The role of microRNAs in liver cancer

Circulating Plasma miR-122 and miR-583 Levels Are Involved in Chronic Hepatitis B Virus Pathogenesis and Serve As Novel Diagnostic Biomarkers

Background: MicroRNAs regulate many biological processes and are involved in the pathogenesis of many diseases including chronic hepatitis B (CHB). Moreover, besides investigation of their roles in hepatitis B virus (HBV) infection, a noninvasive, sensitive, and specific biomarker is essential in the diagnosis of liver diseases. This study was designed to evaluate the role of miR-122, miR-583, and miR-24 in the pathogenesis of CHB both in active chronic hepatitis (ACH) patients and in inactive carriers (IC). Materials and Methods: Plasma samples and all relevant clinical features were collected from 43 patients with CHB (28 ACH and 15 IC) and 43 healthy controls. Quantitative real-time PCR was performed to detect the plasma levels of miR-122, miR-583, and miR-24. Results: Results show miR-122 (p = 0.0001) and miR-583 (p = 0.006) but not miR-24 (p = 0.65) were upregulated in patients with CHB versus the control group. Interestingly, there was a significant increase in the plasma expression of miR-583 in IC versus ACH. Moreover, receiver operating characteristic curve analysis determined plasma levels of miR-122 (area under the ROC curve [AUC] = 0.89, p < 0.0001, sensitivity: 100%, specificity: 62.5%) and miR-583 (AUC = 0.71, p = 0.0007, sensitivity: 90%, specificity: 47.62%) as sensitive biomarkers to discriminate CHB patients from controls. Conclusion: Our data showed an increase in the plasma levels of miR-583 in IC versus ACH patients. Moreover, we demonstrated that miR-122 and miR-583 may serve as potential biomarkers for CHB diagnosis and activity.

CiRS-187 regulates BMPR2 expression by targeting miR-187 in bovine cumulus cells treated with BMP15 and GDF9

Circular RNAs (circRNAs) play vital roles in regulating biological processes. However, the contributions of circRNAs to BMPR2 regulation during follicle development remain unknown. In this study, we first verified the optimal conditions for BMP15 and GDF9 treatment in bovine cumulus cells. Then, we screened and identified candidate microRNAs (miRNAs) that may target the BMPR2 3'UTR with TargetScan, a luciferase reporter assay and RT-qPCR. Next, we transfected miR-187 into bovine cumulus cells, and the results showed that miR-187 regulated BMPR2 and inhibited its expression. To explore the competing endogenous RNA (ceRNA) mechanism, we predicted the sponging circRNAs of miR-187 and identified ciRS-187. We further detected miR-187 and BMPR2 expression and apoptosis levels upon knockdown of ciRS-187 and found that ciRS-187 upregulated BMPR2 expression. The results provide a theoretical basis for a ceRNA mechanism of circRNAs related to follicle development.

Epigenetics of hepatocellular carcinoma

In recent years, large scale genomics and genome-wide studies using comprehensive genomic tools have reshaped our understanding of cancer evolution and heterogeneity. Hepatocellular carcinoma, being one of the most deadly cancers in the world has been well established as a disease of the genome that harbours a multitude of genetic and epigenetic aberrations during the process of liver carcinogenesis. As such, in depth understanding of the cancer epigenetics in cancer specimens and biopsy can be useful in clinical settings for molecular subclassification, prognosis, and prediction of therapeutic responses. In this review, we present a concise discussion on recent progress in the field of liver cancer epigenetics and some of the current works that contribute to the progress of liver cancer therapeutics.

