MicroRNAs as therapeutic strategy for hepatitis B virus-associated hepatocellular carcinoma: Current status and future prospects

Hepatocellular carcinoma (HCC) remains to be one of the top causing cancer-related deaths today. The majority of HCC cases are reported to be the result of chronic hepatitis B virus (HBV) infection. Current treatments for HBV-related HCC revolve around the use of drugs to inhibit viral replication, as a high level of viral load and antigen in circulation often presents a poor patient prognosis. However, existing therapies are inefficient in the complete eradication of HBV, often resulting in tumour recurrence. The involvement of microRNAs (miRNAs) in important processes in HBV-related HCC makes it an important player in the progression of HCC in chronic hepatitis B infected patients. In this review, we discuss the key aspects of HBV infection and the important viral products that may regulate cancer-related processes via their interaction with miRNAs or their closely related protein machinery. Conversely, we also look at how miRNAs may go about regulating the virus, especially in vital processes like viral replication. Apart from miRNAs acting as either oncogenes or tumour-suppressors, we also look at how miRNAs may function as biomarkers that may possibly serve as better candidates than those currently employed in the diagnosis of HBV infection or HBV-related HCC. A summary of the roles of miRNAs in HBV-related HCC will hopefully lead to a gain in understanding of the pathogenesis process and pave the way for new insights in medical therapy.     

Molecular characteristics and stages of chronic hepatitis B virus infection

Hepatitis B virus （HBV） is a common viral pathogen that causes a substantial health burden worldwide. Remarkable progress has been made in our under- standing of the natural stages of chronic HBV infection. A dynamic balance between viral replication and host immune response is pivotal to the pathogenesis of liver disease. Knowledge of the HBV genome organization and replication cycle can unravel HBV genotypes and molecular variants, which contribute to the heterogeneity in outcome of chronic HBV infection. Most HBV infections are spontaneously resolved in immunocompetent adults, whereas they become chronic in most neonates and infants at a great risk of developing complications such as cirrhosis and hepatocellular carcinoma （HCC）. Those with chronic HBV infection may present in one of the four phases of infection： immune tolerance, immune clearance [hepatitis B e antigen （HBeAg）-positive chronic hepatitis B （CHB）], inactive carrier state, and reactivation （HBeAg-negative CHB）. Understanding the dynamic nature of chronic HBV infection is crucial in the management of HBV carriers. Long-term monitoring and optimal timing of antiviral therapy for chronic HBV infection help to prevent progression of HBV-related liver disease to its later stage, particularly in patients with higher risk markers of HCC, such as serum DNA concentration, HBeAg status, serum aminotransferase, HBV genotypes, and pre-core or core mutants.     

Roles of micrornas in the Hepatitis B Virus Infection and Related Diseases

The hepatitis B virus (HBV) is a small enveloped DNA virus that belongs to the Hepadnaviridae family. HBV can cause acute and persistent infection which can lead to hepatocellular carcinoma (HCC). MicroRNAs (miRNAs) play a crucial role in the main cellular events. The dysregulation of their expression has been linked to the development of the cancer as well as to viral interference. This chapter will describe the involvement of miRNAs in the case of HBV infection and their implication in the development of the HBV-related diseases.     

Prevention of hepatocellular carcinoma in chronic viral hepatitis B and C infection

Hepatocellular carcinoma(HCC)is a leading cause of cancer-related mortality worldwide,with the majority of cases associated with persistent infection from hepatitis B virus(HBV)or hepatitis C virus(HCV).Natural history studies have identified risk factors associated with HCC development among chronic HBV and HCV infection.High-risk infected individuals can now be identified by the usage of risk predictive scores.Vaccination plays a central role in the prevention of HBV-related HCC.Treatment of chronic HBV infection,especially by nucleoside analogue therapy,could also reduce the risk of HBV-related HCC.Concerning HCV infection,besides the advocation of universal precautions to reduce the rate of infection,pegylated interferon and ribavirin could also reduce the risk of HCV-related HCC among those achieving a sustained virologic response.Recently there has been mounting evidence on the role of chemopreventive agents in reducing HBV-and HCV-related HCC.The continued advances in the understanding of the molecular pathogenesis of HCC would hold promise in preventing this highly lethal cancer.     

