Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Expression of the class I alcohol dehydrogenase (ADH) gene in the rat hepatoma microcell hybrid cell line, 11-3, was examined. The steady-state level of ADH mRNA in 11-3 was approximately 2-fold higher than that or rat liver and Fao, the parental cell line of 11-3. Removal of steroid hormones by activated charcoal from the serum in which 11-3 cells were maintained resulted in a significant decrease in the level of ADH transcript. Dexamethasone at a concentration of 1 muM increased the ADH mRNA content in 11-3 in a time-dependent fashion, up to 48 hr after its addition to cells that had first been deprived of steroid hormones. In addition, levels of ADH transcript in cells treated with dexamethasone increased in a dose-dependent manner, and the concentration of dexamethasone required to achieve half-maximal activation was 5 nM. By using the techniques of reverse transcription and polymerase chain reaction, and by taking advantage of a restriction polymorphism present between the rat and mouse ADH cDNA, we found that 11-3 contained both the rat and mouse class I ADH transcripts, although the rat sequence accounted for the great majority. Moreover, levels of both rat and mouse class I ADH transcripts increased in a similarly time-dependent manner in cells treated with dexamethasone. These results indicate that expression of class I ADH gene in 11-3 is high and is regulated by glucocorticoids, making the cell line an excellent model for the in vitro study of ADH expression.
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PMID:The class I alcohol dehydrogenase gene is glucocorticoid-responsive in the rat hepatoma microcell hybrid cell line, 11-3. 874 6

Expression of the serum albumin gene is extinguished in rat hepatoma microcell hybrids that retain mouse chromosome 1. These data define a trans-dominant extinguisher locus, Tse-2, on mouse chromosome 1. To localize the human TSE2 locus, we prepared and characterized rat/human microcell hybrids that contained either human chromosome 1 or chromosome 2, the genetic homologues of mouse chromosome 1. Rat hepatoma microcell hybrids retaining a derivative human chromosome 1 [der 1 t(1;17)(p34.3;q11.2)] expressed their serum albumin genes at levels similar to those of parental hepatoma cells. In contrast, microcell transfer of human chromosome 2 into rat hepatoma recipients produced karyotypically heterogeneous collections of hybrid clones, some of which displayed dramatic albumin extinction phenotypes. For example, albumin mRNA levels in several extinguished microcell hybrids were reduced at least 500-fold, similar to albumin mRNA levels in hepatoma x fibroblast whole-cell hybrids. Expression of several other liver genes, including alpha 1-antitrypsin, aldolase B, alcohol dehydrogenase, and phosphoenolpyruvate carboxykinase, was also affected in some of the microcell hybrids, but expression of these genes was not concordant with expression of albumin. Hybrid segregants were prepared from the albumin-extinguished hybrids, and reexpression of albumin mRNA and protein was observed in sublines that had lost or fragmented human chromosome 2. Finally, expression of mRNAs encoding the liver-enriched trans activators HNF-1, HNF-4, HNF-3 alpha, and HNF-3 beta was not affected in any of the chromosome 2-containing hybrids. These data define and map a genetic locus on human chromosome 2 that extinguishes albumin gene expression in trans, and they suggest that TSE2-mediated extinction is independent of HNF-1, -4, -3 alpha, and -3 beta expression.
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PMID:Extinction of albumin gene expression in a panel of human chromosome 2 microcell hybrids. 883 17

