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.     

An update on the molecular genetics of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is associated with multiple risk factors and is believed to arise from preneoplastic lesions, usually in the background of cirrhosis. Extensive studies on HCC and its precursors have demonstrated complex and heterogeneous genetic or chromosomal abnormalities along the way from preneoplastic lesions to HCCs. These genetic abnormalities include loss of heterozygosity, microsatellite instability, gene alterations, and aberrant global gene expression profiles. Although some genetic alterations involving the p53 family, Rb family, and Wnt pathways are particularly important in the development of HCCs, the molecular pathogenesis of HCC differs with etiology in some extent. Recent studies using DNA microarray technique have identified some unique gene expression profiles in hepatitis B virus (HBV)- and hepatitis C virus (HCV)-associated HCCs. Gene expression profiling also allows people to distinguish HCCs from normal tissue or preneoplastic lesions and to evaluate metastatic or recurrent potentials. These unique genes or gene products associated with malignant transformation and recurrent or metastatic potentials may serve as molecular markers for early diagnosis, prediction of prognosis, and responsiveness to therapy. To date, information that has accumulated for the past several decades is still incomplete, and we still are faced with a great challenge in deciphering the molecular mechanisms of HCCs.     

Hepatozelluläres Karzinom

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world. The major etiologic risk factors include toxins (alcohol, aflatoxin B(1)), hepatitis B and C virus infection as well as various inherited metabolic disorders. The prognosis of HCC patients is generally very poor with a 5-year survival rate of less than 5%. The diagnosis is based on biochemical and imaging tests as well as histology. Therapeutic strategies include surgery (resection or liver transplantation) and non-surgical interventions, such as percutaneous ethanol injection or radiofrequency thermal ablation as well as transarterial embolization or chemoembolization. Radio- or chemotherapy are mostly ineffective. Therefore, the development and evaluation of novel HCC treatment strategies as well as the implementation of existing and the development of new measures to prevent HCC are of utmost importance. The better understanding of the clinical and molecular pathogenesis of HCC should lead to improved diagnostic, therapeutic and preventive strategies with the aim to reduce the incidence of HCC, one of the most devastating malignancies worldwide.     

Epidemiology and management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major world health problem because of the high incidence and case fatality rate. In most patients, the diagnosis of HCC is made at an advanced stage, which limits the application of curative treatments. Most HCCs develop in patients with underlying chronic liver disease. Chronic viral hepatitis B and C are the major causes of liver cirrhosis and HCC. Recent improvements in treatment of viral hepatitis and in methods for surveillance and therapy for HCC have contributed to better survival of patients with HCC. This article reviews the epidemiology, cause, prevention, clinical manifestations, surveillance, diagnosis, and treatment approach for HCC.     

Hepatocellular carcinoma prevention： A worldwide emergence between the opulence of developed countries and the economic constraints of developing nations

INTRODUCTION Hepatocellular carcinoma (HCC) is the fifth most common neoplasm, the major cause of death in patients with liver cirrhosis, and the third most common cause of cancer- related death in the world[1,2]. Every year, 560 000 people in the world d…     

Dimensions of hepatocellular carcinoma phenotypic diversity

Hepatocellular carcinoma(HCC) is the 3~(rd) leading cause of cancer-related death worldwide. More than 80% of HCCs arise within chronic liver disease resulting from viral hepatitis, alcohol, hemochromatosis, obesity and metabolic syndrome or genotoxins. Projections based on Western lifestyle and its metabolic consequences anticipate a further increase in incidence, despite recent breakthroughs in the management of viral hepatitis. HCCs display high heterogeneity of molecular phenotypes, which challenges clinical management. However, emerging molecular classifications of HCCs have not yet formed a unified corpus translatable to the clinical practice. Thus, patient management is currently based upon tumor number, size, vascular invasion, performance status and functional liver reserve. Nonetheless, an impressive body of molecular evidence emerged within the last 20 years and is becoming increasingly available to medical practitioners and researchers in the form of repositories. Therefore, the aim this work is to review molecular data underlying HCC classifications and to organize this corpus into the major dimensions explaining HCC phenotypic diversity. Major efforts have been recently made worldwide toward a unifying "clinically-friendly" molecular landscape. As a result, a consensus emerges on three major dimensions explaining the HCC heterogeneity. In the first dimension, tumor cell proliferation and differentiation enabled allocation of HCCs to two major classes presenting profoundly different clinical aggressiveness. In the second dimension, HCC microenvironment and tumor immunity underlie recent therapeutic breakthroughs prolonging patients' survival. In the third dimension,metabolic reprogramming, with the recent emergence of subclass-specific metabolic profiles, may lead to adaptive and combined therapeutic approaches. Therefore, here we review recent molecular evidence, their impact on tumor histopathological features and clinical behavior and highlight the remaining challenges to translate our cognitive corpus into patient diagnosis and allocation to therapeutic options.     

