Downregulation of E-cadherin by hepatitis B virus X antigen in hepatocellullar carcinoma

Hepatitis B virus (HBV)-encoded X antigen (HBxAg) contributes to the development of hepatocellular carcinoma (HCC). A frequent characteristic of HCC is reduced or absent expression of the cell adhesion protein, E-cadherin, although it is not known whether HBxAg plays a role. To address this, the levels of E-cadherin were determined in HBxAg-positive and -negative HepG2 cells in culture, and in tumor and surrounding nontumor liver from a panel of HBV carriers. The results showed an inverse relationship between HBxAg and E-cadherin expression both in tissue culture and in vivo. In HBxAg-positive cells, E-cadherin was suppressed at both the mRNA and protein levels. This was associated with hypermethylation of the E-cadherin promoter. Depressed E-cadherin correlated with HBxAg trans-activation function, as did the migration of HepG2 cells in vitro. Decreased expression of E-cadherin was also associated with the accumulation of beta-catenin in the cytoplasm and/or nuclei in tissues and cell lines, which is characteristic of activated beta-catenin. Additional work showed that HBxAg-activated beta-catenin. Together, these results suggest that the HBxAg is associated with decreased expression of E-cadherin, accumulation of beta-catenin in the cytoplasm and nucleus, and increased cell migration, which may contribute importantly to hepatocarcinogenesis.

Downregulation of E-cadherin by hepatitis B virus X antigen in hepatocellullar carcinoma

Hepatitis B virus (HBV)-encoded X antigen (HBxAg) contributes to the development of hepatocellular carcinoma (HCC). A frequent characteristic of HCC is reduced or absent expression of the cell adhesion protein, E-cadherin, although it is not known whether HBxAg plays a role. To address this, the levels of E-cadherin were determined in HBxAg-positive and -negative HepG2 cells in culture, and in tumor and surrounding nontumor liver from a panel of HBV carriers. The results showed an inverse relationship between HBxAg and E-cadherin expression both in tissue culture and in vivo. In HBxAg-positive cells, E-cadherin was suppressed at both the mRNA and protein levels. This was associated with hypermethylation of the E-cadherin promoter. Depressed E-cadherin correlated with HBxAg trans-activation function, as did the migration of HepG2 cells in vitro. Decreased expression of E-cadherin was also associated with the accumulation of beta-catenin in the cytoplasm and/or nuclei in tissues and cell lines, which is characteristic of activated beta-catenin. Additional work showed that HBxAg-activated beta-catenin. Together, these results suggest that the HBxAg is associated with decreased expression of E-cadherin, accumulation of beta-catenin in the cytoplasm and nucleus, and increased cell migration, which may contribute importantly to hepatocarcinogenesis.

Prevention of hepatitis C virus infection

In spite of advances made in our understanding of the biology of the hepatitis C virus (HCV), the epidemiology and natural history of HCV infection, and the treatment of chronic hepatitis C, the development and worldwide implementation of a comprehensive prevention and control strategy remains necessary. A World Health Organization informal consultation with the Viral Hepatitis Prevention Board was convened and met in Geneva, Switzerland, 13-14 May 2002, to review epidemiological and public health aspects of HCV infection, and the various prevention and control strategies that are currently in place. Based on the presentations and discussions, a number of specific recommendations were made, which should be considered in conjunction with previously published recommendations.

Biological impact of natural COOH-terminal deletions of hepatitis B virus X protein in hepatocellular carcinoma tissues

The hepatitis B virus (HBV) X protein (HBx) is a transcriptional transactivator that has been implicated in the development of HBV-related hepatocellular carcinoma. Mutations in the HBx open reading frame have been reported, but their general impact on the biological function of HBx remains unknown. To address this issue, we comparatively analyzed the structures and biological functions of HBx sequences isolated from sera and from tumor and nontumor tissues of patients with a HBV-related hepatocellular carcinoma. In addition to the HBx sequences derived from free HBV genomes, HBx from HBV integrants was also obtained from the tumor tissues by use of a HBx-Alu PCR-based approach. Sequence analysis showed that the HBx sequences derived from tumor tissues (6 of 7), particularly those isolated from HBV integrants (4 of 4), contained a deletion in the distal COOH-terminal region. Interestingly, most of the COOH-terminally truncated HBx sequences obtained from tumor tissues, in contrast to the full-length HBx isolated from the sera and nontumor tissues, lost their transcriptional activity and their inhibitory effects on cell proliferation and transformation. Importantly, although full-length HBx suppressed the focus formation induced by the cooperation of ras and myc oncogenes in primary rat embryo fibroblasts, COOH-terminally truncated HBx enhanced the transforming ability of ras and myc. Finally, by analyzing the artificial mutants, we were able to more precisely map the functional domains located at the COOH-terminal of HBx. Taken together, our results suggest a key role for the HBx COOH-terminal end in controlling cell proliferation, viability, and transformation. This study further supports the hypothesis that natural HBx mutants might be selected in tumor tissues and play a role in hepatocarcinogenesis by modifying the biological functions of HBx.

