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)

We have determined the structure of the human ferrochelatase gene after isolation and characterization of lambda phage clones mapping discrete regions of the cDNA. This gene was assigned to human chromosome 18 at region q21.3, by fluorescent in situ hybridization. The gene contains a total of 11 exons and has a minimum size of about 45 kb. The exon/intron boundary sequences conform to consensus acceptor (GTn) and donor (nAG) sequences, and the exons in the gene appear to encode functional protein domains. A major site of the transcription initiation, determined by S1 nuclease mapping, was assigned to an adenine base 89 bases upstream from the adenine base of the translation initiation ATG. The promoter region contains a potential binding site for Sp1, NF-E2 and erythroid-specific transcriptional factor GATA-1, but not a typical TATAA or CCAAT sequence. Analysis of primer extension showed that the transcription starts at the same position between hepatoma HepG2 and erythroleukemia K562 cell mRNA, thereby suggesting that there can be a single transcript in erythroid and non-erythroid cells.
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PMID:Structure of the human ferrochelatase gene. Exon/intron gene organization and location of the gene to chromosome 18. 155 82

A solution hybridization/RNase protection assay with riboprobes was developed to quantitate apolipoprotein mRNA concentrations. Previously, radiolabeled DNA probes have been used in solution hybridization/S1 nuclease protection assays for this purpose. The new assay requires less time for probe preparation and hybridization compared to previous assays. In addition, the vector used for riboprobe preparation can also be used to conveniently produce cRNA required to generate the standard curve to quantitate absolute apolipoprotein mRNA levels. The solution hybridization RNase protection assay was used to quantitate apoB, A-I, and E mRNA levels in four human hepatoma cell lines, HepG2, Hep3B, WRL-68, SK-Hep2. HepG2 and Hep3B, but not WRL-68 and SK-Hep2 cells had concentrations of all three apolipoprotein mRNAs comparable to liver in vivo. These data suggest that HepG2 and Hep3B are suitable models to study liver specific apolipoprotein gene expression.
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PMID:A solution hybridization/RNase protection assay with riboprobes to determine absolute levels of apoB, A-I, and E mRNA in human hepatoma cell lines. 216 16

The liver-specific expression of the senescence marker protein 2 (SMP-2) in the male rat is markedly reduced during the androgen-sensitive state of young adulthood, whereas it is up-regulated during the androgen-insensitive phases of prepuberty and senescence. Nuclear runoff studies show that the age-dependent changes in SMP-2 expression are due to transcriptional regulation of the gene. In order to explore the mechanism of the regulatory process, we have cloned the upstream flanking regions of two distinct SMP-2 genes (SMP-2A and SMP-2B) and established their nucleotide sequence. These clones contain approximately 2.2 kb of the 5'-flanking sequence, exons 1 and 2, the first intron, and a portion of the second intron. The SMP-2 genes, as well as the upstream sequences, contain the sequence motifs for a number of cis-acting regulatory elements, such as the hepatocyte-specific element (HP1) and the androgen response element (ARE). S1 nuclease and primer extension analyses have established the transcription initiation sites for these genes. For functional analysis of the upstream sequences, we have constructed a hybrid plasmid containing the SMP-2A gene sequence (-1970 to +38 bases) fused to the structural gene for chloramphenicol acetyl-transferase (CAT). Upon transfection into rat hepatoma cells (FT02B), this construct was able to drive expression of the CAT gene. The same construct, however, failed to function in fibroblast-derived L cells, indicating tissue-specific regulation of the construct promoter.
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PMID:Structure and regulation of the senescence marker protein 2 gene promoter. 230 87