Investigating the mechanism of hepatocellular carcinoma progression by constructing genetic and epigenetic networks using NGS data identification and big database mining method

The mechanisms leading to the development and progression of hepatocellular carcinoma (HCC) are complicated and regulated genetically and epigenetically. The recent advancement in high-throughput sequencing has facilitated investigations into the role of genetic and epigenetic regulations in hepatocarcinogenesis. Therefore, we used systems biology and big database mining to construct genetic and epigenetic networks (GENs) using the information about mRNA, miRNA, and methylation profiles of HCC patients. Our approach involves analyzing gene regulatory networks (GRNs), protein-protein networks (PPINs), and epigenetic networks at different stages of hepatocarcinogenesis. The core GENs, influencing each stage of HCC, were extracted via principal network projection (PNP). The pathways during different stages of HCC were compared. We observed that extracellular signals were further transduced to transcription factors (TFs), resulting in the aberrant regulation of their target genes, in turn inducing mechanisms that are responsible for HCC progression, including cell proliferation, anti-apoptosis, aberrant cell cycle, cell survival, and metastasis. We also selected potential multiple drugs specific to prominent epigenetic network markers of each stage of HCC: lestaurtinib, dinaciclib, and perifosine against the NTRK2, MYC, and AKT1 markers influencing HCC progression from stage I to stage II; celecoxib, axitinib, and vinblastine against the DDIT3, PDGFB, and JUN markers influencing HCC progression from stage II to stage III; and atiprimod, celastrol, and bortezomib against STAT3, IL1B, and NFKB1 markers influencing HCC progression from stage III to stage IV.

Crosstalk between liver-related microRNAs and Wnt/β-catenin pathway in hepatocellular carcinoma patients

BACKGROUND AND STUDY AIMS

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide with highest incidence in Asia and Africa. MicroRNAs (miRNAs), a class of non-coding single stranded RNA, which not only post transcriptionally regulate gene expression but also respond to signaling molecules to affect cell functions such as Wnt/β-catenin signaling specifically in HCC. The goal of this study is to investigate the crosstalk between Wnt/β-catenin signaling proteins and microRNAs expression in HCC patients.

PATIENTS AND METHODS

Fresh tissue samples of 30 primary HCC patients and 10 control subjects were included. Expression level of 13 different miRNAs (miR-10a- miR-106b- miR-99a- miR-148a- miR-125b- miR-30e- miR-183- miR-155- miR-199a- miR-199a3p- miR-24- miR-122 and miR-215) were examined using real-time PCR assay. Five proteins involved in the Wnt/β-catenin pathway (β-catenin, APC, c-myc, survivin and cyclin D1) were analysed by immunohistochemistry technique. The correlation between miRNAs expression levels with protein expressions was assessed.

RESULTS

Up-regulation of miR-155 and miR-183 was reported in HCC patients compared to normal controls and this up-regulation was significantly correlated with liver cirrhosis in the case of miR-155 (p<0.05) referring to their oncogenic activity. Down-regulation was observed for 11 miRNAs in HCC indicating their tumour suppression activity. MiRNA-10a, miR-30e, miR-215, miR-125b and miR-148a were significantly correlated with the expression of important players in Wnt/β-catenin pathway including β-catenin, APC and c-myc (p<0.05). Detailed analysis revealed that miR-215 is associated with the grade of the disease and miR-125b is associated with HCV infection.

CONCLUSION

Collectively, our data showed potential role of miR-10a, miR-30e, miR-215, miR-125b and miR-148a as important mediators in HCC progression. Furthermore, their association with Wnt/β-catenin cascade proteins could be exploited to develop new therapeutic target strategies in HCC.

MicroRNA-187 inhibits tumor growth and metastasis via targeting of IGF-1R in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the primary and most frequently occurring type of malignant liver cancer, accounting for 70-85% of total liver cancer cases worldwide. It has previously been demonstrated that the aberrant expression of microRNAs (miR) contributes to carcinogenesis and progression of various human malignancies, including HCC. However, mechanisms underlying the differential expression and specific roles of miR‑187 in HCC remain to be elucidated, particularly regarding how the modulation of malignant phenotypes in HCC cells occurs. The present study demonstrated that miR‑187 was significantly downregulated in HCC tissues and cell lines. Restoration of miR‑187 expression inhibited cell proliferation, migration and invasion in HCC. Furthermore, insulin‑like growth factor 1 receptor (IGF‑1R) was demonstrated to act as a direct target gene of miR‑187 in HCC. IGF‑1R knockdown mimicked the effects of miR‑187 overexpression in HCC, resulting in a significant inhibition of cell proliferation, migration and invasion. The results of the present study demonstrated that miR‑187 acted as a tumor suppressor in HCC progression via direct targeting of IGF‑1R. miR‑187 may therefore exhibit the potential to act as a novel and therapeutic target for HCC treatment in the future.

