Hepatitis B and C Viruses and Hepatocellular Carcinoma

Etiologic influence on chromosomal aberrations in European hepatocellular carcinoma identified by CGH

Previous studies suggest different pathways in the molecular development of hepatocellular carcinoma (HCC). We investigated the pattern of chromosomal imbalances in HCC depending on the type of underlying liver disease as detected by comparative genomic hybridization in 67 cases of primary HCC occurring in non-cirrhotic livers (n=30), in liver cirrhosis (LC) related to alcohol intake (n=9), cryptogenic or metabolic changes (n=11), and chronic viral hepatitis B or C (n=17). HCC were treated by liver resection in 48 patients and transplantation in 19 patients. The 10-year disease-free and overall survival rates were 51% and 68%, respectively. The copy number changes occurring in more than 10% of cases were gains at 8q (55%), 1q (49%), 7q (15%), 7p (13%), 6p (12%), and 20q (12%), as well as losses at 8p (55%), 4q (33%), 6q (33%), 13q (25%), 14q (24%), 17p (22%), 16q (19%), 1p (18%), 18q (16%), 9p (13%), 10q (13%), 4p (12%), and 9q (12%). HCC arising in alcoholic LC showed a different pattern with significantly fewer net changes (p=0.008), particularly fewer chromosomal gains (p=0.008) and fewer breakpoints (p=0.003) compared to the other investigated HCC subgroups. Future clinical studies should evaluate the prognostic relevance of these findings.

Suppression of AKT anti-apoptotic signaling by a novel drug candidate results in growth arrest and apoptosis of hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the third most common cause of cancer fatalities worldwide, with limited treatment options and five year survival rates of between <5 and 15%. To address this medical need, we conducted a screen of a drug-like small molecule library for HCC-selective cytotoxins. We report here the identification of a disubstituted aminothiazole termed HBF-0079, with remarkable selective toxicity for HCC-derived cell lines versus non-HCC liver lines and most other cancer lines. HBF-0079 caused irreversible growth arrest and apoptosis of the HCC lines Huh7, Hep3B, HepaRG as well as the hepatoblastoma line HepG2, with CC₅₀ values from ∼0.7−7.7 µM, while more than 45 µM was needed to achieve CC₅₀ values for the immortalized normal hepatocyte lines THLE-2 and PH5CH. Of the sixty cancer lines from the National Cancer Institute panel, only five exhibited >50% growth inhibition by HBF-0079. In Huh7 cells, HBF-0079 induced cell cycle arrest in G1 and concomitant apoptosis, and its effects were irreversible after removal of the compound. These observations corroborate a loss of AKT phosphorylation at the mTORC2-targeted residue S473, with concurrent loss of phosphorylation of the mTORC1 targets SK6 and 4EBP1 in Huh7 but not PH5CH cells. Finally, growth of Hep3B-derived tumors in a murine xenograft model was significantly repressed by the compound through either systemic or intratumoral administration of formulated HBF-0079. The potential for development of this drug candidate is discussed.

Distinct mutant hepatitis B virus genomes, with alterations in all four open reading frames, in a single South African hepatocellular carcinoma patient

Sequence variation of hepatitis B virus (HBV) can influence the replication, antigen expression and pathogenicity of the virus. We report on the mutational analysis of HBV performed in a 28-year-old Black South African female diagnosed with HBV-induced hepatocellular carcinoma. Full-genome amplification and DNA sequencing of HBV was carried out. Five distinct complete genomic clones were described with extensive genomic and intragenic variation. Phylogenetic analysis revealed that all five clones belonged to subgenotype A1 and that there were at least four virus populations with genomes of different lengths ranging from 3194 to 3253 base pairs. In this particular patient, four major characteristic features, not previously reported to occur simultaneously in HBV isolated from a single patient, were observed. Firstly, all the clones harboured a 13 base pair deletion and a 45 base pair insertion in the basic core promoter (BCP). Secondly, a 37 base pair insertion in the core gene with three adjacent single nucleotide deletions were observed. Thirdly, premature S gene stop codons were observed in some clones and lastly X gene initiation codon mutations were also observed. The complex nature of the mutations in the HBV isolated from this single patient may have contributed to the early onset of hepatocarcinogenesis.