Association between metabolic factors and chronic hepatitis B virus infection

There are limited data regarding the relationship between chronic hepatitis B virus (HBV) infection and metabolic factors. This article aims to highlight the link of metabolic factors with hepatitis B surface antigen (HBsAg) serostatus, HBV load, and HBV-related hepatocellular carcinoma (HCC). Although HBsAg-positive serostatus was positively correlated with a high risk of metabolic syndrome in students, chronic HBV-infected individuals have high serum adiponectin levels. The androgen pathway in HBV carriers with a low body mass index is more triggered which leads to enhanced HBV replication. High HBV load was inversely associated with obesity in hepatitis B e antigen (HBeAg)-seropositive HBV carriers; while in HBeAg-seronegative HBV carriers, high HBV load was inversely related to hypertriglyceridemia rather than obesity. For overweight and obese HBV-infected patients, high HBV load was positively associated with serum adiponectin levels. Several large cohort studies have revealed a positive link of diabetes with incidence of HBV-related HCC. However, the association between incidence of HCC and metabolic factors other than diabetes is still inconclusive. More long-term prospective studies should elucidate the association of chronic HBV infection and its outcomes with metabolic factors in clinical practice.     

Antiviral therapies for hepatitis B virus-related hepatocellular carcinoma

Chronic hepatitis B virus(HBV) infection is a critical risk factor for the carcinogenesis and progression of hepatocellular carcinoma(HCC). It promotes HCC development by inducing liver fibrogenesis, genetic and epigenetic alterations, and the expression of active viral-coded proteins. Effective antiviral treatments inhibit the replication of HBV, reduce serum viral load and accelerate hepatitis B e antigen serum conversion. Timely initiation of antiviral treatment is not only essential for preventing the incidence of HCC in chronic hepatitis B patients, but also important for reducing HBV reactivation, improving liver function, reducing or delaying HCC recurrence, and prolonging overall survival of HBV-related HCC patients after curative and palliative therapies. The selection of antiviral drugs, monitoring of indicators such as HBV DNA and hepatitis B surface antigen, and timely rescue treatment when necessary, are essential in antiviral therapies for HBVrelated HCC.     

Long noncoding RNAs in hepatitis B virus replication and oncogenesis

Several diverse long noncoding RNAs (lncRNAs) have been identified to be involved in hepatitis B virus (HBV) replication and oncogenesis, especially those dysregulated in HBV-related hepatocellular carcinoma (HCC). Most of these dysregulated lncRNAs are modulated by the HBV X protein. The regulatory mechanisms of some lncRNAs in HBV replication and oncogenesis have been characterized. Genetic polymorphisms of several lncRNAs affecting HBV replication or oncogenesis have also been studied. The prognosis of HCC remains poor. It is important to identify novel tumor markers for early diagnosis and find more therapeutic targets for effective treatments of HCC. Some dysregulated lncRNAs in HBV-related HCC may become biomarkers for early diagnosis and/or the therapeutic targets of HCC. This mini-review summarizes these findings briefly, focusing on recent developments.     

Hepatitis B virus infection and the risk of hepatocellular carcinoma

Epidemiological studies have provided overwhelming evidence for a causal role of chronic hepatitis B virus(HBV) infection in the development of hepatocellular carcinoma(HCC).However,the pathogenesis of HBV infection and carcinogenesis of HBV-associated HCC are still elusive.This review will summarize the current knowledge on the mechanisms involved in HBV-related liver carcinogenesis.The role of HBV in tumor formation appears to be complex,and may involve both direct and indirect mechanisms.Integration of H...     

