MicroRNA-421 functions as an oncogenic miRNA in biliary tract cancer through down-regulating farnesoid X receptor expression

Targeting Farnesoid X Receptor in Tumor and the Tumor Microenvironment: Implication for Therapy

The farnesoid-X receptor (FXR), a member of the nuclear hormone receptor superfamily, can be activated by bile acids (BAs). BAs binding to FXR activates BA signaling which is important for maintaining BA homeostasis. FXR is differentially expressed in human organs and exists in immune cells. The dysregulation of FXR is associated with a wide range of diseases including metabolic disorders, inflammatory diseases, immune disorders, and malignant neoplasm. Recent studies have demonstrated that FXR influences tumor cell progression and development through regulating oncogenic and tumor-suppressive pathways, and, moreover, it affects the tumor microenvironment (TME) by modulating TME components. These characteristics provide a new perspective on the FXR-targeted therapeutic strategy in cancer. In this review, we have summarized the recent research data on the functions of FXR in solid tumors and its influence on the TME, and discussed the mechanisms underlying the distinct function of FXR in various types of tumors. Additionally, the impacts on the TME by other BA receptors such as takeda G protein-coupled receptor 5 (TGR5), sphingosine-1-phosphate receptor 2 (S1PR2), and muscarinic receptors (CHRM2 and CHRM3), have been depicted. Finally, the effects of FXR agonists/antagonists in a combination therapy with PD1/PD-L1 immune checkpoint inhibitors and other anti-cancer drugs have been addressed.

Small but mighty: How microRNAs drive the deadly progression of cholangiocarcinoma

Cholangiocarcinoma, also referred to as CCA, is a highly complex epithelial malignancy that can impact various organs and regions of the body, including the perihilar, intrahepatic, and distal organs. This cancer is characterized by the malignant growth of the epithelial lining in the bile ducts, which spans the entire biliary tree and is accountable for disease progression. The current state of affairs concerning CCA is concerning, with poor prognoses, high recurrence rates, and dismal long-term survival rates significantly burden healthcare facilities worldwide. Studies have identified numerous signaling pathways and molecules involved in the development and progression of CCA, including microRNAs, an important class of non-coding RNAs that have the ability to modulate these cellular signaling pathways significantly. In addition, microRNAs may serve as an innovative target for developing novel therapeutic approaches for CCA. In this review, we explore the underlying mechanisms and signaling pathways implicated in the initiation and progression of CCA, focusing on the future direction of utilizing microRNAs as a promising treatment option for this challenging malignancy.

Clinical role of miR-421 as a novel biomarker in diagnosis of gastric cancer patients: A meta-analysis

BACKGROUND

Gastric cancer (GC) has been identified as one of the most common malignancies. It was found that microRNAs can be used as potential biomarkers for GC diagnosis. The aim of this study was to estimate the diagnostic value of 4 potential microRNAs in GC.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were used to search published studies. The quality of the studies was scored with the Quality Assessment of Diagnostic Accuracy Studies. The pooled sensitivity and specificity, diagnostic odds ratio (DOR) and area under the curve (AUC) were calculated. The heterogeneity was evaluated using Cochrane Q statistics and the inconsistency index.

RESULTS

A total of 22 studies reporting the diagnostic value of miR-21 (n = 9), miR-106 (n = 10), miR-421 (n = 5) and miR-223 (n = 3) were included. Quality Assessment of Diagnostic Accuracy Studies scores showed the high quality of the selected 22 articles. The random effects model was adopted by evaluating the heterogeneity between articles. The DOR, AUC, and Q value of miRNA-21 were 12.37 (95% confidence interval [CI]: 5.36-28.54), 0.86 and 0.79, respectively. The DOR, AUC and Q value of miRNA-106 were 12.98 [95% CI: 7.14-23.61], 0.85 and 0.78, respectively. The DOR, AUC and Q value of miRNA-421 were 27.86 [95% CI: 6.04-128.48], 0.92 and 0.86, respectively. The DOR, AUC and Q value of miRNA-223 were 18.50 [95% CI: 7.80-43.86], 0.87 and 0.80, respectively. These results indicate that miRNA-421 has the highest diagnostic accuracy, followed by miR-223, miRNA-21, and miRNA-106 among the 4 microRNAs in GC.

CONCLUSIONS

miR-21, miR-106, miR-421, and miR-223 have good diagnostic efficacy, especially miR-421, could be used as auxiliary diagnostic indicator for GC.

CircSETD3 (hsa_circ_0000567) inhibits proliferation and induces apoptosis in cholangiocarcinoma cells via downregulation of microRNA-421 expression

Cholangiocarcinoma (CCA) is a fatal tumor associated with chronic inflammation. Circular RNAs (circRNAs) have been evidenced to be involved in tumorigenesis and tumor progression. This study aimed to explore the effects and potential molecular mechanism of circSETD3 in CCA progression. Levels of CircSETD3 and microRNA (miR)-421 in CCA tissue and cell lines were measured using quantitative real-time polymerase-chain reaction (qRT-PCR). A direct target of miR-421 was predicted using TargetScan and further confirmed by a dual-luciferase reporter assay. Cell proliferation and apoptosis were measured using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and flow cytometry, respectively. The activity of caspase-3 was also examined using caspase-3 activity detection kits. Moreover, the levels of B-cell lymphoma-2 modifying factor (BMF), B-cell lymphoma 2 (BCL2), and Bcl-2-associated X protein (BAX) in TFK1 cells were assessed using qRT-PCR and western blot analysis. We found that circSETD3 was downregulated, while miR-421 was upregulated in CCA tissues and cell lines. CircSETD3 negatively regulated miR-421 levels in TFK1 cells. Functional assays revealed that circSETD3-plasmid inhibited cell proliferation, induced apoptosis, promoted caspase-3 activity, enhanced Bax and cleaved-Caspase 3 expression, and reduced Bcl-2 levels, and these effects were reversed by miR-421 mimic. Meanwhile, similar results were observed in miR-421 inhibitor-transfected TFK1 cells, and these results were abolished by BMF-siRNA. BMF, a direct target of miR-421, was downregulated in CCA tissues and cell lines. These findings demonstrate that circSETD3 inhibits proliferation and induces apoptosis in CCA cells by regulating the miR-421/BMF axis, indicating its potential as a promising candidate for CCA therapy.