Upon birth, the liver acquires new functions as a result of the initiation of expression of key enzymes. One example is the initiation of gluconeogenesis which depends on the induced appearance of phosphoenolpyruvate carboxykinase (P-pyruvate-CK) at birth. To characterize other genes that undergo such regulation, a differential screening was performed on a cDNA library from well-differentiated hepatoma cells. The pattern of tissue-specific and developmental-specific expression was determined for seven genes. Three clones, out of which two encode for the known genes alcohol dehydrogenase class I (ADH) and phenylalanine 4-monooxygenase (PAH) and a new gene (clone 116-3), exhibited a pattern of expression similar to that of the P-pyruvate-CK gene, i.e. their expression was liver and kidney specific and induced in the liver upon birth. Determination of the sequence of clone 116-3 revealed that it belonged to the UDP-glucuronosyltransferases type 2 (UGT2) family and thus was named UGT2B-rH4. To examine whether expression of the various genes could be prematurely induced by hormones in the fetal liver, either high levels of cAMP or low levels of insulin were induced in utero. The results demonstrated that cAMP induced a marked expression only of the genes for P-pyruvate-CK and ADH but not of those for PAH or UGT2B-rH4, while insulin deficiency induced premature expression of all four genes. We suggest that a set of genes whose expression is specifically induced in the liver upon birth can be prematurely induced by the hormones in utero.
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PMID:Identification of differentially expressed genes during hepatocytes development and characterization of their prenatal hormonal induction. 902 81

The metabolism of acetaldehyde (ACA), benzaldehyde (BA), propionaldehyde (PA) and valeraldehyde (VA) has been studied in two hepatoma cell lines, the rat HTC and mouse Hepa 1c1c7 cells. The cytotoxicity of the four aldehydes to these two cell lines has been compared. The end-points for evaluating cytotoxicity were 1) total macromolecular content (TMC) of confluent cultures, and 2) colony forming ability of dividing cells. These two assay systems had different sensitivities for the toxicity of aldehydes, probably due to different numbers of target cells. The activities of aldehyde dehydrogenases (NAD- and NADP-dependent, ALDH), alcohol dehydrogenase and aldehyde reductase were markedly greater in the HTC cell line compared to the Hepa 1c1c7 cell line, especially with BA as substrate. The cytotoxicities of aldehydes were generally stronger in the HTC cell line than in the Hepa 1c1c7 cell line; with the CF test. Particularly, BA was highly toxic to the HTC cells, which possessed the highest ALDH levels. Moreover, the treatment with (diethylamino)benzaldehyde, an ALDH inhibitor, completely abolished the toxicity of BA. Taken together, all these findings suggest that several cell lines expressing different aldehyde metabolizing activities could be used especially in the pre-screening phase to distinguish the metabolism-dependent cytotoxic effects from the metabolism independent effects.
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PMID:Comparative evaluation of cytotoxicity and metabolism of four aldehydes in two hepatoma cell lines. 929 76

The ADH4 gene, which encodes human pi-alcohol dehydrogenase, is expressed in a tissue-specific manner, with the highest level in liver and lower levels in the gastrointestinal tract. We examined the location and function of the cis-acting elements that regulate ADH4 transcription. Liver contains proteins that bound to seven sites in the proximal promoter (from bp -387 to bp +17). Proteins from other tissues bound to subsets of these sites and to two additional sites, one of which is a negative cis-acting element. Members of two important transcription factor families, C/EBP and AP-1, bound to several sites in this promoter. The proximal ADH4 promoter functioned in a hepatoma cell line (H4IIE-C3) and a kidney cell line (CV-1). Coexpression of members of the C/EBP family strongly enhanced promoter activity, which can in part explain the high level of expression of ADH4 in liver. At one site that can be bound by both C/EBP and c-Jun, a mutation that abolished binding by C/EBP but not by c-Jun decreased promoter activity in both cell lines. This mutation had a stronger effect in the context of a longer promoter, suggesting interaction among cis-acting elements.
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PMID:Function of cis-acting elements in human alcohol dehydrogenase 4 (ADH4) promoter and role of C/EBP proteins in gene expression. 957 Jan 55