Identification of biomarkers of intrahepatic cholangiocarcinoma via integrated analysis of mRNA and miRNA microarray data

The present study aimed to identify potential therapeutic targets of intrahepatic cholangiocarcinoma (ICC) via integrated analysis of gene (transcript version) and microRNA (miRNA/miR) expression. The miRNA microarray dataset GSE32957 contained miRNA expression data from 16 ICC, 7 mixed type of combined hepatocellular-cholangiocarcinoma (CHC), 2 hepatic adenoma, 3 focal nodular hyperplasia (FNH) and 5 healthy liver tissue samples, and 2 cholangiocarcinoma cell lines. In addition, the mRNA microarray dataset GSE32879 contained mRNA expression data from 16 ICC, 7 CHC, 2 hepatic adenoma, 5 FNH and 7 healthy liver tissue samples. The datasets were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and miRNAs (DEMs) in ICC samples compared with healthy liver tissues were identified via the limma package, following data preprocessing. Genes that exhibited alternative splicing (AS) in ICC samples were identified via AltAnalyze software. Functional enrichment analysis of DEGs was performed using the Database for Annotation, Visualization and Integrated Analysis. Target genes of DEMs were identified using the TargetScan database. The regulatory association between DEMs and any overlaps among DEGs, alternative splicing genes (ASGs) and target genes of DEMs were retrieved, and a network was visualized using the Cytoscape software. A total of 2,327 DEGs, 70 DEMs and 623 ASGs were obtained. Functional enrichment analysis indicated that DEGs were primarily enriched in biological processes and pathways associated with cell activity or the immune system. A total of 63 overlaps were obtained among DEGs, ASGs and target genes of DEMs, and a regulation network that contained 243 miRNA-gene regulation pairs was constructed between these overlaps and DEMs. The overlapped genes, including sprouty-related EVH1 domain containing 1, protein phosphate 1 regulatory subunit 12A, chromosome 20 open reading frame 194, and DEMs, including hsa-miR-96, hsa-miR-1 and hsa-miR-25, may be potential therapeutic targets for the future treatment of ICC.

Serum miR-224 as a biomarker for detection of hepatocellular carcinoma at early stage

BACKGROUND AND OBJECTIVE

Circulating microRNAs (miRNAs) are known as potential noninvasive biomarkers for cancers. Overexpression of mircoRNA-224 (miR-224) has been reported in hepatocellular carcinoma (HCC), so the aim of this study was to determine the value of serum miR-224 in diagnosis of HCC at early stage.

METHODS

Three hundred and thirty-five subjects including early-stage HCC, liver cirrhosis (LC), chronic hepatitis B (CHB) and healthy controls (HC) were enrolled in two cohorts. Association of miR-224 expression with HCC was analyzed. The area under curves (AUC) was calculated for miR-224 and compared with that for AFP in detection of HCC at early stage.

RESULTS

Our results demonstrated that serum miR-224 was significantly higher in early-stage HCC than that in LC, CHB and HC, respectively. Besides, it decreased significantly after surgery in early-stage HCC, and there was a positive correlation between miR-224 in sera and that in paired tumor tissues. Serum miR-224 levels also showed a significant correlation with BCLC stages of HCC. Expression of miR-224 was significantly higher in tumorous tissues than that in adjacent non-tumorous tissues of HCC, pathologic liver tissues of LC and CHB. Further, ROC analysis demonstrated that AUC were 0.880 (95% CI: 0.838-0.923; sensitivity: 86.5%, specificity: 76.7%) for serum miR-224 in discriminating early-stage HCC from all three controls (LC, CHB and healthy subjects), higher than that for AFP (AUC: 0.700, 95% CI: 0.633-0.767; sensitivity: 71.9%, specificity: 63.7%) (P<0.01). Moreover, serum miR-224 also had a better performance than AFP in discriminating HCC from each of the three control groups. When miR-224 and AFP were used together, the diagnostic accuracy increased significantly compared with either marker alone.

