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

Asparagine synthetase (L-aspartate:ammonia ligase (AMP-forming, EC 6.3.1.1) activity in rat liver increased when the animals were put on a low casein diet. The enzyme was purified about 280-fold from the supernatant of rat liver homogenate by a procedure comprising ammonium sulfate fractionation. DEAE-Sepharose column chromatography, and Sephadex G-100 gel filtration. The optimal pH of the enzyme was in the range 7.4-7.6 with glutamine as an amide donor. The molecular weight was estimated to be approximately 110,000 by gel filtration. Chloride ion was required for the enzyme activity. The apparent Km values for L-aspartate, L-glutamine, ammonium chloride, ATP, and Cl- were calculated to be 0.76, 4.3, 10, 0.14, and 1.7 mM, respectively. The activity was inhibited by L-asparagine, nucleoside triphosphates except ATP, and sulfhydryl reagents. It has been observed that the properties of asparagine synthetase from rat liver are not so different from those of tumors such as Novikoff hepatoma and RADA 1.
 ...
PMID:Purification and properties of asparagine synthetase from rat liver. 2 63

trans-Aziridine-2,3-dicarboxylic ester was used to prepare the required beta-chlorohydroxamic acid used in the synthesis of the title compound. The trans configuration of the asparagine analogue was established by hydrogenolysis to erythro-beta-hydroxyasparagine amide. Neither the title compound nor the intermediate aziridinehydroxamic acid (8) showed significant activity against the L1210 and P-388 tumors. The title compound was inactive as an inhibitor of asparagine synthetase from Novikoff hepatoma and did not inhibit the growth of some 25 bacteria and fungi.
 ...
PMID:5-Carboxamido-4-amino-3-isoxazolidone, and asparagine analogue. 2 38

Several derivatives of erythro-beta-hydroxy-DL-aspartic acid (1) were prepared as a potential inhibitors of L-asparagine synthetase (ASase) from rat Novikoff hepatoma. Benzylation of 1 gave the dibenzyl ester 2 which upon coupling with carbobenzoxyglycine afforded the blocked dipeptide 3. Deblocking of 3 gave glycl-erythro-beta-hydroxyl-DL-aspartic acid (4) which could not be diazotized. The dimethyl ester of 1 was coupled with carbobenzoxyglycine to give the blocked dipeptide 7a which was deblocked to give dimethyl glycel-erythro-beta-hydroxy-DL-aspartate hydrochloride (8). Diazotization of 8 gave impure diazo compound 9 which on reaction with HCl gave the chloro compound 10. The methods of isolation, assay, and inhibition of ASase are discribed. At 10 mM concentrations 10, 1, and its D and L enantiomers inhibit ASase by 45, 47, 36 and 66 percent, respectively.
 ...
PMID:Potential inhibitors of L-asparagine biosynthesis. 2. Chemistry and biological activity of beta-hydroxyaspartic acid and its derivatives. 16 50

The N-[p-(fluorosulfonyl)benzyl] derivatives of L-asparagine and L-glutamine (1a,b) were synthesized as potential inhibitors of L-asparagine synthetase (ASase). Condensation of p-(fluorosulfonyl)benzylamine (2) with the suitably protected amino acid in the presence of dicyclohexylcarbodiimide, followed by deblocking, afforded 1a and 1b. Derivatives 1a and 1b at 10 mM inhibit ASase isolated from Novikoff hepatoma (rats) by 60 and 46%, respectively. Preliminary results on inhibition of Jensen sarcoma (L-asparaginase sensitive) and JA-1 sarcoma (L-asparaginase resistant) tissue cultures by 0.3 mM 1a (139,90%) and 1b (101, 103%), respectively, are discussed.
 ...
PMID:Potential inhibitors of L-asparagine biosynthesis. 3. Aromatic sulfonyl fluoride analogs of L-asparagine and L-glutamine. 24 24