Increased hepatic oxidative DNA damage in patients with hepatocellular carcinoma

Since oxidative DNA damage plays a role in experimental carcinogen-induced cancers, the purpose of the present study was to determine if hepatic oxidative DNA damage was increased in patients with HCC compared to patients with benign hepatic tumors or hepatic metastases (non-HCC) or to patients with end-stage alcoholic liver disease undergoing liver transplantation. Oxidative DNA damage was assessed by 8-hydroxy-2'-deoxyguanosine (8-OH-dG). Results showed that peritumoral 8-OH-dG was markedly increased in HCC (N= 51) (180 +/- 74 vs 32 +/- 58-OH-dG/10(6)dG for tumor, P < 0.005) in contrast to patients with non-HCC (N = 17), in whom the peritumoral 8-OH-dG did not differ from that in tumor (39 +/- 7 vs. 31 +/- 108-OH-dG/10(6)dG). Oxidative DNA damage can be both mutagenic and carcinogenic; our data suggested it will be important in future studies to determine the chronology of this type of liver injury relative to hepatocarcinogenesis.

Hepatitis B virus and hepatocellular carcinoma

Chronic hepatitis B virus (HBV) infection is a major global cause of hepatocellular carcinoma (HCC). Individuals who are chronic carriers have a greater than 100-fold increased relative risk of developing the tumour. Several mechanisms of HBV-induced HCC have been proposed. Integration of HBV DNA into the genome of hepatocytes occurs commonly, although integration at cellular sites that are important for regulation of hepatocyte proliferation appears to be a rare event. Functions of the HBx protein are also potentially oncogenic. These include transcriptional activation of cellular growth regulatory genes, modulation of apoptosis and inhibition of nucleotide excision repair of damaged cellular DNA. The effects of HBx are mediated by interaction with cellular proteins and activation of cell signalling pathways. Variations in HBV genome sequences may be important in hepatocarcinogenesis, although their significance has not yet been completely elucidated. Necroinflammatory hepatic disease, which often accompanies chronic HBV infection, may contribute indirectly to hepatocyte transformation in a number of ways, including by facilitating HBV DNA integration, predisposing to the acquisition of cellular mutations and generating mutagenic oxygen reactive species. Although HCC is a malignancy with a poor prognosis, the availability of an effective vaccine against HBV infection, and its inclusion in the Expanded Programme of Immunization of many countries, augurs well for the eventual elimination of HBV-associated HCC.

A cellular gene up-regulated by hepatitis B virus-encoded X antigen promotes hepatocellular growth and survival

Polymerase chain reaction (PCR) select complementary DNA (cDNA) subtraction of hepatitis B x antigen (HBxAg)-positive compared with -negative HepG2 cells resulted in the up-regulated expression of a cellular gene that encodes a transcript of 745 bases and a polypeptide 99 amino acids long. GenBank analysis revealed extensive homology with the amino terminal domain of cellular multidrug resistant proteins (MRP), although overexpression of this gene did not confer an MRP phenotype. In situ hybridization and immunostaining showed colocalized expression with HBxAg in the liver of hepatitis B carriers. Overexpression of this protein stimulated the growth of HepG2 cells in serum-free medium, and partially protected cells from anti-Fas-mediated killing, but did not promote growth in soft agar or tumor formation in nude mice. Introduction of the dominant negative inhibitor of nuclear factor kappaB (IkappaBalpha) into HBxAg-positive HepG2 cells decreased the levels of messenger RNA (mRNA) and protein, suggesting that its up-regulation is nuclear factor kappaB (NF-kappaB) dependent. Hence, HBxAg activation of NF-kappaB may result in the up-regulation of a cellular protein that promotes growth factor-independent survival and protects against Fas-mediated killing. This factor may contribute to the persistence of infected hepatocytes during chronic infection, which is important for the later development of hepatocellular carcinoma (HCC).

