MicroRNA-21 is overexpressed in human cholangiocarcinoma and regulates programmed cell death 4 and tissue inhibitor of metalloproteinase 3

Meta-analysis of microarrays: diagnostic value of microRNA-21 as a biomarker for lung cancer

BACKGROUND

MicroRNA-21 (miR-21) has previously been demonstrated as a potential biomarker in diagnosis of various human tumors. This meta-analysis was performed to evaluate the possibility of miR-21 as a biomarker for early detection of lung cancer.

METHODS

Relevant lung cancer-related miRNA microarray datasets were collected from the NCBI Gene Expression Omnibus (GEO) database and EBI ArrayExpress database up to February 2014. Quality control of the output data was estimated using Limma package and ExiMiR package in R. Standardized mean difference (SMD) with 95% confidence intervals (CIs) from selected datasets was pooled. Heterogeneity was assessed using Cochran's Q test and the I2 statistic, and a p value <0.0.05 or I2 >50% was defined as significant heterogeneity. Furthermore, sensitivity analysis was conducted to evaluate the stability of the pooled results. Four miRNA datasets (GSE24704, GSE17681, GSE27486 and GSE40738) from blood samples were selected, including 153 lung cancer patients and 109 healthy people.

RESULTS

The pooled results generated by random-effects model revealed that no significant difference was observed between case and control groups (SMD = 0.58; 95% CI, -0.04 to 1.19; p = 0.07) with significant heterogeneity (p = 0.0032, I2 = 78.2%; p = 0.06). Sensitivity analysis indicated that the results of the meta-analysis were stable.

CONCLUSIONS

MiR-21 expression levels in whole blood and peripheral blood cells did not show significant differences between lung cancer patients and healthy controls, and it might be ineffective to measure miR-21 expression to achieve an early diagnosis of lung cancer.

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.

Platelet miRNAs and cardiovascular diseases

Activated platelets play a critical role in the acute complications of atherosclerosis that cause life-threatening ischemic events at late stages of the disease. The miRNAs are a novel class of small, non-coding RNAs that play a significant role in both inflammatory and cardiovascular diseases. The miRNAs are known to be present in platelets and exert important regulatory functions. Here we systematically examine the genes that are regulated by platelet miRNAs (miRNA-223,miRNA-126,miRNA-21, miRNA-24 and miRNA-197) and the association with cardiovascular disease risks. Platelet-secreted miRNAs could be novel biomarkers associated with cardiovascular diseases.

Genetics of Opisthorchis viverrini-related cholangiocarcinoma

PURPOSE OF REVIEW

We review the genetic, epigenetic and transcriptional landscape of liver fluke (Opisthorchis viverrini, Ov)-related cholangiocarcinoma (CCA). Its distinct alterations, as compared with non-Ov-related CCA may help shed light on its underlying molecular mechanisms.

RECENT FINDINGS

Recent whole-exome and targeted sequencing not only confirmed frequent mutations in known CCA-related genes including TP53 (44%), KRAS (16.7%) and SMAD4 (16.7%), but also revealed mutations in novel CCA-related genes associated with chromatin remodeling [BAP1 (2.8%), ARID1A (17.6%), MLL3 (13%) and IDH1/2 (2.8%)], WNT signaling [RNF43 (9.3%) and PEG3 (5.6%)] and KRAS/G protein signaling [GNAS (9.3%) and ROBO2 (9.3%)]. Interestingly, there is a significant difference in the frequency of mutated genes between Ov-related CCA and non-Ov-related CCA, such as p53 and IDH1/2, reflecting the impact of cause on pathogenesis. Altered DNA methylation and transcriptional profiles associated with xenobiotic metabolism and pro-inflammatory responses were also found in Ov-related CCA.

SUMMARY

Liver fluke-induced chronic inflammation plays a crucial role in cholangiocarcinogenesis, resulting in distinct signatures of genetic, epigenetic and transcriptional alterations. These alterations, when contrasted with non-Ov-related CCA, indicate a unique pathogenic process in Ov-related CCA and may have potential clinical implications on diagnostics, therapeutics and prevention.

MicroRNA-21 regulates biological behavior by inducing EMT in human cholangiocarcinoma

MicroRNAs (miRNAs) have recently been demonstrated to play a crucial role in malignant progression including differentiation, proliferation, metastasis and invasion, MicroRNA-21 (mir-21) also has been reported to have association with tumor invasion and metastasis in some tumors including cholangiocarcinoma (CCA). In this study, we further investigated the association of mir-21 with CCA biological behavior by transfecting miR-21 mimics or mir-21 inhibitor into QBC939 and RBE cells accompanied with the tumor xenografts experiment. Results indicated that over-expression of miR-21 significantly promoted cell migration, invasion and xenografts growth, whereas contrary phenomenon was observed in mir-21 inhibitor group. Furthermore, we explored the expression of EMT related proteins in CCA cells and tumor xenografts. Results showed that E-cadherin was decreased and N-cadherin, Vimentin were up-regulated significantly when miR-21 was over-expressed. In conclusion, microRNA-21 is crucial for CCA carcinogenesis and metastasis, which could induce EMT process, thereby promote the invasion and migration of CCA cells. These findings may provide new strategy for prevention and treatment of CCA in the future.

Ectopic expression of miR-494 inhibited the proliferation, invasion and chemoresistance of pancreatic cancer by regulating SIRT1 and c-Myc

Recent researches demonstrate that microRNAs (miRNAs) are deregulated in numerous cancers and involved in tumorigenesis, whereas their influences on pancreatic cancer (PC) still need further elucidation. The present research revealed that miR-494 was significantly decreased in PC cell lines and tissues. Functional study showed that overexpressed miR-494 could remarkably inhibit proliferation of PC cells both in vitro and in vivo, which was due to induction of apoptosis, G1-phase arrest and senescence. Moreover, upregulated miR-494 significantly prohibited invasion of PC cells. Meanwhile, both c-Myc and SIRT1 was identified as targets of miR-494 through dual luciferase assay and further confirmed by the reverse correlation between miR-494 and c-Myc/SIRT1 in PC samples. Furthermore, co-transfection with c-Myc-RNAi and SIRT1-RNAi synergistically reduced c-Myc and SIRT1 expression, and inhibited proliferation of PC, which simulated the effects of miR-494 overexpression. On the contrary, co-overexpression of c-Myc and SIRT1 effectively rescued inhibition of overexpressed miR-494 on PC cells. The clinical characteristics further revealed that low miR-494 correlated with larger tumor size, late tumor node metastasis stage, lymphatic invasion, distant metastasis and poor prognosis. In conclusion, the present study indicated that miR-494 might serve as predictor and inhibitor in PC by directy downregulating the loop of c-Myc and SIRT1.

