Figure 4. Presurgical estrogen deprivation in patients with ER+ breast cancer prevents RAD001-induced PI3K/AKT activation in tumors ex vivo.

Patients with early-stage ER+/HER2- breast cancer received either A. no presurgical treatment (Arm A, n = 10), or B. presurgical treatment with letrozole for 10-21 d (Arm B, n = 7). Within 1 h after surgical resection, 1-mm³ punch cores were taken from primary tumors ex vivo. Tumor cores were put in serum-free medium for 5 h, then treated +/− 20 nM RAD001, 4 μM OSI-906, or the combination for 1 h. Tumor lysates were analyzed by immunoblot using the indicated antibodies. Immunoblot film signals were quantified by densitometry. Signal values from control-treated tumors were set at “1.” Data are shown as log₂ P-AKT of inhibitor-treated sample relative to control. Horizontal bars indicate mean values. *p < 0.05 by Bonferroni multiple comparison-adjusted post-hoc test. C. Representative results are shown at right from 3 patients’ tumors from Arms A and B; actin or vinculin was assessed to confirm equal loading.