Hammerhead ribozyme-mediated inhibition of hepatitis B virus X gene expression in cultured cells

BACKGROUND/AIMS

Chronic infection with hepatitis B virus (HBV) is endemic to sub-Saharan Africa and parts of Asia. Common complications of HBV persistence include cirrhosis and hepatocellular carcinoma (HCC). Present treatment of chronic HBV infection is usually ineffective and novel therapeutic approaches are an important objective. The HBV X protein (HBx) is a transcriptional activator that is required for the establishment of HBV infection and is implicated in hepatocarcinogenesis. The aim of this study was to assess the ability of two endogenously expressed hammerhead ribozymes to inhibit expression of HBV genes in transfected cultured cells.

METHODS

Eukaryotic expression plasmids producing two ribozymes targeted to the HBx open reading frame, as well as their catalytically inactive homologues, were generated. Established cell lines and a primary culture of malignant hepatocytes were transfected to assess ribozyme effects on HBx expression and HBV replication.

RESULTS

The ribozyme-expressing vectors inhibit expression of functional HBx protein and decrease HBV mRNA encoding surface and HBx sequences in transfected cells. Moreover, decreased HBsAg and HBeAg secretion from cells transfected with the ribozymes and an HBV replication competent plasmid provide evidence for an antireplicative effect of the ribozymes. However, the data do not exclude a dominant antisense effect that inhibits HBV gene expression.

CONCLUSIONS

Inactivation of HBx, a sequence that is conserved in mammalian hepadnaviruses and found in all HBV transcripts, has potential for the treatment of chronic HBV infection.

Putative role of hepatitis B virus X protein in hepatocarcinogenesis: effects on apoptosis, DNA repair, mitogen-activated protein kinase and JAK/STAT pathways

Chronic infection with hepatitis B virus (HBV) is a major risk factor for the development of hepatocellular carcinoma (HCC). The pathogenesis of HBV-induced malignant transformation is, however, incompletely understood. HBx, the protein encoded by the X open reading frame, is a transcriptional activator that has been implicated in hepatocarcinogenesis. HBx inhibits the function of the tumour suppressor protein p53 in what is thought to be an early event in hepatocyte transformation before the later accumulation of inactivating p53 point mutations. HBx inhibits apoptosis but also exerts pro-apoptotic effects. The effects of HBx on apoptosis may be important not only for the development of HCC but also for the establishment of HBV infection. Further implication of HBx in hepatocyte transformation has been the demonstration that it inhibits the repair of damaged hepatocyte DNA. This effect may be mediated by interaction with p53 or through binding to the damaged DNA binding protein (DDB), which plays an accessory role in nucleotide excision repair. In addition, HBx activates cell signalling cascades involving mitogen-activated protein kinase (MAPK) and Janus family tyrosine kinases (JAK)/signal transducer and activators of transcription (STAT) pathways. The implications of these modulating effects of HBx are not fully understood, but they are likely to have wide-ranging effects on hepatocyte proliferation, apoptosis and the regulation of cell growth checkpoints. The cellular functions ascribed to HBx are unusually diverse, and defining the biologically important role of HBx during HBV replication will go some way to understanding the sequelae of chronic HBV infection.

In situ demonstration of inhibitory effects of hammerhead ribozymes that are targeted to the hepatitis Bx sequence in cultured cells

Chronic hepatitis B virus (HBV) infection is endemic to several populous areas of the world and is frequently complicated by hepatocellular carcinoma. Ribozymes can be designed to cleave target RNA sequences specifically and show promise for the treatment of HBV infection. Demonstration of intracellular inhibition of HBV gene expression, essential to developing therapeutic ribozymes, has been the aim of this investigation. We generated two vectors encoding hammerhead ribozymes that target the HBx region of HBV. Plasmids containing intact HBV sequences or a modification in which the preS2/S region was replaced by DNA encoding enhanced green fluorescent protein (EGFP) were used to test ribozyme action in transfected cells. Both ribozymes inhibited surface antigen secretion and EGFP expression similarly. The measurement of EGFP expression is convenient to assess ribozyme action in situ and effective targeting of HBV sequences that are common to all HBV transcripts is potentially useful to develop strategies to counter HBV infection.

