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.     

Prediction and prevention of intrahepatic recurrence of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has characteristic features of the coexistence of two life-threatening conditions, cancer and cirrhosis, which makes prognostic assessment difficult. In addition, the high rate of intrahepatic recurrence is a key feature that correlates with poor prognosis and its prevention is an issue for urgent investigation. Gene expression in the tumor and adjacent liver tissue for the prediction of intrahepatic recurrence of HCC has been extensively investigated. Among them, the expression of progenitor cell feature markers in the cancer cells such as epidermal cell adhesion molecule (EpCAM), cytokeratin 19 (CK19) and CD 133 have been shown to be associated with intrahepatic recurrence of HCC. Gene expression patterns from adjacent tissues were shown to predict early and overall recurrence in patients with HCC. Insulin resistance should be included in the analysis for the prevention of recurrence. To suppress or eradicate the replication of hepatitis B and C virus must be the most important issue for prevention. Supplementation by branched chain amino acid-enrichment and administration of vitamin K, acyclic retinoid and chemotherapeutic agents have been examined. There is an urgent need to develop a predictive tool and an effective treatment for prevention. It would be extremely valuable to find a useful biomarker for prediction and to develop new molecular targeting agents for the prevention of HCC recurrence in the near future.     

Prevention of hepatocellular carcinoma

Prevention is the only realistic approach for reducing mortality rates associated with hepatocellular carcinoma (HCC) worldwide. Vaccination against hepatitis B and screening of blood donations are effective measures of primary prevention. Screening of blood donations has led to a substantial reduction in viral hepatitis transmission among the general population, and in Taiwan vaccination against hepatitis B caused a significant reduction in HCC incidence among infants. Primary prevention also includes approaches that alter epigenetic and genetic changes in hepatocytes, known to increase susceptibility to HCC, as well as treatments slowing progression to cirrhosis. The only evidence that chemoprevention reduces HCC risk is a multicenter randomized prospective study in Asian patients with advanced hepatitis B who received the oral nucleoside analogue lamivudine. Circumstantial evidence suggests that HCC risk is also reduced in patients with chronic hepatitis C who have had a sustained virological response to interferon therapy. HCC is not substantially reduced in patients with hepatitis B treated with interferon and patients with hepatitis C who did not respond to interferon. Secondary prevention, that is, prevention of tumor recurrence after hepatic resection or local ablative therapies, has been pursued with different approaches. Retinoids, hepatic embolization with (131)I lipiodol, and adoptive adjuvant immunotherapy have yielded encouraging results. Other approaches, including those based on interferon alfa or beta, provided inconclusive evidence for secondary prophylaxis of HCC, mainly because of the poor methodologies and scientific background of the studies. Dietary interventions and antiaflatoxin agents might help to prevent HCC in susceptible individuals, but the real efficacy of these approaches is far from being demonstrated.     

Molecular targets for prevention of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world with an extremely poor prognosis. The major etiologic risk factors for HCC development include toxins (alcohol, aflatoxin B1), androgens and estrogens, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection as well as various inherited metabolic disorders, such as alpha-1-antitrypsin deficiency and hemochromatosis. The molecular pathogenesis of HCC development is very complex and involves alterations in the structure or expression of several tumor suppressor genes, oncogenes and, possibly, mechanisms leading to a genetic instability due to mismatch repair deficiency or chromosomal instability and aneuploidy due to defective chromosomal segregation. Central to the molecular pathogenesis of HCCs are mutations of various genes and a genetic instability which in most cases result from chronic liver disease and the associated enhanced liver cell regeneration and mitotic activity. The prognosis of HCC patients is generally very poor. Most studies report a five year survival rate of less than 5% in symptomatic HCC patients. Furthermore, these tumors have been shown to be quite resistant to radio- or chemotherapy. Investigations of the natural history and clinical course of HCCs revealed long-term survival of patients only with small asymptomatic HCCs that could be treated surgically or by non-surgical interventions. Apart from exploring and refining new HCC treatment strategies, the implementation of existing and the development of novel measures to prevent HCC development are most important. Primary HCC prevention includes among others universal hepatitis B vaccination, antiviral therapy of patients with chronic hepatitis B or C, reduction of food contamination with aflatoxins, elimination of excessive alcohol etc. Also for some genetic diseases there is the potential for HCC prevention by identifying affected family members at risk, such as patients with precirrhotic hemochromatosis. Reduction of iron overload by phlebotomy has been shown to eliminate the progression hemochromatosis to liver cirrhosis and HCC. Preventive measures, therefore, should have a major impact on the incidence of HCCs in patients with acquired and inherited liver diseases. Further, the prevention of a local recurrence or the development of new HCC lesions in patients after successful surgical or non-surgical HCC treatment (secondary prevention) is of paramount importance and is expected to significantly improve disease-free and overall patient survival. Based on rapid scientific advances, molecular diagnosis, gene therapy and molecular prevention are becoming increasingly part of our patient management and will eventually complement and in part replace existing diagnostic, therapeutic and preventive strategies. Overall, this should result in a reduction of the incidence of HCCs, one of the most devastating malignancies worldwide.     

