Expression of differentiated functions in dexamethasone-resistant hepatoma cells.
The expression of liver-specific functions of different dexamethasone-resistant variants derived from a well-differentiated dexamethasone-sensitive Reuber H35 rat hepatoma cell line (Faza 967) was examined during long-term cultivation. The dexamethasone-sensitive Faza 967 cells are characterized by the activity of tyrosine aminotransferase (TAT) and gluconeogenic enzymes, secretion of serum albumin, and the presence of liver isozymes of alcohol dehydrogenase (L-ADH), aldolase (aldolase-B), and five isoenzymes of lactate dehydrogenase (LDH). The hormone-resistant cells undergo a very dramatic change in expression of most liver-specific functions (dedifferentiation) during long-term culture, in contrast to the sensitive cells in which only certain functions (TAT activity, inducibility, and synthesis of serum albumin) exhibit considerable changes. The hormone-dependent growth sensitivity and the expression of other differentiated functions is not controlled in coordinated way in Faza 967 cells. The time course of the expression of liver-specific functions shows that the cells are resistant before they became 'dedifferentiated', i.e., loss of these liver-specific functions is not a prerequisite of the establishment of the hormone-resistant state.
D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004351:Drug Resistance; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism; D005943:Gluconeogenesis; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008114:Liver Neoplasms, Experimental / Q000503:physiopathology*; D051381:Rats; D012709:Serum Albumin / Q000096:biosynthesis; D014444:Tyrosine Transaminase / Q000378:metabolism
D007527:Isoenzymes; D012709:Serum Albumin; D003907:Dexamethasone; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D007770:L-Lactate Dehydrogenase; D014444:Tyrosine Transaminase; D005634:Fructose-Bisphosphate Aldolase