Lack of growth inhibition by OSM in cyclin K–expressing A375 cells.
(A) Expression of cyclin K was verified by RT-PCR (lanes 1-3) and Western blot (using the M2 Flag monoclonal antibody, lanes 4-5) in A375 stable transfectants. (B-C) Parental or cyclin K–expressing A375 cells were plated in triplicate in 96-well dishes in the presence of 2% serum and a dilution series of the indicated cytokines. After 72 hours, 3H-thymidine was pulsed for 4 hours and the cells were assessed for 3H incorporation by scintillation counting. Panel B: ○, OSM; ▵, IL-6; ▪, medium alone. Panel C: ▴, TGF-β; ○, OSM; ■, blank. (D) TUNEL analysis was performed on serum-starved A375 cloned cells after no treatment (lanes 1, 4) or treatment with OSM (10 ng/mL) for 24 hours (lanes 3, 6). DNase was added to a sample of nontreated cells for 10 minutes as a positive control (lanes 2, 5).