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.     

Chemoprevention of hepatocellular carcinoma: concept, progress and perspectives

Hepatocellular carcinoma (HCC) often develops in patients with chronic liver diseases associated with hepatitis B (HBV) and hepatitis C (HCV) virus infections with high incidences. Particularly, post-therapeutic recurrence encountered after the curative treatment of the preceding HCC may limit the prognosis. Thus, prevention of HCC is of great significance. In the present review, immunopreventions with alpha-interferon and glycyrrhizin, as well as chemoprevention with acyclic retinoid, are discussed. alpha-Interferon prevents the development of HCC not only in patients with a long-term elimination of HCV (sustained virological responders), but in ones with normalized serum aminotransferases (sustained biochemical responders). Glycyrrhizin also suppresses serum aminotransferases and thereby prevents the tumor development, even though the compound does not have antiviral activity for HBV or HCV by itself. Therefore, suppression of hepatic necroinflammation by these drugs may serve to prevent hepatocarcinogenesis. In contrast, acyclic retinoid suppresses the post-therapeutic recurrence in cirrhotic patients who underwent curative treatment of preceding tumors. The retinoid induces the disappearance of serum lectin-reactive alpha-fetoprotein (AFP-L3), a tumor marker indicating the presence of unrecognizable tumors in the remnant liver, suggesting a deletion of such minute (pre)malignant clones (clonal deletion). As a molecular mechanism of the clonal deletion, a novel mechanism of apoptosis induction by the retinoid via tissue transglutaminase is implicated. In future, a combination of immunopreventive and chemopreventive therapies may give a clue to the further advances of cancer prevention, and thereby to the improvement of the prognosis of cirrhotic patients.     

Molecular therapy and prevention of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world with an extremely poor prognosis. The major etiologic risk factors for HCC development include hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, toxins (alcohol, aflatoxin B1) and various inherited metabolic liver diseases, such as hemochromatosis and alpha-1-antitrypsin deficiency. Central to the molecular pathogenesis of HCC are mutations of various genes and genetic/chromosomal instability that result from chronic liver disease and the associated enhanced liver cell regeneration and mitotic activity. Alterations in the structure or expression of several tumor suppressor genes and oncogenes have been described. In addition, mechanisms leading to genetic instability due to mismatch repair deficiency or chromosomal instability and aneuploidy due to defective chromosomal segregation appear to be involved. The prognosis of HCC patients is generally very poor. Most studies have shown a five-year survival rate of less than 5% in symptomatic patients. HCC has been found to be quite resistant to radio- or chemotherapy. Investigations of the natural history and clinical course of HCC revealed a long-term survival of patients only with small asymptomatic HCC that could be treated surgically or nonsurgically. For patients with advanced symptomatic HCC, novel therapeutic strategies such as gene therapy are urgently needed. Apart from exploring and refining new HCC treatment strategies, the implementation of the existing measures or the development of novel measures to prevent HCC is most important. Primary HCC prevention could have a major impact on the incidence of HCC. Further, secondary prevention of a local recurrence or of new HCC lesions in patients after successful surgical or nonsurgical HCC treatment is of paramount importance and is expected to significantly improve disease-free and overall survival rates of patients. Based on rapid scientific advances, molecular diagnosis, gene therapy and molecular prevention are becoming increasingly part of our patient management and will eventually complement or in part replace the existing diagnostic, therapeutic and preventive strategies. Overall, this should result in a reduced HCC incidence and an improved clinical outcome for patients with HCC, one of the most devastating malignancies worldwide.     