Pleiotropic roles of FXR in liver and colorectal cancers

Nuclear receptor farnesoid X receptor (FXR) is generally considered a cell protector of enterohepatic tissues and a suppressor of liver cancer and colorectal carcinoma (CRC). Loss or reduction of FXR expression occurs during carcinogenesis, and the FXR level is inversely associated with the aggressive behaviors of the malignancy. Global deletion of FXR and tissue-specific deletion of FXR display distinct effects on tumorigenesis. Epigenetic silencing and inflammatory context are two main contributors to impaired FXR expression and activity. FXR exerts its antitumorigenic function via the following mechanisms: 1) FXR regulates multiple metabolic processes, notably bile acid homeostasis; 2) FXR antagonizes hepatic and enteric inflammation; 3) FXR impedes aberrant activation of some cancer-related pathways; and 4) FXR downregulates a number of oncogenes while upregulating some tumor suppressor genes. Restoring FXR functions via its agonists provides a therapeutic approach for patients with liver cancer and CRC. However, an in-depth understanding of the species-specific pharmacological effects is a prerequisite for assessing the clinical safety and efficacy of FXR agonists in human cancer treatment.

Role of autophagy in cholangiocarcinoma: An autophagy-based treatment strategy

Cholangiocarcinomas (CCAs) are diverse biliary epithelial tumours involving the intrahepatic, perihilar and distal parts of the biliary tree. The three entirely variable entities have distinct epidemiology, molecular characteristics, prognosis and strategy for clinical management. However, many cholangiocarcinoma tumor-cells appear to be resistant to current chemotherapeutic agents. The role of autophagy and the therapeutic value of autophagy-based therapy are largely unknown in CCA. The multistep nature of autophagy offers a plethora of regulation points, which are prone to be deregulated and cause different human diseases, including cancer. However, it offers multiple targetable points for designing novel therapeutic strategies. Tumor cells have evolved to use autophagy as an adaptive mechanism for survival under stressful conditions such as energy imbalance and hypoxic region of tumors within the tumor microenvironment, but also to increase invasiveness and resistance to chemotherapy. The purpose of this review is to summarize the current knowledge regarding the interplay between autophagy and cholangiocarcinogenesis, together with some preclinical studies with agents that modulate autophagy in order to induce tumor cell death. Altogether, a combinatorial strategy, which comprises the current anti-cancer agents and autophagy modulators, would represent a positive CCA patient approach.

The Role of microRNAs in Cholangiocarcinoma

Cholangiocarcinoma (CCA), an aggressive malignancy, is typically diagnosed at an advanced stage. It is associated with dismal 5-year postoperative survival rates, generating an urgent need for prognostic and diagnostic biomarkers. MicroRNAs (miRNAs) are a class of non-coding RNAs that are associated with cancer regulation, including modulation of cell cycle progression, apoptosis, metastasis, angiogenesis, autophagy, therapy resistance, and epithelial–mesenchymal transition. Several miRNAs have been found to be dysregulated in CCA and are associated with CCA-related risk factors. Accumulating studies have indicated that the expression of altered miRNAs could act as oncogenic or suppressor miRNAs in the development and progression of CCA and contribute to clinical diagnosis and prognosis prediction as potential biomarkers. Furthermore, miRNAs and their target genes also contribute to targeted therapy development and aid in the determination of drug resistance mechanisms. This review aims to summarize the roles of miRNAs in the pathogenesis of CCA, their potential use as biomarkers of diagnosis and prognosis, and their utilization as novel therapeutic targets in CCA.

Targeting Farnesoid X receptor (FXR) for developing novel therapeutics against cancer

Cancer is one of the lethal diseases that arise due to the molecular alterations in the cell. One of those alterations associated with cancer corresponds to differential expression of Farnesoid X receptor (FXR), a nuclear receptor regulating bile, cholesterol homeostasis, lipid, and glucose metabolism. FXR is known to regulate several diseases, including cancer and cardiovascular diseases, the two highly reported causes of mortality globally. Recent studies have shown the association of FXR overexpression with cancer development and progression in different types of cancers of breast, lung, pancreas, and oesophagus. It has also been associated with tissue-specific and cell-specific roles in various cancers. It has been shown to modulate several cell-signalling pathways such as EGFR/ERK, NF-κB, p38/MAPK, PI3K/AKT, Wnt/β-catenin, and JAK/STAT along with their targets such as caspases, MMPs, cyclins; tumour suppressor proteins like p53, C/EBPβ, and p-Rb; various cytokines; EMT markers; and many more. Therefore, FXR has high potential as novel biomarkers for the diagnosis, prognosis, and therapy of cancer. Thus, the present review focuses on the diverse role of FXR in different cancers and its agonists and antagonists.

The role of farnesoid X receptor in metabolic diseases, and gastrointestinal and liver cancer

Farnesoid X receptor (FXR) is a ligand-activated transcription factor involved in the control of bile acid (BA) synthesis and enterohepatic circulation. FXR can influence glucose and lipid homeostasis. Hepatic FXR activation by obeticholic acid is currently used to treat primary biliary cholangitis. Late-stage clinical trials investigating the use of obeticholic acid in the treatment of nonalcoholic steatohepatitis are underway. Mouse models of metabolic disease have demonstrated that inhibition of intestinal FXR signalling reduces obesity, insulin resistance and fatty liver disease by modulation of hepatic and gut bacteria-mediated BA metabolism, and intestinal ceramide synthesis. FXR also has a role in the pathogenesis of gastrointestinal and liver cancers. Studies using tissue-specific and global Fxr-null mice have revealed that FXR acts as a suppressor of hepatocellular carcinoma, mainly through regulating BA homeostasis. Loss of whole-body FXR potentiates progression of spontaneous colorectal cancer, and obesity-induced BA imbalance promotes intestinal stem cell proliferation by suppressing intestinal FXR in Apc^min/+ mice. Owing to altered gut microbiota and FXR signalling, changes in overall BA levels and specific BA metabolites probably contribute to enterohepatic tumorigenesis. Modulating intestinal FXR signalling and altering BA metabolites are potential strategies for gastrointestinal and liver cancer prevention and treatment. In this Review, studies on the role of FXR in metabolic diseases and gastrointestinal and liver cancer are discussed, and the potential for development of targeted drugs are summarized.

