Identification of deregulated miRNAs and their targets in hepatitis B virus-associated hepatocellular carcinoma

microRNA changes in liver tissue associated with fibrosis progression in patients with hepatitis C

BACKGROUND & AIMS

Accumulating evidence indicates that microRNAs play a role in a number of disease processes including the pathogenesis of liver fibrosis in hepatitis C infection. Our goal is to add to the accruing information regarding microRNA deregulation in liver fibrosis to increase our understanding of the underlying mechanisms of pathology and progression.

METHODS

We used next generation sequencing to profile all detectable microRNAs in liver tissue and serum from patients with hepatitis C, stages F1-F4 of fibrosis.

RESULTS

We found altered expression of several microRNAs, in particular, miR-182, miR199a-5p, miR-200a-5p and miR-183 were found to be significantly upregulated in tissue from liver biopsies of hepatitis C patients with advanced fibrosis, stage F3 and F4, when compared with liver biopsies from patients with early fibrosis, stages F1 and F2. We also found miR-148-5p, miR-1260b, miR-122-3p and miR-378i among the microRNAs most significantly down-regulated from early to advanced fibrosis of the liver. We also sequenced the serum microRNAs; however, we were not able to detect significant changes in circulating microRNAs associated with fibrosis stage after adjusting for multiple tests.

CONCLUSIONS

Adding measurements of tissue microRNAs acquired during routine biopsies will continue to increase our knowledge of underlying mechanisms of fibrosis. Our goal is that these data, in combination with studies from other researchers and future long-term studies, could be used to enhance the staging accuracy of liver biopsies and expand the surveillance of patients at increased risk for cancer and progression to advanced fibrosis.

Downregulation of miR-522 suppresses proliferation and metastasis of non-small cell lung cancer cells by directly targeting DENN/MADD domain containing 2D

Non-small cell lung cancer (NSCLC), one of the most common causes of cancer-related death, is a worldwide public health problem. MicroRNAs (miRNAs) have recently been identified as a novel class of regulators of carcinogenesis and tumor progression, including miRNAs associated with NSCLC. This study aimed to explore the role of miR-522 in NSCLC and the mechanisms underlying this role. We report here that miR-522 expression was significantly increased in both human NSCLC tissues and cell lines. Furthermore, an MTT assay, 5-Ethynyl-2′-deoxyuridine (EdU) assay kit and flow cytometry confirmed that the inhibition of miR-522 suppressed NSCLC cells proliferation and induced apoptosis. Compared with miR-522 overexpression, miR-522 inhibitor markedly reduced cells migration and invasion, as indicated by wound-healing and transwell assays. In addition, a luciferase assay identified DENN/MADD domain containing 2D (DENND2D) as a direct target of miR-522. qRT-PCR and western blot analyses indicated the reciprocal expression of miR-522 and DENND2D in NSCLC tissue samples. DENND2D was involved in miR-522 induced proliferation and metastasis of NSCLC cells by a miRNA-masking antisense oligonucleotides (miR-mask) technology. These data highlight a novel molecular interaction between miR-522 and DENND2D, which indicates that targeting miR-522 may constitute a potential therapy for NSCLC.

MicroRNA-519a promotes proliferation and inhibits apoptosis of hepatocellular carcinoma cells by targeting FOXF2

Recent studies report that microRNA-519a (miR-519a) is a novel oncomir, which facilitates the onset and progression of human cancers. However, the clinical significance of miR-519a and its functional role and underlying mechanisms in hepatocellular carcinoma (HCC) are poorly investigated. In the present study, elevated expression of miR-519a was observed in HCC tissues compared with adjacent non-tumor tissues. The increased level of miR-519a expression was significantly correlated with adverse clinical features of HCC including hepatitis B virus (HBV) infection, large tumor size, cirrhosis and advanced tumor-node-metastasis tumor stage. Furthermore, high expression of miR-519a was prominently associated with a poorer 5-year overall survival and recurrence-free survival of HCC patients. Gain- and loss-of function experiments showed that miR-519a overexpression enhanced proliferation and reduced apoptosis of Huh7 cells. By contrast, miR-519a knockdown inhibited SMMC-7721 cell proliferation and induced apoptosis. Importantly, up-regulation of miR-519a reduced the expression of FOXF2 mRNA and protein in Huh7 cells, while down-regulation of miR-519a resulted in increased expression of FOXF2 in SMMC-7721 cells. An inverse correlation between mRNA levels of miR-519a and FOXF2 was observed in HCC tissues. Thus, Forkhead box F2 (FOXF2) was identified as a downstream target of miR-519a in HCC. Mechanistically, the effects of miR-519a knockdown on SMMC-7721 cells were abrogated by FOXF2 repression. In conclusion, miR-519a is a novel prognostic predictor for HCC patients and it may potentiate proliferation and inhibits apoptosis of HCC cells by targeting FOXF2.

miRNA-592 is downregulated and may target LHCGR in polycystic ovary syndrome patients

