Earlier studies have suggested that transient hepadnavirus infections in mammals are associated with virus replication in a large fraction of hepatocytes. Although the viremia that occurred during transient infections in some individuals would presumably lead to virus replication in all hepatocytes, these studies did not reveal if this was the case. The question of the extent of hepatocyte infection was therefore reinvestigated because of the implications of the results for the mechanisms of virus clearance. Woodchucks were inoculated with woodchuck hepatitis virus, and the course of hepatic infection was determined. These studies indicated that essentially 100% of the hepatocytes became infected in the majority of woodchucks. In 7 of 10 woodchucks, the viral infection was then rapidly cleared from the liver, generally in less than 4 weeks. In another three woodchucks, though productive infection was just as rapidly cleared, viral covalently closed circular DNA remained for weeks to months after other indicators of virus infection had disappeared from the liver. Bromodeoxyuridine labeling and anti-proliferating cell nuclear antigen staining to detect hepatocytes passing through S phase indicated an increase in hepatocyte proliferation during the recovery phase of infection. The rate of cell division appeared to be sufficient to replace no more than 2 to 3% of the hepatocytes per day, at the times at which the biopsies were performed. Histopathologic evaluation of the biopsy samples did not provide evidence for a massive amount of liver regeneration. Models to explain virus clearance, with or without massive immune system-mediated destruction of infected hepatocytes, are reviewed.

Purpose:The development of hepatocellular carcinoma is associated with the chronic inflammation of the liver caused by various factors such as hepatitis B or C virus infection. Previously, we reported DNA binding protein A (dbpA) as a candidate molecule that can accelerate inflammation-induced hepatocarcinogenesis. DbpA belongs to the Y-box binding protein family, and Y-box binding protein-1 (YB-1), the prototype member of this family, is reported to be a prognostic marker of malignant diseases other than hepatocellular carcinoma. The purpose of this study is to examine the significance of the expression of dbpA or of theT-to-G transversion in the dbpA promoter region, which enhances the promoter activity in vitro, for the progression of hepatocellular carcinoma. Experimental Design: We studied the expression of dbpA (as well as of YB-1) in 82 formalinfixed hepatocellular carcinoma tissues by immunohistochemistry and determined the sequence of the dbpA promoter region in 42 frozen hepatocellular carcinoma tissues. We examined the relationship between these findings and the clinicopathologic factors of hepatocellular carcinoma patients. Results: DbpA expression was associated with the advanced stages of hepatocellular carcinoma, and the cases with the nuclear dbpA expression had a poor prognosis. DbpA contributed more significantly to this association thanYB-1. Furthermore, theT-to-G transversion in the dbpA promoter region was related to the nuclear localization of dbpA. Conclusion: DbpA was a more significant prognostic marker of hepatocellular carcinoma than YB-1. TheT-to-G transversion in the dbpA promoter region was suggested to be a predisposing factor for the progression of hepatocellular carcinoma.

Functional inactivation of tuberous sclerosis 2 gene (Tsc2) leads to renal carcinogenesis in the hereditary renal carcinoma Eker rat models. Recent studies revealed a role of tuberin, a TSC2 product, in suppressing the p70 S6 kinase (p70S6K) activity via inhibition of mammalian target of rapamycin (mTOR). Phosphorylated S6 protein, a substrate of p70S6K, was expressed in the early lesions in Eker rats, and this expression was suppressed by the treatment of rapamycin, an inhibitor of mTOR. We previously isolated the novel gene Niban expressed in renal carcinogenesis of Eker rats. In this study, we demonstrated that the expression of Niban was detected from early preneoplastic lesions in Eker rats. Interestingly, in contrast to the phosphorylated S6 protein, the expression of Niban was unchanged and early lesions still remained even after treatment with rapamycin. These results might suggest the existence of another pathway independent of mTOR-S6K pathway in Tsc2 mutant renal carcinogenesis. In addition, Niban was also expressed in other renal carcinoma models, including Tsc1 and Tsc2 knockout mice, and various types of human renal cell carcinomas. Thus, Niban was commonly expressed in renal carcinomas and might be a new marker for renal carcinogenesis.

