MicroRNA silencing of tumor suppressor DLC-1 promotes efficient hepatitis C virus replication in primary human hepatocytes

MicroRNAs (miRNAs) are approximately 22-nucleotide noncoding RNAs that constitute silencers of target gene expression. Aberrant expression of miRNA has been linked to a variety of cancers, including hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) infection is considered a major cause of chronic liver disease and HCC, although the mechanism of virus infection-associated hepatocarcinogenesis remains unclear. We report a direct role of miRNAs induced in HCV-infected primary human hepatocytes that target the tumor suppressor gene DLC-1 (a Rho GTPase-activating protein), which is frequently deleted in HCC, and other solid human tumors. MicroRNA miR-141 that targets DLC-1 was accentuated in cells infected with HCV genotypes 1a, 1b, and 2a. We present several lines of evidence that efficient HCV replication requires miR-141-mediated suppression of DLC-1. An increase in miR-141 correlated with the inhibition of DLC-1 protein in HCV-infected cells. Depletion of miR-141 with oligonucleotides complementary to the miRNAs inhibited virus replication, whereas artificially increased levels of intracellular miR-141 enhanced HCV replication. HCV-infected hepatocytes showed enhanced cell proliferation that can be countered by overexpression of DLC-1. CONCLUSION: The collective results of this study suggest a novel mechanism of HCV infection-associated miRNA-mediated regulation of a tumor suppressor protein that has the ability to influence cell proliferation and HCV infection-mediated liver cancer.     

MicroRNAs and liver cancer associated with iron overload: Therapeutic targets unravelled

Primary liver cancer is a global disease that is on the increase.Hepatocellular carcinoma(HCC)accounts for most primary liver cancers and has a notably low survival rate,largely attributable to late diagnosis,resistance to treatment,tumour recurrence and metastasis.MicroRNAs(miRNAs/miRs)are regulatory RNAs that modulate protein synthesis.miRNAs are involved in several biological and pathological processes including the development and progression of HCC.Given the poor outcomes with current HCC treatments,miRNAs represent an important new target for therapeutic intervention.Several studies have demonstrated their role in HCC development and progression.While many risk factors underlie the development of HCC,one process commonly altered is iron homeostasis.Iron overload occurs in several liver diseases associated with the development of HCC including Hepatitis C infection and the importance of miRNAs in iron homeostasis and hepatic iron overload is well characterised.Aberrant miRNA expression in hepatic fibrosis and injury response have been reported,as have dysregulated miRNA expression patterns affecting cell cycle progression,evasion of apoptosis,invasion and metastasis.In2009,miR-26a delivery was shown to prevent HCC progression,highlighting its therapeutic potential.Several studies have since investigated the clinical potential of other miRNAs with one drug,Miravirsen,currently in phaseⅡclinical trials.miRNAs also have potential as biomarkers for the diagnosis of HCC and to evaluate treatment efficacy.Ongoing studies and clinical trials suggest miRNA-based treatments and diagnostic methods will have novel clinical applications for HCC in the coming years,yielding improved HCC survival rates and patient outcomes.     

microRNA在乙型、丙型肝炎中的作用

近年来,作为基因表达的重要调节因子microRNA(miRNA),以及与这些miRNA关联或调控的各种肝脏疾病,如肝炎、肝纤维化和肝细胞癌(HCC)等方面的研究取得了新进展.许多编码miRNA的基因及其靶标被发现,它们与肝脏疾病的直接或间接的关联性也通过大量的实验研究(包括人体组织)得到确证.病毒性肝炎是由多种不同肝炎病毒引起的一组以肝脏损伤为主的传染病,根据病原学诊断,肝炎病毒至少有5种,但目前最常见的是HBV和HCV感染.本文就miRNA与病毒性肝炎的关系研究进展作一综述.     