The cellular metabolism of 4-hydroxy-2-nonenal (4-HNE), a cytotoxic and genotoxic product of oxidative stress-induced lipid peroxidation, was investigated in rat H35 hepatoma cells. Previous studies from our laboratory (1) have characterized the degree to which oxidative, reductive, and conjugative metabolic pathways function simultaneously during hepatocellular metabolism of 4-HNE to rapidly eliminate the compound from suspensions of freshly isolated rat hepatocytes. In the current studies, we have extended the investigation of 4-HNE metabolism to examine the pharmacokinetic parameters of 4-HNE elimination and export in a hepatoma cell line and determined that the ensuing oxidative and conjugative metabolites of 4-HNE are rapidly and efficiently transported out the cell. Low concentrations of 4-HNE (25 microM) were used in an attempt to simulate physiologically relevant conditions. The H35 hepatoma cell line studied was first evaluated for enzymes known to play important roles in the metabolism of 4-HNE and were found to possess activities for glutathione S-transferase, aldehyde dehydrogenase (ALDH), and alcohol dehydrogenase of 24.00 +/- 1.12, 3. 45 +/- 0.17, and 6.44 +/- 0.29 nmol min-1 mg-1 protein, respectively. Hepatoma cells were incubated with 25 microM 4-HNE and metabolites in intra- and extracellular fractions were quantitated by reversed-phase HPLC over the time course of treatment. Reduced glutathione (GSH) and the GSH metabolites of 4-HNE were quantitated by reversed-phase HPLC as the dinitrobenzene derivatives. Uptake of 4-HNE from the extracellular medium occurred with an estimated rate of 0.398 +/- 0.181 min-1 10(6) hepatoma cells-1. The oxidative metabolite of 4-HNE, 4-hydroxy-2-nonenoic acid (HNA), produced by ALDH, appeared rapidly in the intracellular fraction achieving concentrations of 0.28 HNA nmol 10(6) hepatoma cells-1 and was efficiently eliminated with a first-order rate constant of 0.988 min-1. The GST-mediated conjugative metabolite, 3-glutathionyl-4-hydroxy-2-nonanal (4-HNE-SG), rapidly reached maximal intracellular concentrations of 1.88 +/- 0.44 nmol 10(6) hepatoma cells-1 and was eliminated at a rate of 0.101 +/- 0.033 min-1. Extracellular rates of formation, representing export, for HNA and 4-HNE-SG were 0.247 +/- 0.045 and 0.044 +/- 0.009 min-1 10(6) hepatoma cells-1, resulting in maximal extracellular concentrations for HNA and 4-HNE-SG of 0.70 +/- 0.10 and 3.03 +/- 0. 84 nmol 10(6) hepatoma cells-1. Approximately 75% of the administered concentration of 4-HNE was converted to measurable metabolites, with the 4-HNE-GSH conjugate accounting for 61% of total administered 4-HNE and HNA accounting for 14%. Collectively, these results demonstrate that oxidative and conjugative pathways are primarily responsible for elimination of 4-HNE at low concentrations in the hepatoma cell line evaluated and that the 4-HNE metabolites resulting from these pathways are rapidly and efficiently exported out of the cell.
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PMID:Formation and export of the glutathione conjugate of 4-hydroxy-2, 3-E-nonenal (4-HNE) in hepatoma cells. 988 35

The human alcohol dehydrogenase 4 gene (ADH4) encodes the human pi-alcohol dehydrogenase (pi-ADH), which can contribute to ethanol metabolism at moderate and high concentrations of ethanol. There are no known structural variants of pi-ADH in humans. We report the first polymorphisms in the ADH4 gene, at three sites in the promoter: -192 bp, -159 bp and -75 bp, respectively. To determine whether these variations affected promoter function, different haplotypes of the ADH4 proximal promoter were subcloned into a luciferase reporter vector, and the relative promoter activity analysed in hepatoma cells. One of the three sites had a dramatic effect on promoter activity, while the others did not detectably affect activity. The -75A allele had promoter activity more than twice that of the -75C allele. Alcohol dehydrogenase activity is rate limiting for ethanol oxidation. We hypothesize that the different ADH4 alleles lead to different amounts of pi-ADH in liver, which affects the risk for alcoholism by modulating alcohol metabolism.
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PMID:Polymorphism of the human alcohol dehydrogenase 4 (ADH4) promoter affects gene expression. 1020 39

