Figure 2

Radiation induced AMPK-dependent senescence and glycolytic enhancement in securin-knockdown MDA-MB-231-2A cells. (a) MDA-MB-231-2A cells were exposed to 6 Gy radiation followed by various recovery periods. The protein expression was examined by western blot analyses. (b) MDA-MB-231-2A cells were pretreated with 5–20 μM compound C for 2 h and then exposed to 6 Gy radiation. The protein expression was examined by western blot analyses after an 8-h recovery period. (c) MDA-MB-231-2A cells were pretreated with 5 or 10 μM compound C for 2 h and then exposed to 6 Gy radiation. After 2 days of recovery, cellular senescence was examined by senescence-associated β-galactosidase (SA-β-gal) staining. Senescent cells (blue staining) were observed by bright-field microscopy, and the percentage of SA-β-gal-positive cells was quantified. **P<0.01 indicates significant differences between control and irradiated cells. ^##P<0.01 indicate significant differences between inhibitor-treated and untreated cells. (d) MDA-MB-231-2A cells were pretreated with 5 or 20 μM compound C for 2 h, and then exposed to 6 Gy radiation. After a 24-h recovery period, the LDH enzymatic activity was examined by protocols described in the Materials and Methods section. **P<0.01 indicates significant differences between control and irradiated cells. ^##P<0.01 indicates significant differences between inhibitor-treated and untreated cells. (e) MDA-MB-231-2A cells were pretreated with 10 μM compound C for 2 h, and then exposed to 6 Gy radiation. After a 24-h recovery period, the lactate concentration in the culture medium was examined by protocols described in the Materials and Methods section. **P<0.01 indicates significant differences between control and irradiated cells. ^##P<0.01 indicates significant differences between inhibitor-treated and untreated cells