miR-373 negatively regulates methyl-CpG-binding domain protein 2 (MBD2) in hilar cholangiocarcinoma

Analytical and therapeutic profiles of DNA methylation alterations in cancer; an overview of changes in chromatin arrangement and alterations in histone surfaces

DNA methylation is the most important epigenetic element that activates the inhibition of gene transcription and is included in the pathogenesis of all types of malignancies. Remarkably, the effectors of DNA methylation are DNMTs (DNA methyltransferases) that catalyze de novo or keep methylation of hemimethylated DNA after the DNA replication process. DNA methylation structures in cancer are altered, with three procedures by which DNA methylation helps cancer development which are including direct mutagenesis, hypomethylation of the cancer genome, and also focal hypermethylation of the promoters of TSGs (tumor suppressor genes). Conspicuously, DNA methylation, nucleosome remodeling, RNA-mediated targeting, and histone modification balance modulate many biological activities that are essential and indispensable to the genesis of cancer and also can impact many epigenetic changes including DNA methylation and histone modifications as well as adjusting of non-coding miRNAs expression in prevention and treatment of many cancers. Epigenetics points to heritable modifications in gene expression that do not comprise alterations in the DNA sequence. The nucleosome is the basic unit of chromatin, consisting of 147 base pairs (bp) of DNA bound around a histone octamer comprised of one H3/H4 tetramer and two H2A/H2B dimers. DNA methylation is preferentially distributed over nucleosome regions and is less increased over flanking nucleosome-depleted DNA, implying a connection between nucleosome positioning and DNA methylation. In carcinogenesis, aberrations in the epigenome may also include in the progression of drug resistance. In this report, we report the rudimentary notes behind these epigenetic signaling pathways and emphasize the proofs recommending that their misregulation can conclude in cancer. These findings in conjunction with the promising preclinical and clinical consequences observed with epigenetic drugs against chromatin regulators, confirm the important role of epigenetics in cancer therapy.

Involvement of miRNA on Epigenetics landscape of Parkinson's disease: From pathogenesis to therapeutics

The development of novel therapeutics for the effective management of Parkinson's disease (PD) is undertaken seriously by the scientific community as the burden of PD continues to increase. Several molecular pathways are being explored to identify novel therapeutic targets. Epigenetics is strongly implicated in several neurodegenerative diseases (NDDs) including PD. Several epigenetic mechanisms were found to dysregulated in various studies. These mechanisms are regulated by several miRNAs which are associated with a variety of pathogenic mechanisms in PD. This concept is extensively investigated in several cancers but not well documented in PD. Identifying the miRNAs with dual role i.e., regulation of epigenetic mechanisms as well as modulation of proteins implicated in the pathogenesis of PD could pave way for the development of novel therapeutics to target them. These miRNAs could also serve as potential biomarkers and can be useful in the early diagnosis or assessment of disease severity. In this article we would like to discuss about various epigenetic changes operating in PD and how miRNAs are involved in the regulation of these mechanisms and their potential to be novel therapeutic targets in PD.

Molecular diagnostics and biomarkers in cholangiocarcinoma

Regardless of anatomic origin, cholangiocarcinoma is generally an aggressive malignancy with a relatively high case fatality. Surgical resection with curative intent remains the best opportunity to achieve meaningful long-term survival. Most patients present, however, with advanced disease and less than 20% of patients are candidates for surgical resection. Unfortunately, even patients who undergo resection have a 5-year survival that ranges from 20 to 40%. Biomarkers are indicators of normal, pathologic, or biologic responses to an intervention and can range from a characteristic (i.e., blood pressure reading which can detect hypertension) to specific genetic mutations or proteins (i.e., carcinoembryonic antigen level). Novel biomarkers and improved molecular diagnostics represent an attractive opportunity to improve detection as well as to identify novel therapeutic targets for patients with cholangiocarcinoma. We herein review the latest advances in molecular diagnostics and biomarkers related to the early detection and treatment of patients with cholangiocarcinoma.

Regulation of RASSF by non-coding RNAs in different cancers

Ras-association domain family (RASSF) proteins are tumor suppressors and have gained phenomenal limelight because of their mechanistic role in the prevention/inhibition of carcinogenesis and metastasis. Decades of research have demystified wide ranging activities of RASSF molecules in multiple stages of cancers. Although major fraction of RASSF molecules has tumor suppressive roles, yet there is parallel existence of proof-of-concept about moonlighting activities of RASSF proteins as oncogenes. RASSF proteins tactfully rewire signaling cascades for prevention of cancer and metastasis but circumstantial evidence also illuminates oncogenic role of different RASSF proteins in different cancers. In this review we have attempted to provide readers an overview of the complex interplay between non-coding RNAs and RASSF proteins and how these versatile regulators shape the landscape of carcinogenesis and metastasis.

miR-29b-3p Inhibitor Alleviates Hypomethylation-Related Aberrations Through a Feedback Loop Between miR-29b-3p and DNA Methylation in Cardiomyocytes

As a member of the miR-29 family, miR-29b regulates global DNA methylation through target DNA methyltransferases (DNMTs) and acts as both a target and a key effector in DNA methylation. In this study, we found that miR-29b-3p expression was inversely correlated with DNMT expression in the heart tissues of patients with congenital heart disease (CHD), but whether it interacts with DNMTs in cardiomyocytes remains unknown. Further results revealed a feedback loop between miR-29b-3p and DNMTs in cardiomyocytes. Moreover, miR-29b-3p inhibitor relieved the deformity of hypomethylated zebrafish and restored the DNA methylation patterns in cardiomyocytes, resulting in increased proliferation and renormalization of gene expression. These results suggest mutual regulation between miR-29b-3p and DNMTs in cardiomyocytes and support the epigenetic normalization of miRNA-based therapy in cardiomyocytes.

Prognostic and Predictive Molecular Markers in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is the second most common primary liver cancer and subsumes a heterogeneous group of malignant tumors arising from the intra- or extrahepatic biliary tract epithelium. A rising mortality from CCA has been reported worldwide during the last decade, despite significant improvement of surgical and palliative treatment. Over 50% of CCAs originate from proximal extrahepatic bile ducts and constitute the most common CCA entity in the Western world. Clinicopathological characteristics such as lymph node status and poor differentiation remain the best-studied, but imperfect prognostic factors. The identification of prognostic molecular markers as an adjunct to traditional staging systems may not only facilitate the selection of patients who would benefit the most from surgical, adjuvant or palliative treatment strategies, but may also be helpful in defining the aggressiveness of the disease and identifying patients at high-risk for tumor recurrence. The purpose of this review is to provide an overview of currently known molecular prognostic and predictive markers and their role in CCA.

Potential Biomarkers of miR-371-373 Gene Cluster in Tumorigenesis

microRNAs (miRNAs) are small non-coding RNA transcripts (20–24 nucleotides) that bind to their complementary sequences in the 3′-untranslated regions (3′-UTR) of targeted genes to negatively or positively regulate their expression. miRNAs affect the expression of genes in cells, thereby contributing to several important biological processes, including tumorigenesis. Identifying the miRNA cluster as a human embryonic stem cell (hESC)-specific miRNAs initially led to the identification of miR-371, miR-372, miR-373, and miR-373*, which can ultimately be translated into mature miRNAs. Recent evidence suggests that miR-371–373 genes are abnormally expressed in various cancers and act either as oncogenes or tumor suppressors, indicating they may be suitable as molecular biomarkers for cancer diagnosis and prevention. In this article, we summarize recent studies linking miR-371–373 functions to tumorigenesis and speculate on the potential applications of miR-371–373 as biomarkers for cancer diagnosis and treatment.