Molecular characterization of subgenotype A1 (subgroup Aa) of hepatitis B virus

Subgenotypes of hepatitis B virus (HBV) were first recognized after a unique segment of genotype A was identified when sequencing the preS2/S region of southern African HBV isolates. Originally named subgroup A', subsequently called subgroup Aa (for Africa) or subgenotype A1, this subgenotype is found in South Africa, Malawi, Uganda, Tanzania, Somalia, Yemen, India, Nepal, the Philippines and Brazil. The relatively higher mean nucleotide divergence of subgenotype A1 suggests that it has been endemic and has a long evolutionary history in the populations where it prevails. Distinctive sequence characteristics could account for the high hepatitis B e-antigen (HBeAg) negativity and low HBV DNA levels in carriers of this subgenotype. Substitutions or mutations can reduce HBeAg expression at three levels: (i) 1762T1764A atthe transcriptional level; (ii) substitutions at nt 1809-1812 at the translational level; and (iii) 1862T at the post-translational level. Co-existence of 1762T1764A and nt 1809-1812 mutations reduces HBeAg expression in an additive manner. In addition, subgenotype A1 has unique sequence alterations in the transcriptional regulatory elements and the polymerase coding region. The distinct sequence characteristics of subgenotype A1 may contribute to the 4.5-fold increased risk of heptocellular carcinoma in HBV carriers infected with genotype A, which is entirely attributable to subgenotype A1.

Liver fibrosis is associated with decreased peripheral platelet count in patients with chronic hepatitis B and C

Thrombocytopenia is a common complication of chronic liver diseases, but its pathogenesis is not clear. Although generally attributed to hypersplenism, other factors should also be considered. We investigated the relationship between the peripheral platelet count and the degree of fibrosis in patients with chronic viral hepatitis. In an effort to avoid the effects of hypersplenism, we excluded patients with splenomegaly and/or bi- or pan-cytopenia. Seven hundred eighty-four patients (265 chronic viral hepatitis C and 519 chronic viral hepatitis B) were included in the study. Univariate analysis showed that the peripheral platelet count had a negative correlation with fibrosis score, necroinflammatory activity, and age in both groups. In multivariate analysis, the peripheral platelet count had a similar correlation with the fibrosis score and age, but not with necroinflammatory activity, in both groups. The peripheral platelet count decreased more significantly in females with chronic hepatitis C but not in the chronic hepatitis B group. In conclusion, a decrease in peripheral platelet count may be a sign of an increase in the degree of fibrosis during the course of chronic viral hepatitis B and C and factors other than hypersplenism may play a role in this decrease in the peripheral platelet count.

Enrichment of low molecular weight fraction of serum for MS analysis of peptides associated with hepatocellular carcinoma

A challenging aspect of biomarker discovery in serum is the interference of abundant proteins with identification of disease-related proteins and peptides. This study describes enrichment of serum by denaturing ultrafiltration, which enables an efficient profiling and identification of peptides up to 5 kDa. We consistently detect several hundred peptide-peaks in MALDI-TOF and SELDI-TOF spectra of enriched serum. The sample preparation is fast and reproducible with an average CV for all 276 peaks in the MALDI-TOF spectrum of 11%. Compared to unenriched serum, the number of peaks in enriched spectra is 4 times higher at an S/N ratio of 5 and 20 times higher at an S/N ratio of 10. To demonstrate utility of the methods, we compared 20 enriched sera of patients with hepatocellular carcinoma (HCC) and 20 age-matched controls using MALDI-TOF. The comparison of 332 peaks at p < 0.001 identified 45 differentially abundant peaks that classified HCC with 90% accuracy in this small pilot study. Direct TOF/TOF sequencing of the most abundant peptide matches with high probability des-Ala-fibrinopeptide A. This study shows that enrichment of the low molecular weight fraction of serum facilitates an efficient discovery of peptides that could serve as biomarkers for detection of HCC as well as other diseases.