The polycystic ovary syndrome (PCOS) is an endocrine disorder mainly associated with infertility. Abnormal regulation of relevant genes is required for follicular development in PCOS. In the current study, the expression of serum miRNAs of PCOS patients was explored using miRNA array followed by qRT-PCR assays. The circulating level of miR-592 was significantly down-regulated in PCOS patients in comparison with healthy controls. Furthermore, we found that miR-592 was inversely correlated with the level of luteinizing hormone/chorionic gonadotropin receptor (LHCGR). Computational analysis predicted that miR-592 interacts with the LHCGR mRNA via binding to a site located in the 3'UTR region. Using a luciferase-based reporter assay we found that miR-592 directly targeted the LHCGR. In KGN cell line, miR-592 overexpression inhibited cell viability and the transition of phase G1 to phase S. Knocking down of LHCGR inhibited cell viability and cell cycle progression in KGN cells, and LHCGR co-transfection reversed the inhibitory effect of miR-592. These results shed new light on the diagnosis and treatment of PCOS syndrome.

A systematic investigation based on microRNA-mediated gene regulatory network reveals that dysregulation of microRNA-19a/Cyclin D1 axis confers an oncogenic potential and a worse prognosis in human hepatocellular carcinoma

MicroRNAs (miRNAs) contribute to a wide variety of human diseases by regulating gene expression, leading to imbalances in gene regulatory networks. To discover novel hepatocellular carcinoma (HCC)-related miRNA-target axes and to elucidate their functions, we here performed a systematic investigation combining biological data acquisition and integration, miRNA-target prediction, network construction, functional assay and clinical validation. As a result, a total of 117 HCC differentially expressed miRNAs were identified, and 728 high confident target genes of these miRNAs were collected. Then, the interaction network of target genes was constructed and 221 key nodes with topological importance in the network were identified according to their topological features including degree, node-betweenness, closeness and K-coreness. Among these key nodes, Cyclin D1 had the highest node-betweenness, implying its bottleneck role in the network. Luciferase reporter assay confirmed that miRNA-19a, which was one of HCC downregulated miRNAs, directly targeted Cyclin D1 in HCC cells. Moreover, miR-19a might play inhibitory roles in HCC malignancy via regulating Cyclin D1 expression. Further clinical evidence also highlighted the prognostic potential of miR-19a/Cyclin D1 axis in HCC. In conclusion, this systematic investigation provides a framework to identify featured miRNAs and their target genes which are potent effectors in the occurrence and development of HCC. More importantly, miR-19a/Cyclin D1 axis might have promising applications as a therapeutic target and a prognostic marker for patients with HCC.

MicroRNA-592 targets DEK oncogene and suppresses cell growth in the hepatocellular carcinoma cell line HepG2

MicroRNAs (miRNAs) are classes of small, non-coding RNAs that regulate the translation of target mRNA transcripts. In this study, we demonstrated that miR-592 was downregulated in human hepatocellular carcinoma (HCC) and could suppress growth of the human HCC cell line HepG2. A tumor oncogene, DEK, was identified as a direct target of miR-592. Luciferase report assay indicated miR-592 regulates DEK expression though bind to its 3'UTR. Furthermore, knockdown of DEK also suppressed cell proliferation of HepG2 cells, which was consist with miR-592. At last, we suggested that DEK was upregulated in HCC tissues inversely with miR-592. These results demonstrated that miR-592 targets DEK transcript and suppresses HCC cell growth, and may provide potential therapeutic target in human HCC.

miR-1275: A single microRNA that targets the three IGF2-mRNA-binding proteins hindering tumor growth in hepatocellular carcinoma

This study aimed to identify a single miRNA or miR (microRNA) which regulates the three insulin-like growth factor-2-mRNA-binding proteins (IGF2BP1, 2 and 3). Bioinformatics predicted miR-1275 to simultaneously target the three IGF2BPs, and screening revealed miR-1275 to be underexpressed in hepatocellular carcinoma (HCC) tissues. Transfection of HuH-7 cells with miR-1275 suppressed IGF2BPs expression and all three IGF2BPs were confirmed as targets of miR-1275. Ectopic expression of miR-1275 and knockdown of IGF2BPs inhibited malignant cell behaviors, and also reduced IGF1R protein and mRNA. Finally IGF1R was validated as a direct target of miR-1275. These findings indicate that the tumor-suppressor miR-1275 can control HCC tumor growth partially through simultaneously regulating the oncogenic IGF2BPs and IGF1R.

