Intratumoral genomic heterogeneity in human hepatocellular carcinoma detected by restriction landmark genomic scanning

BACKGROUND/AIMS

One of the unique features of advanced hepatocellular carcinoma (HCC) is the morphological heterogeneity in a single tumor nodule. In order to investigate the intratumoral genomic heterogeneity of HCC, we performed Restriction Landmark Genomic Scanning (RLGS), which allows genomic DNAs to be surveyed at approximately 2000 landmark sites in a single 2-dimensional gel electrophoresis.

METHODS

RLGS profiles of two regions from a single HCC nodule in six patients were compared with non-tumorous liver tissue. Four HCCs consisting of moderately-differentiated cells were separated into several small parts by thin fibrous septa, but not encapsulated. DNA samples were obtained from both parts of these so-called "nodule-in-nodule" HCC. Two HCCs consisting of well-differentiated cells which did not have a definite partition appeared pathologically homogeneous, and two independent regions of the HCC were used for the analysis.

RESULTS

All six HCCs demonstrated different RLGS profiles (in total about 160 different spots) from the corresponding non-tumorous liver, and the number of different spots was greater in the 4 moderately-differentiated nodule-in-nodule HCCs (39-68 spots) than in the 2 well-differentiated homogeneous HCCs (6 and 3 spots). RLGS profiles of the two parts were different to each other in all 4 nodule-in-nodule HCCs. On the other hand, two other homogeneous HCCs showed the same RLGS profiles in the two regions.

CONCLUSION

Thus, intratumoral genomic heterogeneity was demonstrated in the advanced HCC samples, and the genomic alterations may relate to the progression of HCC.

Effects of chenodeoxycholic and ursodeoxycholic acids on interferon-gamma production by peripheral blood mononuclear cells from patients with primary biliary cirrhosis

Ursodeoxycholic acid (UDCA) administration can obtain marked improvement of primary biliary cirrhosis (PBC). Recently, UDCA has been demonstrated to have a direct effect on immunological reactions in patients with PBC in that the aberrant expression of major histocompatibility complex (MHC) class I molecules was markedly reduced after UDCA treatment. To understand the immunological effect of UDCA, we analyzed interferon (IFN)-gamma production in peripheral blood mononuclear cells (PBMCs) from 29 patients with PBC treated with UDCA (group 1), 19 patients with PBC who were not treated with UDCA (group 2), 11 healthy subjects (group 3), and 12 patients with chronic viral hepatitis (group 4). IFN-gamma production was investigated because the excess production of this cytokine is associated with the aberrant expression of MHC molecules. Whereas IFN-gamma production in the patients in group 2 was significantly increased, the level of production in group 1 was similar to that in the control groups (groups 3 and 4). There was significant improvement in IFN-gamma production in 6 patients with PBC after UDCA treatment. The effect of UDCA and chenodeoxycholic acid (CDCA) on IFN-gamma production in PBMCs from 12 normal subjects was also analyzed. IFN-gamma was produced dose-dependently according to concentrations of CDCA ranging from 0.1 to 10 microM, but the increase in production was markedly suppressed by the addition of UDCA. We conclude that low doses of CDCA enhance IFN-gamma production and may therefore lead to the aberrant hepatic expression of MHC molecules, and that the increase in IFN-gamma production is suppressed by UDCA.

Clinical pathoepidemiology of hepatocellular carcinoma in Japan

There has been a rapid increase in the number of patients with hepatocellular carcinoma (HCC) in Japan. This may be the result of an increased number of patients with hepatitis C virus (HCV)-related liver disease, and of prolonged survival of these patients due to improvement in the management of cirrhosis. Indeed, 96% of recent HCC patients admitted to our hospital were related to viral hepatitis B or C, and HCV infection accounted for three-fourths of these cases. Since most HCCs develop in the course of chronic liver disease, it is important to identify high risk groups for HCC development and to detect small HCCs early. We have established a screening method by combining various imaging studies and the measurement of serum alpha-fetoprotein; this combination has markedly increased the detection of small HCCs less than 2 cm in diameter. Multiple HCCs can occur in the same patient, either simultaneously or successively. Partly for this reason, the cumulative recurrence rate of HCC is very high even after surgical resection. In order to determine whether such HCCs arise from the common or different clonal origins, we have utilized the restriction landmark genomic scanning method. It remains to be clarified whether HCV plays a direct role in hepatocarcinogenesis, and whether antiviral treatments such as interferon eventually will decrease the incidence of HCC among patients with chronic HCV infection.

