Expression of c-Myc, c-Fos, and c-jun in hepatocellular carcinoma

BACKGROUND

Increased expression of the proto-oncogene c-myc is a common phenomenon in hepatocellular carcinoma (HCC). The proto-oncogenes c-fos and c-jun are involved in cell cycle progression and cellular proliferation.

METHODS

The objective of this study was to elucidate the mechanism of hepatocarcinogenesis with regard to the expressions of c-myc, c-fos, and c-jun. One hundred fifty biopsied HCC specimens were stained immunohistochemically for the above phenotypic markers both in tumor tissue and in adjacent nontumor tissue.

RESULTS

Although the expression of c-myc was high (74%) in tumor tissue, it was significantly less compared with the expression in nontumor tissue (100%; P = 0.0002). The expression of c-myc was inversely proportional to the grade of differentiation in tumor tissue (P = 0.0108; correlation coefficient [r] = -0.244); that is, tissue with poorer histologic differentiation had a lower level of c-myc expression. There were inverse associations between the expression of c-myc and the expression of mutated p53 (P = 0.0017; r = -0.285) as well as the expression of Ki67 (P = 0.057; r = -0.147). There was significantly high expression of c-fos in tumor tissue compared with the expression in nontumor tissue (91% vs. 0%; P < 0.0001). Both the tumor tissue and the nontumor tissue had high levels of expression of c-jun (96.53% and 100%, respectively). There was a trend toward a positive association between the expression of c-fos and the expression of c-jun in tumor tissue (P = 0.07; r = 0.162).

CONCLUSIONS

Because c-myc is a known inducer of wild type p53, decreased c-myc expression may lead to uncontrolled cell growth because of the lack of p53 expression that normally induces apoptosis. The coordinated expression of c-fos and c-jun in HCC may reflect the coordinated tumor cell cycle of progression and proliferation; however, future studies are required to elucidate this possibility.

Expression of c-Myc, c-Fos, and c-jun in hepatocellular carcinoma

BACKGROUND

Increased expression of the proto-oncogene c-myc is a common phenomenon in hepatocellular carcinoma (HCC). The proto-oncogenes c-fos and c-jun are involved in cell cycle progression and cellular proliferation.

METHODS

The objective of this study was to elucidate the mechanism of hepatocarcinogenesis with regard to the expressions of c-myc, c-fos, and c-jun. One hundred fifty biopsied HCC specimens were stained immunohistochemically for the above phenotypic markers both in tumor tissue and in adjacent nontumor tissue.

RESULTS

Although the expression of c-myc was high (74%) in tumor tissue, it was significantly less compared with the expression in nontumor tissue (100%; P = 0.0002). The expression of c-myc was inversely proportional to the grade of differentiation in tumor tissue (P = 0.0108; correlation coefficient [r] = -0.244); that is, tissue with poorer histologic differentiation had a lower level of c-myc expression. There were inverse associations between the expression of c-myc and the expression of mutated p53 (P = 0.0017; r = -0.285) as well as the expression of Ki67 (P = 0.057; r = -0.147). There was significantly high expression of c-fos in tumor tissue compared with the expression in nontumor tissue (91% vs. 0%; P < 0.0001). Both the tumor tissue and the nontumor tissue had high levels of expression of c-jun (96.53% and 100%, respectively). There was a trend toward a positive association between the expression of c-fos and the expression of c-jun in tumor tissue (P = 0.07; r = 0.162).

CONCLUSIONS

Because c-myc is a known inducer of wild type p53, decreased c-myc expression may lead to uncontrolled cell growth because of the lack of p53 expression that normally induces apoptosis. The coordinated expression of c-fos and c-jun in HCC may reflect the coordinated tumor cell cycle of progression and proliferation; however, future studies are required to elucidate this possibility.