Regulation of breast cancer metastasis signaling by miRNAs

Despite the decline in death rate from breast cancer and recent advances in targeted therapies and combinations for the treatment of metastatic disease, metastatic breast cancer remains the second leading cause of cancer-associated death in U.S. women. The invasion-metastasis cascade involves a number of steps and multitudes of proteins and signaling molecules. The pathways include invasion, intravasation, circulation, extravasation, infiltration into a distant site to form a metastatic niche, and micrometastasis formation in a new environment. Each of these processes is regulated by changes in gene expression. Noncoding RNAs including microRNAs (miRNAs) are involved in breast cancer tumorigenesis, progression, and metastasis by post-transcriptional regulation of target gene expression. miRNAs can stimulate oncogenesis (oncomiRs), inhibit tumor growth (tumor suppressors or miRsupps), and regulate gene targets in metastasis (metastamiRs). The goal of this review is to summarize some of the key miRNAs that regulate genes and pathways involved in metastatic breast cancer with an emphasis on estrogen receptor α (ERα+) breast cancer. We reviewed the identity, regulation, human breast tumor expression, and reported prognostic significance of miRNAs that have been documented to directly target key genes in pathways, including epithelial-to-mesenchymal transition (EMT) contributing to the metastatic cascade. We critically evaluated the evidence for metastamiRs and their targets and miRNA regulation of metastasis suppressor genes in breast cancer progression and metastasis. It is clear that our understanding of miRNA regulation of targets in metastasis is incomplete.

MicroRNAs Involved in Inflammatory Breast Cancer: Oncogene and Tumor Suppressors with Possible Targets

Inflammatory breast cancer (IBC) as a rare and highly aggressive type of breast cancer displays phenotypic characteristics. To date, the IBC-associated molecular mechanisms are entirely unknown. In addition, there is an urgent need to identify the new biomarkers involved in the diagnosis and therapeutic purposes of IBC. MicroRNAs, a category of short noncoding RNAs, are capable of controlling the post-transcriptional expression of genes and thus can act as diagnostic predictive tools. In this review, we addressed the status of oncogenic and tumor suppressor miRNA-mediated IBC in current studies. Furthermore, based on their targets, their involvement in cancer progression, angiogenesis, metastasis, and apoptosis were determined.

Non-coding RNA crosstalk with nuclear receptors in liver disease

The dysregulation of nuclear receptors (NRs) underlies the pathogenesis of a variety of liver disorders. Non-coding RNAs (ncRNAs) are defined as RNA molecules transcribed from DNA but not translated into proteins. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two types of ncRNAs that have been extensively studied for regulating gene expression during diverse cellular processes. NRs as therapeutic targets in liver disease have been exemplified by the successful application of their pharmacological ligands in clinics. MiRNA-based reagents or drugs are emerging as flagship products in clinical trials. Advancing our understanding of the crosstalk between NRs and ncRNAs is critical to the development of diagnostic and therapeutic strategies. This review summarizes recent findings on the reciprocal regulation between NRs and ncRNAs (mainly on miRNAs and lncRNAs) and their implication in liver pathophysiology, which might be informative to the translational medicine of targeting NRs and ncRNAs in liver disease.

Pathogenetic Role and Clinical Implications of Regulatory RNAs in Biliary Tract Cancer

Biliary tract cancer (BTC) is characterised by poor prognosis and low overall survival in patients. This is generally due to minimal understanding of its pathogenesis, late diagnosis and limited therapeutics in preventing or treating BTC patients. Non-coding RNA (ncRNA) are small RNAs (mRNA) that are not translated to proteins. ncRNAs were considered to be of no importance in the genome, but recent studies have shown they play essential roles in biology and oncology such as transcriptional repression and degradation, thus regulating mRNA transcriptomes. This has led to investigations into the role of ncRNAs in the pathogenesis of BTC, and their clinical implications. In this review, the mechanisms of action of ncRNA are discussed and the role of microRNAs in BTC is summarised. The scope of this review will be limited to miRNA as they have been shown to play the most significant roles in BTC progression. There is huge potential in miRNA-based biomarkers and therapeutics in BTC, but more studies, research and technological advancements are required before it can be translated into clinical practice for patients.

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.

MicroRNA-421 confers paclitaxel resistance by binding to the KEAP1 3'UTR and predicts poor survival in non-small cell lung cancer

MicroRNAs regulate post-transcriptional gene expression and play important roles in multiple cellular processes. In this study, we found that miR-421 suppresses kelch-like ECH-associated protein 1(KEAP1) expression by targeting its 3'-untranslated region (3'UTR). A Q-PCR assay demonstrated that miR-421 is overexpressed in non-small cell lung cancer (NSCLC), especially in A549 cells. Consistently, the level of miR-421 was higher in clinical blood samples from lung cancer patients than in those from normal healthy donors, suggesting that miR-421 is an important lung cancer biomarker. Interestingly, overexpression of miR-421 reduced the level of KEAP1 expression, which further promoted lung cancer cell migration and invasion, as well as inhibited cell apoptosis both in vivo and in vitro. Furthermore, knockdown of miR-421 expression with an antisense morpholino oligonucleotide (AMO) increased ROS levels and treatment sensitivity to paclitaxel in vitro and in vivo, indicating that high miR-421 expression may at least partly account for paclitaxel tolerance in lung cancer patients. To find the upstream regulator of miR-421, one of the candidates, β-catenin, was knocked out via the CRISPR/Cas9 method in A549 cells. Our data showed that inhibiting β-catenin reduced miR-421 levels in A549 cells. In addition, β-catenin upregulation enhanced miR-421 expression, indicating that β-catenin regulates the expression of miR-421 in lung cancer. Taken together, our findings reveal the critical role of miR-421 in paclitaxel drug resistance and its upstream and downstream regulatory mechanisms. Therefore, miR-421 may serve as a potential molecular therapeutic target in lung cancer, and AMOs may be a potential treatment strategy.

miR-421 promotes apoptosis and suppresses metastasis of osteosarcoma cells via targeting LTBP2