CONCLUSION

These results indicate that serum miR-224 is a potential reliable biomarker in detecting early-stage HCC, with better performance than AFP.

Expression of Molecular Differentiation Markers Does Not Correlate with Histological Differentiation Grade in Intrahepatic Cholangiocarcinoma

The differentiation status of tumor cells, defined by histomorphological criteria, is a prognostic factor for survival of patients affected with intrahepatic cholangiocarcinoma (ICC). To strengthen the value of morphological differentiation criteria, we wished to correlate histopathological differentiation grade with expression of molecular biliary differentiation markers and of microRNAs previously shown to be dysregulated in ICC. We analysed a series of tumors that were histologically classified as well, moderately or poorly differentiated, and investigated the expression of cytokeratin 7, 19 and 903 (CK7, CK19, CK903), SRY-related HMG box transcription factors 4 and 9 (SOX4, SOX9), osteopontin (OPN), Hepatocyte Nuclear Factor-1 beta (HNF1β), Yes-associated protein (YAP), Epithelial cell adhesion molecule (EPCAM), Mucin 1 (MUC1) and N-cadherin (NCAD) by qRT-PCR and immunostaining, and of miR-31, miR-135b, miR-132, miR-200c, miR-221 and miR-222. Unexpectedly, except for subcellular location of SOX9 and OPN, no correlation was found between the expression levels of these molecular markers and histopathological differentiation grade. Therefore, our data point toward necessary caution when investigating the evolution and prognosis of ICC on the basis of cell differentiation criteria.

Serum MiRNA panel as potential biomarkers for chronic hepatitis B with persistently normal alanine aminotransferase

BACKGROUND

Circulating miRNAs, a family of miRNAs existing in plasma and serum, have a great potential to serve as novel biomarkers in body fluids for non-invasive diagnosis and prognosis of many diseases.

METHODS

A multistage, case-control study was designed to establish a panel of serum miRNAs that could be surrogate markers for chronic hepatitis B with persistently normal alanine aminotransferase (ALT). A total of 295 CHB patients presenting persistently normal ALT levels with significant histological features (SPNALT group), 243 CHB patients presenting persistently normal ALT levels with no significant histological features (NSPNALT group), and 178 healthy controls (healthy group) were enrolled in the study. An initial screening of miRNAs was performed by Illumina sequencing using serum samples pooled from SPNALT patients and controls. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) assay was performed to evaluate the expression of selected miRNAs. A logistic regression model was constructed using a training cohort (n=380) and validated using a cohort (n=258). The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy.

RESULTS

We identified 9 miRNAs (hsa-miR-885-5p, hsa-miR-122-5p, hsa-miR-10a-5p, hsa-miR-511-5p, hsa-miR-574-5p, hsa-miR-98-5p, hsa-miR-26a-5p, hsa-miR-192-5p, hsa-miR-30b-5p) and established 3 miRNA panels that provided high diagnostic accuracy for SPNALT. The AUC of miRNA panels for SPNALT vs. healthy was 0.882 (95% CI=0.839 to 0.925), for SPNALT vs. NSPNALT was 0.894 (95% CI=0.857 to 0.930), and for SPNALT vs. control was 0.860 (95% CI=0.821 to 0.899).

CONCLUSIONS

We constructed serum miRNA panels with considerable clinical value in diagnosing PNALT.

The potential role of miRNAs 21 and 199-a in early diagnosis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is regarded as one of the most common malignancies and among the leading causes of cancer death among the whole world. The most urgent needs are to find sensitive markers for early diagnosis for HCC. MicroRNAs (miRNAs) are reported as a group of small non-coding RNAs that can function as endogenous RNA interference to regulate expression of the targeted genes. This study was conducted to detect the serum and tissue expression of miR 21 and miR 199-a to be applied as early detectors for HCC.

