Hydrocortisone stimulates fibronectin synthesis in cultured fibroblasts

The effect of hydrocortisone on fibronectin synthesis was investigated in cultured skin fibroblasts. Confluent cells were treated with hydrocortisone (10(-7) M to 10(-5) M) for 2 days and labeled with [3H]proline for 24 h. Fibronectin levels in both the culture medium and the cell layer were studied by gelatin-Sepharose affinity chromatography and SDS-polyacrylamide gel electrophoresis. In control cultures of human fetal skin fibroblasts, fibronectin constituted 8% of the total labeled proteins in the medium. The proportion of fibronectin increased to 13.1% at 10(-7) M hydrocortisone, 15.5% at 10(-6) M and to 19.4% at 10(-5) M. The proportion of fibronectin associated with the cell layer remained at 2-3% of total [3H]proline-labeled proteins and did not increase with hydrocortisone exposure. The stimulating effect of hydrocortisone on medium fibronectin was also demonstrated in cultured human newborn foreskin fibroblasts and in rabbit skin fibroblasts.