Smad2 and Smad4 gene mutations in hepatocellular carcinoma

TGF-beta is a negative regulator of liver growth. Smad family of genes, as mediators of TGF-beta pathway, are candidate tumor suppressor genes in hepatocellular carcinoma (HCC). We studied 35 HCC and non-tumour liver tissues for possible mutations in Smad2 and Smad4 genes. Three tumours displayed somatic mutations; two in Smad4 (Asp332Gly and Cys401Arg) and one in Smad2 (Gln407Arg) genes. All three mutations were A:T --> G:C transitions suspected to result from oxidative stress as observed in mitochondrial DNA. These observation demonstrate that TGF-beta pathway is altered in hepatocellular carcinoma.

The translation initiation factor, hu-Sui1 may be a target of hepatitis B X antigen in hepatocarcinogenesis

The role of hepatitis B virus X antigen in the development of hepatocellular carcinoma was explored by stably transfecting HepG2 cells with an X antigen expression vector, and identifying the differences in gene expression that distinguish X positive from X negative cells by subtractive PCR. One differentially expressed gene, the human homolog of sui1 (hu-sui1), encodes a translation initiation factor whose expression was suppressed by X antigen in HepG2 cells. Hu-Sui1 was also expressed in nontumor liver but not in tumor cells from patients with hepatocellular carcinoma. Introduction of hu-sui1 into HepG2 cells inhibited cell growth in culture, in soft agar, and partially inhibited tumor formation in nude mice. Hence, the suppression of hu-sui1 by X antigen may result in the abrogation of negative growth regulation and contribute to the development of hepatocellular carcinoma.

Allele-specific PCR analysis of p53 codon 249 AGT transversion in liver tissues from patients with viral hepatitis

AGG to AGT mutations in codon 249 of the p53 tumor-suppressor gene are frequently observed in hepatocellular carcinomas (HCC) from areas where exposure to aflatoxin B1 (AFB) occurs. We developed a sensitive allele-specific polymerase chain reaction (AS-PCR) assay to detect this point mutation in non-neoplastic human liver tissues. Three oligonucleotide primers, 1 specific for the mutant allele and 2 specific for the wild-type allele were used. The mutant allele primer differed from the wild-type allele due to a G-to-T transversion in its terminal 3' nucleotide. The first stage involved amplification of exon 7 of p53 followed by a selective amplification of mutant codon 249 sequences. This method allowed for the detection of a mutant codon 249 allele in the presence of as many as 105 copies of the wild-type allele and was 100-fold more sensitive than the restriction fragment length polymorphism-PCR technique. We have applied this AS-PCR protocol to examine codon 249 AGT transversion in tumor and matched non-tumor liver samples from North American patients with hepatitis and from Mozambiquan patients exposed to AFB. Mutations were detected in 5 of 6 samples of non-neoplastic liver from Mozambiquan patients, all of whom were HBsAg- or HBcAg-positive and AFB-exposed. In contrast, no mutations were detected in non-neoplastic liver from North American patients with either HBV- or HCV-derived hepatitis and cirrhosis. This procedure is a simple and powerful approach for screening p53 codon 249 AGT mutation in heterogeneous non-neoplastic hepatocyte populations.

Allele-specific PCR analysis of p53 codon 249 AGT transversion in liver tissues from patients with viral hepatitis

AGG to AGT mutations in codon 249 of the p53 tumor-suppressor gene are frequently observed in hepatocellular carcinomas (HCC) from areas where exposure to aflatoxin B1 (AFB) occurs. We developed a sensitive allele-specific polymerase chain reaction (AS-PCR) assay to detect this point mutation in non-neoplastic human liver tissues. Three oligonucleotide primers, 1 specific for the mutant allele and 2 specific for the wild-type allele were used. The mutant allele primer differed from the wild-type allele due to a G-to-T transversion in its terminal 3' nucleotide. The first stage involved amplification of exon 7 of p53 followed by a selective amplification of mutant codon 249 sequences. This method allowed for the detection of a mutant codon 249 allele in the presence of as many as 105 copies of the wild-type allele and was 100-fold more sensitive than the restriction fragment length polymorphism-PCR technique. We have applied this AS-PCR protocol to examine codon 249 AGT transversion in tumor and matched non-tumor liver samples from North American patients with hepatitis and from Mozambiquan patients exposed to AFB. Mutations were detected in 5 of 6 samples of non-neoplastic liver from Mozambiquan patients, all of whom were HBsAg- or HBcAg-positive and AFB-exposed. In contrast, no mutations were detected in non-neoplastic liver from North American patients with either HBV- or HCV-derived hepatitis and cirrhosis. This procedure is a simple and powerful approach for screening p53 codon 249 AGT mutation in heterogeneous non-neoplastic hepatocyte populations.

