-known signature genes. Based on comparative expression profiles of miRNA real-time PCR microarray in MB cells with and without treatment of demethylation reagent, as well as MSP assay, miR-449a was demonstrated to be significantly silenced by aberrant DNA methylation in tumor cells. Real-time PCR showed that expression level of miR-449a in WNT group was significantly different from other subgroups, although it was down-regulated in most of the MB samples. In conclusion, current study demonstrates for the first time the feasibility of using the Nanostring assay for subgrouping of MBs in Chinese patients. In addition, MiR-449a, a candidate tumor suppressor regulated by hypermethylation, is a novel potential diagnostic marker for WNT group of MBs.

MicroRNA-mediated Th2 bias in methimazole-induced acute liver injury in mice

MicroRNA (miRNA) is a class of small non-coding RNAs containing approximately 20 nucleotides that negatively regulate target gene expression. Little is known about the role of individual miRNAs and their targets in immune- and inflammation-related responses in drug-induced liver injury. In the present study, involvement of miRNAs in the T helper (Th) 2-type immune response was investigated using a methimazole (MTZ)-induced liver injury mouse model. Co-administration of L-buthionine-S,R-sulfoximine and MTZ induced acute hepatocellular necrosis and elevated plasma levels of alanine aminotransferase (ALT) from 4h onward in female Balb/c mice. The hepatic mRNA expression of Th2 promotive factors was significantly increased concomitantly with plasma ALT levels. In contrast, the hepatic mRNA expression of Th2 suppressive factors was significantly decreased during the early phase of liver injury. Comprehensive profiling of hepatic miRNA expression was analyzed before the onset of MTZ-induced liver injury. Using in silico prediction of miRNAs that possibly regulate Th2-related genes and subsequent quantification, we identified up-regulation of expression of miR-29b-1-5p and miR-449a-5p. Among targets of these miRNAs, down-regulation of Th2 suppressive transcription factors, such as SRY-related HMG-box 4 (SOX4) and lymphoid enhancer factor-1 (LEF1), were observed from the early phase of liver injury. In conclusion, negative regulation of the expression of SOX4 by miR-29b-1-5p and that of LEF1 by miR-449a-5p is suggested to play an important role in the development of Th2 bias in MTZ-induced liver injury.

MicroRNA-449a enhances radiosensitivity by downregulation of c-Myc in prostate cancer cells

MicroRNAs (miRNAs) have been reported to be involved in DNA damage response induced by ionizing radiation (IR). c-Myc is reduced when cells treated with IR or other DNA damaging agents. It is unknown whether miRNAs participate in c-Myc downregulation in response to IR. In the present study, we found that miR-449a enhanced radiosensitivity in vitro and in vivo by targeting c-Myc in prostate cancer (LNCaP) cells. MiR-449a was upregulated and c-Myc was downregulated in response to IR in LNCaP cells. Overexpression of miR-449a or knockdown of c-Myc promoted the sensitivity of LNCaP cells to IR. By establishing c-Myc as a direct target of miR-449a, we revealed that miR-449a enhanced radiosensitivity by repressing c-Myc expression in LNCaP cells. Furthermore, we showed that miR-449a enhanced radiation-induced G2/M phase arrest by directly downregulating c-Myc, which controlled the Cdc2/CyclinB1 cell cycle signal by modulating Cdc25A. These results highlight an unrecognized mechanism of miR-449a-mediated c-Myc regulation in response to IR and may provide alternative therapeutic strategies for the treatment of prostate cancer.

Targeting oncomiRNAs and mimicking tumor suppressor miRNAs: Νew trends in the development of miRNA therapeutic strategies in oncology (Review)

MicroRNA (miRNA or miR) therapeutics in cancer are based on targeting or mimicking miRNAs involved in cancer onset, progression, angiogenesis, epithelial-mesenchymal transition and metastasis. Several studies conclusively have demonstrated that miRNAs are deeply involved in tumor onset and progression, either behaving as tumor-promoting miRNAs (oncomiRNAs and metastamiRNAs) or as tumor suppressor miRNAs. This review focuses on the most promising examples potentially leading to the development of anticancer, miRNA-based therapeutic protocols. The inhibition of miRNA activity can be readily achieved by the use of miRNA inhibitors and oligomers, including RNA, DNA and DNA analogues (miRNA antisense therapy), small molecule inhibitors, miRNA sponges or through miRNA masking. On the contrary, the enhancement of miRNA function (miRNA replacement therapy) can be achieved by the use of modified miRNA mimetics, such as plasmid or lentiviral vectors carrying miRNA sequences. Combination strategies have been recently developed based on the observation that i) the combined administration of different antagomiR molecules induces greater antitumor effects and ii) some anti-miR molecules can sensitize drug-resistant tumor cell lines to therapeutic drugs. In this review, we discuss two additional issues: i) the combination of miRNA replacement therapy with drug administration and ii) the combination of antagomiR and miRNA replacement therapy. One of the solid results emerging from different independent studies is that miRNA replacement therapy can enhance the antitumor effects of the antitumor drugs. The second important conclusion of the reviewed studies is that the combination of anti-miRNA and miRNA replacement strategies may lead to excellent results, in terms of antitumor effects.

miR-320a regulates cell proliferation and apoptosis in multiple myeloma by targeting pre-B-cell leukemia transcription factor 3

Aberrant expression of microRNAs (miRNAs) is implicated in cancer development and progression. While miR-320a is reported to be deregulated in many malignancy types, its biological role in multiple myeloma (MM) remains unclear. Here, we observed reduced expression of miR-320a in MM samples and cell lines. Ectopic expression of miR-320a dramatically suppressed cell viability and clonogenicity and induced apoptosis in vitro. Mechanistic investigation led to the identification of Pre-B-cellleukemia transcription factor 3 (PBX3) as a novel and direct downstream target of miR-320a. Interestingly, reintroduction of PBX3 abrogated miR-320a-induced MM cell growth inhibition and apoptosis. In a mouse xenograft model, miR-320a overexpression inhibited tumorigenicity and promoted apoptosis. Our findings collectively indicate that miR-320a inhibits cell proliferation and induces apoptosis in MM cells by directly targeting PBX3, supporting its utility as a novel and potential therapeutic agent for miRNA-based MM therapy.

MicroRNA-126 inhibits cell proliferation in gastric cancer by targeting LAT-1

MicroRNA-126 (miR-126) is a pivotal post-transcriptional regulator, which has been validated as a suppressor in gastric cancer (GC). However, the downstream of its tumor inhibiting function has not been totally clear. L-type amino-acid transporter 1 (LAT-1) is a novel member of system L-type transporters involving in cell proliferation, and we have previously validated that LAT-1 played a role of promotor in GC. In this study, we further detected and confirmed that LAT-1 was exactly targeted by miR-126 in GC. We found LAT-1 was significantly downregulated in GC MKN-45 cell lines by using miR-126 mimics, along with an impairment on cell proliferation and cell cycle. Additionally, by overexpressing LAT-1 in MKN-45 cells which was firstly treated with miR-126 mimics, the ability of cell proliferation in MKN-45 cells was definitely rescued. Thus, our results suggests and consolidates the standpoint that miR-126 plays a pivotal role in GC suppressing the process of GC cell, and this function is at least partly taken to implement by miR-126s's post-transcriptional effect on LAT-1. This might provide us likely potential biomarkers and targets for GC prevention, diagnosis and therapeutic treatment.