Increasing evidence has confirmed that microRNAs (miRs) are involved in tumor development and progression. A previous study reported that miR-421 could serve as a diagnostic marker in patients with osteosarcoma (OS). The present study explored the potential roles of miR-421 in the regulation of cell proliferation, apoptosis, migration, invasion, and epithelial-mesenchymal transition of OS cells. Our results showed that miR-421 was upregulated in OS tissues and cell lines (MG63, U2OS, HOS, and Saos-2) compared with the corresponding adjacent tissues or human osteoblast cells hFOB1.19, while the latent transforming growth factor β-binding protein 2 (LTBP2) expression was reduced. In MG63 and U2OS cells, CCK8 assay displayed that cell proliferation was repressed by the miR-421 inhibitor, conversely increased by miR-421 mimics. Inhibition of miR-421 promoted cell apoptosis rate, caspase 3 activity, cleaved-caspase 3 (c-caspase 3) expression, and Bax/Bcl-2 ratio, restoration of miR-421 showed the opposite functions. Suppression of miR-421 blocked migration and invasion, whereas miR-421 overexpression promoted the migration and invasion of MG63 and U2OS cells. In addition, real-time polymerase chain reaction and Western blot analysis revealed that miR-421 negatively regulated E-cadherin expression, and positively regulated the expression of N-cadherin and vimentin. The luciferase reporter assay determined that miR-421 could target LTBP2-3'-UTR, and LTBP2 expression was regulated negatively by miR-421 both in mRNA and protein levels. Depletion of LTBP2 partly abolished the biological functions of miR-421 inhibitor in OS. In conclusion, miR-421 plays an oncogenic role in OS via targeting LTBP2, suggesting that miR-421 may be a potential therapeutic target against OS.

Expression signatures and roles of microRNAs in inflammatory breast cancer

Inflammatory breast cancer (IBC) is an infrequent but aggressive manifestation of breast cancer, which accounts for 2–4% of all breast cancer cases but responsible for 7–10% of breast cancer-related deaths, and with a 20–30% 10-year overall survival compared with 80% for patients with non-IBC with an unordinary phenotype, whose molecular mechanisms are still largely unknown to date. Discovering and identifying novel bio-markers responsible for diagnosis and therapeutic targets is a pressing need. MicroRNAs are a class of small non-coding RNAs that are capable to post-transcriptionally regulate gene expression of genes by targeting mRNAs, exerting vital and tremendous affects in numerous malignancy-related biological processes, including cell apoptosis, metabolism, proliferation and differentiation. In this study, we review present and high-quality evidences regarding the potential applications of inflammatory breast cancer associated microRNAs for diagnosis and prognosis of this lethal disease.

The FXR agonist obeticholic acid inhibits the cancerogenic potential of human cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive cancer with high resistance to chemotherapeutics. CCA is enriched in cancer stem cells, which correlate with aggressiveness and prognosis. FXR, a member of the metabolic nuclear receptor family, is markedly down-regulated in human CCA. Our aim was to evaluate, in primary cultures of human intrahepatic CCA (iCCA), the effects of the FXR agonist obeticholic acid (OCA), a semisynthetic bile acid derivative, on their cancerogenic potential. Primary human iCCA cell cultures were prepared from surgical specimens of mucinous or mixed iCCA subtypes. Increasing concentrations (0-2.5 μM) of OCA were added to culture media and, after 3-10 days, effects on proliferation (MTS assay, cell population doubling time), apoptosis (annexin V-FITC/propidium iodide), cell migration and invasion (wound healing response and Matrigel invasion assay), and cancerogenic potential (spheroid formation, clonogenic assay, colony formation capacity) were evaluated. Results: FXR gene expression was downregulated (RT-qPCR) in iCCA cells vs normal human biliary tree stem cells (p < 0.05) and in mucinous iCCA vs mixed iCCA cells (p < 0.05) but was upregulated by addition of OCA. OCA significantly (p < 0.05) inhibited proliferation of both mucinous and mixed iCCA cells, starting at a concentration as low as 0.05 μM. Also, CDCA (but not UDCA) inhibited cell proliferation, although to a much lower extent than OCA, consistent with its different affinity for FXR. OCA significantly induced apoptosis of both iCCA subtypes and decreased their in vitro cancerogenic potential, as evaluated by impairment of colony and spheroid formation capacity and delayed wound healing and Matrigel invasion. In general, these effects were more evident in mixed than mucinous iCCA cells. When tested together with Gemcitabine and Cisplatin, OCA potentiated the anti-proliferative and pro-apoptotic effects of these chemotherapeutics, but mainly in mixed iCCA cells. OCA abolished the capacity of both mucinous and mixed iCCA cells to form colonies when administered together with Gemcitabine and Cisplatin. In subcutaneous xenografts of mixed iCCA cells, OCA alone or combined with Gemcitabine or Cisplatin markedly reduced the tumor size after 5 weeks of treatment by inducing necrosis of tumor mass and inhibiting cell proliferation. In conclusion, FXR is down-regulated in iCCA cells, and its activation by OCA results in anti-cancerogenic effects against mucinous and mixed iCCA cells, both in vitro and in vivo. The effects of OCA predominated in mixed iCCA cells, consistent with the lower aggressiveness and the higher FXR expression in this CCA subtype. These results, showing the FXR-mediated capacity of OCA to inhibit cholangiocarcinogenesis, represent the basis for testing OCA in clinical trials of CCA patients.

Upregulated expression of miR-421 is associated with poor prognosis in non-small-cell lung cancer

Background

Non-small-cell lung cancer (NSCLC) represents the most frequent subtype of lung cancer. MicroRNAs (miRNAs) have attracted a lot of attention with regard to their clinical significance and crucial biological functions in various human cancers. This study aimed to investigate the prognostic significance of microRNA-421 (miR-421) and its correlation with tumor progression in NSCLC.

Materials and methods

Expression levels of miR-421 in both serum and tissue samples were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The prognostic value of miR-421 was evaluated using Kaplan–Meier survival analysis and Cox regression assay. To explore the functional role of miR-421 during NSCLC progression, cell experiments were carried out.

Results

Expression of serum and tissue miR-421 was upregulated in the NSCLC patients compared with the normal controls (all P<0.001), and the expression showed a significant correlation between the serum samples and tissues (R=0.475, P<0.001). The increased miR-421 expression was associated with positive lymph-node metastasis and advanced TNM stage (all P<0.05). Moreover, patients with high miR-421 expression had poor overall survival compared with those with low expression (log-rank P=0.007). The overexpression of miR-421 proved to be an independent prognostic factor for NSCLC (HR=1.991, 95% CI=1.046–3.791, P=0.036). According to the cell experiments, the proliferation, migration and invasion of NSCLC cells were suppressed by knockdown of miR-421.

Conclusion

Overexpression of miR-421 serves as a prognostic biomarker and may be involved in the promotion of tumor progression in NSCLC.

