[High expression of p65 transcription factor and its significance in tongue carcinoma]

OBJECTIVE

To examine the correlation between p65 expression and the metastasis and prognosis in tongue carcinoma.

METHODS

The immunohistochemical expression of p65 was examined in 50 cases of tongue carcinoma, and the clinical and histopathologic records were retrospectively analyzed.

RESULTS

Overexpression of p65 in cytoplasma and nucleus was found in 64% cases of tongue carcinoma. There was significant difference of p65 expression among different TNM stages, and the higher expression rate of p65 was found in higher stages. Overexpression of p65 was also related to lymph node metastasis. Significantly greater increase in expression levels of p65 was found in the metastatic cases (n = 22) compared to the nonmetastatic cases (n = 10). However, there was no significant difference of p65 expression among different histopathologic grading. The 5-year survival rate of p65 positive and negative group was 59.3% and 88.9% respectively, and there was significant difference in Kaplan-Meier survival curve (chi2 = 5.6, P < 0.05).

CONCLUSION

The results suggest that the expression of p65 was important to predict the metastasis and prognosis in tongue carcinoma.

Both the establishment and the maintenance of neuronal polarity require active mechanisms: critical roles of GSK-3beta and its upstream regulators

Axon-dendrite polarity is a cardinal feature of neuronal morphology essential for information flow. Here we report a differential distribution of GSK-3beta activity in the axon versus the dendrites. A constitutively active GSK-3beta mutant inhibited axon formation, whereas multiple axons formed from a single neuron when GSK-3beta activity was reduced by pharmacological inhibitors, a peptide inhibitor, or siRNAs. An active mechanism for maintaining neuronal polarity was revealed by the conversion of preexisting dendrites into axons upon GSK-3 inhibition. Biochemical and functional data show that the Akt kinase and the PTEN phosphatase are upstream of GSK-3beta in determining neuronal polarity. Our results demonstrate that there are active mechanisms for maintaining as well as establishing neuronal polarity, indicate that GSK-3beta relays signaling from Akt and PTEN to play critical roles in neuronal polarity, and suggest that application of GSK-3beta inhibitors can be a novel approach to promote generation of new axons after neural injuries.

[Effect of phosphorothioate antisense Bcl-xL oligodeoxynucleotides on apoptosis and thermosensitivity of BcaCD885 cells]

OBJECTIVE

To study the effect of phosphorothioate antisense Bcl-xL oligodeoxynucleotides on apoptosis and thermosensitivity of BcaCD885 cells.

METHODS

After phosphorothioate antisense Bcl-xL oligodeoxynucleotides were transfected into BcaCD885 cells. The characteristics of apoptotic cells were evaluated by morphological observation and TUNEL staining. Apoptotic rate and Bcl-xL protein expression were analyzed with flow cytometry. The influence of phosphorothioate antisense Bcl-xL oligodeoxynucleotides on apoptotic rate of BcaCD885 cells induced by hyperthermia with 43 degrees C 40 min was also examined through flow cytometry.

RESULTS

The BcaCD885 cells transfected with phosphorothioate antisense Bcl-xL oligodeoxynucleotides displayed apoptotic morphological features. The Bcl-xL protein expression level of these cells was down-regulated significantly compared with the controlled group (P < 0.05). The apoptotic rate of these cells induced by hyperthermia was increased significantly compared with the controlled group (P < 0.05).

CONCLUSION

Phosphorothioate antisense Bcl-xL oligodeoxynucleotides can induce apoptosis and improve thermosensitivity of BcaCD885 cells.

[Effects of thermochemotherapy on immunologic function of patients with lip cancer]

OBJECTIVE

To evaluate the effects of thermochemotherapy on the immunologic function of lip cancer patients and to provide a theoretical basis for the clinical application of thermochemotherapy.