The role of the tumor necrosis factor (TNF)--Fas L and HCV in the development of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major public health problem in Egypt due to the high prevalence of hepatitis C viral (HCV) infection. The mechanism by which HCV exerts its carcinogenic effect on the liver is not yet understood. Previous research has suggested that perturbations of the Fas-Fas L tumor necrosis system could result in uncontrolled cancerous cell growth in the liver. This study aims to assess the relationship of Fas ligand (Fas L) to HCC. A total of 28 cases (HCC) and 56 controls (28 cirrhosis and 28 chronic hepatitis) were included in the study. Sera and tissue biopsies were tested for HCV antibody and HCV-RNA. Fas ligand expression in tissue was examined immunohistochemically using a rabbit purified polyclonal antibody. Levels of soluble Fas L were determined in serum by ELISA. The HCC cases were graded as: 17.9% Grade I, 32.1% Grade II, 35.7% Grade III and 14.3% were Grade IV. Among the cases, 81% had evidence of cirrhosis. All the cases and controls were positive for HCV-RNA. Tissue and serum PCR results were identical within the same subjects. Fas ligand cytoplasmic expression was more pronounced in HCC than in cirrhosis, and in cirrhosis more than in chronic hepatitis. This expression was higher with increasing grades of malignancy and in tissues adjacent to the tumor, than in those without nearby tumor. Soluble Fas L levels were higher in cases than in controls, with similar results as that of immunohistochemical expression. These results suggest that HCV and Fas ligand play a key role in hepatocarcinogenesis, consistent with the hypothesis that HCV induces overexpression of Fas ligand in the liver cells, resulting in escape from killing by the immune system cells, with subsequent uncontrolled growth of tissue and the development of malignancy.

Prospective study on the risk of hepatocellular carcinoma among hepatitis C virus-positive blood donors focusing on demographic factors, alanine aminotransferase level at donation and interaction with hepatitis B virus

The risk for hepatocellular carcinoma (HCC) among asymptomatic hepatitis C virus (HCV) carriers is not well understood. A community-based prospective study was conducted for over 8 years by record linkage to the Osaka Cancer Registry. The subjects were 1,927 individuals who were positive for anti-HCV through screening for second-generation HCV antibody (passive hemagglutination assay: >or= 2(12)) in voluntary blood donation. The risk factors for HCC and interaction between HCV and hepatitis B virus (HBV) infection were evaluated by including additional blood donors: 2,519 individuals positive for hepatitis B virus surface antigen (HBsAg) alone, 25 positive for both anti-HCV and HBsAg, 150,379 negative for both anti-HCV and HBsAg. The incidence of HCC (/10(5) person-years) among the HCV-positive individuals increased with age in both genders, ranging from 68 to 1,306 among those aged 45-74 years. In the HCV-positive individuals, the cumulative risk of developing HCC between the ages of 40 and 74 year was 21.6% among males and 8.7% among females. A stepwise increase in risk was noted as the serum alanine aminotransferase level increased or serum cholesterol level at baseline decreased in multivariate Cox proportional hazard analysis. The 9-year cumulative incidence of HCC among individuals positive for HCV alone, those positive for HBsAg alone and those positive for both was 3.0%, 2.0% and 12.0%, respectively. The age-and-sex-adjusted rate ratio was 126, 102 and 572, respectively, when those negative for both were used as a reference. The results demonstrate an increased risk for HCC among asymptomatic HCV-positive individuals in Japan. Coinfection with HBV and HCV carried a superadditive risk for HCC.

High viral load is a risk factor for hepatocellular carcinoma in patients with chronic hepatitis B virus infection

BACKGROUND AND AIMS

Hepatitis B virus (HBV) is considered a major risk factor for the progression to liver cirrhosis and hepatocellular carcinoma (HCC). The serum level of HBV-DNA is correlated with progression of the disease. The aim of the present study was to determine the relationship between the level of HBV-DNA and hepatocarcinogenesis in patients with chronic HBV infection.

METHODS

The authors studied 73 patients who were diagnosed with chronic HBV infection at Nagasaki University Hospital (Nagasaki, Japan) between January 1980 and December 1999. The significance of age, sex, habitual drinking, serum alanine aminotransferase level, HBV viral load, interferon treatment, hepatic fibrosis and hepatic inflammation on the development of HCC were examined using univariate and multivariate analyses.

