Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0345904 (liver cancer)
 15,188 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tamoxifen was administered in the diet (420 p.p.m.) to female F344 (Fischer), Wistar (LAC-P) and LEW (Lewis) rats to determine for each strain the early morphological and biochemical changes associated with the subsequent development of liver cancer. Hepatic DNA damage, as determined by 32P-postlabelling, showed a cumulative increase with time from 500 adducts/10(8) nucleotides at 30 days to almost 3000 adducts/10(8) nucleotides after 180 days, with little difference between strains at this time point. A significant strain difference was found in the number of adducts present in the Fischer rats at 90 days, compared to the Wistar and Lewis strains. There was a marked strain differences in the time to development of liver tumours. After 6 months treatment, both Wistar and Lewis rats had tumours while none were seen in the Fischer animals. After 11 months, all of the Wistar and Lewis rats had developed liver carcinoma, while the Fischer rats developed liver carcinoma by 20 months. Depression in cell proliferation, relative to age-matched controls, was seen in the livers of Fischer rats after six months of exposure to tamoxifen, in contrast to an increase in the Wistar and Lewis rats. This observation is consistent with the promotion of foci to tumours and the subsequent progression of tumours to carcinomas in the latter two strains. These data may assist in establishing the possible risk factors, such as extent of DNA damage and increased liver cell proliferation, to women with long-term prophylactic exposure to tamoxifen.
Carcinogenesis 1995 Jun
PMID:DNA damage as assessed by 32P-postlabelling in three rat strains exposed to dietary tamoxifen: the relationship between cell proliferation and liver tumour formation. 778 46

Forty patients with chronic liver disease and HCC were analyzed for infection with hepatitis C (HCV) and hepatitis B (HBV) viruses. All patients were negative for HBsAg, 16 were alcoholics, 6 had previous blood transfusions and 18 had sporadic chronic hepatitis. Antibodies to HCV were determined by EIA 2nd generation. HBV-DNA was detected by PCR using primers of the precore region. Analysis of HCV-RNA was done with nested PCR amplifying the 5' non-coding region of the HCV genome, using primers complementary to nucleotides 1-20 and 305-320 and nested primers complementary to nucleotides 21-31 and 271-286 of the HCV-J1. Anti-HCV were positive in 35/40 patients (87.5%). HCV-RNA was detected by PCR in 34 patients (85%) all of them positive for the anti-HCV. HCV-RNA was detected in 70.5% of the alcohol abusers, in 100% of patients with history of transfusion(s) and 94.1% of patients with cryptogenic chronic liver disease. HBV-DNA was detected in only 2 patients. In conclusion, there is a high rate of HCV and a low rate of HBV viremia detected by PCR in Spanish patients with HCC HBsAg negative. No patient without anti-HCV presents HCV-RNA. Our results suggest that persistent HCV replication may play a role in hepatic carcinogenesis, as HBV-DNA could be found in only 5% of our HCC patients.
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PMID:Demonstration of HCV-RNA and HBV-DNA in the serum of HBsAg negative patients with hepatocellular carcinoma. 781 97

Chronic liver diseases, in particular chronic HBV and HCV infections, frequently progress to liver cirrhosis and HCC. The molecular events underlying hepatocarcinogenesis are not yet well defined. It appears likely, however, that HCCs result from a stepwise carcinogenesis: due to chronic liver disease there is liver cell necrosis, inflammation and regeneration with a high mitotic rate of liver cells. In this setting, chromosomal DNA rearrangements occur which may result in the activation of cellular oncogenes or inactivation of tumor suppressor genes. Viral genes or gene products as well as cofactors, such as alcohol or aflatoxins, may make a specific contribution to these molecular events. Apart from the molecular aspects of hepatocarcinogenesis, for clinical practice the implementation of measures to prevent or treat chronic liver diseases should reduce the incidence of HCCs, one the most frequent malignancies in some areas of the world.
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PMID:[Hepatocellular carcinoma: molecular biology aspects]. 784 55