Precore/core mutations of hepatitis B virus in hepatocellular carcinomas developed on noncirrhotic livers

BACKGROUND & AIMS

Hepatitis B virus genomes have been detected in hepatocellular carcinoma developed without the pretumoral step of cirrhosis; this finding is consistent with a direct effect of the virus in liver cell transformation. The aim of this study was to investigate the molecular bases for the hepatitis B virus persistence. Three hepatitis B surface antigen-positive and 2 hepatitis B surface antigen-negative patients with hepatocellular carcinoma and without cirrhosis were studied for precore/core mutations in tumorous and nontumorous tissues.

METHODS

The precore/core region was amplified and analyzed both by cloning and sequencing and by direct sequencing.

RESULTS

Nonsynonymous mutations were identified selectively in tumorous tissues. Clusters of mutations were identified in the viral encapsidation (epsilon) signal, in immunodominant epitopes of the core protein, and in the polymerase. Common associated point mutations were found in 3 patients infected with hepatitis B virus genotype A in the epsilon signal and in the polymerase gene.

CONCLUSIONS

Precore/core mutations located in domains involved in hepatitis B virus replication and immune response to the virus were identified. The selective presence of some of these mutations in tumorous tissues is consistent with their role in the persistence of the virus in neoplastic cells and, possibly, in liver oncogenesis.

Selective accumulation of the X transcript of hepatitis B virus in patients negative for hepatitis B surface antigen with hepatocellular carcinoma

In HBsAg-negative patients with hepatocellular carcinoma (HCC), hepatitis B virus (HBV) genomes are present at a low copy number per cell, and the role of HBV in liver transformation is still unclear. We have mapped by polymerase chain reaction (PCR) the HBV genome in 19 HBsAg-negative tumorous and 9 corresponding nontumorous tissues and evaluated, by RT-PCR, the presence of HBV S, X, and C transcripts in the tumorous and nontumorous tissue of nine HBsAg-negative and, for comparison, six HBsAg-positive patients. Disrupted, presumably integrated, HBV genomes were detected by PCR in 10 of 19 tumorous tissues and in only one of nine nontumorous tissues. Significant accumulation of viral RNAs containing X but not C or S sequences was shown in 7/9 tumors and 7/8 nontumorous tissues from HBsAg-negative patients. In contrast, viral RNAs revealed by X-as well as by S- and C-specific primers were detected in five of six tumors and in six of six nontumorous tissues from HBsAg-positive patients. In conclusion, our results suggest the frequent integration of the HBV genome and the accumulation of X-related RNAs in HCCs developing in HBsAg-negative patients. This finding is consistent with a role, in these cases, for the potentially transforming X protein.

Selective accumulation of the X transcript of hepatitis B virus in patients negative for hepatitis B surface antigen with hepatocellular carcinoma

In HBsAg-negative patients with hepatocellular carcinoma (HCC), hepatitis B virus (HBV) genomes are present at a low copy number per cell, and the role of HBV in liver transformation is still unclear. We have mapped by polymerase chain reaction (PCR) the HBV genome in 19 HBsAg-negative tumorous and 9 corresponding nontumorous tissues and evaluated, by RT-PCR, the presence of HBV S, X, and C transcripts in the tumorous and nontumorous tissue of nine HBsAg-negative and, for comparison, six HBsAg-positive patients. Disrupted, presumably integrated, HBV genomes were detected by PCR in 10 of 19 tumorous tissues and in only one of nine nontumorous tissues. Significant accumulation of viral RNAs containing X but not C or S sequences was shown in 7/9 tumors and 7/8 nontumorous tissues from HBsAg-negative patients. In contrast, viral RNAs revealed by X-as well as by S- and C-specific primers were detected in five of six tumors and in six of six nontumorous tissues from HBsAg-positive patients. In conclusion, our results suggest the frequent integration of the HBV genome and the accumulation of X-related RNAs in HCCs developing in HBsAg-negative patients. This finding is consistent with a role, in these cases, for the potentially transforming X protein.

