EKLF induces hemoglobinization and slowing of growth when activated by 4-hydroxytamoxifen.
(A) Photograph of cell pellets of A2 and A2.3 that were seeded at a density of 105 cells/mL and cultured for 72 hours in ethanol (minus sign) or 4-hydroxytamoxifen (plus sign). Cells were washed in PBS, transferred to Eppendorf tubes, repelleted, and photographed. (B,C) Growth curves for cells treated for 3 days in either vehicle (open boxes) or 100 nM 4-hydroxytamoxifen (solid circles). Counts of viable cells were done daily in a hemocytometer by using trypan blue exclusion and plotted as the mean cell numbers from 4 independent experiments. Tamoxifen induced a significant slowing of growth in the 2 subclones of A2 that expressed substantial amounts of EKLF (A2.3 and A2.1) but had no significant effect on the parent line A2 or the derived line A2.4 that expressed barely detectable amounts of EKLF-ER™ (B). There appeared to be some slowing of growth of the A2.6 cell line with tamoxifen, but results were not significant. All 3 subclones of B1 (B1.8, B1.9, and B1.10) showed a marked slowing of growth on activation of EKLF (C). ■ indicates EtOH; ●, tamoxifen.