Three electrophilic amide analogues of (S)-2,3-diaminopropionic acid (1, DAP) have been prepared as potential inhibitors of L-asparagine synthetase (ASase, from Novikoff hepatoma, EC 6.3.5.4). DAP was selectively blocked by the carbobenzoxy (Cbz) group to give 3-N-Cbz-DAP (2a). Esterification of 2a with isobutylene afforded tert-butyl 3-N-carbobenzoxy-(S)-2,3-diaminopropionate (3a), which was then blocked at the 2 position with the tert-butoxycarbonyl (Boc) group to give tert-butyl 2-[(S)-(tert-butoxycarbonyl)amino]-3-[(carbobenzoxy)amino]propionate (4). Selective cleavage of the Cbz group by H2/Pd gave the key intermediate tert-butyl 2-N-(tert-butoxycarbonyl)-(S)-2,3-diaminopropionate (5), which was acylated, via the N-hydroxysuccinimide esters, with bromoacetic acid, dichloroacetic acid, and fumaric acid monoethyl ester to give tert-butyl 2-[(S)-(tert-butoxycarbonyl)-amino]-3-(2-bromoacetamido)propionate (6a), tert-butyl 2-[(S)-(tert-butoxycarbonyl)amino]-3-(2,2-dichloroacetamido)propionate (6b), and tert-butyl 2-[(S)-(tert-butoxycarbonyl)amino]-3-(ethoxycarbonyl)acrylamido]-propionate (6c), respectively. Deblocking of 6a-c gave the corresponding amino acids (S)-2-amino-3-(2-bromoacetamido)propionic acid hydrobromide (7a), (S)-2-amino-3-(2,2-dichloroacetamido)propionic acid (7b), and ethyl N-[(S)-2-amino-2-carboxyethyl]fumarate (7c). By a slightly different procedure, 5 was converted in two steps to (S)-2-amino-3-acetamidopropionic acid hydrobromide (7d). The inhibition of ASase by 7a-c at 1 mM was 93, 19, and 37%, respectively, while 7d was without inhibition at 2 mM. Compounds 7a-c failed to increase the life span of mice infected with B16 melanoma.
 ...
PMID:Potential inhibitors of L-asparagine biosynthesis. 5. Electrophilic amide analogues of (S)-2,3-diaminopropionic acid. 678 98

A full-length cDNA clone for rat asparagine synthetase (AS) was isolated from a cDNA library enriched for amino acid-regulated sequences. The AS cDNA was used to investigate the amino acid-dependent repression of AS mRNA content in rat Fao hepatoma cells. In response to complete amino acid starvation, there was an approximately 10-fold increase in the level of AS mRNA. Three species of mRNA, of approx. sizes 2.0, 2.5 and 4.0 kb, were detected and each was simultaneously regulated to the same degree. The expression of AS mRNA increased by 6 h after removal of amino acids, reached a plateau after 9 h, and was blocked by either actinomycin D or cycloheximide. Partial repression of the AS mRNA content was maintained by the presence of a single amino acid in the culture medium, but the degree of effectiveness for each one varied widely. Glutamine showed the greatest ability to repress the AS mRNA content, even at an extracellular concentration 10 times below its plasma level. Other effective repressors included the amino acids asparagine, histidine and leucine, as well as ammonia. Depletion of selected single amino acids from an otherwise complete culture medium also caused up-regulation. In particular, removal of histidine, threonine or tryptophan from the medium, or the addition of histidinol to inhibit histidinyl-tRNA synthetase, resulted in a significant increase in AS mRNA content. The data indicate that nutrient regulation of AS mRNA occurs by a general control mechanism that is responsive to a spectrum of amino acids.
 ...
PMID:Cloning of rat asparagine synthetase and specificity of the amino acid-dependent control of its mRNA content. 781 76