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.

miR-21 Inhibition Reduces Liver Fibrosis and Prevents Tumor Development by Inducing Apoptosis of CD24+ Progenitor Cells

miR-21 is upregulated in hepatocellular carcinoma and intrahepatic cholangiocarcinoma, where it is associated with poor prognosis. Here, we offer preclinical evidence that miR-21 offers a therapeutic and chemopreventive target in these liver cancers. In mice with hepatic deletion of Pten, anti-miR-21 treatment reduced liver tumor growth and prevented tumor development. These effects were accompanied with a decrease in liver fibrosis and a concomitant reduction of CD24(+) liver progenitor cells and S100A4(+) cancer-associated stromal cells. Notch2 inhibition also occurred in tumors following anti-miR-21 treatment. We further showed that miR-21 is necessary for the survival of CD24(+) progenitor cells, a cellular phenotype mediated by Notch2, osteopontin, and integrin αv. Our results identify miR-21 as a key regulator of tumor-initiating cell survival, malignant development, and growth in liver cancer, highlighting the role of CD24(+) cells in the expansion of S100A4(+) cancer-associated stromal cells and associated liver fibrosis.

Identification of a novel microRNA signature associated with intrahepatic cholangiocarcinoma (ICC) patient prognosis

Background

The clinical significance of microRNAs (miRNAs) in intrahepatic cholangiocarcinoma (ICC) is unclear. The objective of this study is to examine the miRNA expression profiles and identify a miRNA signature for the prognosis of ICC.

Methods

Using a custom microarray containing 1,094 probes, the miRNA expression profiles of 63 human ICCs and nine normal intrahepatic bile ducts (NIBD) were assessed. The miRNA signatures were established and their clinical significances in ICC were analyzed. The expression levels of some miRNAs were verified by quantitative real-time RT-PCR (qRT-PCR).

Results

Expression profile analysis showed 158 differentially expressed miRNAs between ICC and NIBD, with 77 up-regulated and 81 down-regulated miRNAs. From the 158 differentially expressed miRNAs, a 30-miRNA signature consisting of 10 up-regulated and 20 down-regulated miRNAs in ICC was established for distinguishing ICC from NIBD with 100% accuracy. A separate 3-miRNA signature was identified for predicting prognosis in ICC. Based on the 3-miRNA signature, a formula was constructed to compute a risk score for each patient. The patients with high-risk had significantly lower overall survival and disease-free survival than those with low-risk. The expression level of these three miRNAs detected by microarray was verified by qRT-PCR. Multivariate analysis indicated that the 3-miRNA signature was an independent prognostic predictor.

Conclusions

In this study, a 30-miRNA signature for distinguishing ICC from NIBD, and a 3-miRNA signature for evaluating prognosis of ICC were established, which might be able to serve as biomarkers for prognosis of ICC. Further studies focusing on these miRNAs may shed light on the mechanisms associated with ICC pathogenesis and progression.

MiR-21/RASA1 axis affects malignancy of colon cancer cells via RAS pathways

AIM

To determine how the oncogene miR-21 regulates the RAS signaling pathways and affects colon cancer cell behaviors.

METHODS

RAS p21 GTPase activating protein 1 (RASA1) protein expression in six colon cancer cell lines was assessed by Western blot. Colon cancer RKO cells were chosen for transfection because they are KRAS wild type colon cancer cells whose RASA1 expression is significantly decreased. RKO cells were transfected with vectors overexpressing or down-regulating either miR-21 or RASA1. Furthermore, a luciferase reporter assay was used to determine whether RASA1 is a gene target of miR-21. Then, changes in mRNA and protein levels of RASA1, RAS-GTP, and other components of the RAS signaling pathways were assessed in transfected RKO cells by real-time quantitative reverse transcription-polymerase chain reaction, Western blot and immunoprecipitation. Finally, cell proliferation, apoptosis, invasion, and tumor formation ability were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye assay, flow cytometry, transwell assay, and animal experiment, respectively.

RESULTS

RASA1 protein levels were significantly decreased in RKO cells compared with the other 5 colon cancer cell lines, and RASA1 was confirmed as a target gene of miR-21. Interestingly, RASA1 mRNA and protein levels in pre-miR-21-LV (up-regulation of miR-21) cells were lower than those in anti-miR-21-LV (down-regulation of miR-21) cells (P < 0.05). In addition, pre-miR-21-LV or siRASA1 (down-regulation of RASA1) cells showed higher cell proliferation, reduced apoptosis, increased expression of RAS-GTP, p-AKT, Raf-1, KRAS, and p-ERK1/2, and higher invasion and tumor formation ability, compared with control, anti-miR-21-LV or pcDNA3.1-RASA1 (up-regulation of RASA1) cells (P < 0.05).

CONCLUSION

RASA1 is a target gene of miR-21, which promotes malignant behaviors of RKO cells through regulation of RASA1 expression.

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.

Circulating microRNAs as noninvasive diagnostic biomarkers of liver disease in children with cystic fibrosis

OBJECTIVES

Cystic fibrosis liver disease (CFLD), resulting from progressive hepatobiliary fibrosis, causes significant morbidity and mortality in up to 20% of children with cystic fibrosis (CF). Both pathogenesis and early detection of CFLD are elusive. Current diagnostic procedures to detect early CFLD and stage fibrosis severity are inadequate. Recent studies highlight a role for microRNAs (miRNAs) in the pathogenesis of many diseases and have suggested that serum miRNAs could be used as diagnostic biomarkers.

METHODS

We profiled circulating serum miRNA levels in patients with CFLD (n = 52), patients with CF without liver disease (CFnoLD, n = 30), and non-CF pediatric controls (n = 20). Extracted RNA was subjected to polymerase chain reaction (PCR) array of 84 miRNAs detectable in human serum. Seven candidate miRNAs identified were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR), normalizing data to geNorm-determined stable reference genes, miR-19b and miR-93.

RESULTS

miR-122 was significantly elevated in patients with CFLD versus patients with CFnoLD and controls (P < 0.0001). miR-25 (P = 0.0011) and miR-21 (P = 0.0133) were elevated in patients with CFnoLD versus patients with CFLD and controls. CFLD was discriminated by both miR-122 (area under the curve [AUC] 0.71, P = 0.002) and miR-25 (AUC 0.65, P = 0.026). Logistic regression combining 3 miRNAs (-122, -25, -21) was greatly predictive of detecting CFLD (AUC 0.78, P < 0.0001). A combination of 6 miRNAs (-122, -21, -25, -210, -148a, -19a) distinguished F0 from F3-F4 fibrosis (AUC 0.73, P = 0.04), and miR-210 combined with miR-22 distinguished F0 fibrosis from any fibrosis, that is, F1-F4 (AUC 0.72, P = 0.02).

