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Query: UMLS:C0345904 (liver cancer)
 15,188 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is now evident that development of hepatocellular carcinoma (HCC) in human is associated with a long series of cellular and tissue changes that precede the ultimate development of the cancer. During recent years, enormous progress in molecular research on HCC has been made, particularly in the area of integration of HBV DNA to host cell and oncogene association with carcinogenicity. A high ratio of HCCs from patients in endemic area has integrated HBV DNA in cellular DNA and in some cases, chromosomal translocations associated with HBV integration were observed, suggesting that the integration or the results thereof are connected with cancer development. Employing a DNA-mediated transfection assay using NIH3T3 mouse fibroblasts with high molecular weight DNA, we detected three cellular transforming genes (lca, N-ras, hst) in primary human HCC. However, little is known as to the linkage between the activation of these genes and liver carcinogenesis. In most human primary HCC tissues, at least two oncogenes, c-myc and N-ras are overexpressed, while in some cases other oncogenes c-fos or lca are overexpressed. It is likely that multiple c-oncogens are important in HCC, but specific transcripts for the malignancy of HCC were not detected. At present, we could not find any relationship between the expression of c-oncogenes and integration of HBV, serological markers or the degree of differentiation. Of the experimental animals most frequently used for studies of liver cancer, the rat is best understood and mimics closely many of the lesions in humans. It is of interest to consider that the identification and elucidation of the mechanisms underlying carcinogenic processes in the rat may offer testable hypotheses for steps in the human.
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PMID:[Molecular aspects of human hepatocellular carcinoma]. 253 67

Although proliferation of oval cells is often observed during the early stages of chemical hepatocarcinogenesis, the role of these putative hepatic stem cells during the neoplastic process is unknown. In earlier studies our laboratory showed that feeding a choline-deficient (CD) diet containing 0.05% 2-acetylaminofluorene (CD-AAF) to rats produced three subpopulations of oval cells that antigenically resemble biliary duct cells, fetal liver cells, and transitional cells. In the present investigation we have employed a semiallogeneic transplantation protocol in order to study the fate of these nonparenchymal epithelial cells (NPEC) beyond the 4-week endpoint imposed by the lethality of CD-AAF diet. An enriched NPEC suspension containing gamma-glutamyl-transpeptidase (GGT)-positive oval cells (greater than 75%) was isolated from ACI rats maintained on CD-AAF diet for 3 weeks. The donor cells were transplanted via the portal vein into livers of male F1 progeny (LExACI) that had been fed a CD diet for 7 days prior to receiving a partial hepatectomy and the cell suspension. Host rats were then fed either a CD or choline-supplemented (CS) diet for 12 weeks and killed. Colonies of donor-derived cells identified in frozen sections by their lack of reactivity with ACI anti-LE alloantiserum in indirect immunofluorescence (IF) assays were only observed in rats continuously fed the CD diet. Histochemical analysis indicated that the donor-derived colonies expressed GGT, a preneoplastic marker for liver cancer. IF assays using MAbs previously shown to be capable of distinguishing between oval cells and mature hepatocytes indicated that the donor-derived colonies consisted of a mixture of cells with phenotypes resembling those of mature and immature hepatocytes rather than those of oval or ductal cells. Although the cellular origin of the GGT+ donor-derived colonies has not been unequivocally resolved, our results demonstrate that the livers of rats fed a CD-AAF diet contain a chemically altered call population that can be induced to proliferate by a CD diet. In contrast, a CD diet did not promote colonization when normal hepatocytes were employed as the donor cell population, suggesting that the GGT+ oval cells and not the few contaminating GGT- hepatocytes (1%) in the CD-AAF donor cell suspension were the preneoplastic precursors that gave rise to donor-derived colonies. This transplantation protocol will be useful to define the biological potential of chemically altered liver cells during carcinogenesis.
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PMID:Selective proliferation of chemically altered rat liver epithelial cells following hepatic transplantation. 266 41

