STEROID-REGULATED GROWTH OF DDT(1)MF-2 CELLS IS PROFOUNDLY INFLUENCEDBY CULTURE CONDITIONS

DDT(1)MF-2 cells provide an ideal model for studying tumor-growth-stim ulation by steroids. These cells progress to a rapidly proliferating, androgen-independent state after prolonged culture without androgen, A fter brief culture in different lots of fetal bovine serum (FBS), some lots induced a permanent state of hormone-independence in cells that had been androgen-responsive, To test the hypothesis that factors infl uenced androgen-responsive growth even after removal of serum, hormone -responsive DDT(1)MF-2 cells (7000 cells/well) were plated in medium D ulbecco's Modified Eagle Medium/F-12 Nutrition Mixture (1:1)/1% ITS wi th (a) 0.1% FBS, (b) 0.1% nM Serum (c) 0.1% Hyclone, or (d) MCDB-110/0 .1% ITS with 5 ng/ml bFGF. On Days 2-8, medium was replaced with D-MEM /F12/ITS with 10 nM testosterone une (T), 10 nM triamcinolone acetonid e (TA), or ethanol (control) and the cells counted. While testosterone induced a 1.4-fr,ld increase in cell growth after exposure to FBS or NuSerum, maximal testosterone effect (3-6-fold increase) was observed after Hyclone. Hydroxyflutamide antagonized the fivefold increase in g rowth observed with testosterone, with a slight decrease of growth wit h cAMP for cells plated in Hyclone. Androgen-independent cells were un affected by testosterone, hydroxyflutamide. or 8BR-cAMP [medium (a)] M aximal inhibition by triamcinolone acetonide (0.25 of control) was obs erved with medium (d). The effect of testosterone and triamcinolone ac etonide on secretion of mitogenic activity into conditioned medium was also evaluated. Although conditioned media from control and testoster one-treated cells were mitogenic in a dose-dependent manner, the media from cells treated with triamcinolone acetonide and testosterone + TA conditioned medium was not mitogenic-but, of note, it was not growth inhibitory.