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)

A comparative study of glucose-6-phosphatase, alcaline RNase, ATPase, inosine diphosphatase and 5'-nucleotidase activities in isolated rat liver and hepatoma-27 nuclei and nuclear envelopes was performed. The tumor nuclear membranes were shown to be free from G-6-Pase activity in contrast to the liver nuclear membranes. The nuclear RNase activity was strongly inhibited in the hepatoma and could be unmasked in the presence of 3-10(-4) M pCMB. Hepatoma nuclear and nuclear envelopes ATP-ase activity was found to be moderately decreased as compared to those of the normal tissue. The values of inosine diphosphatase activity in hepatoma were similar to those in liver. The role of the nuclear envelope in nuclear-cytoplasmic interactions as well as nuclear location of G-6-Pase are discussed.
 ...
PMID:[Various enzymes of isolated nuclear membranes and cell nuclei of the liver and hepatoma 27 of rats]. 19 29

In rat hepatoma cells the synthetic glucocorticoid dexamethasone causes a 3-fold increase in the activity of the plasma membrane enzyme alkaline phosphodiesterase I (oligonucleat 5'-nucleotidohydrolase, EC 3.1.4.1). The data are consistent with an induction phenomenon mediated by the glucocorticoid receptor involved in tyrosine aminotransferase induction. The effect on alkaline phosphodiesterase I is not a reflection of a general membrane effect of dexamethasone, because the activity of three other enzymes of the plasma membrane is unaffected. On the other hand, nucleoside diphosphatase (nucleoside diphosphate phosphohydrolase acting on ADP) activity is inhibited. Thus, two more enzymes sensitive to glucocorticoids have been identified in a cell line in which these hormones influence only very few gene products. This paper describes enzymatic changes in the plasma membrane of rat hepatoma cells in which glucocorticoids normalize a number of membrane-associated processes that are considered to be characteristic of transformed cells.
 ...
PMID:Glucocorticoid hormones increase the activity of plasma membrane alkaline phosphodiesterase I in rat hepatoma cells. 610 83

Exposure of HTC rat hepatoma cells to a 33% decrease in extracellular osmolality caused the cytosolic Ca(2+) concentration ([Ca(2+)](i)) to increase transiently by approximately 90 nm. This rise in [Ca(2+)](i) was inhibited strongly by apyrase, grade VII (which has a low ATP/ADPase ratio) but not by apyrase grade VI (which has a high ATP/ADPase ratio) or hexokinase, indicating that extracellular ADP and/or ATP play a role in the [Ca(2+)](i) increase. The hypotonically induced rise in [Ca(2+)](i) was prevented by the prior discharge of the intracellular Ca(2+) store of the cells by thapsigargin. Removal of extracellular Ca(2+) or inhibition of Ca(2+) influx by 1-10 microm Gd(3+) depleted the thapsigargin-sensitive Ca(2+) stores and thereby diminished the rise in [Ca(2+)](i). The hypotonically induced rise in [Ca(2+)](i) was prevented by adenosine 2'-phosphate-5'-phosphate (A2P5P) and pyridoxyl-5'-phosphate-6-azophenyl-2',4'-disulfonate, inhibitors of purinergic P2Y(1) receptors for which ADP is a major agonist. Both inhibitors also blocked the rise in [Ca(2+)](i) elicited by addition of ADP to cells in isotonic medium, whereas A2P5P had no effect on the rise in [Ca(2+)](i) elicited by the addition of the P2Y(2) and P2Y(4) receptor agonist, UTP. HTC cells were shown to express mRNA encoding for rat P2Y(1), P2Y(2), and P2Y(6) receptors. Inhibition of the hypotonically induced rise in [Ca(2+)](i) blocked hypotonically induced K(+) ((86)Rb(+)) efflux, modulated the hypotonically induced efflux of taurine, but had no significant effect on Cl(-) ((125)I-) efflux. The interaction of extracellular ATP and/or ADP with P2Y(1) purinergic receptors therefore plays a role in the response of HTC cells to osmotic swelling but does not account for activation of all the efflux pathways involved in the volume-regulatory response.
 ...
PMID:The role of P2Y1 purinergic receptors and cytosolic Ca2+ in hypotonically activated osmolyte efflux from a rat hepatoma cell line. 1213 1