THE CLASS-I ALCOHOL-DEHYDROGENASE GENE IS GLUCOCORTICOID-RESPONSIVE IN THE RAT HEPATOMA MICROCELL HYBRID CELL-LINE, 11-3

Expression of the class I alcohol dehydrogenase (ADH) gene in the rat hepatoma microcell hybrid cell line, 11-3, was examined. The steady-st ate level of ADH mRNA in 11-3 was similar to 2-fold higher than that o f rat liver and Fao, the parental cell line of 11-3, Removal of steroi d hormones by activated charcoal from the serum in which 11-3 cells we re maintained resulted in a significant decrease in the level of ADH t ranscript, Dexamethasone at a concentration of 1 mu M increased the AD H mRNA content in 11-3 in a time-dependent fashion, up to 48 hr after its addition to cells that had first been deprived of steroid hormones . In addition, levels of ADH transcript in cells treated with dexameth asone increased in a dose-dependent manner, and the concentration of d examethasone required to achieve half-maximal activation was 5 nM. By using the techniques of reverse transcription and polymerase chain rea ction, and by taking advantage of a restriction polymorphism present b etween the rat and mouse ADH cDNA, we found that 11-3 contained both t he rat and mouse class I ADH transcripts, although the rat sequence ac counted for the great majority, Moreover, levels of both rat and mouse class I ADH transcripts increased in a similarly time-dependent manne r in cells treated with dexamethasone. These results indicate that exp ression of class I ADH gene in 11-3 is high and is regulated by glucoc orticoids, making the cell line an excellent model for the in vitro st udy of ADH expression.