RESULTS

The cumulative incidence rates of HCC were 14%, 29% and 48% at 5, 10 and 15 years after liver biopsy, respectively. Multivariate analysis identified high viral load, together with age and severe fibrosis, as independent and significant risk factors (P = 0.045, 0.047 and 0.013, respectively) for HCC.

CONCLUSIONS

The present findings indicate that high viral load is a risk factor for HCC in patients with chronic HBV infection. Patients with a high HBV viral load should be carefully monitored for HCC.

Risk factors for hepatocellular carcinoma: synergism of alcohol with viral hepatitis and diabetes mellitus

Risk factors associated with hepatocellular carcinoma (HCC) are well documented, but the synergisms between these risk factors are not well examined. We conducted a hospital-based, case-control study among 115 HCC patients and 230 non-liver cancer controls. Cases and controls were pathologically diagnosed at The University of Texas M. D. Anderson Cancer Center and were matched by 5-year age groups, sex, and year of diagnosis. Information on risk factors was collected by personal interview and medical records review. Blood samples were tested for the presence of antibodies to hepatitis C virus antigen (anti-HCV), hepatitis B surface antigen (HBsAg), and antibodies to hepatitis B core antigen (anti-HBc). Conditional logistic regression was used to determine odds ratios (ORs) by the maximum likelihood method. Multivariate ORs and 95% confidence intervals (CIs) were 15.3 (4.3-54.4), 12.6 (2.5-63.1), 4.5 (1.4-14.8), and 4.3 (1.9-9.9) for anti-HCV, HBsAg, heavy alcohol consumption (>/=80 mL ethanol/d), and diabetes mellitus, respectively. Synergistic interactions on the additive model were observed between heavy alcohol consumption and chronic hepatitis virus infection (OR, 53.9; 95% CI, 7.0-415.7) and diabetes mellitus (OR, 9.9; 95% CI, 2.5-39.3). Independent of the effect of HCV, HBV, and diabetes mellitus, heavy alcohol consumption contributes to the majority of HCC cases (32%), whereas 22%, 16%, and 20% were explained by HCV, HBV, and diabetes mellitus, respectively. In conclusion, the significant synergy between heavy alcohol consumption, hepatitis virus infection, and diabetes mellitus may suggest a common pathway for hepatocarcinogenesis. Exploring the underlying mechanisms for such synergisms may indicate new HCC prevention strategies in high-risk individuals.

Hepatocarcinogenesis in hepatitis viral infection: lessons from transgenic mouse studies

Over the past decade, genetically engineered mouse models have been used for studies of the mechanisms underlying human diseases. One advantage of these models is that the targeted protein executes its function in normal cells in their natural tissue microenvironments. Transgenic mouse models for human viral hepatitis have also been established and have provided new insights into the pathogenesis of hepatitis and hepatocellular carcinoma (HCC). In the search for the mechanism of hepatocarcinogenesis in hepatitis viral infection, two viral proteins, the core protein of hepatitis C virus (HCV) and the HBx protein of hepatitis B virus (HBV), have been shown to possess oncogenic potential through transgenic mouse studies, indicating the direct involvement of the hepatitis viruses in hepatocarcinogenesis. The presence of the hepatitis C virus core or HBx protein, which has an oncogenic potential, may allow some of the steps in multistep hepatocarcinogenesis to be skipped. This may explain the very high frequency of HCC in patients with HCV or HBV infection.

Human immunodeficiency virus infection, aging, and cancer

HIV infection increases non-Hodgkin's lymphoma and Kaposi's sarcoma risk. Among HIV-uninfected persons, risk for these malignancies and others increases with age. As HIV-infected persons age, new patterns in cancer incidence may emerge. In this article, data from the AIDS-Cancer Registry Match study are presented on risk for Kaposi's sarcoma and lung cancer among persons with AIDS. For 132,346 homosexual men with AIDS, Kaposi's sarcoma incidence was highest for men 30-39 years old (5.0 cases/100 person-years) and declined with age (P(trend) <.0001). This trend likely arises from variation in Kaposi's sarcoma herpesvirus prevalence among homosexual men. For 239,257 adults with AIDS (all risk groups), lung cancer incidence increased with age, and was higher than in the general population (P <.0001), probably reflecting heavy smoking among HIV-infected adults. Identifying separate effects of HIV and aging on cancer risk will require detailed data on individuals' HIV infection status and exposures to known carcinogens.