Hepatocellular carcinoma is common among Alaska Natives. The known risk factor in this population is hepatitis B viral infection; fungal toxins, including aflatoxin B1, have not been detected in foodstuffs. In this series of 14 patients (including 4 siblings and 2 second cousins), 3 patients were less than 12 years old at diagnosis of hepatocellular carcinoma, 8 patients were 13-24 years old, and 3 patients were more than 60 years old. Since p53 mutations occur in 29% of hepatocellular carcinomas worldwide, we tested the tumors for p53 mutations and serum samples for anti-p53 antibodies. Serum samples from these 14 patients did not contain detectable levels of anti-p53 antibodies. Loss of heterozygosity within the p53 locus was not detected in any of 9 informative cases. Immunohistochemical analysis for p53 protein accumulation was negative in all of 11 tumors. DNA sequence analysis of 12 tumor samples showed no evidence of p53 mutation in the highly conserved regions included in exons 5-8. These data, combined with one case from a previous report, indicate a mutation frequency of 0 of 13, which differs significantly from the worldwide frequency of 29% (chi 2 3.9; P = 0.048). These results indicate that liver carcinogenesis among Alaska Natives occurs independently of a traditional p53 pathway. The familial clustering and early onset in this population strongly suggest an inherited genetic predisposition to develop liver cancer. Germline mutations in a tumor suppressor or a cancer susceptibility gene are likely. Future studies of these samples should include investigations of candidate suppressor or susceptibility genes which map to chromosomal regions commonly deleted in liver cancers.
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PMID:p53 is not mutated in hepatocellular carcinomas from Alaska Natives. 789 27

Preneoplastic and neoplastic hepatic lesions were induced in male Sprague-Dawley rats by oral exposure to N-nitrosomorpholine (12 mg/kg body wt/day) for 7 weeks (stop model). Twelve, 23 and 34 weeks after withdrawal of the carcinogen, cell proliferation and cell death (apoptosis) were studied in defined phenotypes of preneoplastic foci of altered hepatocytes (FAH), hepatocellular adenomas (HCA) and carcinomas (HCC) by autoradiographic determination of the labelling index (LI) resulting from continuous administration of [3H]thymidine for 48 h and by simultaneous counting of apoptotic bodies respectively. Compared with the liver parenchyma of untreated controls and the extrafocal parenchyma of treated animals, the mean LI was elevated in all types of FAH, HCA and HCC, but the extent of this increase differed markedly between the diverse phenotypes. The increase in the LI was significant for clear/acidophilic, intermediate and mixed/basophilic cell foci, but remained insignificant for the relatively rare tigroid and amphophilic cell foci. The previously established progression-linked phenotypic instability in the predominant cell lineage leading to HCC was associated with a gradual increase in the mean LI showing four significantly different proliferative stages: (i) clear/acidophilic and intermediate cell foci excessively storing glycogen, (ii) mixed/basophilic cell populations in FAH and glycogen-storing HCA, (iii) glycogen-poor HCA and glycogen-storing HCC and (iv) glycogen-poor HCC. The inverse correlation between glycogen accumulation and cell proliferation during progression from glycogenotic FAH to glycogen-poor HCC indicates that the fundamental metabolic shift associated with the gradual disappearance of the glycogenosis is essential for the evolution of the malignant phenotype. The mean ratio of necrotic cells (RN) was somewhat higher in all types of FAH compared to the normal and extrafocal liver parenchyma, but this was not statistically significant. Only when HCA and HCC appeared was there a significant increase in the mean RN, proceeding with the progression of neoplastic development. Our results do not support the concept that cell death (apoptosis) plays a major role in counterbalancing cell replication in FAH, but rather suggest that cell death occurs more frequently in the course of hepatocarcinogenesis the more neoplastic development advances.
Carcinogenesis 1994 Nov
PMID:Cell proliferation and cell death (apoptosis) in hepatic preneoplasia and neoplasia are closely related to phenotypic cellular diversity and instability. 795 93

