Figure 2

Serum starvation-induced activation of ATM/p53 is required for the CDDP sensitization of cancer cells and both ATM and AMPK are necessary for the activation of p53. Western blot results with antibodies against p53 in protein extracts from ZL55 cells (A) and HCT116 (B) treated by Ku-55933 (Ku) alone, serum starvation alone, or both together are shown. Results of colony formation assay for the untreated control HCT116-p53^−/− and HCT116-p53^+/+ cells and those treated by CDDP alone, serum starvation alone (S), or both together p53-knockout (n=6, * P<0.02, ** P<0.01, significances were calculated with two-tailed t-Test) are shown in (C). Results of Western blot with antibodies against pAMPK and AMPK in protein extracts from untreated control ZL55 cells, or treated with CDDP alone or serum starvation alone are shown in (D). Results of Western blot with antibodies against p53-Ser15 (p53-S15), p53, pACC and ACC in protein extracts from the untreated control ZL55 cells and those after treatment with Compound C (C.C) alone, CDDP alone, CDDP and C.C together, serum starvation alone, or serum starvation and C.C together are shown in (E). Results of Western blot with antibodies against phospho-AKT-Ser473 (pAKT) and AKT in protein extracts from the untreated controlZL55 cells and after treatment with serum starvation alone, Ku55933 alone, serum starvation andKu55933 together, Compound C (C.C) alone, or serum starvation and C.C together are shown in (F). Results of Western blot with antibodies against phospho-S6-Ser235/236 (pS6) andS6 in protein extracts from the untreated control ZL55 cells and after treatment with serum starvation alone, Ku55933 alone or Compound C (C.C) alone are shown in (G). β-Actin and vinculin were used as loading controls.