Elevated miR-483-3p expression is an early event and indicates poor prognosis in pancreatic ductal adenocarcinoma

MiR-483-3p has been reported to be widely involved in diverse human malignancies. However, the exact role of miR-483-3p remains elusive in pancreatic ductal adenocarcinoma (PDAC). The objective of this study is to determine the expression pattern and clinical implications of miR-483-3p in PDAC. MiR-483-3p levels were evaluated by locked nucleic acid-in situ hybridization (LNA-ISH) in a tissue microarray including 63 PDAC tumors and 10 normal pancreatic tissues, followed by evaluation in an independent set of 117 pairs of matched PDAC tumors and adjacent tumor-free pancreatic tissues. Expression of miR-483-3p was further evaluated in pancreatic intra-epithelial neoplasias (PanINs) and chronic pancreatitis (CP). The impact of miR-483-3p on cell proliferation, growth, and anchorage-independent colony formation was also assessed in vitro and in vivo. Microarray analysis revealed that miR-483-3p was positively stained in 61 (96.8 %) PDAC samples, but not detectable in normal pancreatic duct tissue. In the 117 PDAC samples, 100 % were miR-483-3p positive, with 55.6 % (65/117) strongly positive, compared to only 13.7 % (16/117) weakly positive in adjacent normal pancreatic duct tissues. MiR-483-3p expression was associated with tumor grading (p < 0.05) and was an independent predictor of poor overall survival in multivariate analysis (HR = 2.584; 95 % CI = 1.268-5.264). Moreover, from PanIN1 to PanIN3, the rate of strong miR-483-3p-positive staining was 0 % (0/39), 14.8 % (4/27), and 87.5 % (14/16), respectively. Six (54.5 %) CP samples were only weakly stained for miR-483-3p. Inhibition of miR-483-3p suppressed cell proliferation, growth, and colony formation in vitro and decreased tumor cell growth in nude mouse xenografts in vivo. These results suggest that aberrant miR-483-3p expression is an early event in PDAC tumorigenesis and is associated with tumor differentiation and prognosis. It also may be a potential target for PDAC molecular therapeutics.

Hepatitis B virus and microRNAs: Complex interactions affecting hepatitis B virus replication and hepatitis B virus-associated diseases

Chronic infection with the hepatitis B virus (HBV) is the leading risk factor for the development of hepatocellular carcinoma (HCC). With nearly 750000 deaths yearly, hepatocellular carcinoma is the second highest cause of cancer-related death in the world. Unfortunately, the molecular mechanisms that contribute to the development of HBV-associated HCC remain incompletely understood. Recently, microRNAs (miRNAs), a family of small non-coding RNAs that play a role primarily in post-transcriptional gene regulation, have been recognized as important regulators of cellular homeostasis, and altered regulation of miRNA expression has been suggested to play a significant role in virus-associated diseases and the development of many cancers. With this in mind, many groups have begun to investigate the relationship between miRNAs and HBV replication and HBV-associated disease. Multiple findings suggest that some miRNAs, such as miR-122, and miR-125 and miR-199 family members, are playing a role in HBV replication and HBV-associated disease, including the development of HBV-associated HCC. In this review, we discuss the current state of our understanding of the relationship between HBV and miRNAs, including how HBV affects cellular miRNAs, how these miRNAs impact HBV replication, and the relationship between HBV-mediated miRNA regulation and HCC development. We also address the impact of challenges in studying HBV, such as the lack of an effective model system for infectivity and a reliance on transformed cell lines, on our understanding of the relationship between HBV and miRNAs, and propose potential applications of miRNA-related techniques that could enhance our understanding of the role miRNAs play in HBV replication and HBV-associated disease, ultimately leading to new therapeutic options and improved patient outcomes.

A critical role of mir-199a in the cell biological behaviors of colorectal cancer

Background

Colorectal cancer (CRC) is one of the most common cancer and the leading causes of cancer mortality worldwide. The critical role of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) are important in the cancer development.

Methods

The purpose of this study was to investigate the association of miR-199a expression in CRC and non-tumor tissues as well as assessed the effect of miR-199a on biological behaviors including cell proliferation, apoptosis, migration and invasion of CRC cells. The expression of miR-199a was distinctly decreased in colorectal cancer tissues compared with non-neoplastic colorectal tissues.

Results

In this study, we found that miR-199a down-regulation was associated with the CRC and metastasis incidence. Advanced study showed that miR-199a up-regulation would lead to decreased CRC proliferation, migration and invasion. However, no significant association of miR-199a treatment and apoptosis rate and cell-cycle were detected in this study. The detection for the mechanisms of miR-199a on the development of CRC showed that the anticarcinogenic effect of miR-199a might be produced through HIF-1α/VEGF pathway.

Conclusion

It was found that miR-199a would reduce the proliferation, migration and invasion. However, overexpression of miR-199a on the apoptosis rate and cell cycles showed no significant results. The potential functionary mechanism of miR-199a might through HIF-1α/VEGF pathway.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9806714131513041.

MicroRNA Expression Profiling in Clear Cell Renal Cell Carcinoma: Identification and Functional Validation of Key miRNAs

OBJECTIVE

This study aims to profile dysregulated microRNA (miRNA) expression in clear cell renal cell carcinoma (ccRCC) and to identify key regulatory miRNAs in ccRCC.