CONCLUSIONS

These data provide the first evidence of changes to circulating miRNA levels in CF, suggesting that serum-based miRNA analysis may complement and extend current CFLD screening strategies with potential to predict early hepatic fibrosis.

MiR-21 enhances melanoma invasiveness via inhibition of tissue inhibitor of metalloproteinases 3 expression: in vivo effects of MiR-21 inhibitor

Metastatic melanoma is the most aggressive form of this cancer. It is important to understand factors that increase or decrease metastatic activity in order to more effectively research and implement treatments for melanoma. Increased cell invasion through the extracellular matrix is required for metastasis and is enhanced by matrix metalloproteinases (MMPs). Tissue inhibitor of metalloproteinases 3 (TIMP3) inhibits MMP activity. It was previously shown by our group that miR-21, a potential regulator of TIMP3, is over-expressed in cutaneous melanoma. It was therefore hypothesized that increased levels of miR-21 expression would lead to decreased expression of TIMP3 and thereby enhance the invasiveness of melanoma cells. miR-21 over-expression in the melanoma cell lines WM1552c, WM793b, A375 and MEL 39 was accomplished via transfection with pre-miR-21. Immunoblot analysis of miR-21-overexpressing cell lines revealed reduced expression of TIMP3 as compared to controls. This in turn led to a significant increase in the invasiveness of the radial growth phase cell line WM1552c and the vertical growth phase cell line WM793b (p < 0.05), but not in the metastatic cell lines A375 or MEL 39. The proliferation and migration of miR-21 over-expressing cell lines was not affected. Reduced expression of TIMP3 was achieved by siRNA knockdown and significantly enhanced invasion of melanoma cell lines, mimicking the effects of miR-21 over-expression. Treatment of tumor cells with a linked nucleic acid antagomir to miR-21 inhibited tumor growth and increased tumor expression of TIMP3 in vivo in 01B74 Athymic NCr-nu/nu mice. Intra-tumoral injections of anti-miR-21 produced similar effects. This data shows that increased expression of miR-21 enhanced the invasive potential of melanoma cell lines through TIMP3 inhibition. Therefore, inhibition of miR-21 in melanoma may reduce melanoma invasiveness.

Possible role of tocopherols in the modulation of host microRNA with potential antiviral activity in patients with hepatitis B virus-related persistent infection: a systematic review

Hepatitis B virus (HBV) infection represents a serious global health problem and persistent HBV infection is associated with an increased risk of cirrhosis, hepatocellular carcinoma and liver failure. Recently, the study of the role of microRNA (miRNA) in the pathogenesis of HBV has gained considerable interest as well as new treatments against this pathogen have been approved. A few studies have investigated the antiviral activity of vitamin E (VE) in chronic HBV carriers. Herein, we review the possible role of tocopherols in the modulation of host miRNA with potential anti-HBV activity. A systematic research of the scientific literature was performed by searching the MEDLINE, Cochrane Library and EMBASE databases. The keywords used were 'HBV therapy', 'HBV treatment', 'VE antiviral effects', 'tocopherol antiviral activity', 'miRNA antiviral activity' and 'VE microRNA'. Reports describing the role of miRNA in the regulation of HBV life cycle, in vitro and in vivo available studies reporting the effects of VE on miRNA expression profiles and epigenetic networks, and clinical trials reporting the use of VE in patients with HBV-related chronic hepatitis were identified and examined. Based on the clinical results obtained in VE-treated chronic HBV carriers, we provide a reliable hypothesis for the possible role of this vitamin in the modulation of host miRNA profiles perturbed by this viral pathogen and in the regulation of some cellular miRNA with a suggested potential anti-HBV activity. This approach may contribute to the improvement of our understanding of pathogenetic mechanisms involved in HBV infection and increase the possibility of its management and treatment.

A meta-analysis of microRNA expression in liver cancer

MicroRNA (miRNA) played an important role in the progression of liver cancer and its diagnostic and prognostic values have been frequently studied. However, different microarray techniques and small sample size led to inconsistent findings in previous studies. We performed a comprehensive meta-analysis of a total of 357 tumor and 283 noncancerous samples from 12 published miRNA expression studies using robust rank aggregation method. As a result, we identified a statistically significant meta-signature of five upregulated (miR-221, miR-222, miR-93, miR-21 and miR-224) and four downregulated (miR-130a, miR-195, miR-199a and miR-375) miRNAs. We then conducted miRNA target prediction and pathway enrichment analysis to find what biological process these miRNAs might affect. We found that most of the pathways were frequently associated with cell signaling and cancer pathogenesis. Thus these miRNAs may involve in the onset and progression of liver cancer and serve as potential diagnostic and therapeutic targets of this malignancy.

MicroRNA-144 suppresses cholangiocarcinoma cell proliferation and invasion through targeting platelet activating factor acetylhydrolase isoform 1b

Background

MicroRNAs are endogenous non-coding RNAs that play important roles in a wide variety of biological processes such as apoptosis, development, aging and cancer. The aberrant expression of miRNAs may contribute to phenotypic features of malignant cells, including resistance to chemotherapy. However, in cholangiocarcinoma (CCA) the correlation between miRNAs and their potential roles in CCA remains unclear.

Methods

MicroRNA profiles were analyzed in three pairs of CCA tumor specimens and non-tumorous-paired biliary tissues using Agilent microRNA microarrays. Expression of selected miRNAs was further confirmed in CCA tissues and CCA cell lines by q-PCR. The effects of miR-144 were evaluated by cell proliferation, migration, transwell, and tumorigenicity assays. Expression of LIS1 (platelet-activating factor acetylhydrolase isoform 1b) was assessed in CCA specimens and CCA cell lines by q-PCR and western blot. Targeting of LIS1 by miR-144 was confirmed by luciferase reporter assays.

Results

We found that the expression of 28 miRNAs in CCA tissues was significantly different from their corresponding adjacent normal bile duct tissues. We focused on miR-144 which was significantly down-regulated in CCA tissues. Reintroduction of miR-144 in CCA cell lines not only inhibited cell growth, but also significantly reduced cell migration and invasion capacities compared with controls. Luciferase assays and western blots verified LIS1 as a direct target of miR-144, and knocking-down LIS1 has similar effect with overexpression of miR-144 in CCA cell lines. Moreover, overexpression of miR-144 expression could suppress tumor growth in nude mice.

Conclusions

Our results showed that miR-144 was reduced in CCA tissues and suggested that miR-144 may be an essential suppresser of CCA cell proliferation and invasion through targeting LIS1.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-917) contains supplementary material, which is available to authorized users.