METHODS

Twenty patients were heated by microwave at (42.5 +/- 0.2) degree C for 40 minutes after venoclysis of Pingyangmycin (8 mg) and Methotrexate (20 mg). Each of the patients received the therapy twice a week for 5 weeks. Venous blood was obtained before the first thermochemotherapy and after the tenth thermochemotherapy. Lymphocyte transformation index was examined by 3H-TdR method, and CD4+ and CD8+ T cells were assayed by flow cytometry.

RESULTS

The tumors of the 20 patients were completely extinctive. The lymphocyte transformation index after treatment was significantly higher than that before treatment (P < 0.01). The CD4+ T cells and CD4+/CD8+ after treatment were significantly higher than those before treatment (P < 0.05); the CD8+ T cells after treatment was lower than that before treatment, but there was no statistically significant difference (P > 0.05).

CONCLUSION

Thermochemotherapy can enhance the lip cancer patient's T lymphocyte immunologic function, which possibly plays an important role in the treatment of lip cancer.

[Effect of microwave thermocoagulation on oral benign tumor]

OBJECTIVE

The purpose of this article was to observe the effect of by microwave thermocoagulation on oral benign tumor and to provide theoretical basis for clinic treatment of oral benign tumor.

METHODS

165 patients with oral benign tumor were included. There were 83 patients with oral bursa cyst, 42 patients with hemangioma, 19 patients with papilloma, 14 patients with fibrous hyperplasia and 7 patients with epulis. All the patients were treated by WB-100 microwave thermocoagulation.

RESULTS

144 patients were effective after the first treatment and 21 patients were effective after the second treatments. No side effect and reoccurrence were found after 3 years.

CONCLUSION

Microwave thermocoagulation is an effective and safe method in clinic treatment of oral benign tumor.

[The expression of urokinase-type plasminogen activator in oral squamous cell carcinoma]

OBJECTIVE

The aim of this study was to reveal the relations between expression and tumor behavior such as invasion, metastasis and prognosis in oral squamous cell carcinoma (SCC) through analyzing the expression of urokinase-type plasminogen activator (UPA).

METHODS

With Labelled streptavidin biotin method (LsAB), the expression of UPA was analyzed in 80 cases of oral squamous cell carcinoma, 10 cases of oral normal mucosa and 10 cases of oral leukoplakia.

RESULTS

Compared to oral normal mucosa and oral leukoplakia, the expression of UPA was significantly higher in SCC. The expression of UPA in SCC cases with lymph node metastasis was significantly higher than in cases without metastasis. The expression in cases with good prognosis was significantly higher than in those with poor prognosis and the expression was significantly higher in cases with invasive growth than in those with ulcerative and papillary growth.

CONCLUSION

The results obtained indicated that high expression of UPA in SCC might be closely related to lymph node metastasis, invasive growth and poor prognosis.

[The effect of heat shock on the expression of urokinase-type plasminogen activator in human tongue squamous cell carcinoma cell line (Tca8113)]

OBJECTIVE

The aim of this study was to observe the expression of urokinase-type plasminogen activator (UPA) in human tongue squamous cell carcinoma cell line (Tca8113) after heat shock with different dosage.

METHODS

The expression of UPA protein of Tca8113 after different heating temperatures(37 degrees C, 40 degrees C, 43 degrees C and 45 degrees C) treatment was examined by immunohistochemical technique (IH) and flow cytometry (FCM).

RESULTS

Compared with 37 degrees C group, the UPA protein expression in 40 degrees C and 43 degrees C groups decreased significantly (P < 0.05); however, the UPA protein expression in 45 degrees C group decreased but no statistical difference was found.

CONCLUSION

Hyperthermia could inhibit invasion and metastasis of oral squamous cell carcinoma and could be considered as a safe method in curing the tumor.