METHODS AND RESULTS

miRNA expression profiles in nine pairs of ccRCC tumor samples at three different stages and the adjacent, non-tumorous tissues were investigated using miRNA arrays. Eleven miRNAs were identified to be commonly dysregulated, including three up-regulated (miR-487a, miR-491-3p and miR-452) and eight down-regulated (miR-125b, miR-142-3p, miR-199a-5p, miR-22, miR-299-3p, miR-29a, miR-429, and miR-532-5p) in tumor tissues as compared with adjacent normal tissues. The 11 miRNAs and their predicted target genes were analyzed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and three key miRNAs (miR-199a-5p, miR-22 and miR-429) were identified by microRNA-gene network analysis. Dysregulation of the three key miRNAs were further validated in another cohort of 15 ccRCC samples, and the human kidney carcinoma cell line 786-O, as compared with five normal kidney samples. Further investigation showed that over-expression of miR-199a-5p significantly inhibited the invasion ability of 786-O cells. Luciferase reporter assays indicated that miR-199a-5p regulated expression of TGFBR1 and JunB by directly interacting with their 3' untranslated regions. Transfection of miR-199a-5p successfully suppressed expression of TGFBR1 and JunB in the human embryonic kidney 293T cells, further confirming the direct regulation of miR-199a-5p on these two genes.

CONCLUSIONS

This study identified 11 commonly dysregulated miRNAs in ccRCC, three of which (miR-199a-5p, miR-22 and miR-429) may represent key miRNAs involved in the pathogenesis of ccRCC. Further studies suggested that miR-199a-5p plays an important role in inhibition of cell invasion of ccRCC cells by suppressing expression of TGFBR1 and JunB.

Identification of ncRNAs as potential therapeutic targets in multiple sclerosis through differential ncRNA - mRNA network analysis

Background

Several studies have revealed a potential role for both small nucleolar RNAs (snoRNAs) and microRNAs (miRNAs) in the physiopathology of relapsing-remitting multiple sclerosis (RRMS). This potential implication has been mainly described through differential expression studies. However, it has been suggested that, in order to extract additional information from large-scale expression experiments, differential expression studies must be complemented with differential network studies. Thus, the present work is aimed at the identification of potential therapeutic ncRNA targets for RRMS through differential network analysis of ncRNA – mRNA coexpression networks. ncRNA – mRNA coexpression networks have been constructed from both selected ncRNA (specifically miRNAs, snoRNAs and sdRNAs) and mRNA large-scale expression data obtained from 22 patients in relapse, the same 22 patients in remission and 22 healthy controls. Condition-specific (relapse, remission and healthy) networks have been built and compared to identify the parts of the system most affected by perturbation and aid the identification of potential therapeutic targets among the ncRNAs.

Results

All the coexpression networks we built present a scale-free topology and many snoRNAs are shown to have a prominent role in their architecture. The differential network analysis (relapse vs. remission vs. controls’ networks) has revealed that, although both network topology and the majority of the genes are maintained, few ncRNA – mRNA links appear in more than one network. We have selected as potential therapeutic targets the ncRNAs that appear in the disease-specific network and were found to be differentially expressed in a previous study.

Conclusions

Our results suggest that the diseased state of RRMS has a strong impact on the ncRNA – mRNA network of peripheral blood leukocytes, as a massive rewiring of the network happens between conditions. Our findings also indicate that the role snoRNAs have in targeted gene silencing is a widespread phenomenon. Finally, among the potential therapeutic target ncRNAs, SNORA40 seems to be the most promising candidate.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1396-5) contains supplementary material, which is available to authorized users.

MiR-592 inhibited cell proliferation of human colorectal cancer cells by suppressing of CCND3 expression

Accumulating evidence shows that microRNA (miRNA) is frequently associated with multiple kinds of human cancers, including colorectal cancer (CRC). Previous studies have shown that miR-592 play critical roles in cancer cell biological processes. However, the function of miR-592 in CRC remains largely unknown. In the present study, we investigated the miR-592's role in cell proliferation of colorectal cancer. MiR-592 expression was markedly down-regulated in CRC tissues and CRC cells. Overexpression of miR-592 reduced the proliferation and anchorage-independent growth of CRC cells. Furthermore, bioinformatics analysis further revealed CCND3, a putative tumor promoter, was found to be a potential target of miR-592 in CRC. The dual-luciferase reporter gene assay results showed that CCND3 was a direct target of miR-592. Ectopic expression of miR-592 led to down-regulation of CCND3 protein, which resulted in the down-regulation of phosphorylated retinoblastoma (p-Rb). In functional assays, CCND3-silenced in miR-592-in-transfected SW48 cells have positive effect to suppress cell proliferation, suggesting that direct CCND3 suppression is required for miR-592-induced cell proliferation of CRC. We conclude that miR-592 can regulate CCND3 and function as a tumor suppressor in CRC. Therefore, miR-592 represents a potential anti-onco-miR and serves as a useful therapeutic agent for miRNA-based CRC therapy.

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.