Genetic heterogeneity of hepatocellular carcinoma

We studied 80 hepatocellular carcinomas from three continents for p53 gene (TP53) mutations and hepatitis B virus (HBV) sequences. p53 mutations were frequent in tumors from Mozambique but not in tumors from South Africa, China, and Germany. Independent of geographic origin, most tumors were positive for HBV sequences. X gene coding sequences of HBV were detected in 78% of tumors, whereas viral sequences in the surface antigen- and core antigen-encoding regions were present in less than 45% of tumors. These observations indicate that hepatocellular carcinomas are genetically heterogeneous. Mozambican-type of hepatocellular carcinomas are characterized by a high incidence of p53 mutations related to aflatoxins. In other tumors, the rarity of p53 mutations combined with the frequent presence of viral X gene coding sequences suggests a possible interference of HBV with the wild-type p53 function.

Selective G to T mutations of p53 gene in hepatocellular carcinoma from southern Africa

Hepatocellular carcinoma (HCC) is a prevalent cancer in sub-Saharan Africa and eastern Asia. Hepatitis B virus and aflatoxins are risk factors for HCC, but the molecular mechanism of human hepatocellular carcinogenesis is largely unknown. Abnormalities in the structure and expression of the tumour-suppressor gene p53 are frequent in HCC cell lines, and allelic losses from chromosome 17p have been found in HCCs from China and Japan. Here we report on allelic deletions from chromosome 17p and mutations of the p53 gene found in 50% of primary HCCs from southern Africa. Four of five mutations detected were G----T substitutions, with clustering at codon 249. This mutation specificity could reflect exposure to a specific carcinogen, one candidate being aflatoxin B1 (ref. 7), a food contaminant in Africa, which is both a mutagen that induces G to T substitution and a liver-specific carcinogen.

c-fos and c-myc oncoprotein expression in human hepatocellular carcinomas

Amounts of the proteins encoded by the two oncogenes c-myc and c-fos have been compared in seven specimens of hepatocellular carcinoma and two normal liver samples using a Western blot procedure. It was found that with the exception of one tumour, the amount of these proteins was markedly increased in the tumours when compared to the normal specimens. Furthermore, there appeared to be elevated c-myc and c-fos mRNA concentrations in the tumours which correlated with the protein levels. This is the first report of such a correlation in human hepatocellular carcinoma. We propose that transactivation of these oncogenes may in part be responsible for transformation in hepatocellular carcinoma.

Polymerase chain reaction to detect hepatitis B virus DNA and RNA sequences in primary liver cancers from patients negative for hepatitis B surface antigen

BACKGROUND AND METHODS

The role of hepatitis B virus (HBV) in the course of patients with primary liver cancer who are negative for hepatitis B surface antigen has been debated. We used the polymerase chain reaction to evaluate 28 such patients for the presence of DNA and RNA sequences of the virus; 22 of these patients had associated cirrhosis. The patients were from areas with different prevalences of HBV infection (South Africa, Italy, France, and Japan).

RESULTS

Antibodies to the surface and core antigens of HBV were detected in 10 of the 23 patients tested. HBV DNA sequences were detected in 17 of the 28 patients, including 8 of the 10 with HBV antibodies and 6 of 13 without HBV serologic markers. HBV RNA molecules were found in four of five tumors tested.

CONCLUSIONS

Our investigation indicates that transcriptionally active HBV genomes are present in various geographic areas among patients with liver cancer who are negative for hepatitis B surface antigen. This observation is consistent with an etiologic role for the virus in the development of these tumors.