The clinical utility of microRNA-21 as novel biomarker for diagnosing human cancers

With cancer being a major cause of death worldwide, microRNAs (miRNAs) have been investigated as novel and non-invasive biomarkers for cancer diagnosis. Recently, microRNA-21 (miR-21) attracts much attention for its aberrant expression and has been widely studied in various cancers. However, the inconsistent results from studies make it hard to evaluate the diagnostic value of miR-21 in cancer diagnosis, which lead us to conduct this meta-analysis. We conducted a comprehensive literature search in the Medline, Embase, PubMed, CNKI, and Web of Science before July 1, 2014. STATA 12.0 software was used for calculation and statistical analysis. The pooled sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR), and diagnostic odds ratio (DOR) were used to assess the diagnostic performance of miR-21 for cancers. Seventy-three studies in 60 articles were involved in this meta-analysis, with a total of 4684 patients with cancer and 3108 controls. The overall parameters were calculated from all the included studies: sensitivity of 0.78 (95% confidence interval (CI) 0.74-0.81), specificity of 0.83 (95% CI 0.80-0.86), PLR of 4.5 (95% CI 3.8-5.4), NLR of 0.27 (95% CI 0.23-0.32); DOR of 17 (95% CI 12-23), and area under the curve (AUC) of 0.88 (95% CI 0.84-0.90). In addition, we performed subgroup analyses based on ethnicity, cancer types, and sample types. Results from subgroup analysis showed that cancer types and sample types were the sources of heterogeneity in our meta-analysis. The overall diagnostic value of miR-21 is not very high for cancer diagnosis; however, it is affected significantly by the types of cancer and specimen. MiR-21 has a relatively high diagnostic value for detecting breast cancer, and miR-21 assays based on plasma, serum, and tissue achieved relatively higher accuracy.

Targeting miR-21 sensitizes Ph+ ALL Sup-b15 cells to imatinib-induced apoptosis through upregulation of PTEN

Philadelphia chromosome positive (Ph+) acute lymphoblastic leukemia (ALL) cells are insensitive to BCR-ABL tyrosine kinase inhibitor imatinib, the underlying mechanisms remain largely unknown. Here, we showed that imatinib treatment induced significant upregulation of miR-21 and downregulation of PTEN in Ph+ ALL cell line Sup-b15. Transient inhibition of miR-21 resulted in increased apoptosis, PTEN upregulation and AKT dephosphorylation, whereas ectopic overexpression of miR-21 further conferred imatinib resistance. Furthermore, knockdown of PTEN protected the cells from imatinib-induced apoptosis achieved by inhibition of miR-21. Additionally, PI3K inhibitors also notably enhanced the effects of imatinib on Sup-b15 cells and primary Ph+ ALL cells similar to miR-21 inhibitor. Therefore, miR-21 contributes to imatinib resistance in Ph+ ALL cells and antagonizing miR-21 demonstrates therapeutic potential by sensitizing the malignancy to imatinib therapy.

Raf kinase inhibitor protein inhibits cholangiocarcinoma cell metastasis by downregulating matrix metalloproteinase 9 and upregulating tissue inhibitor of metalloproteinase 4 expression

Cholangiocarcinoma cells originate in the biliary epithelium. The cells easily metastasize and cause relapse. The effect of Raf kinase inhibitor protein (RKIP) on the biological behavior of cholangiocarcinoma cells is not yet clear. In the present study, RKIP and cytokeratin 19 expression was detected in the extrahepatic tissues of cholangiocarcinoma patients by immunohistochemistry. RKIP small interfering (si)RNA or an RKIP-overexpressing adenoviral vector were used to infect the human cholangiocarcinoma RBE cell line. RKIP protein or gene expression was analyzed by western blotting or reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively. The cells were assayed for proliferation, apoptosis, invasion and migration. Matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 4 (TIMP-4) mRNA was assayed by RT-qPCR. RKIP expression was reduced in the extrahepatic cholangiocarcinoma tumor compared with the adjacent uninvolved peritumoral tissues. The current study revealed that RKIP expression was positively correlated with cell differentiation, but negatively correlated with lymph node or distant metastasis (P<0.05). RKIP siRNA treatment promoted RBE cell invasion, but RKIP overexpression prevented cell invasion. In the pDC316-siRNA recombinant vector group, the cells migrated more quickly compared with the siRNA-negative control group, and in the RKIP-expressing adenoviral vector group, the cells migrated more slowly compared with the adenoviral negative control group. RKIP inhibited the invasive and metastatic ability of the cholangiocarcinoma cell line, RBE, by downregulating MMP-9 and upregulating TIMP-4 mRNA expression. RKIP is negatively associated with cholangiocarcinoma distant metastasis and prevents cholangiocarcinoma cell metastasis through downregulating MMP-9 expression and upregulating TIMP-4 expression.

The significance of genetics for cholangiocarcinoma development

Cholangiocarcinoma (CCA) is a rare malignancy of the liver, arising from bile ducts. The incidence is increasing worldwide, but the prognosis has remained dismal and virtually unchanged in the past 30 years. Although several risk factors have been associated with the development of this cancer, none of them are normally identified in most patients. Diagnosis in advanced stages of the disease and limited therapeutic options contribute to poor survival rates. The recent analysis of genetic and epigenetic alterations occurring in CCA has shed new light in the understanding of the molecular mechanisms leading to the malignant transformation of biliary cells. Further studies in this direction may foster new diagnostic, prognostic and therapeutic approaches. This review provides a global overview of recent advances in CCA and describes the most important genetic mutations and epigenetic alterations so far reported in CCA.

MicroRNAs in liver cancer: a model for investigating pathogenesis and novel therapeutic approaches

MicroRNAs (miRNAs) constitute a large class of short RNAs (e.g., 20-24 nucleotides in length), whose main function is to posttranscriptionally regulate the expression of protein-coding genes. Their importance in tumorigenesis has been demonstrated over the past decade, and correspondingly, they have emerged as potential therapeutic molecules and targets. Liver cancer is one of the most common neoplastic diseases worldwide, and it currently has a poor prognosis owing to largely ineffective therapeutic options. Liver cancer is also an excellent model for testing miRNA-based therapy approaches as it can be easily targeted with the systemic delivery of oligonucleotides. In recent years, the role of miRNAs in hepatocellular carcinoma (HCC) has been established with molecular studies and the development of animal models. These studies have also provided the basis for evaluating the therapeutic potential of miRNAs, or anti-miRNAs. In general, the safety of miRNAs has been proven and antitumor activity has been observed. Moreover, because of the absence or presence of mild side effects, the prophylactic use of miRNA-based approaches may be foreseen.