Biomarkers for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) ranks high among the most common and fatal cancers in the world. HCC develops from chronic liver diseases, especially from hepatitis C virus-related and hepatitis B virus (HBV)-related liver diseases. In this sense, useful biomarkers for HCC detection for the patients at risk of HCC are quite important. Recently, new therapies for HCC have been developed, and the prognosis of the patients has improved. However, considering the recurrence rate of HCC after treatment is very high, biomarkers that detect recurrence at an early stage are also required. In addition, since new drugs such as multikinase inhibitors have been introduced to the clinical scene, surrogate biomarkers to predict the effectiveness of treatment will be required in the near future. So far, many biomarkers for HCC have been developed, and their clinical usefulness has been assessed. As a result, several biomarkers for HCC are widely used. However, investigations to discover more useful biomarkers that fit in clinical settings are under way. In this review article, biomarkers for HCC are overviewed to examine their clinical usefulness.     

Hepatitis B viral load affects prognosis of hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is a complex disease that is dually challenging to treat due to underlying chronic liver disease in addition to the cancer itself.The prognosis of patients with HCC is determined by intrahepatic tumor status and reserved hepatic function.Hepatitis B virus(HBV)is an established major risk factor of HCC development,and HBV viral load is being increasingly recognized as a prognostic factor in the presence of established HCC.High HBV viral load may affect the prognosis of HBV-related HCC patients in several ways.First,it is associated with more frequent recurrence of HBV-related HCC after treatment.Second,it is associated with more occurrence and severity of potentially life-threatening HBV reactivation.Last,it is associated with more worsened liver function,which limits the therapeutic options for HBV-related HCC.HBV,directly or indirectly,can induce hepatocarcinogenesis.In patients with a high HBV DNA level and subsequent active hepatitis,adhesion molecules expressed on the sinusoidal cells are up-regulated and may increase intrahepatic metastasis.HCC progression after treatment can lead to a poor prognosis by reducing number of normal functioning hepatocytes.Thus,high HBV viral load can affect the prognosis of patientswith HCC by frequent recurrence after treatment for HCC and deterioration of hepatic function associated with HCC progression.Recent meta-analysis showed that antiviral treatment reduces HCC recurrence and liver-related mortality after curative therapy of HCC.Given the strong relationship between high HBV DNA load and poor survival outcome of HCC patients due to cancer progression,it is expected that long-term antiviral therapy results in the sustained HBV suppression,control of inflammation,reduction in HCC progression,and eventually in improved overall survival.     

Supportive therapies for prevention of hepatocellular carcinoma recurrence and preservation of liver function

Hepatocellular carcinoma(HCC) is one of the deadliest cancers in the world and is associated with a high risk of recurrence. The development of a wide range of new therapies is therefore essential. In this study, from the perspective of supportive therapy for the prevention of HCC recurrence and preservation of liver function in HCC patients, we surveyed a variety of different therapeutic agents. We show that branched chain amino acids(BCAA) supplementation and late evening snack with BCAA, strategies that address issues of protein-energy malnutrition, are important for liver cirrhotic patients with HCC. For chemoprevention of HCC recurrence, we show that viral control after radical treatment is important. We also reviewed the therapeutic potential of antiviral drugs, sorafenib, peretinoin, iron chelators. Sorafenib is a kinase inhibitor and a standard therapy in the treatment of advanced HCC. Peretinoin is a vitamin A-like molecule that targets the retinoid nuclear receptor to induce apoptosis and inhibit tumor growth in HCC cells. Iron chelators, such as deferoxamine and deferasirox, act to prevent cancer cell growth. These chelators may have potential as combination therapies in conjunction with peretinoin. Finally, we review the potential inhibitory effect of bone marrow cells on hepatocarcinogenesis.     

Prevention of hepatocellular carcinoma in patients with chronic hepatitis B

Patients with chronic hepatitis B are at significant risk for hepatocellular carcinoma(HCC). Globally,over half a million people each year are diagnosed with HCC,with marked geographical variations. Despite overwhelming evidence for a causal role of hepatitis B virus(HBV) infection in the development of HCC and a well-established relationship between high baseline hepatitis B viral load and cumulative risk of HCC,the molecular basis for this association has not been fully elucidated. In addition,a beneficial role for antiviral therapy in preventing the development of HCC has been difficult to establish. This review examines the biological and molecular mechanisms of HBV-related hepatocarcinogenesis,recent results on the effect of modern nucleos(t)ides on the rate of HCC development in high risk HBV cohorts and the potential mechanisms by which long-term antiviral therapy with potent inhibitors of HBV replication might reduce the risk of HCC in patients with chronic hepatitis B. Although evidence from randomized controlled trials shows the favourable effects of antiviral agentsin achieving profound and durable suppression of HBV DNA levels while improving liver function and histology,robust evidence of other long-term clinical outcomes,such as prevention of HCC,are limited.     