Identification of the first trypanosome H/ACA RNA that guides pseudouridine formation on rRNA

In trypanosomes small nucleolar RNA (snoRNA) genes are clustered, and the clusters encode for either single or multiple RNAs. We previously reported on a genomic locus in Leptomonas collosoma that encodes for multiple C/D snoRNAs whose expression is regulated at the processing level (Xu, Y., Liu, L., Lopez-Estraño, C., and Michaeli, S. (2001) J. Biol. Chem. 276, 14289-14298). In this study we have characterized, in the same genomic locus, the first trypanosome H/ACA RNA, which we termed h1. Having a length of 69 nucleotides, h1 has the potential to guide pseudouridylation on 28 S rRNA. The h1 is processed from a long polycistronic transcript that carries both the C/D and h1 snoRNAs. The h1/rRNA duplex obeys the rules for guiding pseudouridylation. Mapping of the pseudouridine site indicated that the predicted U is indeed modified. However, in contrast to all H/ACA RNAs, h1 consists of a single hairpin structure and is the shortest H/ACA RNA described so far.

[Detection of serum Lp(a) level of coronary heart disease and its clinical significance]

OBJECTIVE

To study the association of human serum Lp(a) level and coronary heart diseases.

METHODS

Objects examined were conposed of 2 groups: CHD (39 cases) and healthy controls (52 cases). Lp (a), TC, HDL-C, TG, apoB of two groups were determined and the results were done with statistic analysis.

RESULTS

The mean serum Lp(a) concentrations (mg.L-1) in coronary heart disease group were shown higher significantly than that in the control group (P < 0.01). However, there were no significant correlation between the mean serum Lp(a) and the mean serum TC, HDL-C, TG, spoAI and aopB.(P > 0.05).

CONCLUSIONS

Serum Lp(a) level is closely related to the occurrence of coronary heart disease. Lp(a) is a single risk factor for coronary heart disease. Detecting the determination of serum Lp(a) is extremely valuable to the clinical prediction and diagnosis of CHD.

Beclin 1 contains a leucine-rich nuclear export signal that is required for its autophagy and tumor suppressor function

Beclin 1 encodes a Bcl-2-interacting coiled-coil protein with autophagy and tumor suppressor function and is monoallelically deleted in 40-75% of sporadic human breast and ovarian cancers. Beclin 1 contains a leucine-rich nuclear export signal motif raising the possibility that its autophagy and/or tumor suppressor function may require regulated, CRM1-dependent, nucleocytoplasmic transport. In this study, we show that wild-type Beclin 1 colocalizes with both intracytoplasmic organelles and nuclei in COS7 monkey kidney and MCF7 human breast carcinoma cells. Inhibition of CRM1-dependent nuclear export with leptomycin B or mutation of the nuclear export signal motif of Beclin 1 results in predominantly nuclear localization. Unlike wild-type Beclin 1, the nuclear export mutant of Beclin 1 fails to promote nutrient deprivation-induced autophagy and fails to inhibit in vitro clonigenicity and in vivo tumorigenicity of MCF7 cells. Thus, beclin 1 has a leptomycin B-sensitive leucine-rich nuclear export signal that is required for its autophagy and tumor suppressor function. These findings suggest that the CRM1 nuclear export pathway may be important in the functional regulation of autophagic growth control.

Induction of autophagy and inhibition of tumorigenesis by beclin 1

The process of autophagy, or bulk degradation of cellular proteins through an autophagosomic-lysosomal pathway, is important in normal growth control and may be defective in tumour cells. However, little is known about the genetic mediators of autophagy in mammalian cells or their role in tumour development. The mammalian gene encoding Beclin 1, a novel Bcl-2-interacting, coiled-coil protein, has structural similarity to the yeast autophagy gene, apg6/vps30, and is mono-allelically deleted in 40-75% of sporadic human breast cancers and ovarian cancers. Here we show, using gene-transfer techniques, that beclin 1 promotes autophagy in autophagy-defective yeast with a targeted disruption of agp6/vps30, and in human MCF7 breast carcinoma cells. The autophagy-promoting activity of beclin 1 in MCF7 cells is associated with inhibition of MCF7 cellular proliferation, in vitro clonigenicity and tumorigenesis in nude mice. Furthermore, endogenous Beclin 1 protein expression is frequently low in human breast epithelial carcinoma cell lines and tissue, but is expressed ubiquitously at high levels in normal breast epithelia. Thus, beclin 1 is a mammalian autophagy gene that can inhibit tumorigenesis and is expressed at decreased levels in human breast carcinoma. These findings suggest that decreased expression of autophagy proteins may contribute to the development or progression of breast and other human malignancies.