Overview of host miRNA properties and their association with epigenetics, long non-coding RNAs, and Xeno-infectious factors

MicroRNA-derived structures play impressive roles in various biological processes. So dysregulation of miRNAs can lead to different human diseases. Recent studies have extended our comprehension of the control of miRNA function and features. Here, we overview some remarkable miRNA properties that have potential implications for the miRNA functions, including different variants of a miRNA called isomiRs, miRNA arm selection/arm switching, and the effect of these factors on miRNA target selection. Besides, we review some aspects of miRNA interactions such as the interaction between epigenetics and miRNA (different miRNAs and their related processing enzymes are epigenetically regulated by multiple DNA methylation enzymes. moreover, DNA methylation could be controlled by diverse mechanisms related to miRNAs), direct and indirect crosstalk between miRNA and lnc (Long Non-Coding) RNAs as a further approach to conduct intercellular regulation called "competing endogenous RNA" (ceRNA) that is involved in the pathogenesis of different diseases, and the interaction of miRNA activities and some Xeno-infectious (virus/bacteria/parasite) factors, which result in modulation of the pathogenesis of infections. This review provides some related studies to a better understanding of miRNA involvement mechanisms and overcoming the complexity of related diseases that may be applicable and useful to prognostic, diagnostic, therapeutic purposes and personalized medicine in the future.

Regulatory Mechanisms of Epigenetic miRNA Relationships in Human Cancer and Potential as Therapeutic Targets

Simple Summary

By the virtue of targeting multiple genes, a microRNA (miRNA) can infer variable consequences on tumorigenesis by appearing as both a tumour suppressor and oncogene. miRNAs can regulate gene expression by modulating genome-wide epigenetic status of genes that are involved in various cancers. These miRNAs perform direct inhibition of key mediators of the epigenetic machinery, such as DNA methyltransferases (DNMTs) and histone deacetylases (HDACs) genes. Along with miRNAs gene expression, similar to other protein-coding genes, miRNAs are also controlled by epigenetic mechanisms. Overall, this reciprocal interaction between the miRNAs and the epigenetic architecture is significantly implicated in the aberrant expression of miRNAs detected in various human cancers. Comprehensive knowledge of the miRNA-epigenetic dynamics in cancer is essential for the discovery of novel anticancer therapeutics.

Abstract

Initiation and progression of cancer are under both genetic and epigenetic regulation. Epigenetic modifications including alterations in DNA methylation, RNA and histone modifications can lead to microRNA (miRNA) gene dysregulation and malignant cellular transformation and are hereditary and reversible. miRNAs are small non-coding RNAs which regulate the expression of specific target genes through degradation or inhibition of translation of the target mRNA. miRNAs can target epigenetic modifier enzymes involved in epigenetic modulation, establishing a trilateral regulatory “epi–miR–epi” feedback circuit. The intricate association between miRNAs and the epigenetic architecture is an important feature through which to monitor gene expression profiles in cancer. This review summarises the involvement of epigenetically regulated miRNAs and miRNA-mediated epigenetic modulations in various cancers. In addition, the application of bioinformatics tools to study these networks and the use of therapeutic miRNAs for the treatment of cancer are also reviewed. A comprehensive interpretation of these mechanisms and the interwoven bond between miRNAs and epigenetics is crucial for understanding how the human epigenome is maintained, how aberrant miRNA expression can contribute to tumorigenesis and how knowledge of these factors can be translated into diagnostic and therapeutic tool development.

MBD2 Correlates with a Poor Prognosis and Tumor Progression in Renal Cell Carcinoma

Purpose

DNA methylation plays an important role in regulating gene expression. Methyl-CpG-binding domain (MBD) proteins recognize and bind to methylated DNA, which mediate gene silencing by the interaction with deacetylases and histone methyltransferases. MBD2 has been reported in various human cancers; however, its clinical implication and potential regulatory role in renal cell carcinoma (RCC) have not been elaborated.

Materials and Methods

In the study, we estimated the expression and prognostic value of MBD2 in RCC cell lines and tissues by Western blotting and immunohistochemistry. The associations of MBD2 expression and pathological characters and survival in RCC patients were performed using χ2 and Kaplan-Meier survival analysis, respectively. Univariate and multivariable Cox regression analyses suggested the independent predictors in RCC prognosis. The functional role of MBD2 in RCC progression was assessed by in vitro cell experiments. In addition, we identified the MBD2-mediated alterations of protein-related proliferation and EMT markers in RCC cells after MBD2 overexpression and knockdown.

Results

We found that the protein levels of MBD2 were upregulated in RCC cells and tissues. High MBD2 expression was related to TNM stage and predicted poorer survival in RCC. Enforced expression of MBD2 significantly promoted the proliferation, cycle progress, invasion and migration of RCC cells in vitro. However, downregulating MBD2 remarkably weakened the above cell functions. Mechanistically, the promotive effect of MBD2 overexpression may be regulated by its effects onp21, p53 and Cyclin D1 expression and EMT process.

Conclusion

These results indicated that MBD2confers an oncogenic function in the malignant progression of RCC. MBD2 could be served as a meaningful prognostic biomarker and a latent therapeutic target in RCC patients.

Regulation of DNA methylation machinery by epi-miRNAs in human cancer: emerging new targets in cancer therapy

Disruption in DNA methylation processes can lead to alteration in gene expression and function that would ultimately result in malignant transformation. In this way, studies have shown that, in cancers, methylation-associated silencing inactivates tumor suppressor genes, as effectively as mutations. DNA methylation machinery is composed of several genes, including those with DNA methyltransferases activity, proteins that bind to methylated cytosine in the promoter region, and enzymes with demethylase activity. Based on a prominent body of evidence, DNA methylation machinery could be regulated by microRNAs (miRNAs) called epi-miRNAs. Numerous studies demonstrated that dysregulation in DNA methylation regulators like upstream epi-miRNAs is indispensable for carcinogenesis; consequently, the malignant capacity of these cells could be reversed by restoring of this regulatory system in cancer. Conceivably, recognition of these epi-miRNAs in cancer cells could not only reveal novel molecular entities in carcinogenesis, but also render promising targets for cancer therapy. In this review, at first, we have an overview of the methylation alteration in cancers, and the effect of this phenomenon in miRNAs expression and after that, we conduct an in-depth discussion about the regulation of DNA methylation regulators by epi-miRNAs in cancer cells.