Regulation of albumin gene expression is believed to be mediated by multiple nuclear factors that interact with cis-acting DNA sequences within the first 160 base pairs (bp) of the promoter. The minimal promoter sequence required to generate tissue-specific expression has not been clearly defined. We have constructed a series of transient expression vectors containing progressive deletions of the mouse albumin gene 5'-flanking sequence fused to the bacterial chloramphenicol acetyltransferase (CAT) gene and include the Moloney murine leukemia viral (Mo-MuLV) enhancer. Promoter activity was determined in mouse hepatoma and fibroblast cell lines by chloramphenicol acetyltransferase and S1 nuclease analyses. All constructions were compared with -623 Albcat-Mo-MuLV which contains all the sequence homology between the rat and mouse promoters. Low levels of expression were observed with -60 Albcat-Mo-MuLV (10%) in hepatoma but not fibroblast cells. Addition of promoter sequence to -208 bp progressively increased activity to 190% in the hepatoma cells, while -308 and -1612 Albcat-Mo-MuLV had activity similar to the -623 Albcat-Mo-MuLV level, and -3000 Albcat-Mo-MuLV showed a 2-fold reduction in transcriptional activity. The inclusion of promoter sequences upstream of -60 generated low levels of expression in the fibroblasts. We also show that factors from mouse liver nuclear extracts protect at least five regions of the albumin promoter upstream of -160. Our results indicate that tissue specificity is established within the proximal promoter region and that additional cis-acting elements that may have a functional role in the efficiency of albumin gene expression are located upstream of -160 bp.
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PMID:Cell-specific expression of mouse albumin promoter. Evidence for cell-specific DNA elements within the proximal promoter region and cis-acting DNA elements upstream of -160. 272 22

A probe generated from the coding sequence of the rat hepatic beta-galactoside alpha 2,6-sialyltransferase was used to screen a human cDNA library constructed of human submaxillary gland mRNA lambda gt-11. We report the isolation and characterization of a human cDNA, HSM-ST1, that is putatively the human homolog of the beta-galactoside alpha 2,6-sialyltransferase. The largest human clone contains a 1.3 kb cDNA insert and is predicted to encompass 75% of the coding sequence as well as a small portion of the 3' untranslated region. Comparative analysis of this insert with the rat hepatic alpha 2,6-sialyltransferase sequence indicates 79% nucleotide similarity between the two sequences in the predicted coding region. On the amino acid level, the degree of conservation is 86%. Substantial sequence similarity is observed in the 3'-untranslated region between the rat and human sequences as well. S1 nuclease analysis was performed to demonstrate the expression of HSM-ST1 transcripts in the human hepatoma cell line, HepG2, and in the human colonic adenocarcinoma cell lines, LS174T.
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PMID:Isolation and characterization of a partial cDNA for a human sialyltransferase. 280 95

Hep 3B, a human hepatoma cell line was examined for its RNA hybridizable to the hepatitis B virus sequence. Using probes that covered different regions of the hepatitis B virus genome, five species of RNA were observed of sizes 4.0, 3.3, 2.9, 2.6 and 2.2 kilobases. The RNAs covered surface antigen gene, pre-S and X regions. None of them had a core antigen sequence. RNA with a 4.0 kilobase size was the most abundant. Using S1 nuclease analysis, its 5' end of hepatitis B virus sequence was mapped at pre-S region and its 3' end of viral sequence was mapped at DR region.
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PMID:Hepatitis B virus transcripts in a human hepatoma cell line, Hep 3B. 301 12

A tumorigenic human hepatoma cell line, Hep G2, has been shown to have high steady-state levels of c-myc transcripts compared to normal human liver. We have now characterized c-myc expression in Hep G2 cells with regard to message stability, gene rearrangements, gene amplification, chromosomal translocations, promoter utilization, and the effects of protein synthesis inhibitors. We have determined that the half-life of the Hep G2 c-myc transcript is approximately 20 min and conclude that the high steady-state level of c-myc mRNA is not the result of a specific stabilization of the c-myc message but probably results from increased c-myc gene transcription. c-myc expression in Hep G2 cells appears to be constitutive, since it remains constant in different cell growth states (log phase versus nondividing cells). The high constitutive expression of the c-myc gene in Hep G2 cells could not be explained by gene amplification, gene rearrangements, or chromosomal translocations. However, based on an S1 nuclease protection assay, the P1/P2 promoter utilization ratio is approximately 1/1 which differs from the 1/5 P1/P2 ratio observed in normal human liver. Treatment with cycloheximide, a protein synthesis inhibitor, does not superinduce Hep G2 c-myc transcription based on transcription "run on" and RNA slot blot analysis. However, cycloheximide treatment does exert a posttranscriptional effect involving the specific stabilization of the c-myc message.
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PMID:Analysis of c-myc expression in a human hepatoma cell line. 303 14