Genome-scale analysis to identify prognostic microRNA biomarkers in patients with early stage pancreatic ductal adenocarcinoma after pancreaticoduodenectomy

Background

The aim of the study was to investigate potential prognostic microRNA (miRNA) biomarkers for patients with early stage pancreatic ductal adenocarcinoma (PDAC) after pancreaticoduodenectomy using a miRNA-sequencing (miRNA-seq) data set from The Cancer Genome Atlas (TCGA). A miRNA expression-based prognostic signature was generated, and the potential role of target genes in overall survival (OS) in patients with PDAC was examined.

Methods

A miRNA-seq data set of 112 PDAC patients who underwent pancreaticoduodenectomy was obtained from TCGA. Survival analysis was performed to identify potential prognostic biomarkers.

Results

Eleven miRNAs (hsa-mir-501, hsa-mir-4521, hsa-mir-5091, hsa-mir-24-1, hsa-mir-126, hsa-mir-30e, hsa-mir-3157, hsa-let-7a-3, hsa-mir-133a-1, hsa-mir-4709, and hsa-mir-421) were used to construct a prognostic signature using the step function. The 11-miRNA prognostic signature showed good performance for prognosis prediction (adjusted P<0.0001, adjusted hazard ratio =4.285, 95% confidence interval =2.146–8.554), and the time-dependent receiver operating characteristic analysis showed an area under the curve of 0.864, 0.877, and 0.787 for 1-, 2-, and 3-year PDAC OS predictions, respectively. Comprehensive survival analysis suggested that the prognostic signature could serve as an independent prognostic factor for PDAC OS and performs better in prognosis prediction than other traditional clinical indicators. Functional assessment of the target genes of the miRNAs indicated that they were significantly enriched in multiple biological processes and pathways, including cell proliferation, cell cycle biological processes, the forkhead box O, mitogen-activated protein kinase, Janus kinase/signal transducers and activators of transcription signaling pathways, pathways in cancer, and the ErbB signaling pathway. Several target genes of these miRNAs were also associated with PDAC OS.

Conclusion

The present study identified a novel miRNA expression signature that showed potential as a prognostic biomarker for PDAC after pancreaticoduodenectomy.

Waltonitone inhibits proliferation of hepatoma cells and tumorigenesis via FXR-miR-22-CCNA2 signaling pathway

Waltonitone (WA), an ursane-type pentacyclic triterpene extracted from Gentiana waltonii Burkill, was recently appeared to exert anti-tumor effect. However, the biological underpinnings underlying the role of WA in hepatocellular carcinoma (HCC) cells have not been completely elucidated. Our previous report indicated that the FXR-regulated miR-22-CCNA2 pathway contributed to the progression and development of HCC. Besides, a wide spectrum of microRNAs (miRNAs) could be up- or down-regulated upon WA treatment, including miR-22. Hence, we aimed to determine whether WA inhibited HCC cell proliferation via the FXR-miR-22-CCNA2 axis. In this study, we observed a significant downregulation of FXR and miR-22, along with upregulation of CCNA2 in 80 paired tumors relative to adjacent normal tissues of HCC subjects, which were obtained from the available GEO database in NCBI (GSE22058). Furthermore, we validated the expression patterns of these three targets in another set of HCC samples and found the highly correlation within each other. Additionally, our data demonstrated that WA induced miR-22 and repressed CCNA2 in HCC cells, which contributed to the cell proliferation arrest. In addition, evidence suggested that either miR-22 silencing or FXR knockdown reversed the diminished CCNA2 expression as well as cell proliferation inhibition caused by WA treatment and WA inhibited tumor masses in vivo in a subcutaneous xenograft mouse model of HCC. Overall, our data indicated that WA inhibited HCC cell proliferation and tumorigenesis through miR-22-regulated CCNA2 repression, which was at least partially through FXR modulation.

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-379-5p plays a tumor-suppressive role in human bladder cancer growth and metastasis by directly targeting MDM2

Bladder cancer is the second most common urological malignancy in the US and is the most frequently diagnosed urological malignancy in China. An increasing amount of evidence indicates that microRNAs perform extremely important functions in many biological processes related to the formation and progression of cancers, including bladder cancer. Previous studies have reported that microRNA‑379-5p (miR-379-5p) is involved in tumour initiation and development in human cancers. However, the expression pattern, biological functions and the underlying mechanisms of miR-379-5p in bladder cancer remain unknown. The present study demonstrated that the expression levels of miR‑379-5p in bladder cancer tissues and cell lines were lower than the levels in adjacent normal tissues and the human bladder epithelial immortalized SV-HUC-1 cell line. Restoration of the expression of miR-379-5p inhibited bladder cancer cell proliferation, migration and invasion. Mouse double minute 2 (MDM2) was identified as a direct target gene of miR-379-5p. Furthermore, similar to miR-379-5p overexpression in bladder cancer cells, inhibition of MDM2 exerted tumor-suppressive effects. Rescue experiments showed that upregulation of MDM2 reversed the inhibitory effects of miR-379-5p on bladder cancer cell proliferation, migration and invasion. MDM2 was highly expressed and inversely correlated with miR-379-5p expression in bladder cancer tissues. These findings suggest that the miR-379-5p/MDM2 pathway plays an important role in bladder cancer and could serve as a potential candidate for bladder cancer therapeutics.

Molecular profiling of intrahepatic cholangiocarcinoma: the search for new therapeutic targets

Intrahepatic cholangiocarcinoma (iCCA) is the second most frequent primary tumor of the liver and a highly lethal disease. Therapeutic options for advanced iCCA are limited and ineffective due to the largely incomplete understanding of the molecular pathogenesis of this deadly tumor. Areas covered: The present review article outlines the main studies and resulting discoveries on the molecular profiling of iCCA, with a special emphasis on the different techniques used for this purpose, the diagnostic and prognostic markers identified, as well as the genes and pathways that could be potentially targeted with innovative therapies. Expert commentary: Molecular profiling has led to the identification of distinct iCCA subtypes, characterized by peculiar genetic alterations and transcriptomic features. Targeted therapies against some of the identified genes are ongoing and hold great promise to improve the prognosis of iCCA patients.