METHODS

A total of 40 serum and tissue samples (17 samples from chronic hepatitis and 23 samples from HCC patients) were collected. The levels of the two mature miRNAs (miR-21 and miR-199-a) were detected by real time quantitative reverse-transcriptase PCR (RT-qPCR) in sera and tissues of chronic hepatitis and HCC patients. Besides, miR-21 and miR-199-a levels in relation to clinical and pathological factors were explored.

RESULTS

We found that the expression of serum miR-21 was distinctly increased in HCC compared with chronic hepatitis (P<0.001). miR 199-a was distinctly decreased in HCC compared with chronic hepatitis (P<0.001). In addition, median of miR 21 was increased in malignant when compared to adjacent non-malignant tissues without significant differences (P=0.191) while miR 199-a was significantly decreased in malignant when compared to adjacent nonmalignant tissues (P<0.001). ROC analysis showed that miR-21 and miR-199-a might be potential biomarkers for HCC.

CONCLUSIONS

In conclusion, the expression of miR-21 was significantly up-regulated and miR-199-a was significantly down regulated in serum of patients with HCC. Due to their reasonable sensitivity and specificity for disease progression, miR-21 and miR-199-a could be used as potential circulating biomarkers for HCC.

MicroRNA‑21 regulates the expression of BTG2 in HepG2 liver cancer cells

B-cell translocation gene 2 (BTG2) is a tumor suppressor gene, which belongs to the anti-proliferation gene family. Our previous study demonstrated that microRNA (miR)-21 and the expression of BTG2 were negatively correlated during hepatocarcinogenesis. The aim of the present study was to investigate the effects of miR-21 on the growth and progression of liver cancer cells, and to determine the underlying mechanism. A luciferase reporter assay was used to demonstrate that the BTG2 gene was a direct target of miR-21. In addition, the effects of miR-21 on cell growth and gene expression in HepG2 human hepatocellular carcinoma (HCC) cells were analyzed using reverse transcription-quantitative polymerase chain reaction, western blotting, an MTT assay, flow cytometry, a Transwell invasion assay and a wound healing assay. The expression levels of miR-21 in the HepG2 cells were significantly higher, compared with those in L02 normal liver cells. The expression levels of BTG2 in liver cancer cell lines (HepG2 and Huh7) were significantly lower, compared with that in the L02 cells. These results suggested that BTG2 was the direct target gene of miR-21. The protein expression levels of BTG2 were inhibited by high expression levels of miR-21, and increased by inhibition of the expression of miR-21 in the HepG2 cells. Inhibition of miR-21 reduced cell proliferation and invasion, and increased the rate of apoptosis in the HepG2 cells. These results indicated that miR-21 regulates cell proliferation, invasion, migration and apoptosis in HepG2 cells, which may be associated with its effects on the expression of BTG2. The results of the present study may provide a basis for targeting the miR-21/BTG2 interaction for the treatment of HCC.

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.

Differential expression of serum microRNAs in cirrhosis that evolve into hepatocellular carcinoma related to hepatitis B virus

Circulating microRNAs (miRNAs) exist stably in body fluids and are potential biomarkers for hepatocellular carcinoma (HCC). Twenty-five patients with cirrhosis that evolved into HCC, who were treated at The Third Hospital of Zhenjiang Affiliated to Jiangsu University between January 2005 and December 2012, were enrolled. In the discovery stage, 2 serum samples pooled from 3 cirrhosis and 3 HCC samples were subjected to deep sequencing. Subsequently, differential expression of miRNAs was validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in the serum samples from an independent cohort of 22 patients with cirrhosis and HCC. Twenty-two miRNAs showed a >2-fold upregulation (P<0.01), and 2 miRNAs showed a >2-fold downregulation (P<0.01) in the cirrhosis and HCC samples. Using the comparative Ct method, we calculated the 2-(ΔΔCt) for 40 candidate miRNAs in the sample sets. Eight of the 40 miRNAs demonstrated significantly differential expression levels between the disease categories. The miRNAs exhibiting differential expression were hsa-miR-122-5p, has-miR-199a-5p, hsa-miR-486-5p, has-miR-193b-5p, hsa-miR-206, has-miR-141-3p, has-miR-192-5p and has-miR-26a-5p. We identified the miRNAs differentially expressed in cirrhosis that evolved into hepatitis B virus-related HCC.