Role of noncoding RNAs in cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is a malignant tumour originating from biliary epithelial cells, and is increasing in incidence. Radical surgery is the main treatment. However, the pathogenesis of CCA is unclear. Noncoding RNAs (ncRNAs) are non‑protein‑coding RNAs produced by genomic transcription that include microRNAs (miRNAs), circular RNAs (circRNAs) and long noncoding RNAs (lncRNAs). They play important roles in gene expression, epigenetic modification, cell proliferation, differentiation and reproduction. ncRNAs also serve key roles in cancer development. Numerous studies have been carried out on ncRNAs, and associated publications have shown that ncRNAs are closely associated with the physiological and pathological mechanisms of CCA. The findings of these studies can provide new insights into the diagnosis, treatment and prognosis of CCA. The present review summarizes the pathophysiological mechanisms of different types of ncRNAs, including miRNAs, circRNAs and lncRNAs in CCA, and their applications in the diagnosis and treatment of CCA.

miR-373 inhibits autophagy and further promotes apoptosis of cholangiocarcinoma cells by targeting ULK1

Intrahepatic cholangiocarcinoma is a malignant tumor originating from intrahepatic bile ducts. Surgical therapy, radiotherapy, and chemotherapy are taken to treat this disease, but it is prone to recurrence and metastasis, with poor prognosis. Therefore, it is of great significance to explore new targets and molecular mechanisms for the development of cholangiocarcinoma cells. Clinical cholangiocarcinoma tissues from patients and four human cholangiocarcinoma cell lines were analyzed for microRNA-373 (miR-373) expression. For investigating whether miR-373 directly modulated unc-51 like autophagy activating kinase 1 (ULK1), dual-luciferase reporter assay was performed. In addition, CCK-8 assay, flow cytometry, western blot, and immunofluorescence were applied to evaluate the proliferation, apoptosis, and autophagy of cholangiocytic hepatocellular carcinoma cells. miR-373 downregulation was observed in clinical tissues and cell lines of cholangiocarcinoma. Overexpression of miR-373 reduced proliferation, enhanced apoptosis, and raised expression levels of pro-apoptosis proteins including BCL2 associated X (Bax), Caspase-3, and Caspase-9. Moreover, overexpression of miR-373 downregulated expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, Beclin-1, and promoted P62 expression on mRNA and protein levels. After miR-373 knockdown, all indexes of apoptosis and autophagy mentioned above were reversed. Luciferase activity was decreased after cotransfection of miR-373 mimic and wild-type ULK1 vector. Also, miR-373 overexpression inhibited ULK1 expression. Importantly, overexpression of miR-373 weakened expressions of ULK1, LC3, Beclin-1, and Bcl-2, and enhanced expressions of P62, Bax, Caspase-3, and Caspase-9. miR-373 mimic treatment and subsequent ULK1 overexpression, induced reverse regulation in expressions of these proteins, compared with overexpression of miR-373 only. miR-373 targeted ULK1 to initiate inhibition of autophagy and subsequent promotion of apoptosis in cholangiocarcinoma cells.

CyclinD1 inhibits dicer and crucial miRNA expression by chromatin modification to promote the progression of intrahepatic cholangiocarcinoma

Background

CyclinD1 is crucial for cell cycling and can regulate the expression of Dicer, a crucial regulator of microRNA maturation. However, little is known on how CyclinD1 regulates Dicer and miRNA expression, and the progression of intrahepatic cholangiocarcinoma (ICC).

Methods

The expression of CyclinD1 and Dicer in non-tumor cholangiocytes, ICC cells and tissues as well as their association with clinicopathological characteristics and survival were examined. The potential mechanisms by which CyclinD1 regulates Dicer and relative miRNA expression were determined by immunoprecipitation, ChIP sequence, BSP and luciferase reporter assays following induction of CyclinD1 over-expression or silencing and Dicer silencing. The impact of CyclinD1 and/or Dicer silencing on the growth of ICC was tested in vivo.

Results

Up-regulated CyclinD1 was associated with down-regulated Dicer expression in ICC tissues and poorer overall survival in patients with ICC. CyclinD1 interacted with the nuclear H3K9me3 and SUV39H1 and bound to the Dicer promoter to increase its CpG island methylation in ICC cells. Functionally, CyclinD1 silencing inhibited the malignancy of ICC cells, which were mitigated partially by Dicer silencing in ICC cells. Dicer silencing down-regulated miR-1914-5p and miR-541-5p expression, which targeted and promoted CyclinD1 and CDK6 expression in ICC cells.

Conclusions

Our findings uncover that CyclinD1 inhibits Dicer expression by chromatin modification to reduce miR-1914-5p/miR-541-5p expression, which positively-feedback enhances CyclinD1 and CDK6 expression and progression of ICC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1415-5) contains supplementary material, which is available to authorized users.

MicroRNA‑373 exerts anti‑tumor functions in human liver cancer by targeting Rab22a

Liver cancer is a one of the most frequent types of tumor worldwide. It has long been recognized that microRNAs are important participants in the progression of various types of cancer. The present study explored the role of microRNA‑373 (miR‑373) in liver cancer development. Reverse transcription‑quantitative polymerase chain reaction was performed to evaluate the transcription level of miR‑373 in 96 liver cancer tissues and adjacent normal liver tissues. The association of miR‑373 with clinicopathological characteristics was analyzed using the χ2 test. Kaplan‑Meier univariate analysis and multivariate hazard analysis were performed to identify the clinical potential of miR‑373 in the prognosis of liver cancer patients. Transfection of miR‑373 mimics into Hep3B and HepG2 liver cancer cell lines was conducted to reveal the underlying mechanism in regulating liver cancer progression. The functional assays included proliferation, migration, invasion and luciferase assays. The findings of the present study demonstrated that miR‑373 transcription level was markedly downregulated in liver cancer tissues compared with the adjacent normal tissues and was associated with the clinical prognosis of liver cancer patients. Overexpressing miR‑373 mimics in liver cancer cell lines decreased cell proliferation and invasion, suggesting that miR‑373 exerts anti‑tumor effects in liver cancer. In addition, data from the present study demonstrated the direct effect of miR373 on inhibiting the expression and signaling of Ras‑related protein Rab22a, a well‑known oncoprotein. Taken together, the results from the present study suggested that miR‑373 suppresses liver cancer progression and may serve as a promising prognosis prediction biomarker.

The Expression of MBD6 Is Associated with Tumor Size in Uterine Leiomyomas

Background: Uterine leiomyoma (UL) is the most common benign smooth muscle tumor of the uterus in reproductive women. Prior studies indicated that methyl-CpG-binding domain proteins (MBDs) may be involved in the pathogenesis of UL. Materials and Methods: In this study, UL tissues and paired adjacent myometrium were collected from a total of 51 patients. The expression of MBD mRNAs and their cognate proteins were analyzed via quantitative polymerase chain reaction assays and western blotting, respectively. The relationships between the MBD expression levels and the patients' clinicopathologic variables were assessed using Student's t test, nonparametric tests, or Pearson χ² methods. Results: Our results show that both the mRNA and protein levels of MBD2 were significantly decreased in ULs compared to the adjacent myometrium. In addition, MBD6 protein expression was also decreased significantly in UL samples when compared to the adjacent myometrium. There was, however, no significant difference on the mRNA expression of MBD6 between these two groups. Neither the mRNA nor the protein levels of the other MBD members (MBD1, MBD3, MBD4, MBD5, and MeCP2) showed any significant differences between ULs and the adjacent myometria. The decreased expression of the MBD6 protein was correlated with the tumor size of ULs. Conclusions: These results suggest that the dysregulated expression of MBD2 and MBD6 in ULs may play a role in their development; however, a larger sample size together with cellular functional assays should be carried out to further elucidate the precise role of MBD6 in ULs.

Incidence of cancer (other than gastric cancer) in pernicious anaemia: A systematic review with meta-analysis

BACKGROUND

Pernicious anaemia (PA) is associated with increased gastric cancer risk, but the evidence is conflicting regarding the associated risk of other cancers.