Over-expression of microRNA-940 promotes cell proliferation by targeting GSK3β and sFRP1 in human pancreatic carcinoma

Increasing study reports that Wnt/β-catenin signaling pathway plays an essential role in numerous cancers growth, progression and metastasis. Aberrant miR-940 expression has been studied in gastric and breast cancer. However, the molecular mechanism of miR-940 enhancing proliferation and metastatic ability in human pancreatic carcinoma is far from to know. Real-time PCR was used to quantify miR-940 expression. Luciferase reporter assays here were performed to verify the activity of Wnt/β-catenin signaling pathway and targeting gene relationships, and immunofluorescence assay was applied to observe β-catenin expressed intensity. Bioinformatics analysis together with in vivo and vitro functional analysis indicated the potential targeting genes of miR-940. Specimens from 15 pairs of patients with human pancreatic carcinoma were involoved to confirm the relationship between miR-940 expression and the GSK3β/sFRP1 through real-time PCR and western blot assays. Bioinformatics combined with cell luciferase function researches determined the possible regulation of miR-940 on the 3'-UTR of the GSK3β and sFRP1 genes, resulting in the Wnt/β-catenin signaling activation. Further, miR-940 knockdown significantly recovered GSK3β and sFRP1 expression and relieved Wnt/β-catenin-mediated cell invasion, migration, metastasis and proliferation. The ectopic up-regulation of miR-940 significantly suppressed GSK3β/sFRP1 expression and promoted pancreatic carcinoma proliferation and invasion. Our study suggested mechanistic relationship between miR-940 and Wnt/β-catenin in the development and progression of pancreatic carcinoma through regulation of GSK3β and sFRP1.

MicroRNA-421 inhibits breast cancer metastasis by targeting metastasis associated 1

Dysregulation of microRNAs is involved in the initiation and progression of several human cancers, including breast cancer, as strong evidence of miRNAs acting as oncogenes or tumour suppressor genes has been found. This study was performed to investigate the biological functions of microRNA-421 (miR-421) in breast cancer and the underlying mechanisms. The expression level of miR-421 was detected in 50 pairs of surgical specimens and human breast cancer cell lines. The results showed that miR-421 is downregulated in breast cancer tissues and metastatic cell lines. In addition, the decrease in miR-421 levels was significantly associated with lymph node metastasis, recurrence/metastasis, or pTNM stage. Functions of miR-421 in cell migration and invasion were assessed through its silencing and overexpression. The results showed that miR-421 knockdown promotes invasion and metastasis in MCF-7 cells and its overexpression suppresses invasion and metastasis in MDA-MB-231 cells. The specific target genes of miR-421 were predicted by TargetScan algorithm and determined by dual luciferase reporter assay, quantitative reverse transcriptase PCR, and western blot analysis. miR-421 could suppress luciferase activity of the reporter containing 3'-untranslated region of metastasis associated 1 (MTA1), a potent oncogene. miR-421 overexpression or knockdown had no effect on the mRNA expression of MTA1, but it could modulate MTA1 protein level. Furthermore, MTA1 knockdown receded the effect of miR-421 inhibitor on invasion and metastasis of MCF-7 cells, and its overexpression receded the effect of miR-421 on invasion and metastasis of MDA-MB-231 cells. Our findings clearly demonstrate that miR-421 suppresses breast cancer metastasis by directly inhibiting MTA1 expression. The present study provides a new insight into the tumour suppressor roles of miR-421 and suggests that miR-421/MTA1 pathway is a putative therapeutic target in breast cancer.

Nuclear Receptors as Therapeutic Targets in Liver Disease: Are We There Yet?

Nuclear receptors (NR) are ligand-modulated transcription factors that play diverse roles in cell differentiation, development, proliferation, and metabolism and are associated with numerous liver pathologies such as cancer, steatosis, inflammation, fibrosis, cholestasis, and xenobiotic/drug-induced liver injury. The network of target proteins associated with NRs is extremely complex, comprising coregulators, small noncoding microRNAs, and long noncoding RNAs. The importance of NRs as targets of liver disease is exemplified by the number of NR ligands that are currently used in the clinics or in clinical trials with promising results. Understanding the regulation by NR during pathophysiological conditions, and identifying ligands for orphan NR, points to a potential therapeutic approach for patients with liver diseases. An overview of complex NR metabolic networks and their pharmacological implications in liver disease is presented here.

RNA-seq Analysis of δ9-Tetrahydrocannabinol-treated T Cells Reveals Altered Gene Expression Profiles That Regulate Immune Response and Cell Proliferation

Marijuana has drawn significant public attention and concern both for its medicinal and recreational use. Δ9-Tetrahydrocannabinol (THC), which is the main bioactive component in marijuana, has also been shown to possess potent anti-inflammatory properties by virtue of its ability to activate cannabinoid receptor-2 (CB-2) expressed on immune cells. In this study, we used RNA-seq to quantify the transcriptomes and transcript variants that are differentially regulated by THC in super antigen-activated lymph node cells and CD4(+) T cells. We found that the expressions of many transcripts were altered by THC in both total lymph node cells and CD4(+) T cells. Furthermore, the abundance of many miRNA precursors and long non-coding RNAs was dramatically altered in THC-treated mice. For example, the expression of miR-17/92 cluster and miR-374b/421 cluster was down-regulated by THC. On the other hand miR-146a, which has been shown to induce apoptosis, was up-regulated by THC. Long non-coding RNAs that are expressed from the opposite strand of CD27 and Appbp2 were induced by THC. In addition, THC treatment also caused alternative promoter usage and splicing. The functions of those altered transcripts were mainly related to immune response and cell proliferation.

microRNA-192 suppresses the expression of the farnesoid X receptor

Farnesoid X receptor (FXR, NR1H4) plays an important role in the regulation of bile acid homeostasis in liver and intestine and may exert protective effects against certain forms of cancer such as colon carcinoma. However, the role of FXR in cell growth regulation, apoptosis, and carcinogenesis is still controversial. Similar to FXR, microRNA-192 (miR-192) is mainly expressed in the liver and colon and plays an important role in the pathogenesis of colon carcinoma. In this study, we investigated the extent to which FXR is regulated by miR-192. Two in silico-predicted binding sites for miR-192-3p within the NR1H4-3' untranslated region (UTR) were examined in vitro by luciferase reporter assays. Wild-type and mutated forms of the NR1H4-3'UTR were subcloned into a pmirGLO vector and cotransfected into Huh-7 cells with miR-192-3p. To study the effects of miR-192 on the expression of FXR, FXR target genes and cell proliferation, Huh-7 and Caco-2 cells were transfected with miR-192-5p and -3p mimics or antagomirs. In addition, the correlation between FXR and miR-192 expression was studied by linear regression analyses in colonic adenocarcinoma tissue from 27 patients. MiR-192-3p bound specifically to the NR1H4-3'UTR and significantly decreased luciferase activity. Transfection with miR-192 led to significant decreases in NR1H4 mRNA and protein levels as well as the mRNA levels of the FXR-inducible bile acid transporters OSTα-OSTβ and OATP1B3. Significant inverse correlations were detected in colonic adenocarcinoma between NR1H4 mRNA and miR-192-3p expression. In summary, microRNA-192 suppresses the expression of FXR and FXR target genes in vitro and in vivo.