Molecular pathogenesis of intrahepatic cholangiocarcinoma

Cholangiocarcinoma (CCA) is an orphan cancer of the hepatobiliary tract, the incidence of which has increased in the past decade. The molecular pathogenesis of this treatment-refractory disease is poorly understood. Desmoplasia is a key causal feature of CCA; however, a majority of tumors develop with no apparent etiological background. The impact of the stromal compartment on tumor progression as well as resistance to therapy is in vogue, and the epithelial-stromal crosstalk may present a target for novel treatment strategies. As such, the complexity of tumor cellularity and the molecular mechanisms underlying the diversity of growth patterns of this malignancy remain a clinical concern. It is crucial to advance our present understanding of the molecular pathogenesis of CCA to improve current clinical strategies and patient outcome. This will facilitate the delineation of patient subsets and individualization for precision therapies. Many questions persevere as to the evolutionary process and cellular origin of the initial transforming event, the context of intratumoral plasticity and the causal driver action. Next-generation sequencing has begun to underline the persistent alterations, which may be the trigger of acquired drug resistance, and the cause of metastasis and disease recurrence. A complex issue that remains is to account for the heterogeneous pool of "backseat" aberrations, which in chromosomal proximity to the causative variant are likely to influence, for example, drug response. This review explores the recent advances in defining the molecular pathways implicated in the development of this devastating disease and, which present putative clinical strategies.

miR-21 increases the programmed cell death 4 gene-regulated cell proliferation in head and neck squamous carcinoma cell lines

MicroRNAs (miRs) are small non-coding RNAs that regulate the translation of many genes in normal and cancer cells where they are frequently dysregulated promoting tumor progression. Several studies have illustrated the potential of manipulating miR expression in cancer research and therapy. The aim of the present study was to investigate expression patterns of a panel of miRs in head and neck squamous cell carcinoma (HNSCC) shown to be relevant in other carcinomas and to elucidate their role if dysregulated. We performed analysis of miR‑21, -200c, -138-1, -138-2, -25 and -34 expression by qRT-PCR in 6 HNSCC cell lines and computerized search for genetic targets of dysregulated miRNA-21 (miR‑21). Lipofection of mock and anti-miR-21 and determination of expression efficiencies and final programmed cell death 4 (PDCD4) expression were carried out by luciferase assay and western blotting. MTT assay was used to measure cell proliferation and flow cytometry was performed for cell cycle analysis. Expression of miR-21 was most prominently upregulated in the HNSCC cell lines, particularly in UM-SCC11B (6.45±0.25-fold, P<0.05) and UM-SCC9 (4.35±0.22-fold, P<0.05) as compared to primary epidermal keratinocytes used as control. The expression levels of the other miRs showed no difference except for miR-34 and -138-1 each in one cell line. Subsequent transfection of precursor miR-21 stimulated proliferation while anti-miR-21 inhibited proliferation of both cell lines. PDCD4 was identified with software designed for this purpose as potential target gene of miR-21. Subsequently, its role in HNSCC lines was experimentally confirmed by regulation of PDCD4 transfecting miR-21 mimics and anti-miR-21. Finally, we showed that PDCD4 is negatively regulated by miR-21 at the post-transcriptional level via binding to the 3'-untranslated region of PDCD4 mRNA. A role of upregulated miR-21 and reduced PDCD4 stimulating the proliferation was demonstrated in HNSCC lines and, in turn, transfection of anti-miR-21 upregulating PDCD4 reduced the cellular division rate. We explored miR-21 and PDCD4 expression as markers of progression and prognosis and for a potential translational value in the development of agents slowing growth of HNSCC and other carcinomas useful in palliative therapy or as a component of multi-modality treatments.

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.

Circulating miR-192 in liver fluke-associated cholangiocarcinoma patients: a prospective prognostic indicator

BACKGROUND

This study aimed to investigate the miR-192 levels in patients' sera of liver fluke-associated cholangiocarcinoma (CCA) for a prospective prognostic indicator.

METHODS

MicroRNA polymerase chain reaction (PCR) array was performed using pooled serum samples from 11 CCA patients and nine healthy subjects. Selected miRNAs were verified for the differential levels in both sera and tumor tissues (of patients and Opisthorchis viverrini (Ov)-induced CCA model) using TaqMan miRNA expression assay.

RESULTS

Our results demonstrated that miR-192 was significantly higher in the serum of CCA patients than that in healthy subjects giving a sensitivity of 74% and specificity of 72% (area under the curve [AUC] = 0.803; 95% confidence interval [CI], 0.708-0.897, P < 0.0001). Serum miR-192 examined in Ov infected subjects and subjects with periductal fibrosis were increased but not statistically significantly when compared with healthy subjects. High levels of serum miR-192 were significantly correlated with lymph node metastasis (P = 0.047) and shorter survival compared with individuals with low levels of serum miR-192 (hazard ratio [HR] 2.076, 95% CI 1.004-4.291, P = 0.049). We also found that the expression levels of miR-192 appeared to be elevated in both CCA tissues of patients and in Ov-induced CCA tissues of a hamster model.

CONCLUSIONS

This finding indicates that elevated levels of miR-192 may be involved in CCA genesis and have a potential utility as a noninvasive prognostic indicator for CCA patients.

Targeting miR-21 to treat psoriasis

Psoriasis is a common inflammatory skin disease with limited treatment options that is characterized by a complex interplay between keratinocytes, immune cells, and inflammatory mediators. MicroRNAs (miRNAs) are regulators of gene expression and play critical roles in many human diseases. A number of miRNAs have been described to be up-regulated in psoriasis, but their causal contribution to disease development has not been demonstrated. We confirm that miR-21 expression is increased in epidermal lesions of patients with psoriasis and that this leads to reduced epidermal TIMP-3 (tissue inhibitor of matrix metalloproteinase 3) expression and activation of TACE (tumor necrosis factor-α-converting enzyme)/ADAM17 (a disintegrin and metalloproteinase 17). Using patient-derived skin samples and mouse models of psoriasis, we demonstrate that increased miR-21 may be a consequence of impaired transcriptional activity of Jun/activating protein 1 (AP-1), leading to activation of the interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (Stat3) pathway. Inhibition of miR-21 by locked nucleic acid (LNA)-modified anti-miR-21 compounds ameliorated disease pathology in patient-derived psoriatic skin xenotransplants in mice and in a psoriasis-like mouse model. Targeting miR-21 may represent a potential therapeutic option for the treatment of psoriasis.