Emerging role of microRNA in hepatocellular carcinoma (Review)

Hepatocellular carcinoma is a type of cancer characterized by significant morbidity and high mortality rates worldwide. Previous studies have revealed that alterations in microRNA (miRNA) expression are a common feature of cancer. Furthermore, as evolutionarily conserved, non-encoding RNAs, miRNAs have demonstrated fundamental roles in the various biological processes involved in cancer. Genome-wide miRNA expression profile studies and bioinformatic methods have provided comprehensive insight into the role of cancer-related miRNAs. In addition, investigation of the function and mechanisms of miRNAs has provided an understanding of the association with the pathogenesis of cancer. In the present review, the tumor-promoting or tumor-suppressive roles and underlying mechanisms of certain significant miRNAs at a single and integral level are summarized. Furthermore, the recognition of miRNA-gene networks and current advances in the potential use of miRNA-based diagnosis and therapy are discussed.

MicroRNA expression profiling in PBMCs: a potential diagnostic biomarker of chronic hepatitis C

The expression levels of miR-16, miR-193b, miR-199a, miR-222, and miR-324 in PBMCs were significantly higher in CHC patients compared with healthy controls and significantly different between CHC patients with HCV genotype 1 (GT-1) and non-genotype-1 (non-GT-1). Multivariate logistic regression analysis also showed that patients with high expression levels of the six target miRNAs had an approximately 7.202-fold risk of CHC compared with those with low expression levels of the target miRNAs. We concluded that the expression levels of miR-16, miR-193b, miR-199a, miR-222, and miR-324 target miRNAs in PBMCs of CHC may act as significant risk biomarkers for the development of CHC.

Serum microRNAs as potential biomarkers of primary biliary cirrhosis

BACKGROUND

Circulating microRNAs (miRNAs), which are extremely stable and protected from RNAse-mediated degradation in body fluids, have emerged as candidate biomarkers for many diseases. The present study aimed to identify a serum microRNA (miRNA) expression profile that could serve as a novel diagnostic biomarker for primary biliary cirrhosis (PBC).

METHODS

Serum miRNA expression was investigated using four cohorts comprising 380 participants (healthy controls and patients with PBC) recruited between August 2010 and June 2013. miRNA expression was initially analyzed by Illumina sequencing using serum samples pooled from 3 patients and 3 controls. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was then used to evaluate the expression of selected miRNAs in a screening set (n = 40). A logistic regression model was then constructed using a training cohort (n = 192) and validated using another cohort (n = 142). The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy.

RESULTS

We identified a miRNA panel (hsa-miR-122-5p, hsa-miR-141-3p, and hsa-miR-26b-5p) with a high diagnostic accuracy for PBC (AUC = 0.905, 95% confidence interval (CI) = 0.857 to 0.953; sensitivity = 80.5%, specificity = 88.3%). There was a significant difference between AUC values of the miRNA panel and those of alkaline phosphatase (ALP) (AUC = 0.537, difference between areas = 0.314, 95% CI = 0.195 to 0.434, P<0.001), and those of antinuclear antibody (ANA) (AUC = 0.739, difference between areas = 0.112, 95% CI = 0.012 to 0.213, P = 0.0282).

CONCLUSION

We identified a serum microRNA panel with considerable clinical value in PBC diagnosis. The results indicate that the miRNA panel is a more sensitive and specific biomarker for PBC than ALP and ANA.

