NC downregulated c-Myc protein level by accelerating degradation in K562 cells.

<p>(A and B) K562 cells were treated with 0, 2, 4, 6 or 8 μM NC for 2 days, or 8 μM NC for 0, 4, 8, 12, 24 and 48 hrs. Western blot analysis was performed to examine the expression level of c-Myc, and β-actin was used as internal control. (C) Real time qRT-PCR showed the <i>c-Myc</i> mRNA levels in K562 cells treated with indicated concentrations of NC for 2 days. <i>β-actin</i> was used as internal control. The values represent the means ± S.E. (n = 3). (D) K562 cells were exposed to 8 μM NC for 2 hrs, and then chased with 150 μg/mL CHX for 0, 20 and 40 mins. c-Myc and β-actin were detected by western blot. The values represent the means ± S.E. (n = 3). *, <i>P</i> < 0.05. **, <i>P</i><0.01. (E) K562 cells were stably transfected with shc-Myc or control shRNA. (F) K562 cells were stably transfected with pIRES-c-Myc or control plasmid. c-Myc protein (upper panel) and mRNA (lower panel) level was detected by western blot and real-time qRT-PCR, respectively. The values represent the means ± S.E. (n = 3). **, <i>P</i><0.01. (G) K562 cells stably transfected with shc-Myc, pIRES-c-Myc or control plasmid, were exposed to NC for 2 days. globin γ and β-actin were detected by western blot. (H) K562 cells stably transfected with shc-Myc, pIRES-c-Myc or control plasmid, were exposed to NC for 2 days. Apoptosis rate was detected by annexin V/PI double staining. The values represent the means ± S.E. (n = 3). *, <i>P</i> < 0.05.