Feeding excess orotic acid (OA) in the diet promotes the carcinogenic process in different organs including the liver. A number of metabolic and genetic disorders are associated with increased synthesis of endogenous OA and some of these disorders appear to pose an increased risk of liver cancer development. This study therefore examines whether excess OA of endogenous origin also exerts a promoting effect on hepatocarcinogenesis in the mouse and the rat. Increased endogenous synthesis of OA was achieved by (i) feeding a diet deficient in arginine (AD) and (ii) feeding excess dietary carbamylaspartate (CA), a precursor for the synthesis of OA. A single dose of diethylnitrosamine (DENA) was given i.p. to male Fischer 344 rats (200 mg/kg) or to male DBA/2 mice (90 mg/kg). One week later they were placed on either AD diet or the same diet supplemented with 1.35% arginine (AS) for a total of 4 weeks. Two-thirds partial hepatectomy (PH) was performed at the end of the second week. All animals were then transferred to a control semisynthetic basal diet for a total of 20 weeks before they were killed. The results indicated that AD diet increased the incidence of hepatic nodules in both rats (percentage area occupied by nodules was 4.7 +/- 0.4 in the AD group compared to a control value of 0.7 +/- 0.5) and mice (4/10 mice had nodules > 5 mm diameter in the AD group while none in the AS group had such large nodules). In another experiment male Fischer 344 rats similarly initiated with DENA were exposed to either basal diet or basal diet containing 2% CA for 4 weeks coupled with PH performed at the end of the second week. This regimen was followed by 20 weeks of feeding basal diet to both groups. Rats given CA developed larger hepatic foci and nodules (0.84 +/- 0.56 mm3) compared to the control group, which was fed basal diet throughout the experiment (0.07 +/- 0.03 mm3). Further, both AD diet and dietary CA, like dietary OA, induced an increase in hepatic uridine nucleotides. Taken together, these results suggest that increased levels of endogenously synthesized OA, like exogenously supplied excess OA, can induce an imbalance in hepatic nucleotide pools and can exert a promoting effect on hepatocarcinogenesis.
Carcinogenesis 1994 Nov
PMID:Perturbations of endogenous levels of orotic acid and carcinogenesis: effect of an arginine-deficient diet and carbamyl aspartate on hepatocarcinogenesis in the rat and the mouse. 795 98

The mouse mdr2 gene (and its human homologue MDR3, also called MDR2) encodes a P-glycoprotein that is present in high concentration in the bile canalicular membrane of hepatocytes. The 129/OlaHsd mice with a homozygous disruption of the mdr2 gene (-/- mice) lack this P-glycoprotein in the canalicular membrane. These mice are unable to secrete phospholipids into bile, showing an essential role for the mdr2 P-glycoprotein in the transport of phosphatidylcholine across the canalicular membrane. The complete absence of phospholipids from bile leads to a hepatic disease, which becomes manifest shortly after birth and shows progression to an end stage in the course of 3 months. The liver pathology is that of a nonsuppurative inflammatory cholangitis with portal inflammation and ductular proliferation, consistent with toxic injury of the biliary system from bile salts unaccompanied by phospholipids. Thus, the mdr2 (-/-) mice can serve as an animal model for studying mechanisms and potential interventions in nonsuppurative inflammatory cholangitis (in a generic sense) in human disease, be it congenital or acquired. When the mice are 4 to 6 months of age, preneoplastic lesions develop in the liver, progressing to metastatic liver cancer in the terminal phase. The mdr2 (-/-) mice therefore also provide a tumor progression model of value for the study of hepatic carcinogenesis. Interestingly, also in this regard, the model mimicks human disease, because chronic inflammation of the biliary system in humans may similarly carry increased cancer risk.
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PMID:Mice with homozygous disruption of the mdr2 P-glycoprotein gene. A novel animal model for studies of nonsuppurative inflammatory cholangitis and hepatocarcinogenesis. 797 54

The mechanisms by which the peroxisome proliferator (PP) class of non-genotoxic carcinogens perturb growth regulation and cause rodent liver cancer are unknown. Using a soft agar cloning assay, we have demonstrated that PPs synergize with the physiological liver mitogen epidermal growth factor (EGF) to cause the clonal expansion of rat hepatocytes associated with the early stages of tumourigenesis. In the presence of EGF (25 ng/ml), the PP nafenopin (100 microM) was able to stimulate a 5-fold increase in the number of colonies (35 colonies/50,000 hepatocytes compared to seven in the control). EGF alone or nafenopin alone gave 11 and 14 colonies respectively. TGF alpha, which acts through the EGF receptor, also synergized with nafenopin, whereas HGF was inactive, despite its potency as an hepatocyte growth factor. The ability to promote colony formation was shared by the potent PP Wyeth-14,643 but not by the less potent compounds methylclofenapate or trichloroacetic acid. TGF beta, a physiological negative regulator of liver growth, was able to inhibit the nafenopin/EGF-stimulated colony formation at 0.25 ng/ml, a concentration below that required for TGF beta-induced hepatocyte apoptosis. The colonies formed are derived from and consist of hepatocytes, since they express the hepatocyte-specific marker albumin, although the majority are negative for the PP-induced cytochrome, P4504A1. Pre-treatment in vivo with the genotoxic carcinogen dimethylhydrazine hydrochloride (150 mg/kg) caused a doubling in the number of colonies from 35 to 75/50,000 hepatocytes. Taken together, these data suggest that some PPs act as hepatocarcinogens by synergizing with EGF and/or TGF alpha to promote the clonal expansion of spontaneously initiated hepatocytes. This clonal expansion may be inhibited by TGF beta. Such a synergy may provide a mechanistic basis for the hepatocarcinogenicity of this class of non-genotoxic carcinogens.
Carcinogenesis 1994 Dec
PMID:The peroxisome proliferator class of non-genotoxic hepatocarcinogens synergize with epidermal growth factor to promote clonal expansion of initiated rat hepatocytes. 800 Dec 22

