Characteristics of a cell line (Tong/HCC) established from a human hepatocellular carcinoma

Cell Sources for Bioartificial Liver Support

The present review discusses hepatocyte sources for a bioartificial liver. Intended requirements for cell sources are for example: synthesis of plasma proteins, detoxification and regulation. The need for highly differentiated hepatocytes is stressed. Furthermore, the gap between this objective on the one hand and the real possibilities as they appear today on the other is shown. Alternatives to primarily isolated hepatocytes are discussed, thereby elucidating the limits of established cell lines. In summary, it is postulated that the results expected from a bioartificial liver, are closely related to the source and type of cells used.

Androgen receptor mitigates postoperative disease progression of hepatocellular carcinoma by suppressing CD90+ populations and cell migration and by promoting anoikis in circulating tumor cells

Purpose

Although hepatectomy and liver transplantation surgery for hepatocellular carcinoma (HCC) are effective treatment modalities, the risk of recurrence remains high, particularly in patients with a high number of circulating tumor cells (CTCs) expressing cancer stem/progenitor cell markers. Androgen receptor (AR) signaling has been shown to suppress HCC metastasis in rodent models of HCC. In this study, we investigated whether AR is associated with postoperative HCC recurrence.

Experimental Design

CTCs were obtained from patients with HCC who had undergone hepatectomy to investigate whether they are associated with disease outcome. AR knockout was introduced in two mouse models of spontaneous HCC (carcinogen- and hepatitis B virus-related HCC) to delineate the role that AR plays in HCC recurrence. Biological systems analysis was used to investigate the cellular and molecular mechanisms.

Results

We found that the expression of AR in CTCs was negatively associated with HCC recurrence/progression after hepatectomy. Our results suggest that AR-mediated suppression of HCC recurrence/progression is governed by a three-pronged mechanism. First, AR suppresses the expression of CD90 in CTCs by upregulating Histone 3H2A. Second, AR suppresses cell migration at the transcriptome level. Third, AR promotes anoikis of CTCs via dysregulation of cytoskeletal adsorption.

Conclusions

The results indicate that AR expression may be the gatekeeper of postoperative HCC recurrence. Therefore, targeting AR in presurgical down-staging procedures may serve as a secondary prevention measure against HCC recurrence in the future.

The establishment and characterization of immortal hepatocyte cell lines from a mouse liver injury model

Hepatocytes are an important research tool used for numerous applications. However, a short life span and a limited capacity to replicate in vitro limit the usefulness of primary hepatocyte cultures. We have hypothesized that in vivo priming of hepatocyte could make them more susceptible to growth factors in the medium for continuous proliferation in vitro. Here, a novel approach used to establish hepatocyte cell lines that included hepatocyte priming in vivo prior to culture with a 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet was attempted. The cell line grew in a monolayer while maintaining a granular cytoplasm and a round nucleus. Electron microscopy displayed hepatocyte-like features including mitochondria, glycogen granules, and the presence of bile canaliculi. This cell line expressed many mature hepatocyte-specific genes including albumin, alpha1-antitrypsin, glucose 6-phosphatase, and tyrosine aminotransferase. Functional characteristic of hepatocytes like the ability to store glycogen, lipid, and synthesis of urea is well demonstrated by this cell line. These cells demonstrated anchorage dependent growth properties in soft agar and did not form tumors after transplantation into nude mice. This cell line can be sustained in culture for more than 100 passages (>1.5 years) without undergoing noticeable morphological changes or transformation. This novel method resulted in the establishment of an immortal, non-transformed hepatocyte cell line with functional characteristics that may aid research of cell metabolism, toxicology, and hepatocyte transplantation.

