Biochemical criteria of mammalian cell sensitivity to glucocorticoids

: The resistance of Morris hepatoma cells strain 8994 to glucocorticoids which lack hormonal induction of tyrosine aminotransferase synthesis was studied. The cells of Morris hepatoma 7777 were used as a sensitive strain by a criterion of the enzyme synthesis. Using two-dimensional polyacrylamide gel electrophoresis, it was demonstrated that, i) in the cells of the "resistant" Morris hepatoma strain 8994 glucocorticoids change the rate of synthesis of at least five proteins, ii) two of these proteins are common for both cell strains, while the other ones are individual for each line, iii) in the cells of Morris hepatoma 8994 tyrosine aminotransferase is not controlled by glucocorticoids, iiii) glucocorticoids may not only control the activated genes but also the genes whose expression is suppressed. It was assumed that in the absence of disturbances in the receptor apparatus the resistance of any cell population to glucocorticoids can only be established by the use of a great variety of experimental approaches. The resistance of a cell population to the hormones cannot be judged upon by an analysis of the intensity of synthesis of one or even several proteins.