Fig. 2

JAK2/STAT3 signaling activation is associated with a radioresistance phenotype in CRC cells. a HCT116 cells transfected with the shCTRL vector or shJAK2 vector were subcutaneously injected into mice. When the primary tumor volume reached approximately 200 mm³ (day 0), the primary tumors were irradiated to 8 Gy (shCTRL: n = 9; shCTRL+RT: n = 9; shJAK2: n = 9; and shJAK2 + RT: n = 9), and the primary tumor volume was measured twice a week until death. b The mice were sacrificed on day 42, and the primary tumors were isolated for subsequent experiments. The primary tumor volume on the day of sacrifice is presented. c and d The anchorage-independent growth of cells was estimated by soft agar assays. Cells with JAK2 knockdown (c) or Stattic treatment (d) were irradiated (2 Gy) and seeded on 12-well plates mixed with agar. After 2 months of incubation, the survival fraction was calculated based on the number of surviving colonies (50 μ) as a percent of that of the unirradiated control group. e Effect of JAK2 knockdown or Stattic treatment on radiation-induced apoptotic cells (Annexin V⁺) at 24 h after irradiation (2 Gy). f Radiation-induced apoptosis was evaluated by the expression level of cleaved-PARP (C-PARP) and cleaved caspase 3 (C-caspase-3) at 24 h after irradiation. Statistical analyses were implemented using one-way ANOVA followed by Dunnett’s multiple comparison test against the control group or by Student’s t-test between two groups; *, **, and *** indicate p < 0.05, p < 0.01, and p < 0.001, respectively