MicroRNA-21 regulates the invasion and metastasis in cholangiocarcinoma and may be a potential biomarker for cancer prognosis

BACKGROUND

MicroRNAs are noncoding RNA molecules that posttranscriptionally regulate gene expression. The aim of this study was to determine the role of microRNA-21 in cholangiocarcinomas and its relationship to cholangiocarcinoma RBE cell capacity for invasion and metastasis.

METHODS

MicroRNA-21 expression was investigated in 41 cases of cholangiocarcinoma samples by in situ hybridization and real-time PCR. Influence on cholangiocarcinoma cell line invasion and metastasis was analyzed with microRNA-21 transfected cells. In addition, regulation of reversion-inducing-cysteine-rich protein with kazal motifs (RECK) by microRNA-21 was elucidated to identify mechanisms.

RESULTS

In situ hybridization and real-time quantitative PCR results for patients with lymph node metastasis or perineural invasion showed significantly high expression of microRNA-21 (P<0.05). There was a dramatic decrease in cholangiocarcinoma cell line invasion and metastasis ability after microRNA-21 knockdown (P<0.05). However, overexpression significantly increased invasion and metastasis (P<0.05). Real-time PCR and Western-blot analysis showed that microRNA-21 could potentially inhibit RECK expression in RBE cells. Survival analysis showed that patients with higher expression levels of microRNA-21 more often had a poor prognosis (P<0.05).

CONCLUSIONS

MicroRNA-21 may play an important role in cholangiocarcinoma invasion and metastasis, suggesting that MicroRNA-21 should be further evaluated as a biomarker for predicting cholangiocarcinoma prognosis.

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.

The real-time dynamic monitoring of microRNA function in cholangiocarcinoma

BACKGROUND

Although many studies have confirmed a relationship between microRNAs (miRNAs) and cholangiocarcinoma (CCA), the real-time dynamics of miRNA function have not been examined.

METHODS

miRNA reporter constructs were generated using a recombinant adeno-associated virus vector, which contained complementary sequences for six miRNAs (miR-200a, miR-200b, miR-21, miR-146a, miR-155, and miR-221), along with two independent expression cassettes encoding the fluorescent reporter genes Fluc and Gluc. The spatio-temporal function of each miRNA was monitored both in CCA and control tissues.

RESULTS

All miRNAs participated in CCA development, with distinct patterns of expression over time. The activity of miR-21 was significantly lower in female T3N0M0 CCA tissue relative to controls at three time points, yet was higher in two male T3N1M0 CCA tissues. The difference in miR-200b function between two male T3N1M0 CCA tissues and their corresponding controls peaked at 24 h, while function in a female T3N0M0 CCA was detected only at 72 h. The four remaining miRNAs (miR-200a, miR146a, miR-155, and miR-221) displayed patient-specific activity patterns in both CCA and control tissues.

CONCLUSION

Significant variability was observed in the temporal function of all six miRNAs, which may play an important role in the development of CCA.

Cholangiocarcinoma cell line TK may be useful for the pharmacokinetic study of the chemotherapeutic agent gemcitabine

Cholangiocarcinoma is a disease with a poor prognosis. A human cholangiocarcinoma cell line, TK, was previously established to enable further understanding of the disease. We conducted this investigation to determine whether or not the TK line is useful for pharmacokinetic study of the chemotherapeutic agent gemcitabine (GEM). Along with the BXPC3 human pancreatic adenocarcinoma cell line, the sensitivity to and effects on the TK cell line of GEM were compared. The influence of deoxycytidine kinase (dCK) transduction was also comparatively investigated. The effects of GEM in terms of drug sensitivity of the TK cell line, cell cycle and levels of transcripts of key enzymes were comparable to the BXPC3 cell line. Responses to the drug were similar in both cell lines. In contrast to pancreatic carcinoma, cell lines for research on cholangiocarcinoma have been limited. This study suggests the application of the TK cell line to the pharmacokinetic study of the chemosensitization of therapeutic drugs, such as GEM.

Illustrating the interplay between the extracellular matrix and microRNAs

The discovery of cell surface receptors that bind to extracellular matrix (ECM) components marked a new era in biological research. Since then there has been an increasing appreciation of the importance of studying cells in the context of their extracellular environment. Cell behaviour is profoundly affected by the ECM, whose synthesis and turnover must be finely balanced in order to maintain normal function and prevent disease. In the last decade, microRNAs (miRNAs) have emerged as key regulators of ECM gene expression. As new technologies for the identification and validation of miRNA targets continue to be developed, a growing body of data supporting the role of miRNAs in regulating the ECM biology has arisen from a variety of cell and animal models along with clinical studies. However, more recent findings suggest an intriguing interplay between the ECM and miRNAs: not only can miRNAs control the composition of the ECM, but also the ECM can affect the expression of specific miRNAs. Here we discuss how miRNAs contribute to the synthesis, maintenance and remodelling of the ECM during development and disease. Furthermore, we bring to light evidence that points to a role for the ECM in regulating miRNA expression and function.

miR-21 targets 15-PGDH and promotes cholangiocarcinoma growth

miRNAs are a group of small, noncoding RNAs that modulate the translation of genes by binding to specific target sites in the target mRNA. This study investigated the biologic function and molecular mechanism of miR-21 in human cholangiocarcinoma. In situ hybridization analysis of human cholangiocarcinoma specimens showed increased miR-21 in cholangiocarcinoma tissue compared with the noncancerous biliary epithelium. Lentiviral transduction of miR-21 enhanced human cholangiocarcinoma cell growth and clonogenic efficiency in vitro, whereas inhibition of miR-21 decreased these parameters. Overexpression of miR-21 also promoted cholangiocarcinoma growth using an in vivo xenograft model system. The NAD(+)-linked 15-hydroxyprostaglandin dehydrogenase (15-PGDH/HPGD), a key enzyme that converts the protumorigenic prostaglandin E2 (PGE2) to its biologically inactive metabolite, was identified as a direct target of miR-21 in cholangiocarcinoma cells. In parallel, cyclooxygenase-2 (COX2) overexpression and PGE2 treatment increased miR-21 levels and enhanced miR-21 promoter activity in human cholangiocarcinoma cells.

IMPLICATIONS

Cholangiocarcinogenesis and tumor progression are regulated by a novel interplay between COX-2/PGE2 and miR-21 signaling, which converges at 15-PGDH.

