Figure 4

Hormones reactivate dormant luminal micrometastases. (A) Ovariectomized (Ovx’d) non-obese diabetic/severe combined immunodeficient gamma (NSG) mice were intracardiac (IC)-injected with 10⁵ luciferase- and ZsG-tagged E3 cells without hormone supplementation (cellulose, or C) and monitored for 8 weeks. At week 8, the C pellet was removed and replaced with C (n = 11), estrogen (E) (n = 16), progestin (P) (n = 15), or estrogen + progestin (E+P) (n = 17)-releasing pellets for another 7 to 8 weeks. Weekly bioluminescent luciferase imaging (BLI) imaging in live mice by in vivo imaging systems (IVIS). Data are presented as mean ± standard error of the mean (SEM) of BLI signal. *P <0.05, **P <0.005, Student’s t test. (B) Bar graph shows the percentage of mice in each treatment group—C (green), E (blue), E+P (red), and P (gray)—with E3 metastases in distant organs without (C) or with E, P, or E+P restoration. Data are presented as mean percentages per group. (C) Immunohistochemistry (IHC) for CK8/18, ER, PR, and CK5 in organs with E3 micrometastases (C) and macrometastases (E or E+P). For percentage of CK5⁺ cells, mean ± SEM values are shown (n = 3 per group). Scale bars: 50 μm. (D) IHC for CK8/18 and nuclear proliferation marker (Ki67) in organs with E3 or MCF-7 micrometastases (C) and macrometastases (E+P). For percentage of Ki67⁺ cells, mean ± SEM values are shown (n = 3 per group). Scale bars: 50 μm.