Does antiviral therapy for hepatitis B and C prevent hepatocellular carcinoma?

Approximately 75% to 80% of hepatocellular carcinomas (HCC) worldwide are attributed to chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) infection. Thus, effective prevention of HBV and HCV infection and progression from acute HBV and HCV infection to chronic hepatitis, cirrhosis and HCC might prevent as many as 450,000 deaths from HCC each year. The most effective approach to preventing HCC is to prevent HBV and HCV infection through vaccination. Indeed HBV vaccine is the first vaccine demonstrated to prevent cancers. However, a vaccine for HCV is not available and for persons who are chronically infected with HBV or HCV, antiviral therapy is the only option for preventing HCC. Direct evidence supporting a benefit of antiviral therapy on the prevention of HCC has been shown in a few randomized controlled trials. There is abundant evidence that antiviral therapy, in patients with long-term virological response, can improve liver histology, providing indirect support that antiviral therapy may prevent HCC by slowing progression of liver disease and possibly even reversing liver damage. Nevertheless, the risk of HCC remains in patients with chronic HBV or chronic HCV infection if treatment is initiated after cirrhosis is established. These data indicate that treatment might be of greater benefit if instituted earlier in the course of chronic hepatitis B or C. Safer, more effective, and more affordable antiviral therapies are needed for both hepatitis B and hepatitis C so more patients can benefit from treatment and more HCCs can be prevented.     

Pathogenesis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours worldwide. The major aetiologies and risk factors for the development of HCC are well defined and some of the multiple steps involved in hepatocarcinogenesis have been elucidated in recent years. However, no clear picture of how and in what sequence these factors interact at the molecular level has emerged yet. Malignant transformation of hepatocytes may occur as a consequence of various aetiologies, such as chronic viral hepatitis, alcohol, and metabolic disorders, in the context of increased cellular turnover induced by chronic liver injury, regeneration and cirrhosis. Activation of cellular oncogenes, inactivation of tumour suppressor genes, genomic instability, including DNA mismatch repair defects and impaired chromosomal segregation, overexpression of growth and angiogenic factors, and telomerase activation may contribute to the development of HCC. Overall, HCCs are genetically very heterogeneous tumours. New technologies, including gene expression profiling and proteomic analyses, should allow us to further elucidate the molecular events underlying HCC development and identify novel diagnostic markers as well as therapeutic targets.     

Understanding the hypercarcinogenic state in chronic hepatitis: a clue to the prevention of human hepatocellular carcinoma

Human hepatocellular carcinomas (HCCs) are preceded by chronic hepatitis and cirrhosis. Despite a clear viral etiology (hepatitis B virus [HBV] and hepatitis C virus [HCV] of human hepatocarcinogenesis, the mechanism is complex and the distinct molecular pathway or molecules that explain this phenomenon are not yet known. Viral hepatitis, “inflammation-mediated” hepatocarcinogenesis, greatly influences the incidence of somatic genetic events in hepatocytes, by increasing the number of target cells or the proliferation of once-hit hepatocytes, eventually leading to HCC. We propose that hepatitis virus can cause HCC by a combination of two mechanisms; (i) cell killing and stimulation of mitosis, leading to an accumulation of events necessary for transformation; and (ii) an increase in chromosomal instability mediated by induced recombinogeneic protein(s) during chronic hepatitis. These conditions may be designated as the “hypercarcinogenic state”. Our goal is to change the “hypercarcinogenic state” to the “normo- or hypocarcinogenic” state and to prevent HCC development. Received: August 7, 2002 / Accepted: August 14, 2002 Reprint requests to: O. Hino     