Cloning and genomic organization of beclin 1, a candidate tumor suppressor gene on chromosome 17q21

The beclin 1 (BECN1) gene encodes a 60-kDa coiled-coil protein that interacts with the prototypic apoptosis inhibitor Bcl-2. Previous studies indicate that beclin 1 maps to a region approximately 150 kb centromeric to BRCA1 on chromosome 17q21 that is commonly deleted in breast, ovarian, and prostate cancer. The complete cDNA sequence of beclin 1 encodes a 2098-bp transcript, with a 120-bp 5' UTR, 1353-bp coding region, and 625-bp 3' UTR. Hybridization screening of a human genomic PAC library identified PAC 452O8, which contains the complete beclin 1 gene. Determination of the exon-intron structure of beclin 1 reveals 12 exons, ranging from 61 to 794 bp, which extend over 12 kb of the human genome. FISH analysis of human breast carcinoma cell lines using PAC 452O8 as probe identified allelic beclin 1 deletions in 9 of 22 cell lines. Sequencing of genomic DNA from 10 of these cell lines revealed no mutations in coding regions or splice junctions. Additionally, Northern blot analysis of 11 cell lines did not identify any abnormalities in beclin 1 transcripts. These results indicate that human breast carcinoma cell lines frequently contain allelic deletions of beclin 1, but not beclin 1 coding mutations.

Resistance of interleukin-1beta-deficient mice to fatal Sindbis virus encephalitis

Interleukin-1beta (IL-1beta) concentrations are frequently elevated in central nervous system (CNS) viral infections, but the pathophysiologic significance of such elevations is not known. To examine the role of IL-1beta in CNS viral pathogenesis, we compared the natural histories of IL-1beta-deficient and wild-type 129 SV(ev) mice infected with a neurovirulent viral strain, neuroadapted Sindbis virus (NSV). We found that the incidence of severe paralysis and death was markedly decreased in NSV-infected IL-1beta-/- mice compared to NSV-infected wild-type mice (4 versus 88%, P < 0.001). Despite this marked difference in clinical outcome, no differences in numbers of apoptotic cells or presence of histopathologic lesions in the brains of moribund wild-type mice and those of clinically healthy IL-1beta-/- mice could be detected. These results suggest that IL-1beta deficiency is protective against fatal Sindbis virus infection by a mechanism that does not involve resistance to CNS virus-induced apoptosis or histopathology.

Protection against fatal Sindbis virus encephalitis by beclin, a novel Bcl-2-interacting protein

bcl-2, the prototypic cellular antiapoptotic gene, decreases Sindbis virus replication and Sindbis virus-induced apoptosis in mouse brains, resulting in protection against lethal encephalitis. To investigate potential mechanisms by which Bcl-2 protects against central nervous system Sindbis virus infection, we performed a yeast two-hybrid screen to identify Bcl-2-interacting gene products in an adult mouse brain library. We identified a novel 60-kDa coiled-coil protein, Beclin, which we confirmed interacts with Bcl-2 in mammalian cells, using fluorescence resonance energy transfer microscopy. To examine the role of Beclin in Sindbis virus pathogenesis, we constructed recombinant Sindbis virus chimeras that express full-length human Beclin (SIN/beclin), Beclin lacking the putative Bcl-2-binding domain (SIN/beclinDeltaBcl-2BD), or Beclin containing a premature stop codon near the 5' terminus (SIN/beclinstop). The survival of mice infected with SIN/beclin was significantly higher (71%) than the survival of mice infected with SIN/beclinDeltaBcl-2BD (9%) or SIN/beclinstop (7%) (P < 0.001). The brains of mice infected with SIN/beclin had fewer Sindbis virus RNA-positive cells, fewer apoptotic cells, and lower viral titers than the brains of mice infected with SIN/beclinDeltaBcl-2BD or SIN/beclinstop. These findings demonstrate that Beclin is a novel Bcl-2-interacting cellular protein that may play a role in antiviral host defense.