Polarized release of hepatic microRNAs into bile and serum in response to cellular injury and impaired liver function

BACKGROUND & AIMS

Extracellular microRNAs (miRNAs) in serum and bile are currently under intense investigation for biomarker purposes in liver disease. However, the directions and pathways by which miRNAs are released from hepatic cells remains largely unknown. Here, we investigated the release of hepatocyte and cholangiocyte-derived miRNAs (HDmiRs and CDmiRs) into blood and bile during various (patho)physiological hepatic conditions.

METHODS

MiRNA release was analysed using longitudinally collected tissue and paired bile and serum samples (n = 124) that were obtained from liver transplant recipients during follow-up.

RESULTS

Cell-type specificity of HDmiRs and CDmiRs was confirmed in liver and common bile duct biopsies (P < 0.001). Analysis of paired bile and serum samples showed up to 20-times higher miRNA-levels in bile compared to serum (P < 0.0001). Fractionation of bile showed the majority of miRNAs being present in the unpelletable supernatant, where protein conjunctions protect miRNAs against degradation (P < 0.0001). During episodes of liver injury and histologically proven rejection in liver transplant recipients, relative HDmiR-levels in bile decreased while its levels in serum increased (P ≤ 0.015). Simultaneously, relative CDmiR-levels in bile significantly increased, while their levels in serum decreased. Related to liver excretory function, a strong positive correlation was observed between HDmiR-122 levels and bilirubin excretion into bile (R = 0.694, P < 0.0001), whereas CDmiRs showed an inverse correlation (P < 0.05).

CONCLUSION

During impaired excretory function and injury, the liver shows polarized release of extracellular HDmiRs and CDmiRs. This sheds new light on the biology of hepatic miRNA release which is relevant for the interpretation of hepatic miRNAs as biomarkers.

MicroRNA-421 induces hepatic mitochondrial dysfunction in non-alcoholic fatty liver disease mice by inhibiting sirtuin 3

BACKGROUND AND AIM

Mitochondrial dysfunction plays a major role in critical initiating or propagating events in nonalcoholic fatty liver disease (NAFLD), but its pathogenesis remains obscure. Recently, microRNAs have been found to affect oxidant stress and lipid metabolism. In this study, we elucidated the functions of microRNA-421 in the development of NAFLD and identified its potential targets.

METHODS

An experimental model for the study of NAFLD was constructed by feeding a high fat diet to C57BL/6J mice. Differentially expressed miRNA in livers of NAFLD mice compared with controls were identified by high-throughput sequencing. Relative repression of luciferase expression standardized to a transfection control was analyzed by luciferase reporter assays.

RESULTS

The microRNA profiling presented that microRNA-421 expression was significantly upregulated in hepatic tissues of NAFLD model mouse. The sirtuin 3 was identified as a functionally relevant target of microRNA-421. The microRNA-421 acts upstream of SIRT3/FOXO3 pathway in modulation the oxidant stress and lipid metabolism. Overexpression of microRNA-421 decreased SIRT3 and FOXO3 protein levels, and then led to MnSOD and CAT decrease, the downstream targets of SIRT3/FOXO3 pathway. On the contrary, suppression of microRNA-421 had adverse effects on performance of celluar oxidative damage.

CONCLUSIONS

Regulating or inhibiting hepatic microRNA-421 could decrease celluar oxidative damage and contribute to therapeutic potential in NAFLD.

The role of miRNAs in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a devastating malignancy with high mortality, in part due to the combination of late presentation, significant diagnostic challenges and limited effective treatment options. Late presentation and diagnosis contribute to the high mortality in CCA and there is an urgent unmet need for diagnostic and prognostic biomarkers to facilitate early diagnosis and treatment stratification to improve clinical outcomes. MiRs are small ncRNA molecules that regulate gene expression and modulate both tumor suppressive and oncogenic pathways. They have a well-defined role in carcinogenesis, including CCA. In this review, we outline the evidence for MiRs in the pathogenesis of CCA and their potential utility as diagnostic and prognostic biomarkers to guide clinical management.

Farnesoid X receptor associates with β-catenin and inhibits its activity in hepatocellular carcinoma

The association between the temporal activation of Wnt/β-catenin pathway and the spontaneous hepatocellular carcinoma (HCC) development in Farnesoid X receptor (FXR) knockout mice is not well understood. We found that Huh7 cells depleted with FXR by RNAi showed enhanced cell growth, migration and invasion in vitro and accelerated tumor xenografts formation in nude mice. And these phenotypes were attenuated by simultaneous knockdown of β-catenin with RNAi. Furthermore, we identified that FXR could bind with β-Catenin through AF1 domain, and disrupt the assembly of the core β-Catenin/TCF4 complex. Activation of FXR attenuated the DNA-binding activity of β-Catenin/TCF4, and subsequently, its targeting gene-cyclin D1 expression. Importantly, FXR expression was markedly reduced in human HCC, an event which correlated with aberrant activation of β-Catenin. These data identified FXR as a negative regulator of HCC development through direct suppression of Wnt/β-catenin pathway.

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.

A transcriptional target of androgen receptor, miR-421 regulates proliferation and metabolism of prostate cancer cells

Prostate cancer is one of the most common malignancies, and microRNAs have been recognized to be involved in tumorigenesis of various kinds of cancer including prostate cancer (PCa). Androgen receptor (AR) plays a core role in prostate cancer progression and is responsible for regulation of numerous downstream targets including microRNAs. This study identified an AR-repressed microRNA, miR-421, in prostate cancer. Expression of miR-421 was significantly suppressed by androgen treatment, and correlated to AR expression in different prostate cancer cell lines. Furthermore, androgen-activated AR could directly bind to androgen responsive element (ARE) of miR-421, as predicted by bioinformatics resources and demonstrated by ChIP and luciferase reporter assays. In addition, over-expression of miR-421 markedly supressed cell viability, delayed cell cycle, reduced glycolysis and inhibited migration in prostate cancer cells. According to the result of miR-421 target genes searching, we focused on 4 genes NRAS, PRAME, CUL4B and PFKFB2 based on their involvement in cell proliferation, cell cycle progression and metabolism. The expression of these 4 downstream targets were significantly repressed by miR-421, and the binding sites were verified by luciferase assay. Additionally, we explored the expression of miR-421 and its target genes in human prostate cancer tissues, both in shared microarray data and in our own cohort. Significant differential expression and inverse correlation were found in PCa patients.

