Figure 2.

Beclin1 overexpression in K562 cells induces BCR/ABL downregulation and promotes cell death via autophagic stimulation. (A) K562-NC or K562-Beclin1 cells were subjected to Western blot analysis to assess the levels of BCR/ABL, cleaved caspase-3 and cleaved PARP. The specific caspase-3 inhibitor DEVD was used to inhibit caspase-dependent apoptosis. (B) The indicated cells were cultured with or without the autophagy inhibitor 3-MA (5 mM) or the proteasomal inhibitor Epo (500 nM) for 24 h. Cell viability was measured using the CCK-8 assay. Data are presented as the mean ± SD of three independent experiments; *P<0.05, **P<0.01. (C) Representative TEM photomicrographs of K562-Beclin1 and control K562 cells treated with 3-MA (5 mM) or Epo (500 nM) for 24 h and untreated cells. Arrows, autophagic vacuoles. Scale bars, 0.5 μm. (D) Western blot analysis of the levels of BCR/ABL and other autophagy-related proteins in K562-Beclin1 and K562-NC cells. Cells were pretreated in the absence or presence of 3-MA (5 mM) or Epo (500 nM) for 24 h. The results are representative of three independent experiments.

Abbreviations: NC, negative control; 3-MA, 3-methyladenine; Epo, epoxomicin; DEVD, Z-DEVD-FMK.