Molecular targets for therapy of hepatitis B virus-induced hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is the most frequent risk factor for development of hepatocellular carcinoma (HCC) worldwide. Studies of the molecular genetics and pathophysiology of HCC suggest that there are significant differences in the allelic imbalance, genome copy number, and gene expression patterns of HBV-induced HCC as compared to HCCs from other causes, which are presumably reflected to differences in the mode of presentation and outcomes of HBV-induced HCCs. Unique features of HBV-induced carcinogenesis include the role of HBV DNA integration in carcinogenesis and the powerful synergism between HBV and dietary aflatoxins in the pathogenesis of HCC. A more complete understanding of the biology of HBV-induced HCCs may reveal well-defined differences in the molecular pathways that regulate growth of these HCCs and allow better-targeted approaches to prevention and therapy of HBV-induced HCCs. This review will attempt to summarize the current knowledge about carcinogenic pathways in HBV-induced HCCs, review the agents currently in development for targeted therapy of HCCs, and propose potentially novel approaches to therapy of HBV-induced 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.     

Molecular characteristics of non‐cancerous liver tissue in non‐B non‐C hepatocellular carcinoma

Although chronic infection with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) are the most important risk factors for the development of hepatocellular carcinoma (HCC) worldwide, the proportion of HCC patients negative for the hepatitis B surface antigen and hepatitis C antibody, so‐called “non‐B non‐C HCC”, is rapidly increasing, especially in Japan. The background liver diseases of non‐B non‐C HCC patients can be multifactorial, including occult HBV infection and non‐alcoholic steatohepatitis. It is reasonable to investigate the non‐cancerous liver tissues to identify the potential molecular mechanisms responsible for the processes of hepatocarcinogenesis of non‐B non‐C HCC. However, to date, only a few studies have focused on this research concept based on the idea of “field cancerization”. This review highlights the potential importance of the molecular analysis of non‐cancerous liver tissues to clarify the molecular characteristics in patients with non‐B non‐C HCC. A better understanding of the molecular mechanisms underlying the individual predisposition to non‐B non‐C HCC will lead to improvements in the prevention, early diagnosis and treatment of this neoplastic disease.     

Hepatocellular carcinoma: an Asian perspective

Hepatocellular carcinoma (HCC) is one of the most frequently occurring malignancies in Asia. The incidence exceeds 30 cases/100,000/year in the east Asian region. Worldwide, it accounts for almost 1 million deaths/year. The high incidence in Asia is due to the high prevalence of chronic viral hepatitis, mainly chronic hepatitis B. With the introduction of universal vaccination for hepatitis B in some Asian countries in the mid 1980s, some of these countries are experiencing a decline in the incidence of HCC. This probably underscores the point that HCC caused by hepatitis B is a malignancy preventable by vaccine. Due to the relative paucity of symptoms in the early stages and the rapid doubling time of the tumor, most HCCs are discovered late in advanced stages at presentation. Most Asian countries have adopted a screening program for patients at risk. Earlier and smaller HCCs are detected through such programs but these programs have yet to demonstrate improved patient survival. Physicians managing patients with HCC are faced with two main challenges, the malignancy itself and the underlying liver disease. The extent of the tumor and the existing liver function limits the therapeutic choices available. Hepatic resection remains the treatment of choice. However, the majority of patients present with nonresectable tumors. Transarterial chemoembolization, percutaneous ethanol injection and radiofrequency ablation are the other treatment modalities. In patients with small tumors (<5 cm) and poor liver function, liver transplant offers a viable treatment alternative. In summary, the risk factor for HCC in Asia is predominantly chronic hepatitis B. Universal vaccination against hepatitis B is likely to reduce the incidence. The prognosis and outcome of treatment remains poor with a 5-year survival of 35% for patients treated surgically and less than 10% for nonresectable tumors. Current management is aimed at earlier detection and more effective treatment of early HCC. In future, the challenge will be managing HCC in the premalignant stage.     

