Figure 6

Wnt1-tumorigenesis and wt and RARα1 /KO transplanted tumor growth. (a) Representative histograms of flow cytometry analysis of CD24^low/ALDH^high cells in FVB-wnt1 and FVB-wnt1-RARα1/KO- mammary glands. Primary mammary cells were isolated from glands of seven-week-old mice and processed for flow cytometry analysis as described in Figure 3. (b) Summary of flow cytometry experiments. The experiments were carried out as in A; each dot represents individually processed sample. Statistical analysis, two way ANOVA, P = 0.0025. (c) Tumor-free survival (Kaplan-Meier curve). Forty female mice transgenic for Wnt1 and wt-RAR and 42 RARα/KO were allowed to age and were examined at regular intervals for the appearance of a palpable tumor nodule. The difference in disease-free survival (percent of tumor-free mice), plotted as a function of post-natal age (Kaplan-Meier curve) was statistically significant (P = 0.0002). (d) Transplanted MMTV-RARα1/KO-wnt1 tumor fragments have slower growth rate than MMTV-wnt1 tumors. Fragments of randomly chosen pairs of MMTV-wnt1/wt and MMTV-wnt1/RARα1/KO tumors were transplanted into the opposite flanks of wt-FVB hosts. The tumors were measured every three days. The bars show mean and SE (n = 12 per group, P = 0.01. two-way ANOVA test). (e) Inoculation of MMTV-wnt1/RARα1/KO cell suspensions produces tumors after longer latency. Cell suspensions (10⁵ and 10⁴) prepared from a pair of similar size MMTV-wnt1/RARα1/KO and MMTV-wnt1 tumors were inoculated into eight to ten FVB-mice, (as in D) and appearance of palpable tumors was recorded and plotted as fraction of tumor-free mice vs. days post-inoculation (Kaplan-Meier).