AIM

To systematically determine the incidence rates of gastro-intestinal cancers other than gastric cancers (GI-other-than-GC) and non-gastrointestinal cancers (non-GIC) in PA adults, globally and per tumour site, and the risk associated with PA for GI-other than GC and non-GIC.

METHODS

Studies of PA patients reporting the incidence of GI-other-than-GCs and non-GICs were identified with MEDLINE (PubMed)-EMBASE (from first date available to April 2017). A meta-analysis of annual cancer incidence rates was performed. The outcome was the cumulative incidence of GI-other-than-GCs and non-GICs (ratio between the numbers of new cancer cases identified during the follow-up period and the number of PA patients) and the incidence rate expressed as the rate of events-per-time-unit (person-years).

RESULTS

Of 82,257 PA patients, the pooled incidence rates/100 person-years for non-GCs and non-GICs of 0.27 (95% CI:0.16-0.42) and 0.23 (95% CI:0.22-0.25) were calculated by meta-analysis. Compared to the GLOBOCAN data for the general population from the countries of the included studies, the meta-analysis showed an overall relative risk (RR) of cancer in PA of 0.68 (95% CI:0.48-0.95). PA patients had a lower RR of colorectal, breast, liver, oesophageal, lung, thyroid, ovary, non-melanoma skin and kidney cancers but had a higher RR of biliary tract cancer (1.81:1.21-2.70), multiple myeloma (2.83:1.76-4.55), Hodgkin's lymphoma (3.0:1.35-6.68), non-Hodgkin's lymphoma (2.08: 1.58-2.75), and leukaemia (1.56:1.16-2.12).

CONCLUSION

An overall lower RR of cancers-other-than-gastric-cancer in PA patients but an increased RR of biliary tract cancers and haematological malignancies was observed.

Diagnostic and prognostic value of microRNAs in cholangiocarcinoma: a systematic review and meta-analysis

Background and aim

Several dysregulated microRNAs (miRNAs) have been implicated in the pathogenesis of cholangiocarcinoma (CCA); however, small sample sizes and invariable research designs are limitations, hindering a thorough analysis of miRNAs as diagnostic and prognostic tools for CCA. This study aimed to systematically summarize the clinical value of miRNAs in human CCA both for all available miRNAs and single miRNA with multiple researches.

Methods

Pooled parameters included the area under the curve (AUC), sensitivity, specificity, and hazard ratios (HRs) to separately determine overall diagnostic and prognostic performance. Subgroup and sensitivity analyses were performed only in the event of heterogeneity. Thirty-four studies including 12 diagnostic studies and 22 prognostic studies were eligible for inclusion in this meta-analysis.

Results

We observed that miR-21, miR-26, miR-483, miR-106a, miR-150, miR-192, and miR-194 were employed for distinguishing patients with CCA from healthy controls. Pooled sensitivity, specificity, and AUC were 0.82 (95% confidence interval [CI] 0.77–0.86), 0.83 (95% CI 0.75–0.89), and 0.88 (95% CI 0.85–0.91), respectively. Abnormal expression of miR-21, miR-26a, miR-192, miR-200c, miR-221, miR-29a, miR-191, miR-181c, miR-34a, miR-106a, miR-203, and miR-373 in patients was confirmed to associate with poor survival rate. Pooled HRs and 95% CIs were calculated using STATA, resulting in the pooled HR of 1.47 (95% CI 0.91–2.37) for overall survival (OS), 0.67 (95% CI 0.16–2.81) for disease-free survival (DFS), 2.31 (95% CI 1.59–3.36) for progression-free survival (PFS), and 2.68 (95% CI 0.88–8.15) for relapse-free survival (RFS). Thus, CCA patients with dysregulated miRNA expression were confirmed to have shorter OS, DFS, PFS, and RFS. Data regarding the diagnostic and prognostic roles of miR-21 suggested pooled diagnostic results of miR-21 for sensitivity, specificity, and AUC were 0.85 (95% CI 0.76–0.91), 0.92 (95% CI 0.81–0.97), and 0.93 (95% CI 0.91–0.95), respectively, suggesting better diagnostic performance of miR-21 compared with other miRNAs. Meanwhile, pooled prognostic result of miR-21 for HR was 1.88 (95% CI 1.41–2.51), indicating miR-21 could more appropriately predict shorter OS in patients with CCA.

Conclusion

miRNAs may provide a new approach for clinical application, and miR-21 may be a promising biomarker for diagnosis and prognosis of CCA.

Maternal Phthalate and Personal Care Products Exposure Alters Extracellular Placental miRNA Profile in Twin Pregnancies

Prenatal exposure to endocrine-disrupting chemicals (EDCs) exerts both short- and long-term adverse effects on the developing fetus. However, the mechanisms underlying these effects have yet to be uncovered. Maternal-fetal signaling is mediated in part by signaling molecules (eg, microRNAs [miRNAs]) contained in extracellular vesicles (EVs) that are released by the placenta into the maternal circulation. We investigated whether maternal exposure to the EDCs phthalates and personal care products alters the miRNA profile of placental-derived EVs circulating in maternal blood. Blood and urine samples from pregnant women with uncomplicated term dichorionic, diamniotic twin pregnancies were analyzed as part of a larger study investigating correlations between exposure of phthalate and personal care products and epigenetic alterations in twin pregnancies. We explored correlations between maternal urinary levels of 13 phthalate and 12 personal care products metabolites and the miRNA profile of placental EVs (EV-miRNAs) circulating in maternal blood. The expression of miR-518e was highest among women with high urinary levels of monobenzyl phthalate and methyl paraben. miR-373-3p was the least expressed in women exposed to high levels of methyl paraben, and miR-543 was significantly downregulated in women exposed to high levels of paraben metabolites, dichlorophenol metabolites, and triclosan. In conclusion, this pilot study reveals that prenatal exposure to EDCs is associated with altered profile of circulating placenta-derived EV-miRNAs. Further studies are needed to generalize these results to singleton pregnancies and to assess whether these alterations are associated with pregnancy complications.

MiR-124 induces autophagy-related cell death in cholangiocarcinoma cells through direct targeting of the EZH2-STAT3 signaling axis

Cholangiocarcinoma (CCA) is a lethal cancer associated with chronic inflammation that has increased in prevalence in recent decades. The dysregulated expression of microRNAs (miRNAs) has been detected in various types of malignancies, and depending on the target genes this can result in miRNAs functioning as tumor suppressors or oncogenes. In this study, we investigated the role of miR-124 in cholangiocarcinoma (CCA) and found that its expression was significantly downregulated in the tumor tissue of patients and in CCA cell lines. Our results provided evidence that miR-124 induces apoptotic cell death and triggers the autophagic flux in CCA cells. EZH2 and STAT3 were identified as direct targets of miR-124. The effect of miR-124 on EZH2 expression in CCA cells was evaluated using cell transfection, xenotransplantation into nude mice and a luciferase reporter assay. Silencing of EZH2 restored the effects of miR-124, whereas overexpression of EZH2 abrogated the effects of miR-124. Silencing of Beclin1 or ATG5 abrogated the effects of miR-124 or siEZH2. In vivo, overexpression of miR-124 dramatically induced autophagy-related cell death and suppressed tumorigenicity. Taken together, our findings indicated that downregulation of miR-124 expression was associated with disease progression in human CCA and we revealed that miR-124 exerts a tumor suppressive function in CCA by inducing autophagy-related cell death via direct targeting of the EZH2-STAT3 signaling axis.

