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)

The ability of liver lipid exchange proteins to introduce foreign phospholipids into intact mitochondria was used for a study of the lipid dependence of monoamine oxidase. Introduction of exogenous phosphatidylcholine into rat hepatoma mitochondria, in which both the monoamine oxidase activity and the phosphatidylcholine content are comparatively low, leads to considerable activation of the enzyme. The introduction of exogeneous phosphatidylserine, phosphatidylethanolamine and cardiolipin has no activating effect. This indicates that the decreased activity of monoamine oxidase in the hepatoma may be due to a low amount of phosphatidylcholine. The method described allows the study in situ of the lipid dependence of non-solubilized membrane-bound enzymes.
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PMID:[Lipid dependence of mitochondrial monoamine oxidase from rat hepatoma 27 with the use of rat liver lipid exchange proteins]. 20 7

Protein-mediated lipid exchange between phosphatidylcholine liposomes and hepatoma mitochondria was used to alter the lipid composition of the mitochondria and the resulting changes in the activity of monoamine oxidase were studied. Introduction of additional amounts of phosphatidylcholine substantially increased the activity of the enzyme, but did not affect its substrate specificity and the enzyme sensitivity to inhibitors (chlorgyline and deprenyl). The thermal stability of the enzyme was not increased under supplementation of the hepatoma mitochondria with phosphatidylcholine.
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PMID:[Use of protein-mediated lipid exchange for studies of membrane-bound enzymes. Properties of monoamine oxidase activated by phosphatidylcholine]. 50 57

Metabolism of propranolol by the human hepatoma cell line Hep G2 was studied. Although metabolism qualitatively was similar to that in-vivo, the P450-mediated N-desisopropylation clearly predominated. Pretreatment of cells with 3-methylcholanthrene increased the activity of this pathway 14-fold, whereas phenobarbitone had no effect. This is similar to the pathway-selective inductive response observed for cigarette smoking in-vivo. As in-vivo, secondary metabolism of N-desisopropylpropranolol was extensive. This could, however, be completely blocked by 0.1 microM clorgyline, a potent MAO type A inhibitor. As in human liver microsomes, the stereochemistry of propranolol metabolism demonstrated a preference for the R(+)-enantiomer. These observations emphasize the usefulness of the Hep G2 cell line as a model of man.
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PMID:Induction of propranolol metabolism in the Hep G2 human hepatoma cell line. 135 46

This communication reports on the effects of dimethyl sulfoxide (DMSO) on the oxidative metabolism of propranolol by the homogenate of the human hepatoma cell line Hep G2. The formation of multiple metabolites was monitored in the absence and presence of 0.1 to 2.0% of DMSO. For the primary cytochrome P450-mediated pathways, ring oxidation was significantly reduced by 1.3 to 2.0% DMSO, whereas side-chain oxidation was not affected. A gradual inhibition of the oxidative deamination of N-desisopropylpropranolol to its glycol metabolite was seen with 20% inhibition at a DMSO concentration of 0.1% and a maximum 75% inhibition at a DMSO concentration of 0.7%. This highly selective inhibitory effect of DMSO on oxidative drug metabolism appears to be directed towards MAO type A.
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PMID:Potent inhibition of MAO mediated propranolol metabolism by dimethyl sulfoxide in Hep G2 cells. 150 6

Hypocrellin A (HA), a perylene quinone derivative, is a new photosensitizer extracted from Hypocrella bambusae (B et Br) Sace. A high voltage sodium lamp was used as the light source; the illumination intensity was 105 mW/cm2. After HA 25 micrograms/ml and illumination for 10 min, mitochondrial ATPase and microsomal G-6-Pase of hepatoma cells were intensively inhibited, but mitochondrial MAO was not affected. Sulfhydryl contents of the mitochondrial and microsomal membrane proteins were significantly reduced. Lipid peroxidation of mitochondrial and microsomal membrane lipids were greatly enhanced. It is concluded that mitochondria and microsomes are the sensitive targets in cells with respect to HA photosensitization.
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PMID:[Photodynamic action of hypocrellin A on hepatoma cell mitochondria and microsomes]. 256 Mar 14

Monoamine oxidases (MAO; EC 1.4.3.4.) A and B occur in the outer mitochondrial membrane and oxidize a number of important biogenic and xenobiotic amines. Monoclonal antibodies specific for human MAO A or B and immunocytochemical techniques were used to visualize the respective enzymes in human placenta, platelets, lymphocytes, liver, brain, and a human hepatoma cell line. MAO A was observed in the syncytiotrophoblast layer of term placenta, liver, and a subset of neurons in brain, but was not observed in platelets or lymphocytes, which are known to lack type A enzyme. MAO B was observed in platelets, lymphocytes, and liver, but not in placenta, which contains little or no MAO B. MAO B was also observed in a subset of neurons in the brain that was distinct from that which contained MAO A. MAO A and MAO B were also observed in some glia. Unlike most tissues examined, liver cells appeared to contain both forms of the enzyme. These studies show that MAO A and MAO B can be specifically visualized by immunocytochemical means in a variety of human cells and tissues and can provide a graphic demonstration of the high degree of cell specificity of expression of the two forms of the enzyme.
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PMID:Immunocytochemical localization of monoamine oxidases A and B in human peripheral tissues and brain. 302 89