Determining differentially expressed miRNAs and validating miRNA--target relationships using the SPRET/Ei mouse strain

Micro RNAs (miRs) are involved in many biological processes. The challenge of identifying genes influenced by miRs is evidenced by the relatively few validated miR-target interactions. In this work, we used the Mus spretus SPRET/Ei strain as an in vivo system to identify new miR-target relations. Mus spretus diverged from Mus musculus over one million years ago, making it genetically and phenotypically divergent. SPRET/Ei mice are resistant to inflammation and several cancers, making them attractive for different research fields. Their phenotype is unique and is considerably different from that of almost all other laboratory mouse strains. We exploited the characteristics of SPRET/Ei mice as a tool to identify miR-target relationships. Hepatic genes and miRs differentially expressed between C57BL/6 and SPRET/Ei mice at basal levels were identified with an Affymetrix microarray and a multiplex qPCR, respectively. A total of 955 genes and 38 miRs were identified as differentially expressed. Increased miR expression might result in downregulation of its target mRNA and vice versa. Subsequently, we used our miR and mRNA data to identify possible in vivo miR-target interactions. Ingenuity pathway analysis (IPA) analysis revealed 380 possible miR-target interactions. Five miRs were selected for experimental validation by in vivo overexpression of the miRs. This resulted in the confirmation of six previously unknown miR-target interactions: miR-146a, Zdhhc2; miR-150, Elovl3, Kcnk5, and Nrd1d2; miR-155, Camta1; and miR-592, Steap2. In conclusion, we show that SPRET/Ei mice can be used as a platform for miR-target identification in vivo, and we used this platform to identify and experimentally confirm miR-target interactions.

MicroRNA-520g induces epithelial-mesenchymal transition and promotes metastasis of hepatocellular carcinoma by targeting SMAD7

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Aberrant expression of miRNAs contributes to HCC development. Here, we observed elevated miR-520g expression in tumor samples from HCC patients with relapse and metastasis, and this high miR-520g expression was correlated with poor survival. Through gain- and loss-of-function studies, miR-520g was demonstrated to facilitate HCC cell migration, invasion and epithelial-mesenchymal transition (EMT). SMAD7 was identified as a direct target of miR-520g. Accordingly, we conclude that high miR-520g expression promotes HCC cell mobility and EMT by targeting SMAD7, and this is correlated with reduced survival in HCC patients.

The impact of hepatitis B virus x protein and microRNAs in hepatocellular carcinoma: a comprehensive analysis

microRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs, approximately 22 nucleotides (nts) in length, widely found in animals, plants, and viruses. Mature miRNAs control gene expression at a post-transcriptional level through blocking protein translation or inducing mRNA degradation. Many recent studies have shown that hepatitis B virus x protein (HBx), a viral protein with a crucial role in hepatogenesis, is associated with the regulation of miRNAs. This interaction impacts fundamental tumor processes, such as cell proliferation, differentiation, and apoptosis. In this review, we summarized the recent literature on the roles of HBx-regulated miRNAs in the pathogenesis of hepatocellular carcinoma.

MiR-199a-5p loss up-regulated DDR1 aggravated colorectal cancer by activating epithelial-to-mesenchymal transition related signaling

BACKGROUND

Discoidin domain receptors1 (DDR1) is associated with tumor progression, and its dysregulated expression has been observed in many cancers.

AIM

We aim to explore molecular mechanism underlying the role of DDR1 in colorectal cancer development.

METHODS

Immunohistochemistry and Western blot were applied to examine the DDR1 expression. Real-time RT-PCR and Western blot were performed to determine the expression of miR-199a-5p and DDR1. Luciferase reporter assay was used to determine whether DDR1 was a target of miR-199a-5p. Effects of miR-199a-5p and DDR1 on colorectal cell proliferation, colony formation, cell cycle progression, invasion and migration were then investigated. Western blot was used to determine the relative signal pathways.

RESULTS

Increased DDR1 and decreased miR-199a-5p expression coexisted in CRC, knockdown of DDR1 or overexpression of miR-199a-5p both resulted in reduced colony formation, invasive and migratory capabilities of human CRC LOVE1 and LOVO cells. It was also found that overexpression of miR-199a-5p led to decreased DDR1, MMP2, N-cadherin and vimentin expression and increased E-cadherin expression in both CRC cell lines. However, down-regulation of miR-199a-5p resulted in the opposite effects. Dual luciferase reporter assay confirmed that miR-199a-5p could directly target DDR1 through binding to its 3'-UTR.

CONCLUSIONS

Our findings indicated that up-regulation of DDR1 induced by miR-199a-5p down-regulation may contribute to the development and progression of CRC, and this effect may be associated with increased invasiveness, at least in part, via activating the EMT-related signaling.

