Figure 7

Wnt1 rescues breast tumor cells from the anti-proliferative effects of 4-hydroxytamoxifen (4-HT). T47D (a) or MCF-7 (b) cells were treated with 4-HT (5 μM), PKI166 (5 μM), or a combination of both drugs for 7 or 6 days, respectively, in the presence or absence of Wnt1 conditioned medium (CM) or control CM. For control experiments, the solvents ethanol and dimethyl sulfoxide, respectively, were added in corresponding concentrations. Cultures were re-fed with fresh medium and inhibitors after 3 days, before cell number (± standard error) was determined. For biochemical analysis, T47D cells were treated under corresponding conditions with 4-HT (5 μM), AEE788 (2 μM), or a combination of both in the absence or presence of Wnt1 CM or control CM for 2 hours or 3 days. Total lysates were analyzed by SDS-PAGE/immunoblotting for p-ERK1/2 and ERK1/2. *p < 0.05, **p < 0.005, unpaired Student t test. ERK1/2, extracellular signal-regulated kinase 1/2; n.s., difference not significant; WB, Western blotting.