However, Pazopanib molecular weight a significantly greater amount of fragmen ted DNA was detected three hours after 3 Gy IR treatment in T oligo pretreated cells. Thus, combined treatment with T oligo and radiation results in enhanced response to DNA damage and or impaired DNA repair, leading to growth arrest and cell death. Increased induction of senescence and apoptosis in tumor cells pretreated with T oligo As the above studies show that cells pretreated with T oligo are more sensitive to IR, we next determined whether the Inhibitors,Modulators,Libraries treated cells undergo senescence or apopto sis. Tumor cells isolated from MMT mice were pre treated with T oligo or control oligo followed by radiation and then examined 24 hours later for the induction of senescence or apoptosis using senescence associated b galactosidase and TUNEL staining, respectively.

Increased numbers of large cells positive for S. A. b gal, two markers of senescent cells, were observed after T oligo Inhibitors,Modulators,Libraries treatment compared with control oligo treatment or medium alone. However, b gal positive cells increased signifi cantly in tumor cells treated with T oligo and 3 Gy compared with control oligo or no treatment and 3 Gy. A more profound effect of combined T oligo and IR was detected using the TUNEL assay. The apoptotic rate increased significantly to 20. 8 8. 5%, two to four times the control rates, in tumor cells Inhibitors,Modulators,Libraries trea ted with T oligo and 3 Gy. These results indicate that senescence and apoptosis may be impor tant pathways to inhibit proliferation of murine mam mary tumor cells treated with T oligo and IR. Both responses may also contribute to the observed decrease in clonogenic ability.

Given that rates of senescence and apoptosis have been previously observed to increase steadily in T oligo treated malignant cells over two to four days, depending on cell type, these determina tions made only 24 hours after irradiation, preceded by an overnight T oligo incubation, may underestimate the eventual impact of the treatment. Decreased tumorigenesis in mammary tumor Inhibitors,Modulators,Libraries cells treated with T oligo and irradiation To determine whether tumor cells can still form tumors in vivo after treatment with T oligo and radia tion, mammary tumor cells were preincubated with T oligo or control oligo for 24 hours followed by expo sure to 0 Gy or 3 Gy. The other control groups were tumor cells supplemented with medium alone or exposed to 3 Gy of radiation alone.

The tumor cells were then Inhibitors,Modulators,Libraries injected subcuta neously into the flanks of syngeneic wild type mice. As shown in Figure 4a, all PF-01367338 mice inoculated with tumor cells pretreated with T oligo alone developed tumors, but tumor size was reduced when compared with untreated and control oligo treated tumor cells on Day 30. However, the tumor forming ability of mammary tumor cells treated with combined T oligo and 3 Gy irradiation was almost eradicated. Only one out of four mice developed a tumor and this small tumor did not appear until after Day 25.