NcRNAs and Cholangiocarcinoma

Cholangiocarcinoma (CCA) is the most common primary biliary malignancy with poor prognosis. Less understanding of its etiology and pathogenesis makes the diagnosis and therapy difficult. Recently, accumulating evidences have demonstrated that deregulated expression of non-coding RNAs (ncRNAs) is closely associated with the etiopathogenesis of CCA. NcRNAs which lack open reading frame are a heterogeneous class of transcribed RNA molecules, including microRNAs, long non-coding RNAs and circular RNAs. Several studies have shown ncRNAs dysregulation is a common central event occurring in CCA and has the potential of being therapy targets. Moreover, ncRNAs can be easily detected in cancer tissues and biofluids, representing valuable tools for diagnosis. In this review, we illustrate the role of ncRNA in the CCA and discuss their potential clinical value.

MicroRNA-373 Inhibits Cell Proliferation and Invasion via Targeting BRF2 in Human Non-small Cell Lung Cancer A549 Cell Line

Purpose

The purpose of this study was to investigate the biological role and mechanism of miR-373 targeting of TFIIB-related factor 2 (BRF2) in the regulation of non-small cell lung cancer (NSCLC) cells.

Materials and Methods

miRNA microarray chip analysis of four paired NSCLC and adjacent non-tumor tissues was performed. Quantitative real-time polymerase chain reaction (qRT-PCR) andwestern blotting were used to detect the expression levels of miR-373 and BRF2 in NSCLC tissues and cell lines. The dual-luciferase reporter method was performed to determine if BRF2 is a target of miR-373. MTT, wound-healing, Transwell, and flow cytometric assays were conducted to examine the proliferation, migration, invasion, and cell cycle progression of NSCLC A549 cells, respectively; western blotting was used to detect the expression of epithelial-mesenchymal transition (EMT)–related proteins.

Results

The miRNA microarray chip analysis demonstrated that miR-373 was down-regulated in NSCLC tissues, and this result was confirmed by qRT-PCR. Additionally, miR-373 was confirmed to target BRF2. Moreover, miR-373 expression was inversely correlated with BRF2 expression in NSCLC tissues and cell lines; both miR-373 down-regulation and BRF2 up-regulation were strongly associated with the clinicopathological features and prognosis of NSCLC patients. In vitro, overexpression of miR-373 markedly inhibited cell proliferation, migration, and invasion; up-regulated the expression of E-cadherin; and down-regulated the expression of N-cadherin and Snail in A549 cell. Knockdown BRF2 by siRNA resulted in effects similar to those caused by overexpression of miR-373.

Conclusion

MiR-373 is decreased in NSCLC, and overexpression of miR-373 can suppress cell EMT, and inhibit the proliferation, migration, and invasion of NSCLC A549 cells by targeting BRF2.

Enhancing E-cadherin expression via promoter-targeted miR-373 suppresses bladder cancer cells growth and metastasis

Previous studies showed that miR-373 had the capacity to induce tumor suppressor gene E-cadherin expression in prostate cancer cells. However, whether miR-373 can activate the expression of E-cadherin in human bladder cancer (BCa) cells and inhibit cells remains to be elucidated. Here, we found that both miR-373 and E-cadherin were low expressed in BCa tissues and cell lines, and significantly correlated with tumor stage, grade, and lymph node metastasis. In addition, decreased E-cadherin expression or low expression of both miR-373 and E-cadherin is associated with poor overall survival in patients with BCa. Transfection of miR-373 into BCa cells readily activated E-cadherin expression by targeting promoter. Moreover, miR-373 exhibited robust capacity to inhibit cells proliferation, suppress migration and invasion by enhancing E-cadherin expression, and significantly suppress the growth of xenografts and metastasis in nude mice. Altogether, our findings indicate that miR-373 may as a tumor suppressor in BCa by activating E-cadherin expression.

Excess of a Rassf1-targeting microRNA, miR-193a-3p, perturbs cell division fidelity

Background:

Several microRNA (miRNA) molecules have emerged as important post-transcriptional regulators of tumour suppressor and oncogene expression. Ras association domain family member 1 (RASSF1) is a critical tumour suppressor that controls multiple aspects of cell proliferation such as cell cycle, cell division and apoptosis. The expression of RASSF1 is lost in a variety of cancers due to the promoter hypermethylation.

Methods:

miR-193a-3p was identified as a RASSF1-targeting miRNA by a dual screening approach. In cultured human cancer cells, immunoblotting, qRT–PCR, luciferase reporter assays, time-lapse microscopy and immunofluorescence methods were used to study the effects of excess miR-193a-3p on RASSF1 expression and cell division.

Results:

Here, we report a new miRNA-mediated mechanism that regulates RASSF1 expression: miR-193a-3p binds directly to RASSF1-3′UTR and represses the mRNA and protein expression. In human cancer cells, excess of miR-193a-3p causes polyploidy through impairment of the Rassf1-Syntaxin 16 signalling pathway that is needed for completion of cytokinesis. In the next cell cycle the miR-193a-3p-overexpressing cells exhibit multipolar mitotic spindles, mitotic delay and elevated frequency of cell death.

Conclusions:

Our results suggest that besides epigenetic regulation, altered expression of specific miRNAs may contribute to the loss of Rassf1 in cancer cells and cause cell division errors.

Dicer promotes tumorigenesis by translocating to nucleus to promote SFRP1 promoter methylation in cholangiocarcinoma cells

Dicer, a member of the RNase III family of endoribonucleases, has an important role in regulating methylation of CpG islands in mammal cancer cells. However, the underlying mechanism of action remains unclear. In this study, we demonstrated that upregulation of Dicer in cholangiocarcinoma (CCA) cells and its translocation to nuclues to interact with heterochromatin protein 1α (HP1α). The nuclear Dicer/HP1α complex appeared to promote both H3K9 trimethylation and DNA methylation of the secreted frizzled-related protein 1 (SFRP1) promoter. The expression of Dicer negatively correlated with that of SFRP1 and it appeared to promote CCA cell proliferation and invasion through repression of SFRP1 gene. High expression of Dicer in tumor tissues was significantly associated with larger tumor size (>3 cm) and lymph node metastasis. Our findings help characterize the role of Dicer in epigenetic regulation and tumorigenesis in the context of CCA.

Mutual regulation of microRNAs and DNA methylation in human cancers

microRNAs (miRNAs) and DNA methylation are the 2 epigenetic modifications that have emerged in recent years as the most critical players in the regulation of gene expression. Compelling evidence has indicated the roles of miRNAs and DNA methylation in modulating cellular transformation and tumorigenesis. miRNAs act as negative regulators of gene expression and are involved in the regulation of both physiologic conditions and during diseases, such as cancer, inflammatory diseases, and psychiatric disorders, among others. Meanwhile, aberrant DNA methylation manifests in both global genome changes and in localized gene promoter changes, which influences the transcription of cancer genes. In this review, we described the mutual regulation of miRNAs and DNA methylation in human cancers. miRNAs regulate DNA methylation by targeting DNA methyltransferases or methylation-related proteins. On the other hand, both hyper- and hypo-methylation of miRNAs occur frequently in human cancers and represent a new level of complexity in gene regulation. Therefore, understanding the mechanisms underlying the mutual regulation of miRNAs and DNA methylation may provide helpful insights in the development of efficient therapeutic approaches.