Regulation of gene expression by microRNA in HCV infection and HCV-mediated hepatocellular carcinoma

MicroRNA (miRNA) exert a profound effect on Hepatitis C virus (HCV) replication and on the manifestation of HCV-associated hepatocellular carcinoma (HCC). miR-122 in particular, is highly enriched in liver and has been shown to interact with HCV, suggesting this virus has evolved to subvert and manipulate the host gene silencing machinery in order to support its life cycle. It is therefore likely that miR-122 and other miRNAs play an important role in the pathophysiology of HCV infection. The changes in post-transcriptional gene regulation by the miRNAs may play a key role in the manifestation of chronic liver disease and hepatocellular carcinoma. Understanding of HCV-host miRNA interactions will ultimately lead to the design of therapeutic modalities against HCV infection and HCV-mediated HCC and may also provide important biomarkers that direct treatment options. Here, we review the current knowledge on the role of miRNA and gene expression on HCV infection and hepatocellular carcinoma, in addition to the possible role of miRNA as future therapeutic targets.

microRNA therapies in cancer

MicroRNAs (miRNAs or miRs) are a family of small non-coding RNA species that have been implicated in the control of many fundamental cellular and physiological processes such as cellular differentiation, proliferation, apoptosis and stem cell maintenance. miRNAs regulate gene expression by the sequence-selective targeting of mRNAs, leading to translational repression or mRNA degradation. Some microRNAs have been categorized as “oncomiRs” as opposed to “tumor suppressor miRs” Modulating the miRNA activities may provide exciting opportunities for cancer therapy. This review highlights the latest discovery of miRNAs involved in carcinogenesis as well as the potential applications of miRNA regulations in cancer treatment. Several studies have demonstrated the feasibility of restoring tumor suppressive miRNAs and targeting oncogenic miRNAs for cancer therapy using in vivo model systems.

microRNA therapies in cancer

MicroRNAs (miRNAs or miRs) are a family of small non-coding RNA species that have been implicated in the control of many fundamental cellular and physiological processes such as cellular differentiation, proliferation, apoptosis and stem cell maintenance. miRNAs regulate gene expression by the sequence-selective targeting of mRNAs, leading to translational repression or mRNA degradation. Some microRNAs have been categorized as "oncomiRs" as opposed to "tumor suppressor miRs" Modulating the miRNA activities may provide exciting opportunities for cancer therapy. This review highlights the latest discovery of miRNAs involved in carcinogenesis as well as the potential applications of miRNA regulations in cancer treatment. Several studies have demonstrated the feasibility of restoring tumor suppressive miRNAs and targeting oncogenic miRNAs for cancer therapy using in vivo model systems.

MicroRNA-21 is a unique signature associated with coronary plaque instability in humans by regulating matrix metalloproteinase-9 via reversion-inducing cysteine-rich protein with Kazal motifs

BACKGROUND

Coronary atherosclerotic unstable plaque is one of the leading causes of cardiovascular death. Macrophage-derived matrix metalloproteinase (MMP) 9 is considered for degrading extracellular matrix and collagen, thereby thinning the fibrous cap in plaques. miR-21 is implicated to play an important role in the progression of atherosclerosis. Nevertheless, miR-21 as the biomarker for coronary atherosclerotic unstable plaque remains unknown. We aimed to investigate the prediction role of miR-21 for unstable plaque by pathway study of miR-21 on MMPs and its inhibitor RECK in macrophages.

METHODS

Expression of miR-21 in macrophages and serum miR-21 as well as MMP-9 was measured in patients with coronary non-calcified plaque, calcified plaque and controls. In vitro experiment was done in human macrophages by over-expressing miR-21 or down-regulating RECK. The regulation of RECK and MMP-9 by miR-21 was evaluated by western blotting and siRNA strategy.

RESULTS

Patients with non-calcified coronary artery lesions had significantly higher miR-21 in macrophages and lower miR-21 serum levels compared to the control and calcified plaque patients. At the same time, the serum levels of MMP-9 were significantly elevated in non-calcified patients. Experiments in vitro indicated that over-expressing miR-21 could induce the expression and secretion of pro-MMP-9 and active-MMP-9 in human macrophages via targeting gene RECK, and knocking down RECK expression by specific siRNA can resemble that of miR-21 over-expression.

CONCLUSIONS

miR-21 might be a biomarker for plaque instability by suppressing target gene RECK to promote the expression and secretion of MMP-9 in macrophages.

Morphological study of the TK cholangiocarcinoma cell line with three-dimensional cell culture

Cholangiocarcinoma is an intractable carcinoma originating from the bile duct epithelium. To gain an understanding of the cell biology of cholangiocarcinoma, in vitro cell culture is valuable. However, well‑characterized cell lines are limited. In the present study, the morphology of the TK cholangiocarcinoma cell line was analyzed by three‑dimensional culture. Dispersed TK cells were injected into a gelatin mesh scaffold and cultivated for 3‑20 days. The morphology of the TK cells was investigated by phase‑contrast microscopy, optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TK cells were observed to proliferate three-dimensionally in the scaffold. The cells exhibited a globoid structure and attached to the scaffold. The SEM observation demonstrated typical microvilli and plicae on the surface of the structure. Light microscopy and TEM confirmed intercellular and cell‑to‑scaffold attachment in the three‑dimensional mesh. The culture also exhibited the formation of a duct-like structure covered by structured microvilli. In conclusion, three‑dimensional culture of TK cells demonstrated the morphological characteristics of cholangiocarcinoma in vitro. Production of high levels of carbohydrate antigen (CA)19‑9, CA50 and carcinoembryonic antigen was previously confirmed in the TK cell line. As a characteristic morphology was demonstrated in the present study, the TK cholangiocarcinoma cell line may be useful as an experimental model for further study of cholangiocarcinoma.

Serum microRNA-21 as a potential biomarker for response to hypomethylating agents in myelodysplastic syndromes

Identification of biomarkers that predict responses to hypomethylating agents (HMAs) will allow optimal strategies for epigenetic therapy in myelodysplastic syndromes (MDS) to be established. Serum miR-21 was quantitatively measured in 58 MDS patients treated with HMAs and 14 healthy controls. Serum miR-192 was an internal control, and diagnostic performance was evaluated according to receiver operating characteristics (ROCs). ROC analysis indicated that serum miR-21 levels differentiated responders from non-responders with an area under the curve of 0.648 (95% confidence, 0.49 to 0.72). The baseline level of serum miR-21 was significantly lower in the responder group than in the non-responder group (P = 0.041). The overall response rate (ORR) of the high miR-21 group was significantly lower than that of the low miR-21 group (41.2 vs. 73.2%, P = 0.021). Progression-free survival (PFS) was significantly inferior in the high group versus the low group (14.0 vs. 44.5 months, P = 0.001). Multivariate analyses revealed that the initial serum miR-21 level (P = 0.001) and circulating blasts (P = 0.007) were prognostic factors for PFS. Serum miR-21 level was significantly associated with ORR and PFS in MDS patients treated with HMAs. Although validation with a large prospective study is required, serum miR-21 is a potential biomarker of epigenetic therapy in MDS patients.

