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)

Glucocorticoids induce several phenotypic changes in rat hepatoma cells in tissue culture, including the inhibition of plasminogen activator activity. Variant cell lines resistant to dexamethasone inhibition of plasminogen activator activity have been isolated using an agar-fibrin overlay technique to identify colonies with fibrinolytic (plasminogen activator) activity. The variants are resistant to concentrations of dexamethasone 1,000 times that necessary to completely inhibit plasminogen activator activity in wild-type cells. The variant phenotype has been inherited in a stable manner for more than 300 generations in continuous culture in the absence of dexamethasone. These variants are unique in that the resistance is not secondary to defective or absent glucocorticoid receptors but is due to a lesion specific for regulation of plasminogen activator. Fluctuation analyses support the hypothesis that resistance to dexamethasone arises randomly and is not induced by dexamethasone. Because HTC cells are heteroploid and karyotypically highly variable, variants are thought to arise primarily by chromosomal segregation events. These variants provide a valuable tool for studying the mechanism of hormonal regulation of plasminogen activator as well as the role of proteases in hormonal regulation of membrane functions.
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PMID:Isolation of rat hepatoma cell variants selectively resistant to dexamethasone inhibition of plasminogen activator. 45 95

Forty-three independent variants of the Novikoff hepatoma cell line have been isolated for their ability to use D-xylose, D-ribose, and/or L-arabinose as a sole carbon and energy source. The variants exhibited marked morphological changes and a loss or decrease of cloning efficiency in soft agar. The xylose and arabinose variants showed similar phenotypes while the ribose variants were a phenotypically heterogenous group. Two major classes of variants were found with regard to their specificity for pentoses: one class could grow on ribose, xylose, or arabinose, while the second class grew only on ribose. The lack of specificity for pentose use was correlated with the ability to use pentitols for growth. The frequency of pentose-utilizing clones was 5 X 10(-2) to 10(-3), and nitrosoguanidine treatment increased this frequency tenfold. Fluctuation analyses showed the appearance of pentose-utilizing variants to be a random event. Of the variants examined, 84% expressed a stable pentose phenotype, and of those, 6% were cold sensitive and 8% were temperature sensitive for pentose utilization. In addition to the suggested mutational basis for the pentose phenotype, two variants showed a large increase in chromosome number from 73 +/- 3 to 132 +/- 10.
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PMID:Pentose-utilizing variants of Novikoff hepatoma cells: phenotypic characterization. 57 Mar 6