HepG2 cells, known to support the replication and virion formation of hepatitis B virus (HBV), were transfected with a cosmid constructed to contain 12 tandem head-to-tail repeats of the HBV genome for effective HBV genome expression. We detected previously identified RNAs of 3.3, 2.3, and 2.0 kilobases (kb) that code for core antigen, large surface antigen, and middle/major surface antigen, respectively. We also detected four additional RNAs of 2.1, 1.7, 1.1, and 0.7 kb [the lengths exclude the poly(A) tail]. S1 mapping and nucleotide sequencing data showed that the 2.1-kb RNA is a spliced RNA whose 5' and 3' ends are identical to those of the 3.3-kb RNA. The results suggest that the 2.1-kb RNA codes for an altered core antigen lacking the last amino acid, cysteine, and that expression of the 3.3-kb pregenomic RNA is regulated, at least in part, by splicing. The map positions of the 1.7- and 1.1-kb RNAs suggest that they code for the carboxyl-terminal portions of the putative polymerase, whereas the 0.7-kb RNA codes for the X protein.

The poor prognosis of hepatocellular carcinoma (HCC) is partly the result of the high rate of recurrence that is caused either by intrahepatic metastasis (IM) or independent multicentric occurrence (MO). For convenience, discrimination of IM and MO is based on pathological findings, but reliable parameters are not sufficiently established. In the case of hepatitis B virus (HBV)-associated HCC, molecular discrimination of IM from MO can be achieved by comparison of integrated HBV DNAs. However, Southern blotting cannot be used for this purpose when one tumor is saved in frozen form and the other is in paraffin-embedded form. To solve this problem, we employed polymerase chain reaction (PCR) assays to confirm the clonality of primary and recurrent tumors. From the frozen tissue, we determined the junction between the integrated HBV and flanking genomic DNA by molecular cloning, and checked the existence of an identical junction in the DNA of paraffinembedded tissue by PCR. Using this method, as well as Southern blotting, we proved in 6 of 8 patients that two nodular HCC lesions resected metachronously or simultaneously were caused by MO, while the remaining 2 cases were caused by IM. In 1 IM case, band patterns between two HCCs detected by Southern blotting were not identical. (HEPATOLOGY 1999;29:1446-1452.) Hepatocellular carcinoma (HCC), one of the most common cancers in many parts of the world, is the third-leading cause of death from malignancy in Japan. In 1995, HCC was responsible for about 30,000 deaths, and the number of deaths continues to increase in Japan. 1 Improvement in imaging modalities and strict follow-up of patients with hepatitis B virus (HBV) or hepatitis C virus, including measurement of serum tumor markers, allows early detection of HCCs. In spite of technical advances in the treatment of HCC, such as surgical resection, percutaneous ethanol injection therapy, and microwave coagulation therapy, the longterm survival rate is still low. One of the major reasons for this poor prognosis is the high rate of recurrence, which is 20% to 40% within 1 year, and about 80% in 5 years after curative operation in Japan. 2-5 HCC recurrence may be the result of intrahepatic metastasis (IM) or independent multicentric occurrence (MO). Discrimination between the two is important not only for the study of hepatocarcinogenesis, but also for determination of therapeutic strategies. Some groups have reported that HCC with IM recurs earlier and has a poorer prognosis than its MO counterpart. 2,6 Aggressive therapy may not be warranted in cases with widespread metastatic dissemination, but in cases with MO, intervention should be taken within the limits of liver functional reserve. The diagnosis of IM or MO is mainly based on pathological findings as reported by the Liver Cancer Study Group of Japan 7 with modifications, 6,[8][9][10][11] or on the analysis of HBV-DNA integration by Southern blotting in cases of HBV-associated HCC. 8,[12][13][14][15][16][17][18] The pathological criteria for MO reflect the multiste...

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A modified AFLP (amplified fragment length polymorphism) method was employed to isolate genes differentially expressed in renal carcinogenesis of Tsc2 gene mutant (Eker) rats. One gene, selected for further investigation, was named "Niban" ("second" in Japanese), because it is the second new gene to be found after Erc (expressed in renal carcinoma) in our laboratory. Importantly, "Niban" is well expressed even in small primary rat Eker renal tumors, more than in progressed cell lines, and is also expressed in human renal carcinoma cells, but not in normal human or rat kidneys. Chromosome assignment was to RNO 13 in the rat, and HSA 1. This "Niban" gene is a candidate as a marker for renal tumor, especially early-stage renal carcinogenesis.

Background: Lymph node metastasis is a key event of colorectal cancer (CRC) progression. Mesothelin is