The anti-miR21 antagomir, a therapeutic tool for colorectal cancer, has a potential synergistic effect by perturbing an angiogenesis-associated miR30

Colon cancer has the third highest incidence and mortality among cancers in the United States. MicroRNA-21 (miR21) has been described as an oncomir that is highly overexpressed in tumor tissue from colorectal cancer. Recent studies showed that silencing of miR21 through use of a miR21 inhibitor (anti-miR21) affected viability, apoptosis and the cell cycle in colon cancer cells. We identified an anti-miR21 that targets miR21 to inhibit genes by both post-transcriptional gene silencing and transcriptional gene silencing in the cytoplasm and nucleus, respectively. Overexpression of anti-miR21 in colon cancer cells caused changes in miRNA expression levels. We found that treatment with anti-miR21 down-regulated expression of miR30, which is involved in angiogenesis. In an in vitro angiogenesis assay, network formation induced by an angiogenesis activator was reduced upon treatment with anti-miR21. Sequence analysis of anti-miR21 and pri-miR30 revealed homology between anti-miR21 and the 3′ end of pri-miR30, suggesting that anti-miR21 may bind to pri-miR30 and block processing of the miRNA processing. These results suggest anti-miR21 has a role not only in tumor growth but also in angiogenesis. Therefore, treatment with the anti-miR21 antagomir may have a synergistic effect mediated through suppression of miR30.

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

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

Stress-induced ECM alteration modulates cellular microRNAs that feedback to readjust the extracellular environment and cell behavior

The extracellular environment is a complex entity comprising of the extracellular matrix (ECM) and regulatory molecules. It is highly dynamic and under cell-extrinsic stress, transmits the stressed organism’s state to each individual ECM-connected cell. microRNAs (miRNAs) are regulatory molecules involved in virtually all the processes in the cell, especially under stress. In this review, we analyse how miRNA expression is regulated downstream of various signal transduction pathways induced by changes in the extracellular environment. In particular, we focus on the muscular dystrophy-associated cell adhesion molecule dystroglycan capable of signal transduction. Then we show how exactly the same miRNAs feedback to regulate the extracellular environment. The ultimate goal of this bi-directional signal transduction process is to change cell behavior under cell-extrinsic stress in order to respond to it accordingly.

Inferring the perturbed microRNA regulatory networks in cancer using hierarchical gene co-expression signatures

MicroRNAs (miRNAs), a class of endogenous small regulatory RNAs, play important roles in many biological and physiological processes. The perturbations of some miRNAs, which are usually called as onco-microRNAs (onco-miRs), are significantly associated with multiple stages of cancer. Although hundreds of miRNAs have been discovered, the perturbed miRNA regulatory networks and their functions are still poorly understood in cancer. Analyzing the expression patterns of miRNA target genes is a very useful strategy to infer the perturbed miRNA networks. However, due to the complexity of cancer transcriptome, current methods often encounter low sensitivity and report few onco-miR candidates. Here, we developed a new method, named miRHiC (enrichment analysis of miRNA targets in Hierarchical gene Co-expression signatures), to infer the perturbed miRNA regulatory networks by using the hierarchical co-expression signatures in large-scale cancer gene expression datasets. The method can infer onco-miR candidates and their target networks which are only linked to sub-clusters of the differentially expressed genes at fine scales of the co-expression hierarchy. On two real datasets of lung cancer and hepatocellular cancer, miRHiC uncovered several known onco-miRs and their target genes (such as miR-26, miR-29, miR-124, miR-125 and miR-200) and also identified many new candidates (such as miR-149, which is inferred in both types of cancers). Using hierarchical gene co-expression signatures, miRHiC can greatly increase the sensitivity for inferring the perturbed miRNA regulatory networks in cancer. All Perl scripts of miRHiC and the detailed documents are freely available on the web at http://bioinfo.au.tsinghua.edu.cn/member/jgu/miRHiC/.

Plasma miR-21 is a novel diagnostic biomarker for biliary tract cancer

Biliary tract cancer (BTC) has a generally poor prognosis. Furthermore, it is difficult to distinguish BTC from benign biliary disease (BBD) with commonly used modalities. Therefore, a novel biomarker to facilitate cancer detection is highly desirable. Recent studies have reported the use of circulating microRNAs (miRNAs) as biomarkers for cancers. The purpose of this study was to evaluate whether circulating miRNA-21 (miR-21) could be used as a biomarker for BTC. Plasma samples were obtained from 94 BTC patients, 50 healthy volunteers (HVs), and 23 BBD patients. miR-21 levels in the samples were measured by qRT-PCR. Plasma miR-21 levels in patients with BTC were significantly higher than in HVs or in patients with BBD (P < 0.0001 for both). Receiver-operator curve (ROC) curve analysis in differentiating BTC patients from HVs indicated that area under the curve (AUC), optimal sensitivity and specificity was 0.93, 85.1% and 100%, respectively, and those in differentiating BTC patients from BBD patients was 0.83, 72.3%, 91.3%, respectively. Validation of these results indicated that the negative predictive value, positive predictive value, sensitivity, specificity, and accuracy in differentiating BTC patients from HVs was 76.6%, 98.6%, 84.0%, 98.0%, and 88.9%, respectively, and those in differentiating BTC patients from BBD patients was 42.2%, 93.0%, 71.2%, 82.6%, and 72.6%, respectively. These sets of values were improved by combining miR-21 and CA19-9 measurements. Plasma miR-21 is a novel diagnostic biomarker for BTC, and may be useful in distinguishing between BTC and BBD patients.

Small molecule with big role: MicroRNAs in cancer metastatic microenvironments

Cancer metastasis is closely related to tumor cell microenvironments. Cancer cells and stromal cells interact with one another through extracellular matrix (ECM) and jointly participate in establishing the microenvironments. However, many questions remain to be addressed, in particular, a crucial question is which messengers mediate the mutual interaction and regulation between cancer cells and stromal cells. MicroRNAs (miRNAs), as oncogenic and oncosuppressor genes, regulate the expression and function of their related target genes to affect the biological behaviors of cancer cells and stromal cells, which may play an important role in cancer metastasis. Many miRNAs associated with cancer metastasis have been identified. The molecules of miRNAs are small and relatively easy to be secreted into extracellular microenvironments and devoured by nearby cells. As the regulatory messengers between cells, the secreted miRNAs function to regulate cancer cell proliferation, migration, intercellular communication and stromal modification, thereby helping cancer cells to establish their microenvironments for metastasis. In conclusion, miRNAs are small molecules, but they play a powerful role in regulating cancer metastatic ability by construction and modification of microenvironments.