Isoliquiritigenin as a cause of DNA damage and inhibitor of ataxia-telangiectasia mutated expression leading to G2/M phase arrest and apoptosis in oral squamous cell carcinoma

BACKGROUND

Isoliquiritigenin (ISL), a natural compound extracted from licorice, has chemopreventive and antitumor activities. The purpose of this study was to investigate the anticancer effect of ISL on human oral squamous cell carcinoma (OSCC).

METHODS

The anti-OSCC effects of ISL were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test, flow cytometry, reverse transcription-polymerase chain reaction, Western blotting, promoter activity, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, malignant phenotype analysis, microRNA, and xenografting.

RESULTS

ISL induced OSCC cell cycle G2/M phase arrest, apoptosis, and DNA damage. However, the DNA repair-associated ataxia telangiectasia mutated (ATM) and phospho-ATM were downregulated, ATM mRNA remained unchanged, and the downstream signals were inhibited. ATM recovered when the caspase activity was blocked by Z-DVED-FMK. A low dose of ISL inhibited OSCC malignancy in vitro and reduced the tumor size in vivo.

CONCLUSION

ATM was cleaved by ISL-activated caspase, thus inhibiting DNA repair in OSCC cells. Therefore, ISL is a promising chemopreventive agent against oral cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E360-E371, 2016.

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.

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.

Pathogenesis of cholangiocarcinoma: From genetics to signalling pathways

Cholangiocarcinoma (CCA) is a malignant tumour of bile duct epithelial cells with dismal prognosis and rising incidence. Chronic inflammation resulting from liver fluke infection, hepatitis and other inflammatory bowel diseases is a major contributing factor to cholangiocarcinogenesis, likely through accumulation of serial genetic and epigenetic alterations resulting in aberration of oncogenes and tumour suppressors. Recent studies making use of advances in high-throughput genomics have revealed the genetic landscape of CCA, greatly increasing our understanding of its underlying biology. A series of highly recurrent mutations in genes such as TP53, KRAS, SMAD4, BRAF, MLL3, ARID1A, PBRM1 and BAP1, which are known to be involved in cell cycle control, cell signalling pathways and chromatin dynamics, have led to investigations of their roles, through molecular to mouse modelling studies, in cholangiocarcinogenesis. This review focuses on the landscape genetic alterations in CCA and its functional relevance to the formation and progression of CCA.

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.

Diagnostic Relevance of microRNAs in Other Body Fluids Including Urine, Feces, and Saliva

Beside blood-borne circulating miRNAs, miRNAs have been identified in other body fluid and excrements including stool, bile, saliva, and urine. Given the direct link of these body fluids to certain organs, their analysis for potential diagnostic miRNA markers is plausible. Several independent findings underline the potential utility of stool-derived miRNAs in the diagnosis of colorectal and pancreatic cancer. Given the difficulties in the diagnosis of cholangiocellular cancer, biliary miRNAs might be envisaged as useful markers. Several miRNAs have been identified in the saliva that could be associated with diseases, including tumors of the oral cavity. The urinary pool of miRNAs could be exploited for the diagnosis of urinary tract diseases and some appear to enable early diagnosis. In this chapter, we present findings supporting the potential diagnostic utility of fecal, biliary, salivary, and urinary miRNAs focusing mostly on tumors.

FXR and liver carcinogenesis

Farnesoid X receptor (FXR) is a member of the nuclear receptor family and a ligand-modulated transcription factor. In the liver, FXR has been considered a multi-functional cell protector and a tumor suppressor. FXR can suppress liver carcinogenesis via different mechanisms: 1) FXR maintains the normal liver metabolism of bile acids, glucose and lipids; 2) FXR promotes liver regeneration and repair after injury; 3) FXR protects liver cells from death and enhances cell survival; 4) FXR suppresses hepatic inflammation, thereby preventing inflammatory damage; and 5) FXR can directly increase the expression of some tumor-suppressor genes and repress the transcription of several oncogenes. However, inflammation and epigenetic silencing are known to decrease FXR expression during tumorigenesis. The reactivation of FXR function in the liver may be a potential therapeutic approach for patients with liver cancer.

MiR-421, miR-155 and miR-650: emerging trends of regulation of cancer and apoptosis

It is becoming progressively more understandable that between transcription and translation there lies another versatile regulator that quantitatively controls the expression of mRNAs. Identification of miRNAs as key regulators of wide ranging signaling cascades and modulators of different cell-type and context dependent activities attracted basic and clinical scientists to study modes and mechanisms in details. In line with this approach overwhelmingly increasing in vivo and in vitro studies are deepening our understanding regarding miR-421, mir-155 and miR-650 mediated regulation of cellular activities. We also attempt to provide an overview of long non coding RNAs.

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.

Downregulation of tumor suppressor menin by miR-421 promotes proliferation and migration of neuroblastoma

Neuroblastoma, featured by a high rate of spontaneous remissions, is the most common extra-cranial solid tumor in infants and children. Numerous reports have demonstrated that MicroRNAs (miRNAs) play essential roles in cancer progression, including cell proliferation, apoptosis, invasion, metastasis and angiogenesis. miR-421 functions as an onco-miR in some malignancies. However, its role in neuroblastoma remains poorly understood. In the present study, we found that miR-421 was increased in neuroblastoma tissues compared with matched adjacent normal tissues. Forced overexpression of miR-421 substantially enhanced cell proliferation, cell-cycle progression, migration, and invasion of neuroblastoma cells. At the molecular level, tumor suppressor menin was found to be a target of miR-421. Furthermore, downregulation of menin by small interfering RNA oligos exhibited similar effects with overexpression of miR-421. On the other hand, overexpression of menin partially reversed the proliferative effects of miR-421 in neuroblastoma cells. Collectively, miR-421 may promote neuroblastoma cell growth and motility partially by targeting menin.