Decreased expression of UK114 is related to the differentiation status of human hepatocellular carcinoma

Previous studies have identified that the expression of UK114 is tissue specific and the protein has been found to be most abundant in liver and kidney. However, the expression of UK114 in human hepatocellular carcinoma and its relationship to differentiation and transformation of hepatocellular carcinoma have not been studied. In this study, the expression of UK114 in human hepatocellular carcinoma was examined by Northern and Western blot analyses. We found that UK114 was significantly down-regulated in most of hepatocellular carcinoma tissues compared with adjacent nontumor tissues (72.7%) at both mRNA and protein levels. We looked into the possibility that this decreased expression of UK114 in the hepatocellular carcinoma tissues may play a role in the differentiation or tumorigenicity of hepatocellular carcinoma. Immunohistochemical staining showed that the reduced expression of UK114 in hepatocellular carcinoma tissues was correlated with the tumor differentiation status as graded by the Edmondson-Steiner classification. On the other hand, overexpression of UK114 was not able to suppress the proliferation of human hepatoma cells and tumorigenicity in nude mice. These results suggest that UK114 does not seem to act as a tumor suppressor gene; however, it may useful as a biomarker that will assist in the grading of the differentiation status of hepatocellular carcinoma samples.

Increased CYP3A4 copy number in TONG/HCC cells but not in DNA from other humans

Two recent screens for copy-number variations in the entire human genome found 12.4 gene copy number variations per person, including 2.5% of individuals with gains between 7q21.1 and 7q22.1, the chromosomal location of CYP3A4. CYP3A4 is involved in the metabolism of approximately 50% of all drugs, including many cancer chemotherapeutic agents. CYP3A4 gene copy was determined in DNA from 143 individuals: normal human livers, primary and secondary liver tumors, human hepatic cell lines, and immortalized cell lines representing eight ethnically diverse populations. CYP3A4 gene copy was normal in all but one sample, a primary human hepatocellular carcinoma cell line (TONG/HCC). Southern blots of TONG/HCC DNA revealed an approximate 10-fold increase in CYP3A and a corresponding increase in CYP3A mRNA expression and catalytic activity. Fluorescent in situ hybridization of TONG/HCC revealed specific amplification of the CYP3A4 gene on chromosome 7q21 but no amplification of the MDR1 gene that localizes 11.9 Mb upstream of CYP3A4. High resolution analysis of DNA copy number by comparative genomic hybridization confirmed amplification at 7q21.3-7q22. The amplicon spanned 1.7 Mb and contained 30 known genes, including the entire CYP3A locus. To determine whether CYP3A4 expression affected chemotherapeutic toxicity, LLC-PK1 cells were transduced with adenoviruses expressing CYP3A4 and P450 reductase. CYP3A4 conferred resistance to taxol, vinblastine and topotecan. These studies demonstrate that CYP3A4 copy number differences do not contribute to the normal variation in CYP3A4 expression. Tumors with increased CYP3A copy number (via amplification or increased chromosome 7q) would be expected to show reduced cytotoxicity to some chemotherapeutic drugs and potentially an increase in the outgrowth of drug resistant tumors.

Use of human-derived liver cell lines for the detection of environmental and dietary genotoxicants; current state of knowledge

This article gives an overview of the results of genotoxicity tests, which have been conducted within the last 5 years with the human liver cell line HepG2. It is an update of an earlier review from 1998 (by Knasmüller et al.). In addition, a number of publications are discussed which are relevant for the use of human derived liver cell lines in genetic toxicology. They concern the establishment of new endpoints, the development of new cell lines and possible pitfalls and problems. HepG2 cells have been used to test a wide variety of compounds over the last years. The most interesting observations are that the cells are highly sensitive toward polycyclic aromatic hydrocarbons and that genotoxic effects are seen with a number of carcinogenic mycotoxins, that give negative results in other in vitro assays. Carcinogenic metals such as As and Cd caused positive results as well, whereas only marginal or negative results were seen with nitrosamines. The low sensitivity toward these latter carcinogens is probably due to a lack of cytochrome P4502E1 which catalyses their activation. Also, a number of structurally different synthetic pesticides as well as bioactive plant constituents ("natural pesticides") have been tested and with some of them genotoxic effects were found. In most experiments, the formation of micronuclei was used as an endpoint; however also the single cell gel electrophoresis assay is increasingly used. Several transfectant lines of HepG2 have been constructed which express increased levels of phase I enzymes (such as CYP1A1, CYP1A2, CYP2E1 etc.); furthermore, cell lines became available which express human glutathione-S-transferases. These new clones might be particularly useful for the investigation of specific classes of genotoxicants and also for mechanistic studies. Apart from HepG2 cells, a number of other human derived liver cell lines have been isolated, but so far no data from genotoxicity experiments are available, except for Hep3B cells, which were compared with HepG2 and found to be less sensitive in general. Studies with HepG2 clones of a different origin indicate that the cells differ in regard to their sensitivity toward genotoxicants; also medium effects and the cultivation time might affect the outcome of genotoxicity studies. Overall, the results support the assumption that HepG2 cells are a suitable tool for genotoxicity testing.