Hepatitis B virus X mutants derived from human hepatocellular carcinoma retain the ability to abrogate p53-induced apoptosis

Chronic hepatitis B virus (HBV) infection and the integration of its X gene (HBx) are closely associated with the development of hepatocellular carcinoma (HCC). The integrated HBx frequently is truncated or contains point mutations. Previous studies indicated that these HBx mutants have a diminished co-transactivational activity. We have compared the effects of wild-type (wt) HBx and its naturally occurring mutants derived from human HCCs on transcriptional co-transactivation, apoptosis and interactive effects with p53. We demonstrated that overexpression of mutant, but not wt HBx, is defective in transcriptional co-transactivation of the NF-kappaB-driven luciferase reporter. By using a microinjection technique, the HBx mutants were shown to have an attenuated pro-apoptotic activity. This deficiency may be attributed to multiple mutations in the co-transactivation domain of HBx, that leads to decreased stability of the translated product. However, wt or mutant HBx bind to p53 in vitro and retain their ability to block p53-mediated apoptosis in vivo, which has been implicated as its major tumor suppressor function. The abrogation of p53-mediated apoptosis by integrated HBx mutants may provide a selective clonal advantage for preneoplastic or neoplastic hepatocytes and contribute to hepatocellular carcinogenesis.

Hepatitis B viral transactivator HBx alleviates p53-mediated repression of alpha-fetoprotein gene expression

Chronic infection with hepatitis B virus (HBV) is associated with development of hepatocellular carcinoma (HCC). The exact mechanism by which chronic infection with HBV contributes to onset of HCC is unknown. However, previous studies have implicated the HBV transactivator protein, HBx, in progression of HCC through its ability to bind the human tumor suppressor protein, p53. In this study, we have examined the ability of HBx to modify p53 regulation of the HCC tumor marker gene, alpha-fetoprotein (AFP). By utilizing in vitro chromatin assembly of DNA templates prior to transcription analysis, we have demonstrated that HBx functionally disrupts p53-mediated repression of AFP transcription through protein-protein interaction. HBx modification of p53 gene regulation is both tissue-specific and dependent upon the p53 binding element. Our data suggest that the mechanism by which HBx alleviates p53 repression of AFP transcription is through an association with DNA-bound p53, resulting in a loss of p53 interaction with liver-specific transcriptional co-repressors.

Hepatocellular cancer. A century of progress

Although gratifying progress has been made during the 20th century, much remains to be achieved. The principal objective must be prevention of HCC. Prevention of HBV-related tumors is already feasible, and prevention of HCV-related and aflatoxin-induced tumors should soon become possible. Not all HCCs are yet accounted for causatively, and the remaining risk factors need to be identified. Until primary prevention can be accomplished, attention must also be directed to obtaining a complete understanding of the pathogenesis of HCC so that strategies for secondary and tertiary prevention can be formulated and instituted. Finally, the search for effective anticancer treatment must continue.

Infection, immunity, and cancer

A significant percentage of human cancers worldwide are associated with infections due to known viruses, including human papillomaviruses (cervical cancer and other skin cancers), human T-lymphotropic viruses (adult T-cell leukemias and lymphomas in endemic areas), hepatitis B virus (liver cancer), and Epstein-Barr virus (Burkitt lymphoma and nasopharyngeal carcinoma). The fraction of human cancers attributable to infection may now need to be revised in light of the fact that new viral associations have been discovered and other nonviral associations have been identified. This article addresses the increasingly recognized role of infectious agents as precipitants of human neoplasia and the possibility that novel diagnostic, therapeutic, and chemopreventive strategies may emanate directly from research directed at identifying and understanding these agents.