Characterization of monoclonal antibodies that specifically recognize the palm subdomain of hepatitis C virus nonstructural protein 5B polymerase

The nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase (RdRp) which plays an essential role in viral RNA replication. Antibodies that specifically recognize NS5B will have utilities in monitoring NS5B production and subcellular localization, as well as in structure-function studies. In this report, three mouse monoclonal antibodies (mAbs), 16A9C9, 16D9A4 and 20A12C7, against a recombinant NS5B protein (genotype 1a, H-77 strain) were produced. These mAbs specifically recognize HCV NS5B, but not RdRps of polivirus (PV), bovine viral diarrhea virus (BVDV) or GB virus B (GBV-B). The mAbs can readily detect NS5B in cellular lysates of human osteosarcoma Saos2 cells constitutively expressing the nonstructural region of HCV (NS3-NS4A-NS4B-NS5A-NS5B). NS5B proteins of different HCV genotypes/subtypes (1a, 1b, 2a, 2c, 5a) showed varied affinity for these mAbs. Interestingly, the epitopes for the mAbs were mapped to the palm subdomain (amino acid 188-370) of the HCV RdRp as determined by immunoblotting analysis of a panel of HCV/GBV-B chimeric NS5B proteins. The binding site was mapped between amino acid 231 and 267 of NS5B for 16A9C9, and between 282 and 372 for 16D9A4 and 20A12C7. Furthermore, these mAbs showed no inhibitory effect on the NS5B polymerase activity in vitro.

Expression of c-Myc, c-Fos, and c-jun in hepatocellular carcinoma

BACKGROUND

Increased expression of the proto-oncogene c-myc is a common phenomenon in hepatocellular carcinoma (HCC). The proto-oncogenes c-fos and c-jun are involved in cell cycle progression and cellular proliferation.

METHODS

The objective of this study was to elucidate the mechanism of hepatocarcinogenesis with regard to the expressions of c-myc, c-fos, and c-jun. One hundred fifty biopsied HCC specimens were stained immunohistochemically for the above phenotypic markers both in tumor tissue and in adjacent nontumor tissue.

RESULTS

Although the expression of c-myc was high (74%) in tumor tissue, it was significantly less compared with the expression in nontumor tissue (100%; P = 0.0002). The expression of c-myc was inversely proportional to the grade of differentiation in tumor tissue (P = 0.0108; correlation coefficient [r] = -0.244); that is, tissue with poorer histologic differentiation had a lower level of c-myc expression. There were inverse associations between the expression of c-myc and the expression of mutated p53 (P = 0.0017; r = -0.285) as well as the expression of Ki67 (P = 0.057; r = -0.147). There was significantly high expression of c-fos in tumor tissue compared with the expression in nontumor tissue (91% vs. 0%; P < 0.0001). Both the tumor tissue and the nontumor tissue had high levels of expression of c-jun (96.53% and 100%, respectively). There was a trend toward a positive association between the expression of c-fos and the expression of c-jun in tumor tissue (P = 0.07; r = 0.162).

CONCLUSIONS

Because c-myc is a known inducer of wild type p53, decreased c-myc expression may lead to uncontrolled cell growth because of the lack of p53 expression that normally induces apoptosis. The coordinated expression of c-fos and c-jun in HCC may reflect the coordinated tumor cell cycle of progression and proliferation; however, future studies are required to elucidate this possibility.

Generation and characterization of a hepatitis C virus NS3 protease-dependent bovine viral diarrhea virus