Diverse cellular transformation capability of overexpressed genes in human hepatocellular carcinoma

For isolation of novel cellular transforming genes that potentially participated in hepatocarcinogenesis, we conducted anchorage-independent growth (AIG) assays on 10 human liver cancer cell lines and observed strong AIG capabilities in PLC5 and Huh7 but negligible in Tong cells. After cloning of genes by differential subtractive chain reactions (DSC) from strong AIG to AIG negative cells, we sequenced 2304 clones and identified 245 genes. After four stringent criteria for selection of transforming genes among DSC clones, our results of quantitative RT-PCR analysis indicated that six genes, DDX3, EIF3S2, CLIC1, HDGF, GPC3, and HSPCA were overexpressed in 64%, 62%, 60%, 58%, 49%, and 47%, respectively, of 45 hepatocellular carcinoma (HCC) tissues. The results of cellular transformation capability by AIG assays indicated that the transfectants of EIF3S2 showed the strongest (> 100-fold), DDX3 and CLIC1 were moderate, GPC3 and HSPCA were weak, and HDGF was none in forming colonies in soft agar. Together, our results suggested that Tong is a suitable human cell line for screening of overexpressed and/or cellular transforming genes. In addition, our results suggested that diverse functions of cellular transforming genes in various biological pathways could transform human Tong cells and potentially reveal new targets for drug development of HCC.

The presence of hepatitis B surface antigen and deoxyribonucleic acid in amniotic fluid and cord blood

OBJECTIVE

It is uncertain whether neonatal infection with hepatitis B, despite treatment after delivery with immunoglobulin and vaccine, is the result of prior in utero transmission of the virus or treatment failure. Furthermore, the potential risk of hepatitis B transmission from the mother to the fetus at the time a genetic amniocentesis is performed is also a concern. In an attempt to better elucidate these controversies, amniotic fluid and cord blood specimens obtained from pregnant women positive for hepatitis B surface antigen were analyzed for the presence of hepatitis B surface antigen and hepatitis B deoxyribonucleic acid.

STUDY DESIGN

This study was a prospective longitudinal analysis that identified hepatitis B surface antigen-positive patients who presented for amniocentesis. Cord blood was obtained from these patients at the time of delivery. Cord blood was also obtained from a group of hepatitis B surface antigen-positive patients for whom no amniocentesis was performed. All samples were analyzed for the presence of hepatitis B surface antigen and hepatitis B deoxyribonucleic acid.

RESULTS

A total of 121 hepatitis B surface antigen-positive pregnant women were identified. In the 72 pregnancies in which amniocentesis was not performed, 18% of the cord blood samples were positive for hepatitis B surface antigen and 4% were positive for hepatitis B deoxyribonucleic acid. Of 47 amniocentesis fluid samples, 32% were positive for hepatitis B surface antigen but all were negative for hepatitis B virus deoxyribonucleic acid. Of 30 cord blood samples from patients who underwent an amniocentesis, 27% were positive for hepatitis B surface antigen, but all were negative for hepatitis B virus deoxyribonucleic acid.