Woodchuck hepatitis virus surface antigen (WHsAg) stimulated hepatocytes in culture to produce nitric oxide (NO.), as evidenced by the accumulation of nitrite in the medium. NO. synthesis by hepatocytes was positively correlated with WHsAg concentration. WHsAg-induced NO. synthesis was inhibited by NG-monomethyl-L-arginine and anti-WHsAg antibody. To our knowledge, this is the first demonstration of an increase in NO. formation by a viral antigen. These data, when considered in the light of the known genotoxicity of NO., raise the possibility that viral hepatitis increases the risk of liver cancer by increasing the production of NO.. Long-term elevated production of NO. free radicals due to stimulation by WHsAg in chronic hepatitis may directly cause reactions with cellular DNA leading to mutagenesis, as well as the formation of hepatocarcinogenic N-nitroso compounds. This provides a new mechanism by which hepatitis B virus infection might hypothetically increase the risk of liver cancer.
Carcinogenesis 1994 Dec
PMID:Woodchuck hepatitis virus surface antigen induces nitric oxide synthesis in hepatocytes: possible role in hepatocarcinogenesis. 800 Dec 49

The dose and time dependence of the cellular phenotype in preneoplastic and neoplastic liver lesions was evaluated quantitatively in groups of male Sprague-Dawley rats exposed for 7 weeks to 0, 12 and 24 mg/kg body wt of N-nitrosomorpholine (NNM) and studied at different time points up to 80 weeks after withdrawal of NNM (stop model). NNM-treated rats showed a dose- and time-dependent increase in the total number and volume of preneoplastic foci of altered hepatocytes (FAH) and in the incidence of hepatocellular adenomas (HCA) and carcinomas (HCC) at both dose levels, compared with the untreated controls. After stopping treatment with 12 mg/kg body wt, the well-known sequence of cellular changes leading from glycogenotic clear and clear/acidophilic cell foci to mixed and diffusely basophilic cell populations poor in glycogen was found. In contrast, at the higher NNM dose level (24 mg/kg) predominantly mixed and diffusely basophilic cell foci appeared immediately after cessation of treatment, but their number rapidly declined up to 13 weeks after withdrawal. At the same time, there was a reciprocal increase in the number of the less altered clear/acidophilic cell foci, indicating an early reversion-linked phenotypic instability of FAH. However, in spite of this reversion higher numbers of mixed and diffusely basophilic cell foci were retained after treatment with 24 compared to 12 mg/kg of NNM at all time points studied, and there was even a slow additional increase in the number of these types of FAH 20 weeks after withdrawal of NNM. At both dose levels, the volume fraction of the persistent mixed cell foci correlated positively with the incidence of HCA and HCC, suggesting that this phenotype of FAH represents a direct precursor of the neoplastic lesions. Tigroid cell foci, which appeared most frequently after treatment with the lower dose of NNM, were not integrated into the predominant sequence of cellular changes leading to HCC, but they may represent an intermediate stage in a side lineage of this sequence, endowed with the potential to progress at least to HCA. Our results show that reversion-linked phenotypic instability of FAH occurs mainly after high dose treatment, possibly resulting from rapid adaptive cellular responses to the primary carcinogenic lesion(s) which may be fixed by genetic or epigenetic mechanisms. In contrast, progression-linked phenotypic instability of FAH is a slow process developing in a dose- and time-dependent manner at all dose levels leading to hepatic neoplasia.
Carcinogenesis 1994 Jun
PMID:Dose and time dependence of the cellular phenotype in rat hepatic preneoplasia and neoplasia induced in stop experiments by oral exposure to N-nitrosomorpholine. 802 Jan 60


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