Since the early 1960s, when aflatoxin, the mold-produced contaminant of a number of important food commodities, was found to be a potent hepatocarcinogen for laboratory rats, there has been a sustained search for evidence to support the regulatory presumption that aflatoxin is a probable human carcinogen. The developing laboratory evidence of differences between species in metabolism of aflatoxin and susceptibility to its oncogenic effects indicated that humans were probably refractory to aflatoxin carcinogenesis, but the early epidemiological evidence indicated otherwise. That epidemiological evidence, however, contained flaws so that Working Groups of the International Agency for Research on Cancer (IARC) meeting in 1970, 1976, and 1982, although ignoring the biochemical evidence, did consider the available epidemiological evidence insufficient for a conclusion of human carcinogenicity. During the 1970s and 1980s, studies on the connection between chronic infection with hepatitis B virus (HBV) and primary liver cell cancer (PLC), the expected lesion from aflatoxin exposure, had established a very strong etiological relationship between HBV and PLC. Since all the epidemiological studies of aflatoxin and PLC conducted prior to 1982 had been of populations with endemic HBV infection, and, in addition to other flaws, had not been controlled for this confounding factor, there was a solid basis for their rejection. Most epidemiological studies in the 1980s of aflatoxin and PLC were either in the United States, where HBV-infected groups could be excluded from the study, or, when in areas of chronic HBV infection, attempts were made to include that factor. The study of U.S. populations showed no difference in mortality rates from PLC that could be attributed to aflatoxin exposure. The studies of populations with endemic HBV infection produced no convincing evidence to support a primary role for aflatoxin in the induction of human PLC, although an accessory role to HBV infection for aflatoxin could not be ruled out. However, the epidemiological studies of the HBV/PLC relation indicate that an accessory factor is not an essential condition, a conclusion supported by animal models and a laboratory study that specifically found no interaction between aflatoxin and a hepatitis virus in the duck, a species in which liver cancer can be induced by either agent. It was surprising that an IARC Working Group meeting in 1987 concluded, on the basis of much of this evidence that was available at that time, and citing other studies that appear to be irrelevant to the issue, that there was sufficient evidence to consider aflatoxin a probable human carcinogen.
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PMID:Aflatoxin is not a probably human carcinogen: the published evidence is sufficient. 269 Jan 97

Serum thyroxine was significantly higher in 59 patients with hepatocellular carcinoma than in normal subjects, patients with uncomplicated cirrhosis (48), or other primary tumours with or without hepatic metastases (50). Elevated thyroxine levels appeared attributable to high levels of thyroxine binding globulin which showed a positive linear correlation with serum thyroxine in all groups studied. Despite this hyperthyroxinaemia all patients appeared clinically euthyroid and, consistent with this, T3 was elevated in only one patient and the free thyroxine index was normal in all. Amongst a group of 25 cirrhotic patients who were followed-up for between 12 and 72 months, there was a striking dissociation between the TBG values of those destined to develop HCC and those who did not. In the former group TBG rose steadily with time whereas in the latter group levels remained stable, or, more often, fell. The rises in TBG occurred prior to any clinical signs of tumour development and may be one of the earliest serological changes to occur during carcinogenesis in the cirrhotic liver.
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PMID:Hyperthyroxinaemia in hepatocellular carcinoma: relation to thyroid binding globulin in the clinical and preclinical stages of the disease. 283 1

Rat hepatocytes maintained for up to 6 days in primary culture were used to test a variety of xenobiotics and steroids for effects on the activity of gamma-glutamyltranspeptidase (GGT) in normal cells. In control cultures GGT activity was low and increased slowly with time. When added to cultures for 5 days, a variety of xenobiotics and steroids increased GGT activity to levels 2- to 6-times those of control cultures. Induction of GGT was potentiated for most test compounds by 20-30 nM dexamethasone and diminished by nicotinamide or adenosine-3',5'-monophosphate. Effective non-genotoxic inducers included phenobarbital and some structurally related compounds, p,p'-dichlorodiphenyltrichloroethane,alpha- and gamma-hexachlorocyclohexanes, Aroclor 1254, butyl hydroxytoluene, nafenopin, various estrogens, progesterone, pregnenolone-16 alpha-carbonitrile and cyproterone acetate. A number of compounds including barbituric acid, butyl hydroxyanisole, acetaminophen, saccharin, caffeine, clofibrate and some bile acids failed to induce GGT. Except for 2-acetylaminofluorene and diethylnitrosamine, genotoxic compounds tested did not increase GGT. The results establish that a structurally diverse group of xenobiotics and steroids, many of which are considered to be liver tumour promoters, may directly enhance GGT gene expression in normal hepatocytes. Thus, a variety of compounds used in experimental studies of liver cancer induction as promoters may elevate GGT by mechanism(s) not necessarily related to carcinogenesis.
Carcinogenesis 1985 May
PMID:Induction of gamma-glutamyl transpeptidase in primary cultures of normal rat hepatocytes by liver tumor promoters and structurally related compounds. 286 Sep 80