Multicentric occurrence of hepatocellular carcinoma: diagnosis and clinical significance

To evaluate current knowledge on the multicentric occurrence (MO) of hepatocellular carcinoma (HCC) and its clinical significance was the purpose of this review. The criteria for MO of HCC are defined as follows: (1) the recurrent tumor consists of well differentiated HCC occurring in a different hepatic segment from moderately or poorly differentiated preexisting HCC, (2) both the primary and recurrent tumors are well differentiated HCC, (3) the recurrent tumors contain regions of dysplastic nodules in peripheral areas and, (4) multiple HCCs, indicating the “nodule‐in‐nodule” form, in which nodules consisting of moderately or poorly differentiated HCC cells are contained in a nodule of well differentiated HCC cells. However, these criteria assume rare or no metastasis of well differentiated HCC, and are also not applicable to cases in which some HCCs of multicentric origin are rapidly dedifferentiated, presenting morphologic features of moderately or poorly differentiated tumors. Diagnostic methods, besides histopathologic methods, for determining multicentric origin in multiple HCCs in the liver, or recurrent tumor(s) of HCC, include clonal analysis of the integration pattern of hepatitis B virus (HBV) DNA in HBV carrier patients, and analysis of thep53 mutation patterns or loss of heterozygosity of chromosomal DNA. The prognosis of patients with MO of HCC after curative resection is significantly better than that of patients with intrahepatic HCC metastasis. Moreover, the Liver Cancer Study Group of Japan has reported that patients with hepatic resection for small‐sized HCCs showed higher survival rates than a nonsurgical treatment group. Consequently, HCC with MO, whether this is synchronous or metachronous, should be surgically removed as the treatment of first choice.     

Iron in the pathogenesis of hepatocellular carcinoma.

Several data indicate that iron may be involved in the pathogenesis of hepatocellular carcinoma (HCC). A high prevalence of HCC has been reported in patients with genetic hemochromatosis and the risk of HCC appears to be related to the amount and duration of iron overload. Iron, which has been demonstrated to facilitate persistent hepatitis B or C infection, could also act as a co-factor in the pathogenesis of HCC in patients with hepatitis B or C. Among the possible mechanisms by which iron could exert its cancerogenetic potential, free radicals production responsible for heritable genetic alterations appears to be one of the most important, although the fibrogenetic capability of iron, potentially leading to cirrhosis, cannot be underestimated.     

Pathways and gene expression profiles in hepatocellular carcinoma

Hepatocarcinogenesis is a process attributed to progressive genomic changes which alter the hepatocellular phenotype producing cellular intermediates evolving into clearly neoplastic cells (hepatocellular carcinoma, HCC). During the preneoplastic phase, the liver is often the site of chronic hepatitis and/or cirrhosis, and this process leads to the production of monoclonal populations of aberrant and dysplastic hepatocytes that develop genetic and chromosomal alterations. At the moment three main molecular pathways of liver carcinogenesis have been described and several attempts of genetic classification of HCC have been proposed. The definition of genomic and molecular changes which occur during the development of HCC should improve the classification and prognostis of liver tumors. The development of sorafenib and other new targeted developing therapies were rendered possible by the discovery and understanding of the molecular and genetic pathogenesis of hepatocellular carcinoma. Besides viruses, such as Hepatitis B virus (HBV) and Hepatitis C virus (HCV), may contribute to cancer development by several ways; however, additional factors, such as host immunity and chronic inflammation and host cellular mutations also play a role in the transformation process. The understanding of these pathways will in the future enable the clinician to focus the treatment patients with HCC and customize single or combination therapy.     