The core promoter of hepatitis B virus

The core promoter (CP) of hepatitis B virus (HBV) plays a central role in HBV replication and morphogenesis, directing the transcription of both species of 3.5 kb mRNA: pregenomic (pg) RNA and precore (pre-C) mRNA. The CP overlaps the 3' end of the X open-reading frame (ORF) and the 5' end of the pre-C/C ORF. The major functional elements of the CP are the upper regulatory region (URR) and the basic core promoter (BCP). The BCP is sufficient for accurate initiation of both pre-C mRNA and pgRNA transcription. It contains four AT-rich regions and the initiators for pre-C mRNA and pgRNA transcription. The upstream regulatory region consists of the negative regulatory element and the core upstream regulatory sequence. Co-operative interaction of various liver-enriched and ubiquitous transcription factors is necessary for liver-specific expression from the CP. These factors bind to the CP. Sequence conservation within the CP is crucial for maintaining active viral replication, and variation may contribute to the persistence of HBV within the host, leading to chronic infection and, ultimately, hepatocarcinogenesis. The most frequently described mutations within this region are an A to T transversion at position 1762 together with a G to A transition at position 1764. This double mutant is accompanied by a reduced level of hepatitis B e antigen (HBeAg) expression. Deletions, insertions and duplications occur within the CP.

Structure and expression of Tg737, a putative tumor suppressor gene, in human hepatocellular carcinomas

Deletions of the Tg737 gene, whose product is involved in liver oval cell proliferation, differentiation, and ploidy control, have been recently shown in chemically induced rat liver tumors and in a limited series of patients with hepatocellular carcinoma (HCC). Thus, Tg737 has been proposed as a candidate new liver-specific tumor suppressor gene. To investigate this important issue, we analyzed the structure and expression pattern of the Tg737 gene in a group of 23 tumorous and adjacent nontumorous liver tissues, by combining polymerase chain reaction (PCR) and Southern and Northern blot-based analyses. We failed to identify deletions or gross alterations of the Tg737 gene by both PCR and Southern blot analyses. Northern blots showed comparable accumulation of normal Tg737 transcripts in both tumorous and nontumorous tissues. Collectively, therefore, our results do not support the hypothesis of frequent Tg737 genetic alterations in human HCC.

High prevalence of 1762(T) 1764(A) mutations in the basic core promoter of hepatitis B virus isolated from black Africans with hepatocellular carcinoma compared with asymptomatic carriers

The purpose of this study was to identify mutations in the basic core promoter and enhancer II region of the hepatitis B virus (HBV) that might cause the HBV e antigen (HBeAg)-negative phenotype and contribute to hepatocarcinogenesis in black African carriers of the virus. The basic core promoter/enhancer II overlaps with the X gene. HBV DNA from serum of 47 asymptomatic carriers and 50 patients with hepatocellular carcinoma and from 28 tumor and 10 nontumor liver tissues was amplified and sequenced directly. That part of the enhancer II region not overlapping the basic core promoter was completely conserved in all samples. Missense mutations at nucleotides 1809 and 1812 in the basic core promoter were found in 80% of all sequences and may represent wild-type sequence in Southern African isolates. Nucleotide and amino acid divergences were higher in the basic core promoter of hepatocellular carcinoma patients when compared with asymptomatic carriers (P <.0001). This applied particularly to the paired 1762 adenine to thymine (1762(T)) and 1764 guanine to adenine (1764(A)) missense mutations, the prevalence of which was 66% in patients with hepatocellular carcinoma compared with 11% in asymptomatic carriers (P <.0001). There was no association between the presence of 1762(T) 1764(A) and HBeAg negativity, although these mutations suppressed HBeAg titers in HBeAg-positive patients. Suppression of HBeAg expression as well as alteration of the amino acid sequence of the X protein may play a role in hepatocarcinogenesis.

Primary and metastatic liver cancer

OBJECTIVES

To review liver physiology, the disease process, diagnostic tests, and current treatment options for primary and metastatic liver cancer.

DATA SOURCES

Research studies, review articles, and textbooks relating to liver cancer.

CONCLUSIONS

Surgical resection offers the best available treatment modality, but only a small percentage of patients are eligible. However, combined treatment of radiation therapy and chemotherapy (systemic and intra-arterial), as well as chemoembolization, cryosurgery, and transplantation, offers hope of palliation, conversion of unresectable to resectable disease, and prolonged survival.

