Glucocorticoids increase the 1,25(OH)2D3 receptor concentration in rat osteogenic sarcoma cells

We have used cultured osteoblastlike rat osteogenic sarcoma cells (ROS 17/2) which have receptors for 1,25(OH)2D3 and for glucocorticoids, and have examined the modulation of the 1,25(OH)2D3 receptor by the potent glucocorticoid triamcinolone acetonide. We report that triamcinolone acetonide caused an increase of the 1,25(OH)2D3 receptor concentration in these cells but it did not affect the affinity of the receptor to 1,25(OH)2D3; this phenomenon occurred in a dose-dependent fashion for triamcinolone (10(-9) to 10(-7) M) with a maximum increase of 1,25(OH)2D3 receptor concentration of approximately equal to twofold. During the culture period, the 1,25(OH)2D3 receptor concentration was altered both in untreated as well as in triamcinolone-treated cells, being highest at the early logarithmic phase and diminished progressively as cells approached confluence. However, throughout the culture period, the 1,25(OH)2D3 receptor concentration was higher in the triamcinolone-treated cells.