In order to investigate whether different 'promoters' have the same qualitative and/or quantitative effects on rat hepatocarcinogenesis, 0.05% of phenobarbital (PB), 0.05% of dichlorodiphenyltrichloroethane (DDT), 0.5% butylated hydroxytoluene (BHT) and 0.1% of nafenopin (NAF) were chronically administered in the diet to rats previously submitted to an initiation by diethylnitrosamine and a selection with 2-acetylaminofluorene plus CC14. The animals were killed after 3, 6 and 14 weeks of 'promoters' administration to analyse their effect on premalignant lesions. The quantitative analysis of the gamma-glutamyltransferase positive lesions indicates that as compared to a control group receiving a basal diet after initiation and selection, PB, DDT and BHT enhance the development of these lesions whereas NAF inhibits it. Rats were also killed after 22 weeks of administration to analyse the incidence and the yield of liver cancer. As compared to the control group, PB, DDT and surprisingly NAF enhance the development of liver cancer whereas BHT does not. This suggests that the effect of potential 'promoters' should be analysed on cancer development rather than on premalignant lesions.
Carcinogenesis 1986 Jun
PMID:Comparative analysis of the effect of phenobarbital, dichlorodiphenyltrichloroethane, butylated hydroxytoluene and nafenopin on rat hepatocarcinogenesis. 287 46

In order to further analyze the biological effects of phenobarbital (PB) and nafenopin (NAF) on rat hepatocarcinogenesis, four experiments were undertaken. In the first one, their "promoting" effect on an ongoing carcinogenic process was analyzed. Rats were initiated by diethylnitrosamine treatment (I) and submitted two weeks later to a selection procedure (S). One week after 2-acetylaminofluorene (2-AAF) release, the animals received for up to 56 weeks a basal diet or a diet containing 0.05% of PB or 0.1% of NAF. The quantitative analysis of the gamma-glutamyl-transferase-positive lesions showed that, 8 to 19 weeks after I, PB enhanced the development of preneoplastic lesions whereas NAF inhibited it as compared to a group receiving a basal diet. However, both compounds enhanced the incidence and the yield of liver cancer starting 27 weeks after I (67% and 95%, respectively, vs 10%). In the second experiment, the effect of chronic administration of PB and NAF given after I without S or after S without I was analyzed. Within a period of observation of 27 to 32 weeks, the incidence of cancer was 10% after I/PB and 75% after I/NAF. No cancer developed after S/PB, S/NAF or NAF alone. The third experiment was designed to test whether NAF had an initiating or selecting effect. The results of the quantitative analysis of the gamma-glutamyl-transferase-positive lesions showed that as compared to diethylnitrosamine, NAF had no initiating effect. When NAF replaced 2-AAF in the selection procedure, few gamma-glutamyl-transferase-positive lesions and no cancer were detected 8 and 32 weeks after I. The fourth experiment indicated that NAF could not prevent the remodeling of preneoplastic lesions induced in the I/S protocol. Even though they both have a "promoting" effect in liver carcinogenesis as evidenced by the increased incidence and yield of cancer, PB and NAF act differently.
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PMID:Comparison of the biological effects of phenobarbital and nafenopin on rat hepatocarcinogenesis. 287 50

Previously we established that 'LEC rats' have displayed spontaneous fulminant hepatitis with severe jaundice, which progressed to liver cancer, and a single autosomal recessive gene is responsible for the cause of the diseases. The activities of drug metabolizing enzymes were assayed in livers from LEC and control (LEA) rats at 4 weeks and 3 months before the onset of liver cancer. At 4 weeks the cytochrome P-450 content of the LEC rat livers was 43% of the control (LEA) value. At 3 months the level was 65% of the control. Epoxide hydrolase, gamma-glutamyltranspeptidase and UDP-glucuronyltransferase activities were 2.6-, 6.9- and 2.4-times higher than those in the LEA rats at 4 weeks, respectively, while glutathione S-transferase activity was not significantly different between the two strains. The enzyme changes in the LEC rats are quite similar to those observed in hyperplastic foci and nodules in chemical carcinogenesis of hepatocytes.
Carcinogenesis 1988 Sep
PMID:Metabolic predisposition of a novel mutant (LEC rats) to hereditary hepatitis and hepatoma: alterations of the drug metabolizing enzymes. 290 Jul 2

