GlucocorticoidReceptorsin Morris Hepatomasand Host Liver and the Correlationof BiologicalActivity with Receptor Levels1

SUMMARY Glucocorticoid-binding macromolecules were examined inMorrishepatomas7787,5123tc,3683F,7800,and 3683 and the Reuber hepatoma H-35with the use of the synthetic glucocorticoid , tniamcinobone acetonide. The physical properties of the triamcinobone acetonide-binding macro molecules of the hepatomas indicate that they are specific glucocorticoid receptors. The equilibrium association con stants (Ka), sedimentation coefficients, and sensitivity to sulfhydryl-bbocking reagents were found to be similar when hepatoma receptors were compared with the known prop erties of the liver receptor. Probably the most convincing criterion that the tniamcinobone acetonide-binding macro molecules from the hepatomas are specific receptors is that 50 to 90% @ of the receptor can be depleted from hepatoma cytosob by treating rats with cortisol. In adrenal ectomized tumor-bearing rats, the receptor levels in hepa tomas 7787, 7800, 5123tc, and H-35 are comparable to or greater than receptor levels of host liver. However, trypto phan oxygenase was not responsive to glucocorticoids in hepatoma 7800 although receptor levels were quite high, and there were no indications that the receptor molecules were altered. Hepatomas 3683 and 3683F have low levels of receptor which may be rebated to resistance of these tumors to glucocorticoid treatment.