Unique to pestiviruses, the N-terminal protein encoded by the bovine viral diarrhea virus (BVDV) genome is a cysteine protease (Npro) responsible for a self-cleavage that releases the N terminus of the core protein (C). This unique protease is dispensable for viral replication, and its coding region can be replaced by a ubiquitin gene directly fused in frame to the core. To develop an antiviral assay that allows the assessment of anti-hepatitis C virus (HCV) NS3 protease inhibitors, a chimeric BVDV in which the coding region of Npro was replaced by that of an NS4A cofactor-tethered HCV NS3 protease domain was generated. This cofactor-tethered HCV protease domain was linked in frame to the core protein of BVDV through an HCV NS5A-NS5B junction site and mimicked the proteolytic function of Npro in the release of BVDV core for capsid assembly. A similar chimeric construct was built with an inactive HCV NS3 protease to serve as a control. Genomic RNA transcripts derived from both chimeric clones, P(H/B) (wild-type HCV NS3 protease) and P(H/B(S139A)) (mutant HCV NS3 protease) were then transfected into bovine cells (MDBK). Only the RNA transcripts from the P(H/B) clone yielded viable viruses, whereas the mutant clone, P(H/B(S139A)), failed to produce any signs of infection, suggesting that the unprocessed fusion protein rendered the BVDV core protein defective in capsid assembly. Like the wild-type BVDV (NADL), the chimeric virus was cytopathic and formed plaques on the cell monolayer. Sequence and biochemical analyses confirmed the identity of the chimeric virus and further revealed variant viruses due to growth adaptation. Growth analysis revealed comparable replication kinetics between the wild-type and the chimeric BVDVs. Finally, to assess the genetic stability of the chimeric virus, an Npro-null BVDV (BVDV-Npro in which the entire Npro coding region was deleted) was produced. Although cytopathic, BVDV-Npro was highly defective in viral replication and growth, a finding consistent with the observed stability of the chimeric virus after serial passages.

TT virus infection in patients with chronic hepatitis C virus infection--effect of primers, prevalence, and clinical significance. Hepatitis Interventional Therapy Group

BACKGROUND/AIM

A novel DNA virus, TT virus (TTV), was recently identified in patients with post-transfusion non-A-G hepatitis. The aim of this study was to determine the prevalence and clinical significance of TTV infection in patients with chronic hepatitis C virus (HCV) infection.

METHODS

We analyzed pretreatment serum samples from 171 United States and European patients who relapsed after interferon-alpha treatment and were recruited into an interferon-alpha-2b/ribavirin combination treatment trial. TTV DNA was detected by PCR using two different set of primers (TTV-A and TTV-B) derived from open reading frames 1 and 2, respectively.

RESULTS

TTV was detected in 29.2% of the patients with the TTV-A primer set, 70.8% with the TTV-B primer-set, and 72.5% if positive by either/both sets of the primers. The amplicons generated by primer set A were sequenced and a phylogenetic tree was constructed. The 50 isolates belonged to group la (n=8), 1b (n=17), 2a (n=21), 2b (n=3), and 4 (n=1). There was no difference in demographic (age, sex distribution, estimated duration of HCV infection), biochemical (serum ALT levels), virologic (serum HCV RNA levels, HCV genotype distribution), or histologic scores, and their subsequent response to either interferon-alpha-2b or interferon-alpha-2b/ribavirin combination treatment.

CONCLUSIONS

The prevalence of TTV infection reported previously may have been significantly underestimated, based on the primers originally described and used by most studies. Although TTV infection is very common in patients with chronic HCV infection, it has no identifiable clinical significance.

Mutational analysis of bovine viral diarrhea virus RNA-dependent RNA polymerase

Recombinant bovine viral diarrhea virus (BVDV) nonstructural protein 5B (NS5B) produced in insect cells has been shown to possess an RNA-dependent RNA polymerase (RdRp) activity. Our initial attempt to produce the full-length BVDV NS5B with a C-terminal hexahistidine tag in Escherichia coli failed due to the expression of insoluble products. Prompted by a recent report that removal of the C-terminal hydrophobic domain significantly improved the solubility of hepatitis C virus (HCV) NS5B, we constructed a similar deletion of 24 amino acids at the C terminus of BVDV NS5B. The resulting fusion protein, NS5BDeltaCT24-His, was purified to homogeneity and demonstrated to direct RNA replication via both primer-dependent (elongative) and primer-independent (de novo) mechanisms. Furthermore, BVDV RdRp was found to utilize a circular single-stranded DNA as a template for RNA synthesis, suggesting that synthesis does not require ends in the template. In addition to the previously described polymerase motifs A, B, C, and D, alignments with other flavivirus sequences revealed two additional motifs, one N-terminal to motif A and one C-terminal to motif D. Extensive alanine substitutions showed that while most mutations had similar effects on both elongative and de novo RNA syntheses, some had selective effects. Finally, deletions of up to 90 amino acids from the N terminus did not significantly affect RdRp activities, whereas deletions of more than 24 amino acids at the C terminus resulted in either insoluble products or soluble proteins (DeltaCT179 and DeltaCT218) that lacked RdRp activities.