Influence of diabetes mellitus and effectiveness of metformin on hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers, and it is important to elucidate the carcinogenic factors and improve the recurrence and prognosis of HCC patients. Diabetes mellitus (DM) has been reported to be a risk factor for the carcinogenesis of many cancers including HCC, and the mechanism of DM for carcinogenesis is gradually being elucidated. Metformin, a drug for DM, has been reported to have anticancer effects on many cancers, including HCC. Metformin not only suppresses carcinogenesis but also improves the prognosis of recurrence after treatment, and there are many reports on the mechanism of these effects. In this review, we describe the mechanism of action of hyperglycemia and hyperinsulinemia on carcinogenesis by DM against HCC. The carcinogenic effects of DM on hepatitis B, hepatitis C, and nonalcoholic fatty liver disease by etiology are also described. In addition, the carcinogenic effect of metformin on HCC and its mechanism of action are reviewed. We also discuss the effects of metformin on recurrence after hepatectomy and radiofrequency therapy and the effects of metformin in combination with anticancer medicine, focusing on the inhibition of HCC development.     

食管癌和环氧合酶-2关系的研究进展

环氧化酶是花生四烯酸代谢中的一种限速酶,其中的同工酶之一的环氧合酶-2,通过多种途径与诸多肿瘤的发生、发展和预后密切相关.食管癌具有高发病率和死亡率,近年来认为环氧合酶-2通过异型生物质(xenobiotic)代谢,抑制凋亡,参与慢性炎症、免疫抑制,上调血管生成因子的表达,以及促进肿瘤的浸润和转移在其致癌中起重要作用.实验证据表明利用选择性环氧合酶-2抑制剂抑制环氧合酶-2活性可以预防各种组织中肿瘤的形成,包括食管癌.本文就环氧合酶-2对食管癌的致癌作用及选择性环氧合酶-2抑制剂的预防和/或治疗作用作一综述.     

Significance of viral status on prognosis of hepatitis B‐related hepatocellular carcinoma after curative resection in East Asia

Tumor recurrence remains one major obstacle for further improving the prognosis of hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC) patients after curative liver resection. It has been widely reported that tumor size, positive surgical margin, macroscopic vascular invasion, tumor–node–metastasis stage and Edmondson's grade were significantly related to HCC recurrence. However, the association between HCC recurrence and important viral factors, including the HBV DNA levels, status of hepatitis B surface antigen and hepatitis B e‐antigen, levels of cccDNA and hepatitis B core‐related antigen, viral genotypes and specific viral sequence mutations remained controversial. Meanwhile, studies on the effect of postoperative adjuvant antiviral therapy on HCC recurrence have been relatively limited and have yielded conflicting results. Identification of certain viral risk factors for HCC recurrence and stratification of patient risk are very important to perform future surveillance programs. As a HBV hyperendemic region, the majority of HBV‐related HCC patients develop in East Asia. In this article, we thus systematically reviewed the risk of important viral factors involved in recurrent carcinogenesis and the role of adjuvant antiviral therapy in preventing tumor recurrence in this area.     

Management of chronic hepatitis B in severe liver disease

In the past few decades,chronic hepatitis B(CHB)has evolved from a disease that was untreatable and progressive,to one that can be easily controlled with antiviral therapy.However,patients with severe liver disease still remain difficult to treat despite the availability of highly potent nucleos(t)ide analogs.These include those with underlying cirrhosis,severe flares of CHB,hepatocellular carcinoma(HCC),and for those undergoing liver transplantation.For those with established cirrhosis,antiviral therapy should be considered for all,as unpredictable flares can still occur,which can be fatal for those with advanced chronic liver disease.However,even with effective viral suppression,the development of HCC can still occur.For patients with severe flares of CHB,although the use of antiviral can improve long term outcomes,a significant proportion may still die without liver transplantation.The short term prognosis of these patients is dependent on both the severity of flare and underlying pre-existing liver disease.In patients with decompensated cirrhosis,liver failure secondary to severe flares,or those with HCC,liver transplantation may be curative.After liver transplantation,long term antiviral therapy is required to prevent graft loss from recurrent hepatitis B infection.The use of hepatitis B immune globulin(HBIG)in combination with an oral antiviral agent has been the mainstay of post-transplant antiviral regimen for over adecade.With newer and more potent antiviral agents such as tenofovir and entecavir,use of these agents along with HBIG have demonstrated to be effective in preventing significant recurrence in the long term.     