MicroRNAs: the fine modulators of liver development and function

MicroRNAs are a class of small non-coding RNAs involved in the transcriptional and post-transcriptional regulation of gene expression. The function of miRNAs in liver disease including hepatocellular carcinoma (HCC), hepatitis, and alcoholic liver disease, have been widely studied and extensively reviewed. Increasing evidence demonstrates that miRNAs also play a critical role in normal liver development and in the fine-tuning of fundamental biological liver processes. In this review, we highlight the most recent findings on the role of miRNAs in liver specification and differentiation, liver cell development, as well as in the many metabolic functions of the liver, including glucose, lipid, iron and drug metabolism. These findings demonstrate an important role of miRNAs in normal liver development and function. Further researches will be needed to fully understand how miRNAs regulate liver generation and metabolic function, which should then lead to greater insights in liver biology and perhaps open up the possibility to correct errors that cause liver diseases or metabolic disorders.

miRNAs affect the development of hepatocellular carcinoma via dysregulation of their biogenesis and expression

The pathogenesis of hepatocellular carcinoma (HCC) is not fully understood, which has affected the early diagnosis and treatment of HCC and the survival time of patients. MicroRNAs (miRNAs) are a class of evolutionarily conserved small, non-coding RNAs, which regulate the expression of various genes post-transcriptionally. Emerging evidence indicates that the key enzymes involved in the miRNA biosynthesis pathway and some tumor-specific miRNAs are widely deregulated or upregulated in HCC and closely associated with the occurrence and development of various cancers, including HCC. Early studies have shown that miRNAs have critical roles in HCC progression by targeting many critical protein-coding genes, thereby contributing to the promotion of cell proliferation; the avoidance of apoptosis, inducing via angiogenesis; and the activation of invasion and metastasis pathways. Experimental data indicate that discovery of increasing numbers of aberrantly expressed miRNAs has opened up a new field for investigating the molecular mechanism of HCC progression. In this review, we describe the current knowledge about the roles and validated targets of miRNAs in the above pathways that are known to be hallmarks of HCC, and we also describe the influence of genetic variations in miRNA biosynthesis and genes.

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.

AP-1/c-Jun transcription factors: regulation and function in malignant melanoma

Malignant melanoma is an aggressive form of skin cancer with an increasing incidence worldwide. One way to address the pathology of the disease is through molecular research. In addition to the analysis of melanoma-relevant signaling pathways, the investigation of important transcription factors is a fundamental objective. The AP-1 transcription factor family is known to play an important role in melanoma progression and development. The AP-1 family member c-Jun is highly expressed and active in melanoma cells, and the mechanisms and signaling pathways regulating c-Jun protein are diverse. In addition to the common regulation and activation of c-Jun by mitogen-activated protein kinases (MAPKs), there are several other signaling pathways and interactions leading to c-Jun protein expression and thus AP-1 activation. In malignant melanoma, and many other cancer types, c-Jun has mainly oncogenic functions; however, other AP-1 proteins also have anti-oncogenic roles. Interestingly, several studies have revealed that a strong AP-1 activity in melanoma mainly depends on c-Jun. Recently, it has also been shown that the c-Jun protein is regulated and activated by several other mechanisms, including miRNAs and the cytoskeleton. In summary, there are a variety of mechanisms underlying the induction of c-Jun protein expression and activity leading to tumor progression and development, and this diverse regulatory machinery is due to the heterogeneity of different tumor types, particularly in malignant melanoma.

Up-regulation of Ago2 expression in gastric carcinoma

Argonaute (Ago) proteins have been demonstrated to be widely expressed and involved in post-transcriptional gene silencing and thus play key roles in carcinogenesis. Nevertheless, little is known about the specific role of Ago2 in gastric cancer (GC). Thus, we aimed to study the expression of Ago2 in 363 primary GC, 8 corresponding lymph node metastases and 10 non-neoplastic surrounding gastric epithelium tissues by immunohistochemical analyses and tissue microarray. The expression of Ago2 was also correlated with clinicopathological characteristics and HER-2 status. Ago2 expression levels in primary GC and corresponding lymph node metastases were significantly higher compared with healthy controls (P < 0.05). But, there was no difference of Ago2 between GC and its metastatic lymph node (P > 0.05). Ago2 up-regulation had no correlation with GC patients' age, tumor location, tumor size, gross morphology or tumor infiltration. However, we found that Ago2 was different between HER-2 positive and HER-2 negative groups (P = 0.044), which had been demonstrated to be related to GC prognosis. And there was a great correlation between Ago2 expression and the tumor differentiation (P = 0.007), lymph node invasion (P = 0.000) and clinical stage (P = 0.006). Interestingly, Ago2 was also correlated to patients' gender (P = 0.004), which may suggest a possible role of hormonal signal in the mechanisms of Ago2. Thus, our results suggested that up-regulation of Ago2 may play an important role in GC carcinogenesis and progression. Further studies on the cellular functions of Ago2 need to address these issues.