Monoclonal antibodies that immunoprecipitate human monoamine oxidase (MAO) A or human MAO B, but not the corresponding mouse enzymes, were used to assay for the presence of immunoprecipitable MAO A or MAO B (presumably coded by the respective human genes) in mouse-human hybrid somatic cell lines containing small numbers of human chromosomes. The results were as follow: Extracts of a human lymphoblastoid x mouse hepatoma hybrid line that retained the human X chromosome contained immunoprecipitable MAO B, while a similar hybrid line that contained the same human chromosomes, except for the human X, did not. Extracts of a human fibroblast x mouse neuroblastoma hybrid cell line, whose human chromosomal material consisted solely of the X, contained both immunoprecipitable MAO A and MAO B. Extracts of a related hybrid line, whose human chromosomal material consisted solely of an autonomous fragment and a fragment translocated to a mouse chromosome, contained immunoprecipitable MAO A. However, the level of immunoprecipitable MAO B activity in extracts of this hybrid was low or undetectable. Among extracts of 33 human fibroblast x mouse hepatoma hybrids that had been selected for expression of the X-linked human enzyme HPRT, 60% contained immunoprecipitable MAO B. This figure was comparable to the 58% that expressed the X-linked human isozyme for glucose-6-phosphate dehydrogenase (G6PD). When 11 of these hybrid lines, which contained immunoprecipitable MAO B and human HPRT, were selected for loss of HPRT, all lost immunoprecipitable MAO B in addition to HPRT. These data demonstrate that genes controlling the expression of MAO A and MAO B, which can be immunoprecipitated with the human-specific monoclonal antibodies, are located on the human X chromosome. Properties of the immunological epitopes recognized by the monoclonal antibodies suggest that the X-linked genes detected in this study are probably structural genes for the enzymes.
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PMID:Assignment of genes for human monoamine oxidases A and B to the X chromosome. 354 Mar 17

A rapid method for determining urinary indole-3-acetic acid (IAA) is introduced as the tumor-marker for the screening and diagnostic purpose of cancer patients by means of high performance liquid chromatography (HPLC). Its clinical significance is discussed along with a review of literatures. The IAA concentration and creatinine level of optionally collected urine samples were measured and used for the calculation of IAA amount per unit creatinine (microgram IAA/mg creatinine) in urine. Thus, an amount of 24-hours urinary IAA could be calculated without collecting a whole day's urine supply. Analysis of urinary IAA was performed within 10 minutes by HPLC. Urinary IAA level is usually high in the patients with the upper G-I tract cancers such as gastric cancer, esophageal cancer and hepato-biliary tract cancer, and also malignant hematopoietic disorders. But it is also high in non-cancer patients such as liver cirrhosis, diabetes mellitus and cholelithiasis occasionally. The patients with high urinary IAA level also showed high urinary levels of 5-hydroxy indoleacetic acid (5-HIAA) and monoamine oxidase activity (MAO). It was characteristic that hepatocellular carcinoma showed slight elevation of urinary IAA with normal levels of 5-HIAA and MAO. It is conclusive that the positive rate of elevated urinary IAA level was high in the patients with gastric cancer with ulcer-forming type in its morphological classification, and its level tends to elevate as the disease progresses. Therefore, the measurement of urinary IAA level in an optionally collected urine sample, as the tumor-marker, can be useful to check the progression and regression of gastric cancer.
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PMID:[A rapid method for determining urinary indoleacetic acid concentration and its clinical significance as the tumor-marker in the diagnosis of malignant diseases]. 620 79

The incorporation of lysophosphatidylcholine into biological membranes and its effect on some membrane-bound enzymes of mitochondria and microsomes from rat liver and hepatoma were studied. It was shown that in the presence of lipid-exchange proteins of the liver a far greater amount of lysophosphatidylcholine is incorporated into the membranes than in the-iv absence. The increase of the lysophosphatidylcholine content in the membranes has no effect on the activity of mitochondrial monoamine oxidase, inhibits the activity of microsomal cytochrome P-450 and activates glucose-6-phosphatase.
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PMID:[New method of lysophospholipid incorporation into biological membranes. Effect of lysophosphatidylcholine on the activity of membrane-bound enzymes]. 626 66

The majority of cell proteins are non-cytosolic and are found in specific extracytosolic cytomorphological sites. Rat liver mitochondria and outer mitochondrial membrane (OMM) vesicles were transplanted homologously into rat hepatocytes and heterologously into rat hepatoma (HTC) cells by polyethylene glycol-mediated organelle--cell or OMM vesicle-cell fusion. The subsequent destructive fate of these non-cytosolic proteins was studied. During culture of hepatocyte monolayers in conditions which give in vivo catabolic rates, the transplanted organelle proteins and monoamine oxidase were degraded at rates similar to in vivo rates, although the transplanted material was not found in the hepatocyte mitochondria. Degradation was preceded by internalization (1-6 h) of the transplanted material and its translocation to a perinuclear, vesicular cytoplasmic position. Prevention of translocation by the disruption of the cytoskeleton inhibited subsequent degradation. In contrast, rat OMM heterologously transplanted into HTC cells was patched, capped and internalized into 'unique' vesicles and degraded 2.5 times faster than in hepatocytes. In both hepatocytes and HTC cells mitochondrial protein degradation was partially susceptible to lysosomotropic agents. The results are discussed in terms of a protein turnover cycle which attempts to coordinate the biochemistry and cell biology of protein synthesis and degradation in eukaryotic cells.
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PMID:Degradative fate of transplanted proteins. 656 Nov 34


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