We have cloned and sequenced cDNA of asparagine synthetase (AS) from rat Sertoli cells. The nucleotide sequence was derived by analysis of cloned cDNA of reverse transcription-polymerase chain reaction (RT-PCR) product that spanned overall the cDNA coding region. The sequence contains three nucleotide differences when compared with that of rat Fao hepatoma cells (Hutson, R.G., and Kilberg, M.S. (1994) Biochem. J. 304, 745-750). Accordingly, amino acid residues Ser at position 330 and His at 491 of Sertoli cells were replaced by Pro and Tyr, respectively, in the sequence of the hepatoma cells. Mutational nucleotide changes may occur during carcinogenesis. The testis contained the most abundant AS mRNA among the tissues studied and others revealed by far a little amount of message. Expressions of AS mRNA in the liver and brain were high in fetal period and reduced rapidly after birth, showing importance of AS in cell proliferation.
 ...
PMID:Cloning of cDNA for asparagine synthetase from rat Sertoli cell. 893 34

Complete amino acid deprivation in mammalian cells causes a significant enhancement in gene expression for a number of important cellular activities; among these is asparagine synthetase (AS). The data presented demonstrate that, in both nonleukemic (rat Fao hepatoma cells) and human leukemia cells (MOLT-4, NALL-1, and BALL-1), AS mRNA levels, protein content, and enzymatic activity are induced after incubation in an otherwise complete tissue culture medium that is deficient in a single amino acid or in medium that has been depleted of the amino acid asparagine by the addition of asparaginase. Complete amino acid deprivation results in a concerted increase in AS mRNA, protein, and enzymatic activity, which, in conjunction with previously published research, suggests that the mechanism of this cellular response involves transcriptional control of the AS gene. Asparaginase treatment is a standard component of acute lymphoblastic leukemia therapy for which the effectiveness is related to the inability of these cells to upregulate AS activity to a sufficient level. With regard to the asparaginase sensitivity of the three human leukemia cell lines, there was a trend toward an inverse relation to the degree of AS expression. Selection for asparaginase-resistant MOLT-4 sublines resulted in enhanced AS mRNA and protein content regardless of whether the cells had been selected by asparaginase treatment directly or asparagine was removed from the culture medium. Collectively, the data illustrate that further advances in asparaginase therapy will require additional knowledge of amino acid-dependent regulation of AS gene expression and, conversely, that asparaginase resistance represents a model system for investigating metabolite control in a clinically relevant setting.
 ...
PMID:Amino acid control of asparagine synthetase: relation to asparaginase resistance in human leukemia cells. 957 15

Transcription of the asparagine synthetase (AS) gene is induced by amino acid deprivation. The present data illustrate that this gene is also under transcriptional control by carbohydrate availability. Incubation of human HepG2 hepatoma cells in glucose-free medium resulted in an increased AS mRNA content, reaching a maximum of about 14-fold over control cells after approx. 12 h. Extracellular glucose caused the repression of the content of AS mRNA in a concentration-dependent manner, with a k1/2 (concentration causing a half-maximal repression) of 1 mM. Fructose, galactose, mannose, 2-deoxyglucose and xylitol were found to maintain the mRNA content of both AS and the glucose-regulated protein GRP78 in a state of repression, whereas 3-O-methylglucose did not. Incubation in either histidine-free or glucose-free medium also resulted in adaptive regulation of the AS gene in BNL-CL.2 mouse hepatocytes, rat C6 glioma cells and human MOLT4 lymphocytes, in addition to HepG2 cells. In contrast, the steady-state mRNA content of GRP78 was unaffected by amino acid availability. Transient transfection assays using a reporter gene construct documented that glucose deprivation increases AS gene transcription via elements within the proximal 3 kbp of the AS promoter. These results illustrate that human AS gene transcription is induced following glucose limitation of the cells.
 ...
PMID:Transcriptional regulation of the human asparagine synthetase gene by carbohydrate availability. 1008 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.
 ...
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


1 2 Next >>