Anti-proliferative effect of NTAPP on doxorubicin-resistant cancer cells.

<p>(A–D) (A, B) HCT15/CLO2 (C, D) and MES-SA/dx5 cells were exposed with 5 V input NTAPP for 30 s every h 10 times, and cell viability was evaluated at each indicated exposure frequency. Incubation time indicates the time after the initial NTAPP exposure. The 24-h incubation was prepared with 10 repetitive exposures of NTAPP and further incubation for 15 h. (A, C) The relative percentage of viable cells is shown compared with the initial cell number prior to the exposure and incubation as 100%. Viable cells were quantified with MTT assays, and data are shown as the mean ± SEM from three independent experiments. <i>p</i><0.01 (**) indicates a significant difference compared with the control. (B, D) For the same NTAPP-exposed samples of (A) and (C), respectively, γ-H2AX, caspase-3, cleaved caspase-3, PARP, and cleaved PARP were assessed by western blot analyses. Actin is shown as a loading control for western blot.