RELATIONSHIPS BETWEEN STEROID BINDING AND ELEVATION OF ALKALINE PHOSPHATASE IN HELA CELLS

1. 1. Elevation of alkaline phosphatase (orthophosphoric monoester phosphohydrolase, EC 3.1.3.1) by prednisolone in growing cultures of HeLa-S3 cells was partially inhibited by several C21 steroids. The requirement necessary to bring about this effect included the 11-deoxy structure of the steroid. The reversal was observed also with those 11-hydroxysteroids which were inactive as alkaline phosphatase inducers because they lacked a hydroxyl in position 17 (e.g. corticosterone). In contrast, the 11-ketosteroids were inactive as inhibitors of alkaline phosphatase induction. The reduced derivatives of cortisol (e.g. tetrahydrocortisol) were similarly inactive. 2. 2. Ability to reverse elevation of alkaline phosphatase seemed to be related to the interference with binding of cortisol at the cell surface. This was evidenced by the lack of specific binding competition in cells detached from glass by treatment trypsin or by mechanical removal. © 1969.