Loss of heterozygosity suggests tumor suppressor gene responsible for primary hepatocellular carcinoma

Primary hepatocellular carcinoma (PHC), epidemiologically associated with chronic hepatitis B virus (HBV) infection, has historically been felt to be caused by the activation or introduction of an oncogene. However, transforming sequences from human PHC have not been reproducibly isolated. In this paper, evidence is presented that suggests PHC may result instead from the loss of an anti-oncogene. Seven of 12 human primary liver tumors tested against a panel of restriction fragment length polymorphisms (RFLPs) demonstrated loss of constitutional heterozygosity for markers on chromosome 4. Tumor and nontumor liver tissue were typed for 11 chromosome 4 RFLPs. In addition, at least one RFLP on nine other chromosomes (1, 2, 6, 7, 9, 11, 13, 14, and 17) was tested for allelic loss. Seven of nine tumors constitutionally heterozygous for chromosome 4q markers showed allele loss in tumor tissue. Six of the seven samples were jointly informative for both 4p and 4q markers. Five of the six demonstrated loss for only 4q RFLPs. In one individual, in which two samples were taken from distant locations within the same tumor, both samples showed loss of the same alleles. Among the other chromosomes informative for allele loss, one tumor showed changes on 13q. No other changes were observed in RFLPs located on the eight other chromosomes tested. These results indicate that an anti-oncogene may be located on 4q and suggest a mechanism for PHC and other cancers seroepidemiologically related to virus infection. Liver cancer caused by chronic HBV infection or other environmental agents may be linked through genetic events responsible for the loss of a tumor suppressor locus (anti-oncogene) located on chromosome 4.

Expression of c-erbA in human hepatocellular carcinomas

The expression of the oncogene c-erbA was studied in six hepatocellular carcinoma specimens and normal hepatic tissue. Total RNA isolated from these samples was analysed by Northern as well as slot blot hybridisation to a radioactive c-erbA probe. When compared to normal tissue, expression in the tumour and tissue adjacent to tumour was markedly elevated. These results suggest that overexpression of c-erbA is related to hepatocarcinogenesis. Southern blot analysis of DNA from the tumours gave no evidence of c-erbA rearrangements.

Cell-surface changes associated with transformation of human hepatocytes to the malignant phenotype

Hepatocellular carcinoma is one of the leading causes of cancer death in the world. To understand the cellular changes associated with transformation of hepatocytes to the malignant state, we have made several libraries of monoclonal antibodies against the hepatocellular carcinoma cell line FOCUS and have found six antibodies (AF-20, SF-25, SF-31, SF-90, XF-4, and XF-8) that recognize antigens expressed at consistently higher levels on hepatoma cells. We have studied malignant and nontransformed liver tissue from the same individual by using direct 125I-labeled antibody binding and immunoperoxidase staining techniques. For each of these antibodies, we found striking increases in antigen expression on the transformed tissues. These antigens were found to be expressed throughout the tumor and on distant metastases, with little, if any, expression on the nontransformed adjacent liver. These antibodies demonstrate that hepatic transformation may be accompanied by stereotyped and predictable antigenic changes. The uniformity of such antigenic changes suggests an association between these cell-surface alterations and the malignant transformation process.

Combination chemotherapy of hepatocellular cancer. Comparison of adriamycin + VM 26 + 5-fluorouracil with mAMSA + VM 26 + 5-fluorouracil

Forty-seven patients with hepatocellular cancer were treated in a randomised trial comparing adriamycin + VM 26 + 5-Fluorouracil (5-FU) to mAMSA + VM 26 + 5-FU. Thirteen patients had a partial response to treatment (28%) and another 6 (13%) showed disease stabilisation. There were no significant differences in the response rates between the two treatment regimens. Patients who responded to treatment showed significant prolongation of survival (48 weeks) when compared to non-responders (5 weeks).

Deletion in chromosome 11p associated with a hepatitis B integration site in hepatocellular carcinoma

Hepatitis B virus (HBV), a virus with known carcinogenic potential, integrates into cellular DNA during long-term persistent infection in man. Hepatocellular carcinomas isolated from viral carriers often contain clonally propagated viral DNA integrations. As small chromosomal deletions are associated with several types of carcinomas, the occurrence of chromosomal deletions in association with HBV integration in hepatocellular carcinoma was studied. HBV integration was accompanied by a deletion of at least 13.5 kilobases of cellular sequences in a human hepatocellular carcinoma. The viral DNA integration and deletion of cellular sequences occurred on the short arm of chromosome 11 at location 11p13-11p14. The cellular sequences that were deleted at the site of HBV integration were lost from the tumor cells, leaving only a single copy of the remaining cellular allele.