MicroRNA-373 Promotes Growth and Cellular Invasion in Osteosarcoma Cells by Activation of the PI3K/AKT-Rac1-JNK Pathway: The Potential Role in Spinal Osteosarcoma

Spinal osteosarcoma (OS) has been proven to be more difficult to treat owing to potently malignant metastasis. The present study aimed to explore the functional role of microRNA (miR)-373 in cell growth and invasion of OS cells, as well as its underlying mechanism. The expression of miR-373 was analyzed in spinal OS tissues and cell lines. MG-63 cells were transfected with the miR-373 mimic or inhibitor and/or treated with the phosphoinositide 3-kinase (PI3K) (LY294002) inhibitor or Ras-related C3 botulinum toxin substrate 1 (Rac) guanosine triphosphate (GTPase) (NSC23766) inhibitor, and then the impact of miR-373 aberrant expression on cell growth and invasion was measured, along with the impact of overexpressing miR-373 on the expression of p53 and PI3K/AKT pathway-related proteins. We found that miR-373 was specifically upregulated in spinal OS tissues (p < 0.01) and OS cell lines (p < 0.01 or p < 0.001). Moreover, miR-373 expression was significantly associated with TNM stage (p = 0.035) and tumor size (p = 0.002). Overexpression of miR-373 promoted MG-63 cell viability, migration, invasion, and colony formation (all p < 0.05), while silencing of miR-373 and LY294002 exerted the opposite effects. Additionally, miR-373 overexpression downregulated p53 as well as its downstream targeted genes and orderly activated the PI3K/AKT-Rac1-JNK signaling pathway. In conclusion, miR-373 promotes growth and cellular invasion in OS cells by activating the PI3K/AKT-Rac1-JNK pathway. Therefore, miR-373 might be a candidate for molecular targeted therapy of spinal OS.

LncRNAs H19 and HULC, activated by oxidative stress, promote cell migration and invasion in cholangiocarcinoma through a ceRNA manner

Background

Long non-coding RNAs (lncRNAs) are known to play important roles in different cell contexts, including cancers. However, little is known about lncRNAs in cholangiocarcinoma (CCA), a cholangiocyte malignancy with poor prognosis, associated with chronic inflammation and damage to the biliary epithelium. The aim of the study is to identify if any lncRNA might associate with inflammation or oxidative stress in CCA and regulate the disease progression.

Methods

In this study, RNA-seqs datasets were used to identify aberrantly expressed lncRNAs. Small interfering RNA and overexpressed plasmids were used to modulate the expression of lncRNAs, and luciferase target assay RNA immunoprecipitation (RIP) was performed to explore the mechanism of miRNA-lncRNA sponging.

Results

We firstly analyzed five available RNA-seqs datasets to investigate aberrantly expressed lncRNAs which might associate with inflammation or oxidative stress. We identified that two lncRNAs, H19 and HULC, were differentially expressed among all the samples under the treatment of hypoxic or inflammatory factors, and they were shown to be stimulated by short-term oxidative stress responses to H₂O₂ and glucose oxidase in CCA cell lines. Further studies revealed that these two lncRNAs promoted cholangiocyte migration and invasion via the inflammation pathway. H19 and HULC functioned as competing endogenous RNAs (ceRNAs) by sponging let-7a/let-7b and miR-372/miR-373, respectively, which activate pivotal inflammation cytokine IL-6 and chemokine receptor CXCR4.

Conclusions

Our study revealed that H19 and HULC, up-regulated by oxidative stress, regulate CCA cell migration and invasion by targeting IL-6 and CXCR4 via ceRNA patterns of sponging let-7a/let-7b and miR-372/miR-373, respectively. The results suggest that these lncRNAs might be the chief culprits of CCA pathogenesis and progression. The study provides new insight into the mechanism linking lncRNA function with CCA and may serve as novel targets for the development of new countermeasures of CCA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0348-0) contains supplementary material, which is available to authorized users.

Serum miR-26a as a diagnostic and prognostic biomarker in cholangiocarcinoma

In order to determine the diagnostic and prognostic value of miR-26a in Cholangiocarcinoma (CCA), we compared miR-26a levels in serum from 66 CCA patients and 66 healthy controls, which was followed by serum analysis between the pre-operative serum and post-operative serum of these CCA patients. We found the concentration levels of miR-26a in serum of CCA patients were significantly higher than that from healthy controls (P < 0.01). Furthermore, the concentration levels of miR-26a in the post-operative serum were significantly reduced when compared to the pre-operative serum (P < 0.001). High miR-26a in serum was correlated significantly with clinical stage, distant metastasis, differentiation status, and poor survival of CCA patients. More importantly, serum miR-26a was an independent prognostic marker for CCA. In conclusion, our results suggested that miR-26a in serum might be a potential and useful noninvasive biomarker for the early detection of CCA.

Functional Profiling of Human MeCP2 by Automated Data Comparison Analysis and Computerized Expression Pathway Modeling

OBJECTIVES

Methyl-CpG binding protein 2 (MeCP2) is a ubiquitous epigenetic factor that represses gene expression by modifying chromatin. Mutations in the MeCP2 gene cause Rett syndrome, a progressive neurodevelopmental disorder. Recent studies also have shown that MeCP2 plays a role in carcinogenesis. Specifically, functional ablation of MeCP2 suppresses cell growth and leads to the proliferation of cancer cells. However, MeCP2's function in adult tissues remains poorly understood. We utilized a weight matrix-based comparison software to identify transcription factor binding site (TFBS) of MeCP2-regulated genes, which were recognized by cDNA microarray analysis.

METHODS

MeCP2 expression was silenced using annealed siRNA in HEK293 cells, and then a cDNA microarray analysis was performed. Functional analysis was carried out, and transcriptional levels in target genes regulated by MeCP2 were investigated. TFBS analysis was done within genes selected by the cDNA microarray analysis, using a weight matrix-based program and the TRANSFAC 6.0 database.

RESULTS

Among the differentially expressed genes with a change in expression greater than two-fold, 189 genes were up-regulated and 91 genes were down-regulated. Genes related to apoptosis and cell proliferation (JUN, FOSL2, CYR61, SKIL, ATF3, BMABI, BMPR2, RERE, and FALZ) were highly up-regulated. Genes with anti-apoptotic and anti-proliferative functions (HNRPA0, HIS1, and FOXC1) were down-regulated. Using TFBS analysis within putative promoters of novel candidate target genes of MeCP2, disease-related transcription factors were identified.

CONCLUSIONS

The present results provide insights into the new target genes regulated by MeCP2 under epigenetic control. This information will be valuable for further studies aimed at clarifying the pathogenesis of Rett syndrome and neoplastic diseases.

MicroRNAs in cholangiopathies: Potential diagnostic and therapeutic tools

Cholangiopathies are the group of diseases targeting the bile duct epithelial cells (i.e. cholangiocytes). These disorders arise from different etiologies and represent a current diagnostic, prognostic and therapeutic challenge. Different molecular mechanisms participate in the development and progression of each type of biliary disease. However, microRNA deregulation is a common central event occurring in all of them that plays a key role in their pathogenesis. MicroRNAs are highly stable small non-coding RNAs present in cells, extracellular microvesicles and biofluids, representing valuable diagnostic tools and potential targets for therapy. In the following sections, the most novel and significant discoveries in this field are summarized and their potential clinical value is highlighted.

