The effect of dexamethasone on epidermal growth factor binding and stimulation of proliferation in young and senescent WI38 cells.

Addition of 0.14 microM dexamethasone (DEX) to young log-phase WI38 cultures seeded at various densities in serum-free medium containing 4.1 nM epidermal growth factor (EGF) resulted in a synergistic increase in proliferation and final cell density. The action of DEX plus EGF was stimulatory but not synergistic in young confluent cultures. DEX plus EGF had no synergistic effect on senescent cells either during log phase or at confluence. Analysis of the effect of DEX on [125I]EGF binding revealed no statistically significant changes in either the number of binding sites or the apparent dissociation constant of the EGF-receptor complex.