Figure 5. Combination therapy extends survival of mice bearing intracerebral BT74 tumors.

A. (Upper) Athymic mice intracerebrally implanted with BT74 were sacrificed on day 30. Shown is a representative section of the brain with untreated BT74 tumor (H&E staining) illustrating intratumoral hemorrhage (arrow). (Lower) Mice treated with MG18L (2×10⁶ pfu) on day 28 were sacrificed 12 hrs (left) and 36 hr (right) later. Sections were stained with X-gal (blue) to indicate MG18L infected cells. B. A region at the edge of the tumor from a 36 hr pi brain after immunostaining with antibodies against β-gal (green; MG18L infected cells) and human nucleus (red; BT74 cells), followed by DAPI (total nuclei) (scale bar = 100 μm). Virus was injected to the right of the displayed field. C. Kaplan-Meier survival curves of mice bearing BT74 tumors after treatment with intratumoral MG18L (2×10⁶ pfu) or Mock, and intraperitoneal LY294002 (LY; 25mg/Kg/day) or vehicle (Mock, n=10; MG18L, n=10; LY294002, n=6; Combination n=6). p<0.05 (mock vs LY294002 and LY294002 vs MG18L+LY294002), <0.0005 (mock vs MG18L) (Log-rank test). D. Mice with BT74 tumors treated with mock, MG18L, LY294002, or the combination were sacrificed 36 hrs after MG18L injection. Brains were sectioned and tumors immunostained with antibodies to β-gal (green; MG18L) and cleaved caspase-3 (red; apoptosis) followed by DAPI (scale bars = 100μm). E. The ratio of cleaved caspase-3 positive cells/total was determined in three randomly selected fields (* p < 0.05, ** < 0.01).