Figure 2. Rapamycin induces regression of primary tumors and peri-tumoral hyperplastic epithelium in MMTV-c-Neu mice.

A. Rapamycin inhibits or regresses growth of primary tumors. Mice bearing mammary tumors were treated with 150 μg of rapamycin (n=5) or vehicle (n=5) every other day for 32 days. External tumor volumes were measured for rapamycin and vehicle treated mice every four days using external calipers. Volumes were computed as described in Materials and Methods. Fold changes in tumor volume, normalized to the initial volume, are shown for each tumor. Black lines represent vehicle-treated tumors and grey lines represent rapamycin-treated tumors. B. Rapamycin induces necrotic cavitation of primary tumors. Representative H&E stained sections of tumors taken from mice treated for 32 days with either vehicle or rapamycin. The dark line circumscribes the perimeter of the tumor. The dotted inner line in the rapamycin treated section circumscribes a grossly necrotic core. C/D. Representative H&E stained sections (100x, bar 50μM) of peri-tumoral regions collected from mice treated with either C) vehicle or D) rapamycin. The tumor is marked with an asterisk (*) and a hyperplastic, distended duct is marked with an arrow