Quantitative fluorescence resonance energy transfer measurements using fluorescence microscopy

Fluorescence resonance energy transfer (FRET) is a technique used for quantifying the distance between two molecules conjugated to different fluorophores. By combining optical microscopy with FRET it is possible to obtain quantitative temporal and spatial information about the binding and interaction of proteins, lipids, enzymes, DNA, and RNA in vivo. In conjunction with the recent development of a variety of mutant green fluorescent proteins (mtGFPs), FRET microscopy provides the potential to measure the interaction of intracellular molecular species in intact living cells where the donor and acceptor fluorophores are actually part of the molecules themselves. However, steady-state FRET microscopy measurements can suffer from several sources of distortion, which need to be corrected. These include direct excitation of the acceptor at the donor excitation wavelengths and the dependence of FRET on the concentration of acceptor. We present a simple method for the analysis of FRET data obtained with standard filter sets in a fluorescence microscope. This method is corrected for cross talk (any detection of donor fluorescence with the acceptor emission filter and any detection of acceptor fluorescence with the donor emission filter), and for the dependence of FRET on the concentrations of the donor and acceptor. Measurements of the interaction of the proteins Bcl-2 and Beclin (a recently identified Bcl-2 interacting protein located on chromosome 17q21), are shown to document the accuracy of this approach for correction of donor and acceptor concentrations, and cross talk between the different filter units.

Expression of a biologically active antiviral antibody using a sindbis virus vector system

Monoclonal antibodies to the Sindbis virus E2 envelope glycoprotein protect mice against lethal encephalitis and mediate viral clearance from neurons. To facilitate structure-function analyses of anti-E2 mAbs, we developed an expression system that can be used for the construction of genetically engineered anti-E2 mAbs. We constructed recombinant Sindbis/immunoglobulin gene chimeric viruses that express heavy and light chains of an anti-E2 monoclonal antibody, R6. We used a PCR-based strategy to clone the entire rearranged heavy and light chain genes from R6 hybridoma cell cDNA into a double subgenomic Sindbis virus vector. The recombinant viruses, SIN/R6L and SIN/R6H, were generated by transfecting BHK-21 cells with in vitro transcribed RNA from Sindbis virus/R6 light chain and Sindbis virus/R6 heavy chain cDNA clones, respectively. Twelve hours after co-infection of BHK cells with SIN/R6L and SIN/R6H, the tissue culture supernatant contained up to 1.4 mg/ml of recombinant R6 IgG. The heavy and light chains of recombinant R6 were associated as judged by co-purification on protein A/G sepharose and co-electrophoresis of non-reduced proteins. The ELISA reactivity to Sindbis virus antigen was similar for recombinant R6 and R6 purified from ascites fluid. Furthermore, the in vivo biologic activity of recombinant R6 was similar to that of R6 purified from ascites; recombinant R6 treatment completely protected Balb/cJ mice from paralysis and death due to infection with neuroadapted Sindbis virus and also resulted in the clearance of infectious virus from the brains of immunodeficient scid mice persistently infected with wild-type Sindbis virus. Thus, the co-infection of BHK cells with SIN/R6L and SIN/R6H leads to the expression, assembly, and secretion of a biologically active recombinant antiviral antibody. Our results suggest that the Sindbis virus vector system is a simple and powerful tool for the production of functional, genetically engineered antibodies.