Imbalance between cell proliferation and cellular DNA fragmentation in hepatocellular carcinoma

AIM/BACKGROUND

Hepatocellular carcinoma (HCC) is known for its rapid growth. This study was undertaken to determine the expression of proliferative markers, apoptosis (DNA fragmentation) and oncogene products known to regulate apoptosis (p53, bcl-2) in HCC.

METHODS

150 Chinese patients with HCC were studied (M:F 128:22, age 14-88 years). Immunohistochemistry was employed to detect cell proliferative markers (PCNA, Ki67), and oncogene products known to regulate apoptosis (p53, bcl-2). DNA fragmentation was determined by terminal dUTP nick end labeling (TUNEL).

RESULTS

98% and 95% of HCC had PCNA (median 2+) and Ki67 (median 2+) detected respectively. TUNEL labeling was detected in only a small number of tumor cells (no labeling in 11%, median 1/1000 cell labeled, range: 0-70/1000 cells). There was no correlation between TUNEL labeling and the clinical parameters (sex, age, cirrhosis, and survival) and the expression of cell proliferative markers. p53 was detected in 53% of the patients (median 1+, range: 0-4+) and bcl-2 was detected in a small proportion of tumor cells in only 13% of the HCCs (range: 0-1 +). The expression of p53 and Bcl-2 did not correlate with TUNEL labeling or the natural survival.

CONCLUSIONS

Cell proliferation in HCC is unmatched by apoptosis, accounting for the rapid growth of this tumor. This lack of apoptosis in HCC is unrelated to the expression of p53 or bcl-2 over-expression.

Nucleic acid-based cross-linking assay for detection and quantification of hepatitis B virus DNA

A nucleic acid photo-cross-linking technology was used to develop a direct assay for the quantification of hepatitis B virus (HBV) DNA levels in serum. Cross-linker-modified DNA probes complementary to the viral genomes of the major HBV subtypes were synthesized and used in an assay that could be completed in less than 6 h. The quantification range of the assay, as determined by testing serial dilutions of Eurohep HBV reference standards and cloned HBV DNA, was 5 x 10(5) to 3 x 10(9) molecules of HBV DNA/ml of serum. Within-run and between-run coefficients of variation (CVs) for the assay were 4. 3 and 4.0%, respectively. The assay was used to determine HBV DNA levels in 302 serum samples, and the results were compared to those obtained after testing the same samples with the Chiron branched-DNA (bDNA) assay for HBV DNA. Of the samples tested, 218 were positive for HBV DNA by both assays and 72 gave results below the cutoff for both assays. Of the remaining 12 samples, 10 were positive for HBV DNA by the cross-linking assay only; the 2 other samples were positive by the bDNA assay only. Twenty-eight samples had to be retested by the bDNA assay (CV, >20% between the results obtained from the testing of each sample in duplicate), whereas only three samples required retesting by the cross-linking assay. The correlation between the HBV DNA levels, as measured by the two tests, was very high (r = 0.902; P = 0.01). We conclude that the cross-linking assay is a sensitive and reproducible method for the detection and quantification of HBV DNA levels in serum.

Quantitative detection of serum HBV DNA in Chinese patients

The relationship between serum hepatitis Be antigen (HBeAg) and serum hepatitis B virus (HBV) DNA determined by two commercially available assays was examined in 345 Chinese patients with chronic HBV infection. HBV DNA was detected by these commercial assays in 85% of the HBeAg-positive patients. Discrepancies between test results were found to occur when serum HBV DNA levels were low (< 5 pg ml-1 for the Abbott Genostics and < 100 MEq ml-1 for Chiron Quantiplex assays). An equation for the conversion between results generated by these two assays was derived, which was found to be very similar to the equation recently described by Kapke et al.