HBV/HCV相关miRNAs研究进展

microRNAs（miRNAs）是一类由约22个核苷酸组成的非编码单链RNAs,通过抑制蛋白质翻译或降解mRNAs调节基因的表达。目前发现有2000多种人源miRNAs,参与调节发育、细胞增殖、凋亡以及压力反应过程中的基因表达等,而miRNAs基因突变或者异常表达可能会引发肿瘤等疾病。已有研究表明miRNAs在肝炎病毒（HBV、HCV等）感染以及肝癌的发生发展过程中,也发挥了重要的作用。本文主要就HBV/HCV调控宿主miRNAs,以及miRNAs如何影响病毒的复制等方面进行阐述。     

Inhibition of hepatitis C virus replication using adeno-associated virus vector delivery of an exogenous anti-hepatitis C virus microRNA cluster

RNA interference (RNAi) is being evaluated as an alternative therapeutic strategy for hepatitis C virus (HCV) infection. The use of viral vectors encoding short hairpin RNAs (shRNAs) has been the most common strategy employed to provide sustained expression of RNAi effectors. However, overexpression and incomplete processing of shRNAs has led to saturation of the endogenous miRNA pathway, resulting in toxicity. The use of endogenous microRNAs (miRNAs) as scaffolds for short interfering (siRNAs) may avoid these problems, and miRNA clusters can be engineered to express multiple RNAi effectors, a feature that may prevent RNAi-resistant HCV mutant generation. We exploited the endogenous miRNA-17-92 cluster to generate a polycistronic primary miRNA that is processed into five mature miRNAs that target different regions of the HCV genome. All five anti-HCV miRNAs were active, achieving up to 97% inhibition of Renilla luciferase (RLuc) HCV reporter plasmids. Self-complementary recombinant adeno-associated virus (scAAV) vectors were chosen for therapeutic delivery of the miRNA cluster. Expression of the miRNAs from scAAV inhibited the replication of cell culture-propagated HCV (HCVcc) by 98%, and resulted in up to 93% gene silencing of RLuc-HCV reporter plasmids in mouse liver. No hepatocellular toxicity was observed at scAAV doses as high as 5 × 10(11) vector genomes per mouse, a dose that is approximately five-fold higher than doses of scAAV-shRNA vectors that others have shown previously to be toxic in mouse liver. Conclusion: We have demonstrated that exogenous anti-HCV miRNAs induce gene silencing, and when expressed from scAAV vectors inhibit the replication of HCVcc without inducing toxicity. The combination of an AAV vector delivery system and exploitation of the endogenous RNAi pathway is a potentially viable alternative to current HCV treatment regimens.     

Non-coding RNAs in hepatitis C-induced hepatocellular carcinoma:Dysregulation and implications for early detection,diagnosis and therapy

Hepatitis C virus(HCV)infection is one of main causes of hepatocellular carcinoma(HCC)and the prevalence of HCV-associated HCC is on the rise worldwide.It is particularly important and helpful to identify potential markers for screening and early diagnosis of HCC among high-risk individuals with chronic hepatitis C,and to identify target molecules for the prevention and treatment of HCV-associated-HCC.Small noncoding RNAs,mainly microRNAs(miRNAs),and long non-coding RNAs(lncRNAs)with size greater than 200nucleotides,are likely to play important roles in a variety of biological processes,including development and progression of HCC.For the most part their underlying mechanisms of action remain largely unknown.In recent years,with the advance of high-resolution of microarray and application of next generation sequencing techniques,a significant number of non-coding RNAs(ncRNAs)associated with HCC,particularly caused by HCV infection,have been found to be differentially expressed and to be involved in pathogenesis of HCVassociated HCC.In this review,we focus on recent studies of ncRNAs,especially miRNAs and lncRNAs related to HCV-induced HCC.We summarize those ncRNAs aberrantly expressed in HCV-associated HCC and highlight the potential uses of ncRNAs in early detection,diagnosis and therapy of HCV-associated HCC.We also discuss the limitations of recent studies,and suggest future directions for research in the field.miRNAs,lncRNAs and their target genes may represent new candidate molecules for the prevention,diagnosis and treatment of HCC in patients with HCV infection.Studies of the potential uses of miRNAs and lncRNAs as diagnostic tools or therapies are still in their infancy.     