Dominant inhibitory Ras delays Sindbis virus-induced apoptosis in neuronal cells

Mature neurons are more resistant than dividing cells or differentiating neurons to Sindbis virus-induced apoptotic death. Therefore, we hypothesized that mitogenic signal transduction pathways may influence susceptibility to Sindbis virus-induced apoptosis. Since Ras, a 21-kDa GTP-binding protein, plays an important role in cellular proliferation and neuronal differentiation, we investigated the effect of an inducible dominant inhibitory Ras on Sindbis virus-induced death of a rat pheochromocytoma cell line, PC12 cells. Dexamethasone induction of dominant inhibitory Ras (Ha Ras(Asn17)) expression in transfected PC12 cell lines (MMTV-M17-21 and GSrasDN6 cells) resulted in a marked delay in Sindbis virus-induced apoptosis, compared with infected, uninduced cells. The delay in death after Sindbis virus infection in induced versus uninduced PC12 cells was not associated with differences in viral titers or viral infectivity. No delay in Sindbis virus-induced apoptosis was observed in Ha Ras(Asn17)-transfected PC12 cells if dexamethasone induction was initiated less than 12 h before Sindbis virus infection or in wild-type PC12 cells infected with a chimeric Sindbis virus construct that expresses Ha Ras(Asn17). The delay in Sindbis virus-induced apoptosis in induced Ha Ras(Asn17)-transfected PC12 cells was associated with a decrease in cellular DNA synthesis as measured by 5'-bromo-2'-deoxyuridine incorporation. Thus, in PC12 cells, inducible dominant inhibitory Ras inhibits cellular proliferation and delays Sindbis virus-induced apoptosis. These findings suggest that a Ras-dependent signaling pathway is a determinant of neuronal susceptibility to Sindbis virus-induced apoptosis.

Bcl-2 protooncogene expression in cervical carcinoma cell lines containing inactive p53

Bcl-2 protein expression has been found to block apoptosis and its overexpression has been implicated in lymphoid malignancies where the chromosomal translocation t(14;18) is present. In this study we investigated bcl-2 transcription and protein expression in cultured cervical carcinoma cell lines and keratinocytes. Western blotting and immunofluorescence microscopy demonstrated bcl-2 expression in the cytoplasm of 4 out of 5 cervical carcinoma cell lines examined (HeLa, CaSki, C-33A, and HT-3, but not SiHa). Bcl-2 protein expression was undetectable in normal keratinocytes. None of the cell lines examined demonstrated chromosomal translocation or rearrangement at the major breakpoint-cluster region (MBR) of the bcl-2 gene using either Southern blot or polymerase chain reaction (PCR) analyses. Northern blot analysis demonstrated low levels of bcl-2 transcription in HeLa, CaSki, and C-33A cell lines while reverse transcriptase (RT)-PCR demonstrated bcl-2 transcription in all cervical carcinoma cell lines which had bcl-2 protein expression. Thus, these data suggest that bcl-2 expression occurs in cervical carcinoma cell lines in the absence of chromosomal translocation or rearrangement of the bcl-2 gene. However, each of these cervical carcinoma cell lines contains inactive p53, either due to mutation (C-33A and HT-3) or via complexation and degradation with human papillomavirus (HPV) 16/18 E6 protein (HeLa and CaSki). Thus, functional p53, which can induce apoptosis in certain cells, is not present in these cervical cells which have increased bcl-2 expression. Increased bcl-2 expression under conditions of p53 inactivation may provide cells with a selective advantage for survival and consequently play a role in the development of cervical carcinogenesis.