The detection and quantitation of carcinogen-DNA adducts in human cells are the key parameters in the molecular dosimetry of human exposure to environmental carcinogens. For investigating the possible relevance of alkylating N-nitroso compounds as causative agents in human carcinogenesis, we have quantitated O4-ethyl-2'-deoxythymidine (O4-EtdThd) in human liver DNA obtained from 33 autopsy specimens, i.e., 13 cases with primary liver cancer (LC), 8 with cancers other than liver cancer (OC), and 12 with noncancerous diseases (NC). None of the cases analyzed had a history of known occupational exposure to ethylating agents. The detection limit for O4-EtdThd was 3 X 10(-8) as a O4-EtdThd/dThd molar ratio in DNA, which was attained by the combination of prefractionation of DNA hydrolysates (= 20 mg of DNA/sample) by high performance liquid chromatography and competitive radioimmunoassay using anti-(O4-EtdThd) monoclonal antibody ER-01. Except for one case in each group, O4-EtdThd [or, alternatively, (an) unidentified structural modification(s) of DNA recognized by monoclonal antibody ER-01] was detected at mean (+/- SD) O4-EtdThd/dThd molar ratios of 39.9 +/- 40.2 x 10(-8), 53.5 +/- 74.0 X 10(-8), and 11.7 +/- 6.5 X 10(-8), respectively, in LC, OC, and NC. The difference of the O4-EtdThd content in DNA between LC and NC, or between LC + OC and NC, was statistically significant at P less than 0.05. These results suggest that humans are exposed to ethylating agents in vivo and that a premutagenic DNA lesion (O4-EtdThd) eventually accumulates in DNA, possibly to a biologically significant extent.
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PMID:Immunoanalytical detection of O4-ethylthymine in liver DNA of individuals with or without malignant tumors. 290 56

Quantitative comparisons of the time course of biochemical and morphological changes induced by peroxisome proliferators resulting in low and high incidences of hepatic cancer have not been conducted previously under bioassay conditions. [4-Chloro-6-(2,3-xylidino)-2-pyrimidyl-thio]acetic acid (Wy-14,643) at 0.1% in the diet produced a much higher incidence of hepatic cancer in male rats than 1.2% di(2-ethylhexyl)phthalate (DEHP) in the diet. Both diets, however, caused similar degrees of peroxisome proliferation. To investigate this difference in carcinogenicity, H2O2-detoxification mechanisms and indices of oxidative damage were evaluated in male F-344 rats fed 1.2% DEHP or 0.1% Wy-14,643 for up to one year. DEHP or Wy-14,643 treatment increased hepatic catalase activity approximately 25% from 8 to 365 days. DEHP or Wy-14,643 treatment decreased hepatic glutathione peroxidase activity by 50% from 8 to 365 days. Glutathione concentrations were not affected by 151 days of DEHP or Wy-14,643 feeding. The similar effects of DEHP and Wy on H2O2 detoxification enzymes and glutathione concentrations suggests that these factors are not responsible for the widely different carcinogenicities of Wy-14,643 and DEHP. Hepatic vitamin E concentrations were 50% lower in rats receiving Wy-14,643 for 151 days as compared to rats fed DEHP or control diets. Lipofuscin, which was contained within lysosomes, was increased 3-fold after 39 days of DEHP and remained at this level up to 365 days of treatment. In comparison, lipofuscin was increased 4-fold after 18 days of Wy-14,643 and continued to accumulate in a linear manner reaching values 30-fold over controls after 365 days of treatment. DEHP treatment for 39-365 days increased the activities of the lysosomal enzymes alpha-fucosidase, beta-galactosidase and N-acetylglucosaminidase 50-100%. The same enzyme activities were increased approximately 4-fold after 39-365 days of Wy-14,643. Lysosomal cathepsin B activity was unchanged by DEHP but doubled by 151 and 365 days of Wy-14,643. Acid phosphatase activity was unchanged by DEHP but increased by 50% after 151 and 365 days of Wy-14,643. In addition, conjugated dienes were increased (approximately 45%) only in rats receiving Wy-14,643 for 151 and 365 days. These data show for the first time that the magnitude and time course of lipofuscin deposition, induction of lysosomal enzymes and conjugated diene accumulation, is correlated closely with the degree of carcinogenicity. Wy-14,643-induced decreases in hepatic vitamin E concentrations could contribute to the observed accumulation of conjugated dienes at later time points.(ABSTRACT TRUNCATED AT 400 WORDS)
Carcinogenesis 1989 Mar
PMID:Relationship of oxidative damage to the hepatocarcinogenicity of the peroxisome proliferators di(2-ethylhexyl)phthalate and Wy-14,643. 292 96


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