Hepatitis C virus infection,microRNA and liver disease progression

Hepatitis C virus (HCV) is a global health problem with an estimated 170-200 million peoples (approximately 3% of world population) are chronically infected worldwide and new infections are predicted to be on rise in coming years. HCV infection remains categorized as a major risk factor for chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. There has been considerable improvement in our understanding of virus life cycle since, the discovery of HCV two-decades ago. MicroRNAs (miRNAs) are important players in establishment of HCV infection and their propagation in infected hepatocytes. They target crucial host cellular factors needed for productive HCV replication and augmented cell growth. Very first anti-miRNA oligonucleotides, miravirsen has been tested in clinical trial and shown promising results as therapeutic agent in treatment against chronic HCV infection. Deregulated expression of miRNAs has been linked to the pathogenesis associated with HCV infection by controlling signaling pathways such as, proliferation, apoptosis and migration. Circulating miRNAs emerging as growing field in identification of biomarkers in disease progression and their potential as a means of communication between cells inside the liver is an exciting area of research in future. This review focuses on recent studies enforcing the contribution of miRNAs in HCV life cycle and coordinated regulation in HCV mediated liver disease progression.     

MicroRNAs,Hepatitis C Virus,and HCV/HIV-1 Co-Infection: New Insights in Pathogenesis and Therapy

MicroRNAs (miRNAs) can exert a profound effect on Hepatitis C virus (HCV) replication. The interaction of HCV with the highly liver-enriched miRNA, miR-122 represents one such unique example of viruses having evolved mechanism(s) to usurp the host miRNA machinery to support viral life cycle. Furthermore, HCV infection can also trigger changes in the cellular miRNA profile, which may ultimately contribute to the outcome of viral infection. Accumulating knowledge on HCV-host miRNA interactions has ultimately influenced the design of therapeutic interventions against chronic HCV infection. The importance of microRNA modulation in Human Immunodeficiency Virus (HIV-1) replication has been reported, albeit only in the context of HIV-1 mono-infection. The development of HCV infection is dramatically influenced during co-infection with HIV-1. Here, we review the current knowledge on miRNAs in HCV mono-infection. In addition, we discuss the potential role of some miRNAs, identified from the analyses of public data, in HCV/HIV-1 co-infection.     

Association of single nucleotide polymorphisms in microRNAs with susceptibility to hepatitis B virus infection and HBV‐related liver complications: A study in a Saudi Arabian population

The aim of this study was to evaluate the association of 10 SNPs in different microRNAs (miRNAs) with susceptibility to hepatitis B virus (HBV) infection, HBV clearance, persistence of chronic HBV infection, and progression to liver cirrhosis and hepatocellular carcinoma (HCC). Patients were categorized into the following groups: inactive HBV carrier, active HBV carrier, HBV‐cleared subject and cirrhosis+HCC. Samples were analysed for 10 SNPs in microRNAs using either PCR‐based genotyping or the TaqMan assay. We found that rs1358379 was associated with susceptibility to HBV infection, HBV clearance, persistent chronic HBV infection and liver cirrhosis+HCC. In addition, we found that rs2292832 and rs11614913 were associated with risk of HBV infection, viral clearance and cirrhosis+HCC, whereas rs2910164 was associated with proneness to HBV infection, and ability to clear the virus. There was evidence of associations between rs6505162 and HBV clearance and the development of liver disease, whereas a single association was found between rs2289030 and HBV clearance. Similarly, rs7372209 and rs4919510 were specifically associated with the development of HBV‐induced liver complications. SNPs in miRNAs affect the susceptibility, clearance and progression of HBV infection in Saudi Arabian patients. We found, using Gene Ontology or pathway analyses, that these genes may contribute to the pathophysiology of HBV infection and related liver complications. However, differences in the association of examined SNPs with various clinical stages indicate variations in the respective functional roles of these polymorphisms and their miRNAs, and thus, further investigation to fully explore their therapeutic potential is warranted.     