IMPLICATIONS FOR NURSING PRACTICE

Understanding and knowledge of the disease process and treatment modalities for primary and metastatic liver cancer will assist the oncology nurse in educating patients and families during their diagnostic and treatment phases.

Malignant neoplasm in kidney transplantation

BACKGROUND

The kidney recipient is at a higher risk for cancer than is the general population, although the incidence of neoplasms in general is considered lower in Japan than in Western countries. The cause of this increased risk associated with either transplantation or geography has not yet been established.

METHOD

The incidences and sites of malignant neoplasms were analyzed in 285 kidney recipients, who had been followed up for 3007 patient-years. The relationship between immunosuppressive states, the numbers of CD4-positive T lymphocytes, and the presence of malignant neoplasms was studied retrospectively.

RESULTS

Eighteen malignant neoplasms were found in 17 of the 285 patients (6%). The malignancies developed in these patients an average of++ 1 26.5 months after transplantation. The incidence was only 3.9% at 10 years, increasing to 13.9% at 20 years. No difference in the time-course incidence was found between azathioprine-based and cyclosporin-based immunosuppressive regimens. The malignancies developed in the digestive organs in more than half of the patients, and were mainly in the liver, colon and rectum, and stomach, with a relatively low incidence of skin cancer and lymphoma. There was only one case of Epstein-Barr virus genome found in 5 specimens that were tested. Concerning the immunosuppressive state, CD4-positive T lymphocyte counts were not related directly with malignancies in our series.

CONCLUSION

The cumulative incidence of malignancy increased markedly in the second posttransplant decade. The site of cancers in kidney recipients mirrors that of general Japanese malignancies. Our results revealed neither the cause nor predictor for malignancies in kidney transplant patients.

Gene expression in hepatomas

Gene expression changes in accordance with cell growth, differentiation and carcinogenesis. To elucidate the molecular mechanisms for hepatocarcinogenesis as well as maintenance of normal hepatocytes, it is important to identify the genes that have altered expression with carcinogenesis. We established a new and efficient cDNA subtraction method via two cDNA populations. By using this method along with rat hepatomas made by the Soh-Farber protocol, we identified a number of genes, some of which are activated in hepatocellular carcinoma (HCC). These genes include ones which code for a transcription factor and a metabolic enzyme. One particular gene can be used as a tumour marker. Our method is beneficial for the isolation of a wide range of HCC-related genes in rats which, in turn, enables easy identification of their human counterparts. In this review, we describe details of our method and the isolated genes. We also briefly describe transcription factors in the liver.

A meta-analysis of epidemiological studies on the combined effect of hepatitis B and C virus infections in causing hepatocellular carcinoma

The aim of the study was to assess whether co-infection by hepatitis-B virus (HBV) and hepatitis-C virus (HCV) is associated with a higher risk of developing hepatocellular carcinoma (HCC) than each infection alone. A meta-analysis of data published up to June 1997 was performed. HBsAg and anti-HCV antibodies or HCV RNA (anti-HCV/HCV RNA) were considered as serological markers of current HBV and HCV infection respectively. A total of 32 case-control studies were suitable for a quantitative overview. The summary odds ratios (OR) were 13.7 for HBsAg positivity and 11.5 for anti-HCV/HCV RNA positivity. The OR for anti-HCV was lower among studies using second- or third-generation anti-HCV or HCV RNA (OR, 8.2) with respect to studies with first-generation anti-HCV test (OR, 19.1). When combining data from the studies with second- or third-generation anti-HCV or HCV RNA, the OR for HBsAg positivity and anti-HCV/HCV RNA negativity was 22.5 (95% confidence interval (CI), 19.5-26.0), the OR for anti-HCV/HCV RNA positivity and HBsAg negativity was 17.3 (95% CI, 13.9-21.6), and the OR for both markers positivity was 165 (95% CI: 81.2-374, based on 191 cases and 8 controls exposed). A synergism was found between HBV and HCV infections, the OR for co-infection being greater than the sum and lower than the product of those for each infection alone. The interaction was therefore negative according to the multiplicative model, providing epidemiological evidence both of an independent effect and of interference between the 2 viruses in the carcinogenic process.