Corticosteroids and transaminase activity. III. A relationship between changes in alanine transaminase activity and the growth of Walker carcinosarcoma 256.

The effects of treatment with cortisol on the growth and alanine-a-ketoglutarate transaminase 1 activity of Walker carcinosarcoma 256 were studied. Similarly, the effects of other conditions known to enhance gluconeogenic activity, such as diabetes, fasting, and high protein intake, were investigated. Each of these conditions was previously shown to be associated with elevated activity of alanine transaminase in liver. The administration of cortisol after the subcutaneous implantation of the Walker tumor resulted in marked retardation in the growth of the tumors and in fourto fourteen-fold increases in their alanine-a-ketoglutarate transaminase activity depending on the dose administered. In rats fed diets containing 75 and 95 per cent protein, tumor growth was inhibited by as much as 75 per cent, and alanine transaminase activity was stimulated threefold. The marked growth inhibition of this tumor in alloxandiabetic or fasted rats was not accompanied by any notable increase in the activity of this transaminase enzyme in the tumor, whereas significant elevation of the enzyme did occur in the liver of these animals. In each instance in which alanine transaminase activity in the Walker tumor was increased by the injection of corticosteroids or by other treatments, marked inhibition of tumor growth was observed.