Figure 5

N1ICD induction promotes a tumorigenic behavior. (A) Growth of xenografts derived from MCF-7 B12 clone with induced N1ICD (-Doxy) or without N1ICD (+Doxy) expression. Mice also had 17α-ethynyl estradiol (+EE2) in the drinking water. The arrow indicates the 12^th week when DOXY treatment was switched between both groups of mice. (B) Growth of N1ICD-induced B12 cells in the absence of estrogen (+EE2) administration. The arrow indicates the week 12^th when DOXY treatment was switched. Data are mean ± SEM of n = 8 (four mice and two tumors per mice; *P <0.05 determined by two-way ANOVA with Bonferroni post-test). (C) Western blot showing expression of myc-tagged N1ICD in B12 tumors at 12^th week of cell inoculation. (D) MCF-7 Tet-Off or the MCF-7 B12 clone engineered to express luciferase injected in the mammary gland of BALBc/SCID mice were monitored by bioluminescence emission at the time of cell inoculation and after 12 weeks as indicated. Selected images of two independents experiments, four animals per group. (E) Growth dynamics measured by luminescence of MCF-7 B12 clone with (-DOXY) or without (+DOXY) N1ICD expression. (F) Growth of control MCF-7 clones in the same conditions. Data are mean ± SEM of n = 8 (four mice and two tumors per mice; ***P <0.001 determined by two-way ANOVA with Bonferroni post-test), representative of two independents experiments. DOXY, doxyxycline; MCF-7, Michigan Cancer Foundation-7 breast cancer cell line; N1ICD, Notch one intracellular domain