Effects of IM/BOR and IM/PSI on BCR-ABL signaling pathway.

(A): K562 cells treated with the agents for 24 h, and effects of IM/BOR and IM/PSI on phosphorylated BCR-ABL (pBCR-ABL, using an anti-pY20 antibody) and BCR-ABL oncoprotein (using an anti-ABL antibody), and on pSTAT5 (IP: anti-Stat5; WB: anti-pY20 antibody), pMAPK, E2F1 and c-Myc, were analyzed by western blot. (B): K562 cells treated with the agents for 24 h, and effects of IM/BOR and IM/PSI on BCR-ABL tyrosine kinase activity was assayed by a a tyrosine kinase assay kit. *, **: combination treatment groups compared with IM treatment alone, P = .004 and .006, respectively. (C): IM/BOR and IM/PSI inhibit pBCR-ABL in BCR-ABL/32D cells. (D): Treatment with IM/BOR and IM/PSI trigger catabolism of BCR-ABL characterized by generation of a catabolic fragment (CF) which is inhibited by caspase inhibitor z-VAD.fmk. NS, non-specific band. An anti-ABL antibody is used in this experiment. (E): K562 cells treated with the agents for 24 h, RNA was extracted, RT-PCR was conducted, and effects of IM/BOR and IM/PSI on E2F1 and c-Myc at mRNA level was detected.