Currently, one of the most popular applications of proteomics is in the area of cancer research. In Africa, Southeast Asia, and China, hepatocellular carcinoma is one of the most common cancers, occurring as one of the top five cancers in frequency. This project was initiated with the purpose of separating and identifying the proteins of a human hepatocellular carcinoma cell line, HCC-M. After two-dimensional gel electrophoresis separation, silver staining, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analyses, tryptic peptide masses were searched for matches in the SWISS-PROT and NCBI nonredundant databases. Approximately 400 spots were analyzed using this approach. Among the proteins identified were housekeeping proteins such as alcohol dehydrogenase, alpha-enolase, asparagine synthetase, isocitrate dehydrogenase, and glucose-6-phosphate 1-dehydrogenase. In addition, we also identified proteins with expression patterns that have been postulated to be related to the process of carcinogenesis. These include 14-3-3 protein, annexin, prohibitin, and thioredoxin peroxidase. This study of the HCC-M proteome, coupled with similar proteome analyses of normal liver tissues, tumors, and other hepatocellular carcinoma cell lines, represents the first step towards the establishment of protein databases, which are valuable resources in studies on the differential protein expressions of human hepatocellular carcinoma.
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PMID:Two-dimensional electrophoresis map of the human hepatocellular carcinoma cell line, HCC-M, and identification of the separated proteins by mass spectrometry. 1087 Sep 66

The human alcohol dehydrogenase gene ADH6 is expressed at the highest levels in fetal and adult liver. We have mapped cis-acting elements that affect its expression. The sequence from bp -34 to -62 (site C) that includes the TATA box was strongly bound by nuclear proteins from liver, hepatoma cells, and fibroblasts. A truncation that removed the upstream part of site C but left the TATA homology intact dramatically reduced transcription; altering 5 bp in this region had much less effect. Part of site C can be bound by C/EBPalpha, but cotransfection with C/EBPalpha or C/EBPbeta did not stimulate transcription. The proximal region did not display tissue specificity, so we cloned the upstream region to search for additional regulatory sequences. The region between -1.6 and -2.3 kb stimulated transcription in hepatoma cells and inhibited it in fibroblasts. We identified two sites in this region that affect transcription independently of their orientation. Site 1 was a negative regulatory element in fibroblasts but had no effect in hepatoma cells. Site 2 was a positive regulatory element in hepatoma cells but had no effect in fibroblasts. This combination of positive and negative regulatory elements can play a significant role in the tissue-specific expression of ADH6.
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PMID:Tissue-specific regulatory elements in the human alcohol dehydrogenase 6 gene. 1097 66

Fatty acids are ligands for the peroxisome proliferator-activated receptor alpha (PPAR alpha). Fatty acid levels are increased in liver during the metabolism of ethanol and might be expected to activate PPAR alpha. However, ethanol inhibited PPAR alpha activation of a reporter gene in H4IIEC3 hepatoma cells expressing alcohol-metabolizing enzymes but not in CV-1 cells, which lack these enzymes. Ethanol also reduced the ability of the PPAR alpha ligand WY14,643 to activate reporter constructs in the hepatoma cells or cultured rat hepatocytes. This effect of ethanol was abolished by the alcohol dehydrogenase inhibitor 4-methylpyrazole and augmented by the aldehyde dehydrogenase inhibitor cyanamide, indicating that acetaldehyde was responsible for the action of ethanol. PPAR alpha/retinoid X receptor extracted from hepatoma cells exposed to ethanol or acetaldehyde bound poorly to an oligonucleotide containing peroxisome proliferator response elements. This effect was also blocked by 4-methylpyrazole and augmented by cyanamide. Furthermore, in vitro translated PPAR alpha exposed to acetaldehyde failed to bind DNA. Thus, ethanol metabolism blocks transcriptional activation by PPAR alpha, in part due to impairment of its ability to bind DNA. This effect of ethanol may promote the development of alcoholic fatty liver and other hepatic consequences of alcohol abuse.
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PMID:The transcriptional and DNA binding activity of peroxisome proliferator-activated receptor alpha is inhibited by ethanol metabolism. A novel mechanism for the development of ethanol-induced fatty liver. 1102 51


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