Understanding the role of NRF2-regulated miRNAs in human malignancies

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is a key transcription factor that regulates the expression of over a hundred cytoprotective and antioxidant genes that provide cellular protection from reactive oxygen species. Chemotherapy resistance in several cancers has been linked to dysregulation of the NRF2 signalling pathway, moreover there is growing evidence that NRF2 may contribute to tumorigenesis. MicroRNA (miRNA) are small non-coding RNA sequences that post-transcriptionally regulate mRNA sequences. In cancer pathogenesis, aberrantly expressed miRNAs can act as either tumor suppressor or oncogenic miRNA. Recent evidence has been described that identifies a number of miRNA that can be regulated by NRF2. This review outlines the importance of NRF2 in regulating miRNA, and the functional role this may have in the tumorigenesis of human malignancies and their chemotherapy resistance.

Association of miRNA-122-binding site polymorphism at the interleukin-1 α gene and its interaction with hepatitis B virus mutations with hepatocellular carcinoma risk

This study was designed to investigate the contribution of miRNA-122-binding site polymorphism at the IL-1A gene and its multiplicative interactions with hepatitis B virus (HBV) mutations in the risk of hepatocellular carcinoma (HCC). A total of 1021 healthy controls, 302 HBV surface antigen (HBsAg) seroclearance subjects, and 2011 HBsAg-positive subjects (including 1021 HCC patients) were enrolled in this study. Quantitative PCR was used to genotype rs3783553. HBV mutations were determined by direct sequencing. Multivariate logistic regression analyses were performed to test the associations of rs3783553, mutations, and their interactions with the risk of HCC. No significant association was found between rs3783553 and the risk of HCC among healthy controls, HBsAg seroclearance subjects, HBsAg-positive subjects without HCC, and all controls. Additionally, rs3783553 was not significantly associated with chronic HBV infection, liver cirrhosis, HBV e antigen seroconversion, abnormal alanine aminotransferase, and high viral load (> 10(4) copies/ml). However, the TTCA insertion allele of rs3783553 was significantly associated with an increased frequency of HBV C7A mutation compared with homozygous TTCA deletion carriers [(del/ins + ins/ins) vs. del/del, adjusted odds ratio (OR)= 1.48, 95% confidence interval (CI)= 1.09-2.02, P = 0.013]. Multiplicative interaction of rs3783553 with HBV preS deletion significantly reduced the risk of HCC in males, with an adjusted OR of 0.64 (95% CI = 0.42-0.98; P = 0.041) after age and HBV genotype were adjusted. Although rs3783553 did not significantly affect genetic susceptibility to HBV-related HCC, its variant allele may predispose the host to selecting HBV C7A mutation during evolution and significantly reduce the risk of HCC caused by HBV preS deletion. This study provides an insight into the complex host-virus interaction in HBV-induced hepatocarcinogenesis and is helpful in determining HBsAg-positive subjects who are likely to develop HCC.

Modulation of HBV replication by microRNA-15b through targeting hepatocyte nuclear factor 1α

Hepatitis B virus (HBV) infection remains a major health problem worldwide. The role played by microRNAs (miRNAs) in HBV replication and pathogenesis is being increasingly recognized. In this study, we found that miR-15b, an important miRNA during HBV infection and hepatocellular carcinoma development, directly binds hepatocyte nuclear factor 1α (HNF1α) mRNA, a negative regulator of HBV Enhancer I, to attenuate HNF1α expression, resulting in transactivation of HBV Enhancer I, in turn causing the enhancement of HBV replication and expression of HBV antigens, including HBx protein, finally leading to the down-regulated expression of miR-15b in both cell lines and mice in a long cascade of events. Our research showed that miR-15b promotes HBV replication by augmenting HBV Enhancer I activity via direct targeting HNF1α, while HBV replication and antigens expression, particularly the HBx protein, then repress the expression of miR-15b. The reciprocal regulation between miR-15b and HBV controls the level of HBV replication and might play a role in persistent HBV infection. This work adds to the body of knowledge concerning the complex interactions between HBV and host miRNAs.

Tumor suppressor function of miR-483-3p on squamous cell carcinomas due to its pro-apoptotic properties

The frequent alteration of miRNA expression in many cancers, together with our recent reports showing a robust accumulation of miR-483-3p at the final stage of skin wound healing, and targeting of CDC25A leading to an arrest of keratinocyte proliferation, led us to hypothesize that miR-483-3p could also be endowed with antitumoral properties. We tested that hypothesis by documenting the in vitro and in vivo impacts of miR-483-3p in squamous cell carcinoma (SCC) cells. miR-483-3p sensitized SCC cells to serum deprivation- and drug-induced apoptosis, thus exerting potent tumor suppressor activities. Its pro-apoptotic activity was mediated by a direct targeting of several anti-apoptotic genes, such as API5, BIRC5, and RAN. Interestingly, an in vivo delivery of miR-483-3p into subcutaneous SCC xenografts significantly hampered tumor growth. This effect was explained by an inhibition of cell proliferation and an increase of apoptosis. This argues for its further use as an adjuvant in the many instances of cancers characterized by a downregulation of miR-483-3p.