Co-localization of the tumor-suppressor protein p53 and human papillomavirus E6 protein in human cervical carcinoma cell lines

The loss of the tumor-suppressor activity of p53, either by mutation or by interaction with the human papillomavirus (HPV) E6 protein, is considered to be an important mechanism in the carcinogenesis of cervical cancer. We have studied the cytological distribution of these proteins in human cervical carcinoma cell lines using polyclonal anti-p53 and monoclonal anti-E6 antibodies. The antibody specificity was confirmed by immunoblot and immunocompetition analyses. The intracellular localization of p53 and E6 was detected using the techniques of conventional and three-dimensional confocal microscopy. In the HPV-18 or -16 integrated cell lines, HeLa, CaSki and SiHa, viral oncoprotein E6 and endogenous tumor-suppressor protein, p53, were observed by immunofluorescence in the cytoplasm; p53 also had a weak punctate staining in the nuclei of HeLa and CaSki cells. In the HPV-negative cervical carcinoma cell lines, C-33A and HT-3, which have mutated p53, p53 was localized predominantly to the nucleus, with C-33A cells having elevated levels of p53 compared with the other cell lines. High spatial resolution imaging, using confocal microscopy, was performed on the cells after double fluorescence staining for p53 (fluorescein) and E6 (rhodamine). The images showed that both p53 and E6 had similar cytoplasmic distributions, which implied that these two proteins may exist as a cytoplasmic complex. To substantiate this implication, fluorescence resonance energy transfer microscopy was performed, which provided direct evidence of a close association between p53 and E6 within individual HeLa cells. The results from this study support the theory that p53 protein binds HPV-16/18 E6 protein in the cell cytoplasm, thus preventing p53 from exerting its tumor-suppressor function in the nucleus. Hence, inactivation of wild-type p53 by p53-E6 complex formation in cervical cancer may be a critical step in malignant transformation.

[Clonal origin of intrahepatic recurrence after resection of hepatocellular carcinoma]

Using integrated hepatitis B virus (HBV) DNA in the cancer cells as a genetic marker, clonal origin of intrahepatic recurrence of hepatocellular carcinoma was studied by Southern blot technique. Comparing 5 cases of postoperative recurrent hepatocellular carcinoma with their primary tumors, it was found that 1 case had identical HBV DNA integration patterns, 3 cases were of different clonality and 1 case with multiple nodular recurrences contained either a unicentric origin or a new distinctive clone origin. The results suggest that, in addition to recurrence from residual cancer cells, in some cases, hepatocellular carcinoma may develop repeatedly during a continuous process of carcinogen action, even after a radical resection.

Resection of hepatocellular carcinoma: oligocentric origin of recurrent and multinodular tumours

The structure of integrated hepatitis B virus (HBV) DNA was analysed to determine the origin of recurrent and multinodular hepatocellular carcinoma (HCC). In 5 cases, recurrent tumours were compared with the respective primary tumours, all of which had chromosomally integrated viral DNA. In only one of these cases, an identical HBV DNA integration pattern was found, indicating a monocentric origin of primary and secondary tumour. In all other cases a polycentric origin was deduced. Particular features observed were: (i) the apparent absence of integrated viral DNA in a recurrent tumour; and (ii) an integration pattern identical to that of the primary tumour and a distinct new pattern in two different foci of multinodular recurrent HCC. For multinodular primary HCC one case was analysed and found to be of independent origin.

Replication of hepatitis B virus in a hepatocellular carcinoma

Hepatitis B virus transcripts and DNA from paired samples of neoplastic and nonneoplastic liver tissue of HBsAg seropositive patients were analyzed. The data obtained support the view that transcription of integrated DNA is frequent, both in neoplastic as well as in nonneoplastic liver tissue. In the case of one patient, integrated and free forms of hepatitis B virus DNA were detected in the tumor. Complete cycles of viral replication in this tumor were suggested by the following markers: (i) DNA and RNA intermediates expected to occur during replication of the viral genome, (ii) HBcAg and HBsAg, (iii) core and Dane particles. Viral DNA cloned from tumor tissue was proven to be replication competent in a transient replication assay. Five independent clones of viral DNA were established and found to be closely related at the nucleotide level. A preX open reading frame and a stop codon within preC were common features. In tissue surrounding the tumor, a nonreplicative state of virus infection prevailed, characterized by free viral DNA exclusively of the covalently closed, circular form. The replication of the viral DNA appeared to be blocked at the level of transcription.