Fig. 1

WNT4 is necessary for estrogen-induced growth in invasive lobular carcinoma (ILC) cells. a Breast cancer cell lines (BCCLs) were reverse-transfected with 10 nM siWNT4 or siSCR (Scrambled siRNA control) pools. WNT4 expression was assessed by quantitative polymerase chain reaction. Bars represent mean of biological triplicate ± SD. p < 0.05 for each siSCR vs siWNT4 (t test). b BCCLs were transfected as in (a) with increasing concentrations of small interfering RNA (siRNA), and proliferation was assessed 6 days posttransfection. siWNT4-treated cell proliferation was normalized to siSCR of equivalent concentration. *p < 0.01 by analysis of variance (ANOVA) of siRNA effect (siSCR vs siWNT4). c MDA-MB-134-VI (MM134) cells were hormone-deprived and reverse-transfected with siSCR or individual siWNT4 constructs. Cells were then treated with 100 pM 17β-estradiol (E2) or 0.01 % EtOH approximately 16 h posttransfection, and proliferation was assessed at the indicated time posttreatment. *,p < 0.0001 by ANOVA of E2 effect (siSCR without E2 vs with E2). x p = n.s. by ANOVA of E2 effect (siSCR without E2 vs either siWNT4). d Cells were treated as in (c), and proliferation was assessed 6 days posttreatment. *p < 0.05 for condition with E2 siSCR vs siWNT4 (t test). n.s. Not significant. e BCCLs were reverse-transfected with 10 nM siWNT4 or siSCR. The following day (after approximately 16 h), cells were treated with CellTox Green dye and 1 μM ICI 182,780 (fulvestrant; ICI) or staurosporine (STS) as indicated. Increased fluorescence represents accumulation of nonviable cells. Time points represent repeated measures of the same initial cell populations. *p < 0.05 by two-way ANOVA vs control, treatment effect. IDC Invasive ductal carcinoma, 44PE SUM44PE cell line