Immune suppression in chronic hepatitis B infection associated liver disease: A review

Hepatitis B virus(HBV) infection is one the leading risk factors for chronic hepatitis, liver fibrosis, cirrhosis and hepatocellular cancer(HCC), which are a major global health problem. A large number of clinical studies have shown that chronic HBV persistent infection causes the dysfunction of innate and adaptive immune response involving monocytes/macrophages, dendritic cells, natural killer(NK) cells, T cells. Among these immune cells, cell subsets with suppressive features have been recognized such as myeloid derived suppressive cells(MDSC),NK-reg, T-reg, which represent a critical regulatory system during liver fibrogenesis or tumourigenesis. However, the mechanisms that link HBVinduced immune dysfunction and HBV-related liver diseases are not understood.In this review we summarize the recent studies on innate and adaptive immune cell dysfunction in chronic HBV infection, liver fibrosis, cirrhosis, and HCC, and further discuss the potential mechanism of HBV-induced immunosuppressive cascade in HBV infection and consequences. It is hoped that this article will help ongoing research about the pathogenesis of HBV-related hepatic fibrosis and HBV-related HCC.     

Hepatitis B Virus Pre-S Gene Deletions and Pre-S Deleted Proteins: Clinical and Molecular Implications in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent and fatal human cancers worldwide and its development and prognosis are intimately associated with chronic infection with hepatitis B virus (HBV). The identification of genetic mutations and molecular mechanisms that mediate HBV-induced tumorigenesis therefore holds promise for the development of potential biomarkers and targets for HCC prevention and therapy. The presence of HBV pre-S gene deletions in the blood and the expression of pre-S deleted proteins in the liver tissues of patients with chronic hepatitis B and HBV-related HCC have emerged as valuable biomarkers for higher incidence rates of HCC development and a higher risk of HCC recurrence after curative surgical resection, respectively. Moreover, pre-S deleted proteins are regarded as important oncoproteins that activate multiple signaling pathways to induce DNA damage and promote growth and proliferation in hepatocytes, leading to HCC development. The signaling molecules dysregulated by pre-S deleted proteins have also been validated as potential targets for the prevention of HCC development. In this review, we summarize the clinical and molecular implications of HBV pre-S gene deletions and pre-S deleted proteins in HCC development and recurrence and highlight their potential applications in HCC prevention and therapy.     

Management of hepatitis B virus infection during treatment for hepatitis B virus-related hepatocellular carcinoma

Although liver resection is considered the most effective treatment for hepatocellular carcinoma (HCC), treatment outcomes are unsatisfactory because of the high rate of HCC recurrence. Since we reported hepatitis B e-antigen positivity and high serum hepatitis B virus (HBV) DNA concentrations are strong risk factors for HCC recurrence after curative resection of HBV-related HCC in the early 2000s, many investigators have demonstrated the effects of viral status on HCC recurrence and post-treatment outcomes. These findings suggest controlling viral status is important to prevent HCC recurrence and improve survival after curative treatment for HBV-related HCC. Antiviral therapy after curative treatment aims to improve prognosis by preventing HCC recurrence and maintaining liver function. Therapy with interferon and nucleos(t)ide analogs may be useful for preventing HCC recurrence and improving overall survival in patients who have undergone curative resection for HBV-related HCC. In addition, reactivation of viral replication can occur after liver resection for HBV-related HCC. Antiviral therapy can be recommended for patients to prevent HBV reactivation. Nevertheless, further studies are required to establish treatment guidelines for patients with HBV-related HCC.     

Molecular mechanisms of gender disparity in hepatitis B virus-associated hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is one of the most common causes of hepatocellular carcinoma (HCC), a malignant tumor with high mortality worldwide. One remarkable clinical feature of HBV-related HCC is that its incidence is higher in males and postmenopausal females compared to other females. Increasing evidence indicates that HBV-associated HCC may involve gender disparity and that it may be a type of hormone-responsive malignant tumor. Sex hormones, such as androgen and estrogen, have been shown to play very different roles in the progression of an HBV infection and in the development of HBV-related HCC. Through binding to their specific cellular receptors and affecting the corresponding signaling pathways, sex hormones can regulate the transactivation of HBx, cause the chronic release of inflammatory cytokines in the hepatocellular microenvironment, and participate in epigenetic and genetic alternations in hepatocytes. All of these functions may be related to the initiation and progression of HBV-associated HCC. A thorough investigation of the molecular mechanisms underlying the gender-related disparity in HBV-related HCC should provide a new perspective for better understanding its pathogenesis and exploring more effective methods for the prevention and treatment of this disease.     

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。