Aberration of genomic DNA in association with human hepatocellular carcinomas detected by 2-dimensional gel analysis

Alterations of genomic DNAs in primary hepatocellular carcinomas (HCCs) were examined by restriction landmark genomic scanning (I. Hatada et al., Proc. Natl. Acad. Sci. USA, 88: 9523-9527, 1991) which is a 2-dimensional gel analysis that allows detection of deletion, amplification, or other rearrangements of genomic DNA. Sixteen HCC samples together with their normal counterparts were tested in this manner. Each HCC sample was micromanipulated to minimize possible carryover from non-malignant cells. DNAs from HCCs and their normal counterparts were cleaved with the restriction enzyme NotI, end labeled with 32P, and size fractionated by 2-dimensional electrophoresis using HinfI as the second cleavage enzyme. The resulting spots (about 2000) in HCC samples were compared with their normal counterparts. Five spots were more intense in 10-14 of the 16 HCCs (63-88%). The intensity of several spots was reduced to about half, suggesting the loss of one of two alleles. Some of these decreases were observed frequently in different HCC samples, whereas others were sporadic. Sixty of these spots reproducibly decreased in > 2 cases, with 27 showing a decrease in > 50% of the informative cases. The highest incidence was observed in 14 of 16 samples (88%). No significant correlations were observed between these changes in spots and hepatitis B virus or hepatitis B virus infection. The use of landmarks that show a reproducible increase or decrease in intensity is discussed in conjunction with future studies of genomic alterations inherent in HCC.

Mixed types of chronic active hepatitis and primary biliary cirrhosis associated with the anti-phospholipid antibody syndrome: a case report

An understanding of the pathogenesis of mixed types of chronic active hepatitis and primary biliary cirrhosis is important for the treatment of the patients. A 40-year-old Japanese woman with antiphospholipid syndrome has been treated with prednisolone for two years since she was diagnosed as having a mixed type of chronic active hepatitis and primary biliary cirrhosis. Biochemical tests for liver function were normal during treatment. Laparoscopy revealed a white liver, and histology demonstrated disappearance of the findings of piecemeal necrosis or chronic nonsuppurative destructive cholangitis in the specimen. Steroid treatment of patients with mixed types of chronic active hepatitis and primary biliary cirrhosis is controversial, since it is contra-indicated in some. Although the clinical features of the patients varies from one to another, this case suggests that the autoimmune mechanism of some patients may resemble autoimmune hepatitis rather than primary biliary cirrhosis, and treatment with steroid is effective.

Detection of chemiluminescence in lipid peroxidation of biological systems and its application to HPLC

A combined system of chemiluminescence detection and high performance liquid chromatography (CL-HPLC) was developed to determine primary peroxidation products in biological tissues, such as phosphatidylcholine hydroperoxide (PCOOH). The CL-HPLC assay consists of separation of lipid classes with HPLC and detection of hydroperoxide-specific chemiluminescence. Hydroperoxides react with heme compounds to produce oxidants as suggested by our early studies on tissue low-level chemiluminescence in which singlet molecular oxygen is generated as one of the excited species in several biological systems involving free radical events. In the CL-HPLC method, a cytochrome c-luminol mixture was used as a hydroperoxide-specific luminescent reagent, and the quantification of hydroperoxide was performed by detecting chemiluminescence due to the luminol oxidation caused by the oxidant produced during the lipid hydroperoxides with heme. The detection limit of PCOOH was 10 pmole hydroperoxide-O2. PCOOH in normal human blood was found to be 10-500 pmol/ml plasma and significantly higher levels of PCOOH were observed in some hospitalized patients.