Effect of triamcinolone acetonide on the growth of NEL-M1 human melanoma cells cultured in the presence and absence of growth stimulatory agents.

The human melanoma cell line NEL-M1 proliferates in Ham's F-12 medium in the absence of serum, hormones, and growth factors. Culturing NEL-M1 cells in defined medium supplemented with insulin (5 micrograms/ml) and transferrin (5 micrograms/ml) results in a 94% increase in [3H]thymidine incorporation after 24 h and a 6- to 8-fold increase in cell number after 5 days. The addition of 17 beta-estradiol, testosterone, and progesterone to defined medium, either as single agents or in combination with insulin and transferrin, had no effect on cell growth. No specific estrogen, androgen, or progesterone receptor proteins were detected in NEL-M1 cells. In contrast, the synthetic glucocorticoid triamcinolone acetonide (10 nM) inhibited growth of NEL-M1 cells in serum-free Ham's F-12 medium by 50%. The 6- to 8-fold stimulation of cell growth by insulin and transferrin was reduced to 1.75-fold when triamcinolone acetonide (10 nM) was added to the medium. Additional studies show that medium conditioned by NEL-M1 cells stimulated [3H]thymidine incorporation into cellular DNA of NEL-M1 cells and increased the growth of NEL-M1 cells 3-fold over cells maintained in defined medium. The addition of triamcinolone acetonide (10 nM) to defined medium supplemented with conditioned medium resulted in only a 1.48-fold increase in cell number. These results show that triamcinolone acetonide inhibits growth of NEL-M1 human melanoma cells in serum-free defined medium, medium supplemented with insulin and transferrin, and medium supplemented with an endogenous growth stimulatory factor(s). Thus, NEL-M1 cells are an excellent model system to study the mechanism of action of glucocorticoids and also the interplay between exogenous hormones and growth factors and endogenous growth factors.