Chemoprevention against hepatocellular carcinoma

Since the majority of hepatocellular carcinoma (HCC) arises from a background of chronic liver diseases caused by infection with hepatitis?C virus (HCV) and hepatitis?B virus (HBV), chemoprevention targeting patients at high risk of HCC is feasible. In this review article, we summarize current knowledge of chemoprevention against HCC mostly using phytochemicals which have less toxicity than pharmaceutical agents. We describe in?vivo and in?vitro evidence and proposed mechanisms of beneficial effects of several compounds on the liver, including acyclic retinoid (ACR), angiotensin-converting enzyme inhibitors (ACEIs), caffeine, capsaicin, cepharanthine (CEP), cinnamaldehyde, curcumin, diallyl sulfide (DAS), eicosapentaenoic acid (EPA), epigallocatechin-3-gallate (EGCG), genistein, lycopene, resveratrol, silymarin, sulforaphane (SFN), and xanthohumol (XN). Because antihepatocarcinogenic effects by these compounds are mostly based on experimental studies, clinical evidence is urgently necessary.     

Hepatocellular carcinoma in noncirrhotic young adult patients with chronic hepatitis B viral infection

Background The aims of this study were to define the clinical characteristics of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in young adult patients without cirrhosis and to evaluate the efficacy of interferon (IFN) therapy on HCC recurrence.Methods Of 187 patients with HBV-related HCC treated at our hospital, 4 had no liver cirrhosis and were less than 30 years of age (10, 22, 23, and 26 years).Results At the time of diagnosis of HCC, all cases had antibody to hepatitis B e antigen (anti-HBe) and histological staging of nontumorous liver was F0 or F1, i.e., low-grade hepatitis. The mothers of all 4 young adult patients with HCC had HBV-related liver disease. Three cases developed recurrence of HCC. In these patients, long-term intermittent IFN therapy after reresection of HCC resulted in long-term survival without recurrence for more than 3 years of follow-up.Conclusions (1) Young adult patients with HCC are positive for anti-HBe, lack cirrhosis, and the route of infection seems to be mother-to-infant transmission. Transplacental transmission of HBV and HBV DNA integration into the cellular genomic DNA during fetal life is a possible explanation of HBV-related hepatocarcinogenesis in young adults; and (2) long-term IFN therapy seems to be useful for prevention of tumor recurrence after radical operation for HBV-related HCC.     

肝移植术后肝癌复发防治进展

肝移植是根治性治疗肝癌的方法之一,但肝移植术后肝癌复发严重影响移植患者的长期生存。通过积极的预防措施,免疫抑制剂调整,早期发现以及全面制订肝癌复发后的干预措施,有助于提高肝癌肝移植患者临床疗效并改善长期生存。为了进一步改善肝移植患者预后,从预防复发及复发后的治疗两大方面对肝移植术后肝癌复发的最新防治进展进行归纳和总结。     

Secondary prevention of recurrence by interferon therapy after ablation therapy for hepatocellular carcinoma in chronic hepatitis C patients

Chronic hepatitis C is a leading cause of hepatocellular carcinoma （HCC） worldwide. Interferon （IFN） therapy decreases the incidence of HCC in patients with chronic hepatitis C. Prevention of chronic-hepatitisC-related HCC is one of the most important issues in current hepatology. We have previously reported that male gender and high titer of hepatitis C virus （HCV） RNA are predictive factors for the development of HCC in HCV-related cirrhosis. Clinical efforts at eradicating or reducing the viral load may reduce the risk for HCC. Furthermore, because HCC often recurs after ablation therapy, we performed a trial of IFN in patients with chronic liver disease caused by HCV to see whether IFN therapy decreases recurrence after ablation therapy of HCV-related HCC. By using IFN therapy as a secondary prevention, patients with HCC who had received complete tumor ablation showed better survival, primarily as a result of the preservation of liver function and also probably prevention of recurrence. Postoperative IFN therapy appears to decrease recurrence after ablation therapy such as radiofrequency ablation （RFA） therapy of HCV-related HCC. We believe that there is a survival benefit in secondary prevention using IFN therapy. However, a controlled study is essential to obtain conclusive evidence of the efficacy of this strategy.