TGF-β1 Reduces miR-29a Expression to Promote Tumorigenicity and Metastasis of Cholangiocarcinoma by Targeting HDAC4

Transforming growth factor β1 (TGF-β1) and miRNAs play important roles in cholangiocarcinoma progression. In this study, miR-29a level was found significantly decreased in both cholangiocarcinoma tissues and tumor cell lines. TGF-β1 reduced miR-29a expression in tumor cell lines. Furthermore, anti-miR-29a reduced the proliferation and metastasis capacity of cholangiocarcinoma cell lines in vitro, overexpression of miR-29a counteracted TGF-β1-mediated cell growth and metastasis. Subsequent investigation identified HDAC4 is a direct target of miR-29a. In addition, restoration of HDAC4 attenuated miR-29a-mediated inhibition of cell proliferation and metastasis. Conclusions: TGF-β1/miR-29a/HDAC4 pathway contributes to the pathogenesis of cholangiocarcinoma and our data provide new therapeutic targets for cholangiocarcinoma.

MiR-373 targeting of the Rab22a oncogene suppresses tumor invasion and metastasis in ovarian cancer

Metastasis is major cause of mortality in patients with ovarian cancer. MiR-373 has been shown to play pivotal roles in tumorigenesis and metastasis; however, a role for miR-373 in ovarian cancer has not been investigated. In this study, we show that the miR-373 expression is down-regulated in human epithelial ovarian cancer (EOC) and inversely correlated with clinical stage and histological grade. Ectopic overexpression of miR-373 in human EOC cells suppressed cell invasion in vitro and metastasis in vivo, and the epithelial–mesenchymal transition process. Silencing the expression of miR-373 resulted in an increased migration and invasion of EOC cells. Using integrated bioinformatics analysis, gene expression arrays, and luciferase assay, we identified Rab22a as a direct and functional target of miR-373 in EOC cells. Expression levels of miR-373 were inversely correlated with Rab22a protein levels in human EOC tissues. Rab22a knockdown inhibited invasion and migration of EOC cells, increased E-cadherin expression, and suppressed the expression of N-cadherin. Moreover, overexpression of Rab22a abrogated miR-373-induced invasion and migration of EOC cells. Taken together, these results demonstrate that miR-373 suppresses EOC invasion and metastasis by directly targeting Rab22a gene, a new potential therapeutic target in EOC.

Genetic alteration regulated by microRNAs in biliary tract cancers

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

Diverse functions of miR-373 in cancer

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post-transcriptionally. They are involved in almost all cellular processes, and many have been described as potential oncogenes or tumor suppressors. MicroRNA-373 (miR-373), which was first identified as a human embryonic stem cell (ESC)-specific miRNA, is suggested to be implicated in the regulation of cell proliferation, apoptosis, senescence, migration and invasion, as well as DNA damage repair following hypoxia stress. Deregulation of miR-373 has been demonstrated in a number of cancers, whether it acts as an oncogene or a tumor suppressor, however, seems to be context dependent. In this review, we focus on the diverse functions of miR-373 and its implication in cancers.

A microRNA profile associated with Opisthorchis viverrini-induced cholangiocarcinoma in tissue and plasma

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is a highly aggressive tumor of the bile duct, and a significant public health problem in East Asia, where it is associated with infection by the parasite Opisthorchis viverrini. ICC is often detected at an advanced stage and with a poor prognosis, making a biomarker for early detection a priority.

METHODS

We have comprehensively profiled miRNA expression levels in ICC tumor tissue using small RNA-Seq and validated these profiles using quantitative PCR on matched plasma samples.

RESULTS

Distinct miRNA profiles were associated with increasing histological differentiation of ICC tumor tissue. We also observed that histologically normal tissue adjacent to ICC tumor displayed miRNA expression profiles more similar to tumor than liver tissue from healthy donors. In plasma samples, an eight-miRNA signature associated with ICC, regardless of the degree of histological differentiation of its matched tissue, forming the basis of a circulating miRNA-based biomarker for ICC.

CONCLUSIONS

The association of unique miRNA profiles with different ICC subtypes suggests the involvement of specific miRNAs during ICC tumor progression. In plasma, an eight-miRNA signature associated with ICC could form the foundation of an accessible (plasma-based) miRNA-based biomarker for the early detection of ICC.

MicroRNAs and benign biliary tract diseases

Cholangiocytes, the epithelial cells lining the biliary tree, represent only a small portion of the total liver cell population (3-5%), but they are responsible for the secretion of up to 40% of total daily bile volume. In addition, cholangiocytes are the target of a diverse group of liver diseases affecting the biliary tract, the cholangiopathies; for most of these conditions, the pathological mechanisms are unclear. MicroRNAs (miRNAs) are small, noncoding RNAs that posttranscriptionally regulate gene expression. Thus, it is not surprising that altered miRNA profiles underlie the dysregulation of several proteins involved in the pathobiology of the cholangiopathies, as well as showing promise as diagnostic and prognostic tools. Here the authors review recent work relevant to the role of miRNAs in the etiopathogenesis of several of the cholangiopathies (i.e., fibroinflammatory cholangiopathies and polycystic liver diseases), discuss their value as prognostic and diagnostic tools, and provide suggestions for further research.

Involvement of microRNA-24 and DNA methylation in resistance of nasopharyngeal carcinoma to ionizing radiation

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating in the epithelium. Radiotherapy is the standard therapy, but tumor resistance to this treatment reduces the 5-year patient survival rate dramatically. Studies are urgently needed to elucidate the mechanism of NPC radioresistance. Epigenetics--particularly microRNAs (miRNA) and DNA methylation--plays an important role in carcinogenesis and oncotherapy. We used qRT-PCR analysis and identified an miRNA signature from differentially expressed miRNAs. Our objectives were to identify the role of miR24 in NPC tumorigenesis and radioresistance and to identify the mechanisms by which miR24 is regulated. We found that miR24 inhibited NPC cell growth, promoted cell apoptosis, and suppressed the growth of NPC xenografts. We showed that miR24 was significantly downregulated in recurrent NPC tissues. When combined with irradiation, miR24 acted as a radiosensitizer in NPC cells. One of the miR24 precursors was embedded in a CpG island. Aberrant DNA methylation was involved in NPC response to radiotherapy, which linked inactivation of miR24 through hypermethylation of its precursor promoter with NPC radioresistance. Treating NPC cells with the DNA-hypomethylating agent 5-aza-2'-deoxycytidine compensated for the reduced miR24 expression. Together, our findings showed that miR24 was negatively regulated by hypermethylation of its precursor promoter in NPC radioresistance. Our findings defined a central role for miR24 as a tumor-suppressive miRNA in NPC and suggested its use in novel strategies for treatment of this cancer.

MicroRNAs in Cholangiopathies

Cholangiocytes, the cells lining bile ducts, comprise a small fraction of the total cellular component of the liver, yet perform the essential role of bile modification and transport of biliary and blood constituents. Cholangiopathies are a diverse group of biliary disorders with the cholangiocyte as the target cell; the etiopathogenesis of most cholangiopathies remains obscure. MicroRNAs are small non-coding RNAs that post-transcriptionally regulate gene expression. These small RNAs may not only be involved in the etiopathogenesis of disease, but are showing promise as diagnostic and prognostic tools. In this brief review, we summarize recent work regarding the role of microRNAs in the etiopathogenesis of several cholangiopathies, and discuss their utility as prognostic and diagnostic tools.