The challenge of cholangiocarcinoma: dissecting the molecular mechanisms of an insidious cancer

Cholangiocarcinoma is a fatal cancer of the biliary epithelium and has an incidence that is increasing worldwide. Survival beyond a year of diagnosis is less than 5%, and therapeutic options are few. Known risk factors include biliary diseases such as primary sclerosing cholangitis and parasitic infestation of the biliary tree, but most cases are not associated with any of these underlying diseases. Numerous in vitro and in vivo models, as well as novel analytical techniques for human samples, are helping to delineate the many pathways implicated in this disease, albeit at a frustratingly slow pace. As yet, however, none of these studies has been translated into improved patient outcome and, overall, the pathophysiology of cholangiocarcinoma is still poorly understood. There remains an urgent need for new approaches and models to improve management of this insidious and devastating disease. In this review, we take a bedside-to-bench approach to discussing cholangiocarcinoma and outline research opportunities for the future in this field.

Regulation of ca(2+) signaling in pulmonary hypertension

Understanding the cellular and molecular mechanisms involved in the development and progression of pulmonary hypertension (PH) remains imperative if we are to successfully improve the quality of life and life span of patients with the disease. A whole plethora of mechanisms are associated with the development and progression of PH. Such complexity makes it difficult to isolate one particular pathway to target clinically. Changes in intracellular free calcium concentration, the most common intracellular second messenger, can have significant impact in defining the pathogenic mechanisms leading to its development and persistence. Signaling pathways leading to the elevation of [Ca(2+)](cyt) contribute to pulmonary vasoconstriction, excessive proliferation of smooth muscle cells and ultimately pulmonary vascular remodeling. This current review serves to summarize the some of the most recent advances in the regulation of calcium during pulmonary hypertension.

MicroRNA miR-125b controls melanoma progression by direct regulation of c-Jun protein expression

A fundamental event in the development and progression of malignant melanoma is the deregulation of cancer-relevant transcription factors. We recently showed that c-Jun is a main regulator of tumor progression in melanoma and thus the most important member of the AP-1 transcription factor family for this disease. Interestingly, we revealed that c-Jun expression was regulated on the post-transcriptional level and therefore speculated that miRNAs could be involved in c-Jun regulation. We determined seed sequences for miR-125b and miR-527 in the coding region of c-Jun mRNA that hints at the direct involvement of miRNA-dependent regulation on the protein level. We found that the expression of miR-125b was significantly reduced in malignant melanoma cell lines and tissue samples compared with melanocytes, whereas miR-527 remained unchanged. In further functional experiments, treatment of melanoma cells with pre-miR-125b resulted in strong suppression of cellular proliferation and migration, supporting the role of miR-125b in melanoma. In addition, transfection of pre-miR-125b led to strong downregulation of c-Jun protein but not mRNA expression in melanoma cells. Luciferase assays using reporter plasmids containing the miR-125b seed sequence in the luciferase coding region confirmed the direct interaction with miR-125b. Furthermore, immunoprecipitation of Ago-2 revealed that c-Jun mRNA accumulated in the RNA-induced silencing complex after pre-miR-125b transfection in melanoma cells. In summary, we identified an important role for miR-125b in malignant melanoma. Moreover, we demonstrated post-transcriptional regulation of c-Jun by this miRNA and showed that c-Jun is a main mediator of the effects of miR-125b on melanoma cells.