Recombinant leukocyte interferon treatment of chronic hepatitis B

We have investigated the efficacy of a relatively prolonged course of recombinant leukocyte interferon treatment in 14 chronic HBsAg-, HBeAg-, hepatitis B virus DNA- and DNA polymerase-positive carriers. alpha-Interferon was administered for 9 weeks. Six of 14 treated carriers have a sustained loss of HBeAg, hepatitis B virus DNA and DNA polymerase. Four subsequently lost HBsAg (28.5%). Elevated pretreatment SGPT concentrations, histologic chronic active hepatitis, an exacerbation of chronic hepatitis with an increase in SGPT concentrations in the last weeks of treatment and possibly recent onset of the carrier state was associated with complete inhibition of viral replication. None of 11 matched, untreated HBsAg-, HBeAg-, hepatitis B virus DNA- and DNA polymerase-positive carriers monitored during the same period lost HBsAg. The effect of recombinant leukocyte interferon may require an appropriate host-immune response. The efficacy of recombinant leukocyte interferon therapy is restricted, but it may be of benefit in a proportion of carriers, if these carriers can be precisely identified.

Lymphocyte subtypes in patients with atopic eczema, protein calorie malnutrition, SLE and liver disease

Peripheral blood lymphocytes from patients with protein calorie malnutrition, atopic eczema, systemic lupus erythematosus and in three groups of patients with liver disease, were characterized by reactivity with monoclonal antibodies to the surface antigens of helper-inducer (OKT4) and suppressor-cytotoxic (OKT8) T cell subsets and to a common T cell antigen (OKT3). The protein calorie malnutrition group showed a considerable decrease in all subsets while patients with atopic eczema displayed an increase in the total number of OKT3+ cells, attributable primarily to an increase in the OKT4+ cell population with the OKT8+ cells remaining within normal values. In the SLE group, only 3 of the 16 patients had OKT8+ numbers below that of normal controls, whereas the mean number of OKT4+ cells in the group was less than normal controls. The striking feature of patients with liver disease, was the altered ratio of OKT4+ to OKT8+ cells in the hepatocellular carcinoma and amebic liver abscess groups due primarily to decreased OKT4+ and raised OKT8+ cell subpopulations.

Depressed natural killer cell activity in patients with hepatocellular carcinoma. In vitro effects of interferon and levamisole

Enriched lymphocytes from patients with primary hepatocellular carcinoma showed considerably reduced natural cytotoxicity against two established hepatoma cell lines and against the myelogenous derived cell line K562, as compared to lymphocytes from normal volunteers or from patients with various nonmalignant liver diseases. The serum of hepatoma patients did not effect normal or patient NK cell activity. When lymphocytes from patients or controls were treated for three hours with human leukocyte interferon, NK cell cell activity was significantly improved. Levamisole did not produce a significant increase in normal NK cytotoxicity but did improve the killing of lymphocytes from patients with hepatocellular carcinoma.

Serum somatomedin and insulin levels in tumor hypoglycemia

Serum concentrations of somatomedin and immunoreactive insulin were measured during the hypoglycemic phase of 3 patients with tumor hypoglycemia. Normal amounts of somatomedin were detected in their fasting sera, but they may have been inappropriate (or associated with enhanced insulin-like activity) considering the degree of hypoglycemia. Fasting serum insulin levels were consistently depressed, and in two of the cases remained low even after an oral glucose load. Nevertheless, the blood glucose concentrations of these two patients fell to hypoglycemic levels again by 3 hours; the mechanism of this reactive hypoglycemia remains unclear.

57-cobalt-bleomycin as a tumor scanning agent in primary hepatocellular cancer

57Co-bleomycin and 99mTc-sulfur colloid scans were performed in 13 southern African black patients with primary hepatocellular cancer (PHC) and 3 patients with other space-occupying hepatic lesions. Selective concentration of 57Co-bleomycin in the defect or defects seen on the 99mTc-sulfur colloid scan occurred in only 4 of the 13 (31%) patients with PHC. In the remaining PHC patients, as well as in the 2 patients with metastatic liver disease and the 1 patient with an amebic liver abscess, the 57 Co-bleomycin and 99mTc-sulfur colloid scans were identical. 57Co-bleomycin appears to have only a limited place as a tumor-seeking agent in the diagnosis of PHC in southern African blacks.