Fig. 3.

Ganetespib sensitizes HCT 116 colon cancer cells to ionizing radiation. a HCT 116 cells were treated with increasing doses of ganetespib either alone or in combination with 2 Gy dosing of irradiation (Ganetespib + 2 Gy). At 48 h post-IR, quantification of apoptosis was assessed by Annexin V-positivity measured by flow cytometry. b HCT 116 cells were treated with increasing doses of ganetespib (0, 25, 50 and 100 nM), either alone or in combination with 2 Gy irradiation. At 24 h post-treatment, lysates were prepared and immunoblotted using antibodies against CHK1, CHK2, RAD51, phosphorylated histone H2AX (p-histone H2AX), cleaved Caspase 7, and cleaved PARP. GAPDH was included as a loading control. c Representative images of HCT 116 cells treated with vehicle, 100 nM ganetespib, irradiated with a single dose of 2 Gy or simultaneously treated with the combination for 48 h, as indicated. Immunofluorescence was performed on cells stained for actin (red) and DAPI (blue). Arrowheads depict examples of large, multinucleated cells. Original magnification, 20×