Impact of previous hepatitis B infection on the clinical outcomes from chronic hepatitis C? A population‐level analysis

Chronic coinfection with hepatitis C virus (HCV) and hepatitis B virus (HBV) is associated with adverse liver outcomes. The clinical impact of previous HBV infection on liver disease in HCV infection is unknown. We aimed at determining any association of previous HBV infection with liver outcomes using antibodies to the hepatitis B core antigen (HBcAb) positivity as a marker of exposure. The Scottish Hepatitis C Clinical Database containing data for all patients attending HCV clinics in participating health boards was linked to the HBV diagnostic registry and mortality data from Information Services Division, Scotland. Survival analyses with competing risks were constructed for time from the first appointment to decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver‐related mortality. Records of 8513 chronic HCV patients were included in the analyses (87 HBcAb positive and HBV surface antigen [HBsAg] positive, 1577 HBcAb positive and HBsAg negative, and 6849 HBcAb negative). Multivariate cause‐specific proportional hazards models showed previous HBV infection (HBcAb positive and HBsAg negative) significantly increased the risks of decompensated cirrhosis (hazard ratio [HR]: 1.29, 95% CI: 1.01‐1.65) and HCC (HR: 1.64, 95% CI: 1.09‐2.49), but not liver‐related death (HR: 1.02, 95% CI: 0.80‐1.30). This is the largest study to date showing an association between previous HBV infection and certain adverse liver outcomes in HCV infection. Our analyses add significantly to evidence which suggests that HBV infection adversely affects liver health despite apparent clearance. This has important implications for HBV vaccination policy and indications for prioritization of HCV therapy.     

Risk factors and prevention of hepatocellular carcinoma in HCV infection

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide. Several risk factors for HCC development have been identified, including cirrhosis, hepatitis B virus (HBV) infection, and hepatitis C virus (HCV) infection. With regard to cirrhosis, multivariate analysis indicates that alcohol abuse, HBsAg positivity, and anti-HCV seropositivity are independent variables associated with an increased risk for HCC in the cirrhotic patient. A close relationship between chronic HBV infection and HCC has been established by epidemiological studies and laboratory investigations. Evidence indicates that HCV also plays a leading role in development of HCC. Most patients with HCV-related HCC develop the tumor as a consequence of long-standing infection accompanied by chronic and progressive liver damage. In our study of 290 consecutive patients with cirrhosis, patients with persistently elevated or fluctuating ALT levels had a significantly greater rate of HCC development. The mechanism of HCC development in HCV infection remains to be elucidated. The annual cumulative risk of developing HCC is approximately 1% in patients without cirrhosis at inclusion and 3–10% in those with cirrhosis, depending on the stage of cirrhosis and presence of etiological cofactors. Although some evidence suggests that patients infected with the HCV genotype 1b are at increased risk for development of more severe liver disease, including HCC, results of our prospective study do not support a difference between cirrhotic and noncirrhotic patients in terms of the natural course of cirrhosis and the rate of developing HCC based on genotype. Strategies to prevent HCV-related HCC include blood screening and treatment of chronic HCV infection with interferon-α. Recent studies suggest that interferon-α treatment may prevent the development of HCC in HCV infection. Further research is warranted.     

Circulating microRNAs for the diagnosis of hepatocellular carcinoma

AimThere are no existing biomarkers that demonstrate very reliable performance in the diagnosis of hepatocellular carcinoma (HCC), especially in the early stage. Studies have shown that numerous aberrantly expressed circulating microRNAs (miRNAs) can be used as a diagnostic tool for HCC; however, these studies have produced inconsistent results.MethodsWe performed a meta-analysis to summarize the diagnostic accuracy of circulating miRNAs, alpha-fetoprotein (AFP), and AFP combined with miRNAs in differentiating HCC patients from non-HCC controls, healthy controls and chronic liver disease controls. We also evaluated the diagnostic accuracy of circulating miRNAs for early-stage HCC. Furthermore, we systematically reviewed the diagnostic effectiveness of single miRNAs and individual miRNA panels.ResultsCirculating miRNAs showed good diagnostic performance. Compared with single miRNAs, the diagnostic accuracy of miRNA panels was clearly better. The combination of AFP and miRNAs improved the diagnostic accuracy compared with the use of miRNAs or AFP alone. For early-stage HCC patients, circulating miRNAs exhibited relatively satisfactory diagnostic accuracy.ConclusionsCirculating miRNAs can be used as an early diagnostic marker of HCC. The combination of miRNAs and AFP has great potential as a novel strategy for the diagnosis of HCC.     