Hepatocellular carcinoma occurring in nonfibrotic liver: epidemiologic and histopathologic analysis of 80 French cases

Hepatocellular carcinoma (HCC) occurring in nonfibrotic liver represents a rare, ill-defined subgroup of HCC without cirrhosis in which mechanisms of hepatocarcinogenesis remain unclear. The aim of our study was to assess epidemiological factors and detailed histopathologic changes in the nontumoral liver of patients developing such tumors. Of 330 HCCs resected in our institution between 1985 and 1998, we retrospectively analyzed 80 cases (53 men, 27 women; mean age, 51 +/- 16 years) in which the nontumoral liver showed no (n = 28) or minimal (n = 52) portal fibrosis without any septal fibrosis. In the group with no portal fibrosis there was no male predominance, and patients were significantly younger (44 +/- 19 years vs. 54 +/- 14 years) than those with minimal portal fibrosis. Sixty-seven tumors were typical HCCs, 8 were of fibrolamellar type, and 5 were hepatocholangiocarcinomas. Mean tumor size was 10 +/- 5 cm. Risk factors for HCC development were found in 30 patients: hepatitis B (n = 17) or C (n = 2) virus infections, alcohol consumption (n = 11), and hemochromatosis (n = 1). In the nontumoral liver, periportal and lobular necrosis, mild portal inflammation, steatosis, and iron overload were present in 15%, 57%, 52%, and 54% of cases, respectively. Liver cell changes were noted in 6%. This study emphasizes the need for strict criteria to classify HCC without cirrhosis. HCC in nonfibrotic liver is a distinct subgroup in which nontumoral liver shows nonspecific minimal changes without regeneration or premalignant lesion. Etiologic factors are often unidentified, although presence of HBV infection in 21% suggests a direct oncogenic role of this virus.     

Inherited hepatocellular carcinoma

Inherited liver disorders that cause chronic inflammation, fibrosis, and cirrhosis can lead to the development of liver cancer. Because of the rarity and diversity of some of these syndromes, the relative risk of developing HCC in these patients and the age at which tumours typically arise cannot be accurately estimated. Among patients with hereditary hemachromatosis (HH), the annual incidence of HCC is 4% once cirrhosis has been established. Fibrosis and portal hypertension associated with HH can be partially reversed with therapeutic phlebotomy, but it is unclear whether this treatment alters the incidence of HCC in these patients. Importantly, it seems likely that coincidence of these genetic disorders with known HCC risk factors such as alcoholism and viral hepatitis would amplify their oncogenic potential. For this reason, patients with known genetic disorders of the liver should be repeatedly counselled to avoid environmental and toxic injury to the liver. Treatment of HCC in patients with inherited liver disease mirrors that of HCC associated with other etiologies. Unfortunately, there are case series which suggest these patients with inherited liver disease and HCC tend to present at more advanced stages and are therefore not eligible for curative therapies, causing overall decreased survival relative to patients with HCC of viral or other etiologies.     

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.     

Hepatocellular carcinoma in non-alcoholic fatty liver disease: an emerging menace

Hepatocellular carcinoma (HCC) is a common cancer worldwide that primarily develops in cirrhosis resulting from chronic infection by hepatitis B virus and hepatitis C virus, alcoholic injury, and to a lesser extent from genetically determined disorders such as hemochromatosis. HCC has recently been linked to non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of obesity and related metabolic disorders such as diabetes. This association is alarming due to the globally high prevalence of these conditions and may contribute to the rising incidence of HCC witnessed in many industrialized countries. There is also evidence that NAFLD acts synergistically with other risk factors of HCC such as chronic hepatitis C and alcoholic liver injury. Moreover, HCC may complicate non-cirrhotic NAFLD with mild or absent fibrosis, greatly expanding the population potentially at higher risk. Major systemic and liver-specific molecular mechanisms involved include insulin resistance and hyperinsulinemia, increased TNF signaling pathways, and alterations in cellular lipid metabolism. These provide new targets for prevention, early recognition, and effective treatment of HCC associated with NAFLD. Indeed, both metformin and PPAR gamma agonists have been associated with lower risk and improved prognosis of HCC. This review summarizes current evidence as it pertains to the epidemiology, pathogenesis, and prevention of NAFLD-associated HCC.