Figure 4.
IR + ABT-888 induces persistent IRIF and senescence in vivo and suppresses MCF7Tet-On GFP-IBD tumor regrowth. A, Dose-response of IRIF formation in xenograft tumor cells 24 h after IR. Scale bar, 10 μm. B, IR + ABT-888 increases residual IRIF compared to IR alone. Intravital imaging of GFP-IBD foci in tumors at 3 and 24 h after 3 Gy ± ABT-888. Scale bar, 10 μm. C, SA-βGal activity in tumors treated with IR ± ABT-888. Frozen sections of excised tumors 7 d after IR were fixed and stained. Scale bar, 20 μm. D, ABT-888 + IR suppresses tumor regrowth. Tumor growth was significantly delayed after 6 Gy + ABT-888 (solid squares) compared to 6 Gy (solid circles). Data graphed as mean fractional volume (V/Vo) ± SEM (n = 4/group).