Mir-592 regulates the induction and cell death-promoting activity of p75NTR in neuronal ischemic injury

The neurotrophin receptor p75(NTR) has been implicated in mediating neuronal apoptosis after injury to the CNS. Despite its frequent induction in pathologic states, there is limited understanding of the mechanisms that regulate p75(NTR) expression after injury. Here, we show that after focal cerebral ischemia in vivo or oxygen-glucose deprivation in organotypic hippocampal slices or neurons, p75(NTR) is rapidly induced. A concomitant induction of proNGF, a ligand for p75(NTR), is also observed. Induction of this ligand/receptor system is pathologically relevant, as a decrease in apoptosis, after oxygen-glucose deprivation, is observed in hippocampal neurons or slices after delivery of function-blocking antibodies to p75(NTR) or proNGF and in p75(NTR) and ngf haploinsufficient slices. Furthermore, a significant decrease in infarct volume was noted in p75(NTR)-/- mice compared with the wild type. We also investigated the regulatory mechanisms that lead to post-ischemic induction of p75(NTR). We demonstrate that induction of p75(NTR) after ischemic injury is independent of transcription but requires active translation. Basal levels of p75(NTR) in neurons are maintained in part by the expression of microRNA miR-592, and an inverse correlation is seen between miR-592 and p75(NTR) levels in the adult brain. After cerebral ischemia, miR-592 levels fall, with a corresponding increase in p75(NTR) levels. Importantly, overexpression of miR-592 in neurons decreases the level of ischemic injury-induced p75(NTR) and attenuates activation of pro-apoptotic signaling and cell death. These results identify miR-592 as a key regulator of p75(NTR) expression and point to a potential therapeutic candidate to limit neuronal apoptosis after ischemic injury.

Epigenetics in hepatocellular carcinoma: An update and future therapy perspectives

Hepatocellular carcinoma (HCC), the predominant form of adult liver malignancies, is a global health concern. Its dismal prognosis has prompted recent significant advances in the understanding of its etiology and pathogenesis. The deregulation of epigenetic mechanisms, which maintain heritable gene expression changes and chromatin organization, is implicated in the development of multiple cancers, including HCC. This review summarizes the current knowledge of epigenetic mechanisms in the pathogenesis of HCC, with an emphasis on HCC mediated by chronic hepatitis B virus infection. This review also discusses the encouraging outcomes and lessons learnt from epigenetic therapies for hematological and other solid cancers, and highlights the future potential of similar therapies in the treatment of HCC.

Strong reduction of AGO2 expression in melanoma and cellular consequences

Background:

Processing of microRNAs (miRNAs) is a highly controlled process. Deregulation of miRNA expression was observed in several types of cancer but changes in the miRNA-processing enzymes have not been analysed until today. In this study, we analysed Argonaute2 (AGO2, EIF2C2), as one main factor of the miRNA processing ensemble, in the context of cancer development, especially in melanoma.

Methods:

We determined the AGO2 expression level in melanoma, as well as in other cancers, with biochemical approaches (qRT–PCR, western blot and immunofluorescence studies) and analysed the cell behaviour in migration assays.

Results:

Specifically in melanoma, we revealed a strong reduction of AGO2 expression compared with primary melanocytes. The reduction of AGO2 expression was only found on protein level, whereas the mRNA level stayed unchanged hinting to post-transcriptional regulation. We could show that re-expression of AGO2 in melanoma leads to a strong improvement of regulatory effects due to increased functionality of small-interfering RNAs and short hairpin RNAs.

Conclusion:

We identified melanoma-specific downregulation of AGO2 and corresponding reduced RNAi efficiency. These findings will help to understand the molecular basis of malignant melanoma and can potentially lead to an improvement of therapeutic strategies.

Regulation of hepatitis B virus replication by epigenetic mechanisms and microRNAs

The hepatitis B virus (HBV) genome forms a covalently closed circular DNA (cccDNA) minichromosome that persists in the nucleus of virus-infected hepatocytes. HBV cccDNA serves as the template for viral mRNA synthesis and is subject to epigenetic regulation by several mechanisms, including DNA methylation and histone acetylation. Recently, microRNAs (miRNAs), a class of small non-coding RNAs, were also directly connected to the epigenetic machinery through a regulatory loop. Epigenetic modifications have been shown to affect miRNA expression, and a sub-group of miRNAs (defined as epi-miRNAs) can directly target effectors of the epigenetic machinery. In this review, we will summarize recent findings on the epigenetic mechanisms controlling HBV cccDNA function, primarily focusing on the epi-miRNA functions operating in HBV replication. Investigation of the epigenetic regulation of HBV replication may help to discover novel potential therapeutic targets for drug development with the goal to eradicate the HBV cccDNA pool in hepatocytes.