The region flanking the 5'-end of the rat gene encoding the cytoplasmic precursor of carbamyl-phosphate synthetase I, a mitochondrial matrix enzyme, has been cloned and partially characterized. S1 nuclease and primer extension analyses position the starts of transcription 138-140 nucleotides upstream of the translation initiation codon. Exon 1 contains this untranslated sequence and extends downstream to include the coding region for the pre-enzyme signal peptide (38 amino acids) plus 4 amino acids from the amino terminus of the mature protein. The 5'-flanking sequence contains typical promoter elements, including putative TATA and CAAT motifs at -21 and -82 nucleotides, respectively. In addition, several copies of consensus sequences corresponding to the H4TF-1 recognition element, GATTTC, together with the enhancer-like octamer, ATTTGCAT, are also present. Carbamyl-phosphate synthetase I is a cell-type specific enzyme, being expressed only in hepatocytes and epithelial cells of the intestinal mucosa. It is also synthesized at relatively high levels in the hepatoma cell line, Hep G2. Employing pCPS2.1, a minigene containing the promoter and part of exon 1, we show that nuclear extracts from Hep G2 support accurate carbamyl-phosphate synthetase I gene transcription in vitro. No such activity was observed, however, in extracts from HeLa, a cell line which does not express carbamyl-phosphate synthetase I.
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PMID:Rat carbamyl-phosphate synthetase I gene. Promoter sequence and tissue-specific transcriptional regulation in vitro. 303 78

Significant changes in aldehyde dehydrogenase (ALDH) activity occur during rat hepatocarcinogenesis in vivo. To compare the structure and expression of the tumor aldehyde dehydrogenase gene in rat hepatoma cell lines and normal rat liver, several rat hepatoma cell lines, including HTC, H4-II-EC3, JM2, McA-RH7777, and four lines established in this laboratory have been examined for T-ALDH gene expression using a tumor ALDH complementary DNA. Northern blot analysis of polyadenylate-containing RNA from log-phase cells and normal rat liver with T-ALDH complementary DNA indicates production of a single major 1.7-kilobase transcript in the high activity lines HTC, JM2, RLT-2M, RLT-3C, RLT-9F, and intermediate activity line RLT-5G. There is a direct correlation between expression of T-ALDH enzyme activity and the amount of 1.7-kilobase transcript. S1 nuclease protection experiments confirm that there is only one major T-ALDH transcript in the high activity lines. Thus, cell line differences in T-ALDH activity are reflected in the level of a single T-ALDH transcript. Southern analysis was used to identify the T-ALDH gene in genomic DNA. The results indicate that no significant amplification or rearrangement of the T-ALDH gene has occurred in these hepatoma cells. DNA methylation has been proposed to play an important role in gene expression. Genomic DNA from HTC, JM2, McA-RH7777, H4-II-EC3, RLT-2M, RLT-9F, RLT-3C, RLT-5G, rat embryo and normal rat liver were digested with MspI and HpaII to examine methylation patterns. A digestion pattern consistent with hypomethylation was detected only in DNA from the high T-ALDH activity cell lines HTC, JM2, RLT-2M, and RLT-9F. This suggests that constitutive expression of T-ALDH in the hepatoma cells is related to changes in DNA methylation patterns.
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PMID:Expression of tumor-associated aldehyde dehydrogenase gene in rat hepatoma cell lines. 326 98

Nuclear extract from Morris hepatoma 3924A was fractionated by DEAE-Sephadex chromatography. The fraction eluting with 300 mM (NH4)2SO4 (DE-C) was used for transcribing cloned mouse metallothionein-I (MT-I) gene in a run-off assay. This fraction contained the majority of RNA polymerase II as well as the transcription factor(s). Accuracy of MT-I DNA transcription was confirmed by S1 nuclease mapping. Low concentrations (1 microgram/ml) of alpha-amanitin inhibited the reaction, indicating that RNA polymerase II directed the transcription. Unfractionated nuclear extracts from the hepatoma or a rat mammary adenocarcinoma as well as whole cell extract obtained from the mammary tumor also transcribed MT-I gene. The extent of transcriptional activity was in the following order: hepatoma nuclear fraction DE-C greater than whole cell extract derived from rat mammary adenocarcinoma cells greater than nuclear extract derived from rat hepatoma or rat mammary adenocarcinoma cells. These studies have demonstrated that a fractionated nuclear extract obtained from a tissue supports efficient and accurate RNA polymerase II-mediated transcription of MT-I DNA.
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PMID:Accurate transcription of mouse metallothionein-I gene in a fractionated nuclear extract from a rat hepatoma. 355


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