Analysis of U2 small nuclear RNA fragments in the bile differentiates cholangiocarcinoma from primary sclerosing cholangitis and other benign biliary disorders

BACKGROUND AND OBJECTIVES

Up to now the diagnosis of early stage cholangiocarcinoma (CC) has remained difficult, with low sensitivities reported for current diagnostic methods. Based on recent promising findings about circulating U2 small nuclear RNA fragments (RNU2-1f) as novel blood-based biomarkers for pancreatic and colorectal adenocarcinoma, we studied the utility of RNU2-1f as a diagnostic marker of CC in bile fluid.

METHODS

Bile fluid was collected from patients with CC (n = 12), controls (patients with choledocholithiasis) (n = 11) and with primary sclerosing cholangitis (PSC; n = 11). RNU2-1f levels were measured by real-time polymerase chain reaction normalized to cel-54.

RESULTS

Measurement of RNU2-1f levels in bile fluids enabled the differentiation of patients with CC from controls in all cases. Furthermore, RNU2-1f levels in bile fluids of patients with CC were significantly higher than in patients with PSC, resulting in a receiver-operating characteristic curve area of 0.856, with sensitivity of 67 % and specificity of 91 %.

CONCLUSIONS

Our data suggest that the measurement of RNU2-1 fragments detected in the bile fluid can be used as a diagnostic marker for CC and should be included in future prospective diagnostic studies for this disease entity.

Emerging insights into the role of microRNAs in the pathogenesis of cholangiocarcinoma

The microRNAs (miRNAs) are small noncoding RNAs that are potent regulators of gene expression and can regulate several diverse biological functions. This minireview provides an overview of recent studies that have examined the role and involvement of miRNAs in cholangiocarcinomas. These studies provide evidence for deregulated expression of miRNA and are providing new insights into the potential contribution of these in the pathogenesis of cholangiocarcinoma.

microRNAs in liver disease: from diagnostics to therapeutics

There is a need to identify effective biomarkers for diagnosis, prognosis and prediction of treatment efficacy for many liver diseases such as hepatocellular cancer, and chronic viral hepatitis. The identification of disease-specific alterations in microRNA expression and the ability to detect microRNAs in the circulation provide the basis for identifying novel clinically effective treatments and biomarkers. Knowledge regarding miRNA in human liver disease may eventually lead to serum or tissue biomarkers with clinical utility. A selection of relevant studies is reviewed. There are major challenges that need to be addressed prior to clinical application such as the need for careful validation of diagnostic miRNA candidates in well described clinical cohorts, and technical issues such as quantitation and standardization of assays. The rapid progress in therapeutic interventions using miRNA based strategies for chronic hepatitis C and hepatocellular cancer provides optimism for novel approaches that will build on the existing and emerging knowledge regarding miRNA in liver diseases.

CUL4B promotes replication licensing by up-regulating the CDK2-CDC6 cascade

CUL4B up-regulates CDK2 by repressing miR-372 and miR-373, leading to increased phosphorylation and stabilization of CDC6, thus promoting replication licensing.

Cullin-RING ubiquitin ligases (CRLs) participate in the regulation of diverse cellular processes including cell cycle progression. Mutations in the X-linked CUL4B, a member of the cullin family, cause mental retardation and other developmental abnormalities in humans. Cells that are deficient in CUL4B are severely selected against in vivo in heterozygotes. Here we report a role of CUL4B in the regulation of replication licensing. Strikingly, CDC6, the licensing factor in replication, was positively regulated by CUL4B and contributed to the loading of MCM2 to chromatin. The positive regulation of CDC6 by CUL4B depends on CDK2, which phosphorylates CDC6, protecting it from APC^CDH1-mediated degradation. Thus, aside being required for cell cycle reentry from quiescence, CDK2 also contributes to pre-replication complex assembly in G1 phase of cycling cells. Interestingly, the up-regulation of CDK2 by CUL4B is achieved via the repression of miR-372 and miR-373, which target CDK2. Our findings thus establish a CUL4B–CDK2–CDC6 cascade in the regulation of DNA replication licensing.

Downregulation of microRNA-138 enhances the proliferation, migration and invasion of cholangiocarcinoma cells through the upregulation of RhoC/p-ERK/MMP-2/MMP-9

microRNAs (miRs) play an important role in tumor initiation and progression in many types of cancer, including cholangiocarcinoma (CC). miR-138 dysregulation is frequently observed in a variety of tumors. In the present study, miR-138 was found to be downregulated in CC tissues by quantitative real-time RT-PCR. Furthermore, its potential target molecule, Ras homolog gene family, member C (RhoC) protein, was found to be highly expressed in CC tissues examined by western blot analysis. Luciferase reporter assay further demonstrated that miR-138 directly targeted RhoC. We found that the introduction of miR-138 mimics to RBE and QBC939 CC cells could reduced RhoC mRNA and protein expression, and suppressed the proliferation, G1/S transition, migration and invasion of CC cells. However, transfection with a miR-138 inhibitor induced an inverse effect in CC cells. The expression of phosphorylated extracellular signal-regulated kinase (p-ERK), matrix metalloproteinase (MMP)-2 and MMP-9 decreased following transfection with miR-138, and increased following transfection with miR-138 inhibitor in CC cells. In conclusion, RhoC upregulation induced by miR-138 downregulation promotes the malignant progression of CC cells and the underlying mechanisms of this effect involve the increase in the expression of p-ERK/MMP-2/MMP-9. Consequently, miR-138/RhoC is a potential target for the clinical diagnosis and treatment of CC.

microRNAs in liver disease: from diagnostics to therapeutics

There is a need to identify effective biomarkers for diagnosis, prognosis and prediction of treatment efficacy for many liver diseases such as hepatocellular cancer, and chronic viral hepatitis. The identification of disease-specific alterations in microRNA expression and the ability to detect microRNAs in the circulation provide the basis for identifying novel clinically effective treatments and biomarkers. Knowledge regarding miRNA in human liver disease may eventually lead to serum or tissue biomarkers with clinical utility. A selection of relevant studies is reviewed. There are major challenges that need to be addressed prior to clinical application such as the need for careful validation of diagnostic miRNA candidates in well described clinical cohorts, and technical issues such as quantitation and standardization of assays. The rapid progress in therapeutic interventions using miRNA based strategies for chronic hepatitis C and hepatocellular cancer provides optimism for novel approaches that will build on the existing and emerging knowledge regarding miRNA in liver diseases.

MicroRNAs in biliary diseases

Cholangiopathies are a group of diseases primarily or secondarily affecting bile duct cells, and result in cholangiocyte proliferation, regression, and/or transformation. Their etiopathogenesis may be associated with a broad variety of causes of different nature, which includes genetic, neoplastic, immune-associated, infectious, vascular, and drug-induced alterations, or being idiopathic. miRNAs, small non-coding endogenous RNAs that post-transcriptionally regulate gene expression, have been associated with pathophysiological processes in different organs and cell types, and are postulated as potential targets for diagnosis and therapy. In the current manuscript, knowledge regarding the role of miRNAs in the development and/or progression of cholangiopathies has been reviewed and the most relevant findings in this promising field of hepatology have been highlighted.