CONCLUSIONS

This study found that hepatitis B viral deoxyribonucleic acid is rarely present in cord blood and was not identified in amniotic fluid obtained by amniocentesis. This finding suggests that in utero transmission of the virus is rare prior to the onset of labor. These data further confirm the reports in the current literature that the risk of hepatitis B transmission to the fetus during amniocentesis is low. Because hepatitis B surface antigen can exist as an isolated entity devoid of nuclear material, in some cases this protein may be able to traverse the placental and amniotic membrane barrier in a manner similar to other proteins, such as alpha-fetoprotein. Recommendations for genetic amniocentesis in women positive for hepatitis B surface antigen are discussed.

Establishment and characterization of a nontumorigenic cell line derived from a human hepatocellular adenoma expressing hepatocyte-specific markers

In the present study the establishment and characterization of a nontumorigenic liver epithelial cell line (HACL-1) derived from a human hepatocellular adenoma is described. The HACL-1 cells have a finite life span (i.e., they proliferate for a period of 2 months and then senesce), show cell-cell contact inhibition, do not grow in soft agar, are not tumorigenic when injected in nude mice, and possess a normal diploid karyotype. The cultured cells resemble hepatocytes, but exhibit some features of dedifferentiation. At the ultrastructural level the cells are endowed with round or oval nuclei, abundant cytoplasmic organelles, and varying amounts of glycogen. The rough endoplasmic reticulum is disorganized, while peroxisomes and matrix granules within mitochondria are lacking. HACL-1 cells are cytokeratin 18-positive as well as (transiently) albumin- and alpha-fetoprotein-positive, but do not express cytokeratin 19. Furthermore, no mutations were observed in exons 5-8 of the tumor suppressor gene p53. Taken together these results show that HACL-1 cells are nontumorigenic proliferating liver epithelial cells, which might prove to be of great value in future studies on diverse aspects of human liver cell biology and carcinogenesis.

Report of a complex karyotype in recurrent metastatic fibrolamellar hepatocellular carcinoma and a review of hepatocellular carcinoma cytogenetics

Metastatic fibrolamellar hepatocellular carcinoma (HCC) was detected in the abdominal lymph nodes of an adolescent male after resection of the primary tumor. No dividing cells were isolated from attempted cytogenetic studies of the primary tumor. However, cytogenetic analysis of lymph node metastases detected 9 and 12 months after partial hepatectomy revealed abnormal hypertriploid karyotypes, with a suggestion of clonal evolution: 62-92 < 3n >,XX, -Y, +3, +6, +6, +7, +7, +8, +10, +13, +15, +16, +20, -21, -22, +mar1 x 2, +mar[cp6]/46,XY[8] and 78 < 3n >,XX, -Y,der(1)t(1;1)(p36.1;q21), +4, +6, +6, +7, +7,i(8)(q10), +10, +15, +20, -21, -22, +mar1 x 2, +mar2[3]/46, XY[17], respectively. Karyotypes of this variant of HCC have not been reported previously. The cytogenetics of HCC are reviewed.

Identification and Characterization of Glucocorticoid Receptors in Liver of Nude Mice

Glucocorticoids regulate the expression of many liver-specific genes via glucocorticoid receptors. The presence of glucocorticoid receptors in liver has been reported in many mammalian species but not in nude mice. In the present study, we demonstrate the presence of specific glucocorticoid receptors in nude mouse liver. The binding of ligands to these receptors could be completely inhibited by RU486, and partially blocked by hydrocortisone and progesterone, whereas estrogen and testosterone had no effect. Hydrocortisone downregulated the level of glucocorticoid receptors in livers of nude mice and correspondingly enhanced the activities of tyrosine aminotransferase and gamma-glutamyltransferase. Our results indicate that glucocorticoid receptors in nude mouse liver are specific, fully functional, and present at levels 28.5-fold higher than in the liver of normal inbred mice. We suggest that the nude mouse is a valuable model for studies of hepatic glucocorticoid action and may provide a clue to a putative hepatic-thymic interaction. Copyright 1994 S. Karger AG, Basel

Regulation of human liver cytochromes P-450 in family 3A in primary and continuous culture of human hepatocytes