The Role of MicroRNA in Hepatitis C Virus Replication

Hepatitis C virus (HCV) infection is a major global health problem. There is no effective vaccine and the current treatment regimen with pegylated interferon α and ribavirin is associated with significant adverse events. Therefore, there is an urgent need to identify new antiviral targets for HCV therapy. In recent years, a growing number of microRNAs (miRNAs) have been reported to be able to regulate HCV replication and infection by interacting with the HCV genome directly or by regulating host innate immunity to build a nonspecific antiviral state within cells. In this review, we discuss HCV virology and standard of care followed by miRNA in general, and then give a brief overview of miRNAs involved in HCV infection and discuss their potential application as a therapeutic option for the treatment of HCV infection.     

Circulating MicroRNAs as Biomarkers in Hepatocellular Carcinoma Screening: A Validation Set From China

Hepatocellular carcinoma (HCC) is a global public health concern. Current diagnostic methods show poor performance in early-stage HCC detection. Accumulating evidences revealed the great potential of microRNAs (miRNAs) as noninvasive biomarkers in HCC detection. In this study, we examined the diagnostic performance of serum miR-10b, miR-106b, and miR-181a for HCC screening in China. Furthermore, a systematic review of previous related studies was conducted to confirm our results.One hundred eight participants including 27 HCC patients, 31 chronic liver disease (CLD) patients, and 50 healthy people were recruited in this study. Blood specimen was drawn from each participant to extract serum miRNAs. Statistical analyses were performed to assess the 3 miRNAs levels in HCC, CLD patients, and normal controls. A meta-analysis was conducted to further assess the diagnostic value of miRNAs in HCC detection based on previous studies.All these miRNAs (miR-10b, miR-181a, miR-106b) could well discriminate HCC patients from normal controls, with area under the receiver-operating characteristic curve (AUC) values of 0.85 (95% confidence interval [CI]: 0.76–0.94), 0.82 (95% CI: 0.72–0.91), and 0.89 (95% CI: 0.81–0.97), respectively. In addition, these miRNAs could distinguish HCC cases from CLD controls with a medium accuracy. However, the ability of these miRNAs in differentiating CLD patients from normal controls was not satisfactory. Panel of these miRNAs displayed a better performance compared with single miRNA assay, with AUC values of 0.94 (95% CI: 0.89–0.99) in discriminating HCC patients from normal controls and 0.91 (95% CI: 0.80–0.97) in discriminating HCC patients from CLD controls. Results of meta-analysis of previous studies combined with the current study suggested that circulating miRNAs could well differentiate HCC from normal controls, with AUC values of 0.86 (95% CI: 0.82–0.89) for single miRNA assay and 0.94 (95% CI: 0.91–0.96) for miRNA panel assay.Serum miR-10b, miR-106b, and miR-181a have great potential to serve as accurate and noninvasive biomarkers for HCC preliminary screening. Meta-analysis of previous studies combined with current study further confirmed that circulating miRNAs could play an important role in HCC detection. Further large-scale studies are needed to confirm the clinical significance of circulating miRNAs in HCC screening.     

循环microRNA早期诊断肝细胞癌研究现状及方法学探讨

肝细胞癌（HCC）是发病率和死亡率很高的恶性肿瘤,对高危人群的筛查和监测十分重要。定期检查肝脏超声和血清AFP是目前主要的筛查手段,但灵敏度和准确性仍不尽如人意。microRNA与HCC的发生、转移、复发等病理过程密切相关,相关研究也方兴未艾。循环microRNA是HCC血清学标志物中的重要成员,在HCC诊断和筛查方面具有广阔的应用前景。选择合适的microRNA和确定高效的诊断方法是相关研究的重点,更多高质量的研究还在持续进行中。