MicroRNA-433 inhibits liver cancer cell migration by repressing the protein expression and function of cAMP response element-binding protein

We show for the first time that potent microRNA-433 (miR-433) inhibition of expression of the cAMP response element-binding protein CREB1 represses hepatocellular carcinoma (HCC) cell migration. We identified a miR-433 seed match region in human and mouse CREB1 3'-UTRs. Overexpression of miR-433 markedly decreased human CREB1 3'-UTR reporter activity, and the inhibitory effect of miR-433 was alleviated upon mutation of its binding site. Ectopic expression of miR-433 reduced CREB1 protein levels in a variety of human and mouse cancer cells, including HeLa, Hepa1, Huh7, and HepG2. Human CREB1 protein levels in highly invasive MHCC97H cells were diminished by expression of miR-433 but were induced by miR-433 antagomir (anti-miR-433). The expression of mouse CREB1 protein negatively correlated with miR-433 levels in nuclear receptor Shp(-/-) liver tissues and liver tumors compared with wild-type mice. miR-433 exhibited a significant repression of MHCC97H cell migration, which was reversed by anti-miR-433. Overexpressing miR-433 inhibited focus formation dramatically, demonstrating that miR-433 may exert a tumor suppressor function. Knockdown of CREB1 by siRNAs impeded MHCC97H cell migration and invasion and antagonized the effect of anti-miR-433. Interestingly, CREB1 siRNA decreased MHCC97H cell proliferation, which was not influenced by anti-miR-433. Overexpressing CREB1 decreased the inhibitory activity of miR-433. The CpG islands surrounding miR-433 were hypermethylated, and the DNA methylation agent 5'-aza-2'-deoxycytidine, but not the histone deacetylase inhibitor trichostatin A, drastically stimulated the expression of miR-433 and miR-127 in HCC cells. The latter is clustered with miR-433. The results reveal a critical role of miR-433 in mediating HCC cell migration via CREB1.

MicroRNA-657 promotes tumorigenesis in hepatocellular carcinoma by targeting transducin-like enhancer protein 1 through nuclear factor kappa B pathways

Growing evidence indicates that deregulation of microRNAs (miRNAs) contributes to tumorigenesis. Dysregulation of miR-657 has been observed in several types of cancers, but its biological function is still largely unknown. Our results showed that miR-657 expression can be induced by hepatitis viral proteins and is significantly increased in hepatocellular carcinoma (HCC) tissues. Moreover, introduction of miR-657 dramatically increases proliferation and colony formation of HCC cells in vitro and induces tumor development in immunodeficient mice. Further studies showed that miR-657 directly targets the transducin-like enhancer protein 1 (TLE1) 3' untranslated region (UTR) and activates nuclear factor kappa B (NF-κB) pathways that contribute to hepatocarcinogenesis.

CONCLUSION

This study identified a mechanism whereby miRNA-657 contributed to HCC through novel cancer pathways and provides new insights into the potential molecular mechanisms of hepatic carcinogenesis.

MicroRNA-22 is down-regulated in hepatitis B virus-related hepatocellular carcinoma

MicroRNAs (miRNAs) are a new class of short noncoding RNAs with post-transcriptional regulation and participate in diverse physiological and pathological processes. MiR-22, ubiquitously expressed in various tissues, plays a functional important role in life processes and is recently proved to involve in many cancers. In present study, we had shown that miR-22 was down-regulated much more obviously in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) cell lines as well as in clinical tissues. Cyclin-dependent kinase inhibitor 1A (CDKN1A) was found to be inversely correlated with miR-22 and was identified as a target of miR-22. Overexpression of miR-22 in vitro effectively suppressed CDKN1A expression and inhibited cell proliferation. We conclude that miR-29c may play an important role as a tumor suppressive microRNA in the development and progression of HBV-related HCC by targeting CDKN1A.

CDC25A targeting by miR-483-3p decreases CCND-CDK4/6 assembly and contributes to cell cycle arrest

Disruption of contact inhibition and serum afflux that occur after a tissue injury activate cell cycle, which then stops when confluence is reached again. Although the events involved in cell cycle entry have been widely documented, those managing cell cycle exit have remained so far ill defined. We have identified that the final stage of wound closure is preceded in keratinocytes by a strong accumulation of miR-483-3p, which acts as a mandatory signal triggering cell cycle arrest when confluence is reached. Blocking miR-483-3p accumulation strongly delays cell cycle exit, maintains cells into a proliferative state and retards their differentiation program. Using two models of cell cycle synchronization (i.e. mechanical injury and serum addition), we show that an ectopic upregulation of miR-483-3p blocks cell cycle progression in early G1 phase. This arrest results from a direct targeting of the CDC25A phosphatase by miR-483-3p, which can be impeded using an anti-miRNA against miR-483-3p or a protector that blocks the complex formation between miR-483-3p and the 3'-untranslated region (UTR) of CDC25A transcript. We show that the miRNA-induced silencing of CDC25A increases the tyrosine phosphorylation status of CDK4/6 cyclin-dependent kinases which, in turn, abolishes CDK4/6 capacity to associate with D-type cyclins. This prevents CDK4/6 kinases' activation, impairs downstream events such as cyclin E stimulation and sequesters cells in early G1. We propose this new regulatory process of cyclin-CDK association as a general mechanism coupling miRNA-mediated CDC25A invalidation to CDK post-transcriptional modifications and cell cycle control.