The cytochrome P-450 3A gene family comprises the dominant forms of cytochrome P-450 found in human liver. We examined as a possible useful system for studying the regulation of cytochrome P-450 3A under controlled conditions in vitro, primary monolayer cultures of human hepatocytes and compared the results with those obtained from the study of cytochrome P-450 3A in the human hepatoblastoma cell line HepG2 or in the human hepatocellular carcinoma cell line TONG/HCC. Using 3A antibodies, 3A cDNAs and 3A3, 3A4, 3A5 and 3A7 isozyme-specific oligonucleotides as probes, we determined that primary human hepatocyte cultures routinely expressed a 3A3/4* immunoreactive protein and 3A mRNA. These gene products were well maintained for many days and were induced by treatment of the cultures with dexamethasone, phenobarbital, macrolide antibiotics, the HMG CoA reductase inhibitor lovastatin or an antifungal agent, clotrimazole. Of six donor livers examined, only two contained mRNA or protein for 3A5, a form found in only a few adult human subjects. In cultures prepared from one of these two livers, 3A5 mRNA was detectable for several days. In cultures of hepatocytes from the remaining four human livers that did not contain 3A5 mRNA or protein, we detected neither spontaneous nor inducible 3A5 proteins or mRNAs. HepG2 cells contained only 3A7 protein, a form found in human fetal liver, even after treatment with inducers. treatment of HepG2 cells with dexamethasone, macrolide antibiotics, phenobarbital and phenobarbital-like inducers or lovastatin produced dose-dependent induction of 3A7 mRNA and 3A7 immunoreactive protein. TONG/HCC cells contained 3A3, 3A4 and 3A5 mRNAs, but only 3A5 immunoreactive protein could be detected.(ABSTRACT TRUNCATED AT 250 WORDS)

New hepatocellular carcinoma cell line SUHC-1 established from a patient with hepatitis C virus RNA in serum

A new human hepatocellular carcinoma cell (HCC) line, designated SUHC-1, was derived from a Japanese patient with hepatocellular carcinoma having antibody to hepatitis C virus (HCV) and HCV-RNA in his serum, and established in tissue culture. This cell line exhibited typical epithelial cell morphology in culture as observed by phase-contrast and electron microscopy. The SUHC-1 cells produced albumin and alpha 2-macroglobulin. Chromosomal analysis showed several rearrangements at short and long arms of chromosome 1, 17 and 20 (1p-, 1q-, i(1q), i(17q) and 20q+) with a modal number of 91. HCV-RNA was not detected in the supernatant of SUHC-1 cells by nested polymerase chain reaction assay or in the SUHC-1 cells by the in situ hybridization method. We concluded that complete HCV does not exist in the SUHC-1 cell line. The SUHC-1 cell line is the first line of HCC to have been derived from a patient with persistent HCV infection, and may provide a suitable model for studies of hepatocarcinogenesis related to HCV.

Growth-factor independence of a new differentiated hepatitis B virus DNA-negative human hepatoma cell line

The establishment of a new, differentiated, hepatitis B virus DNA-negative, human hepatoma cell line (named PLC/AN/2) is described. Neoplastic liver tissue was obtained during hepatectomy in an HBsAg-negative man. The established cell line is negative for alpha-fetoprotein and carcinoembryonic antigen; it has retained in vitro some of the differentiated functions of normal hepatocytes. Additionally, it presents a distinctive rearrangement (translocation) at the long arm of chromosome 4. The high degree of independence from serum growth factor requirements appears to be a major in vitro characteristic of PLC/AN/2 cells, making them a suitable model system for the more precise definition of the human hepatocellular carcinoma phenotype, including mechanisms of growth control.

Evidence of autocrine regulation in human hepatoma cell lines

Human hepatoma cell lines were studied for the expression of platelet-derived growth factor (PDGF), insulin-like growth factor-I (IGF-I) and their receptors at the mRNA level. Transcripts of PDGF were consistently detected in these cell lines. In addition, some cell lines also expressed PDGF receptor RNA. Moreover, RNA of IGF-I and its receptor were detected in every cell line examined. These results suggest that autocrine regulation may be an important mechanism for the maintenance of the transformed state of human hepatoma cells.