Incomplete biologic resistance of 32D_Bcr-Abl cells expressing mutants resistant to CGP76030 and PP1.

Incomplete biologic resistance of 32D_Bcr-Abl cells expressing mutants resistant to CGP76030 and PP1 correlates with inhibition of Src kinases and Akt. (A-B) Proliferation (panel A) and survival (panel B) of 32D cells expressing Bcr-Ablwt or the various mutants of Bcr-Abl at positions 315 and 380 in response to imatinib mesylate, PP1, or CGP76030. First, 5 × 10⁴ cells were seeded per 6 wells and treated with DMSO, 2.5 μM imatinib mesylate, 50 μM PP1, and 5 μM CGP76030. Survival and proliferation were determined 48 hours later by FACS analysis and trypan blue exclusion. (C-D) Phospho-Abl, phospho-Src, panphosphotyrosine, phospho-STAT5, phospho-Jnk, and phospho-Akt Western blots of 32D_Bcr-Ablwtor 32D_{Bcr-AblThr315Gln} cells treated with the indicated concentrations of imatinib mesylate, PP1, and CGP76030 1.5 hours prior to lysis. Equal expression of the various signaling molecules in the presence of the various inhibitors was assessed with the use of rabbit polyclonal antibodies to Abl, Src, Fyn, Lyn, STAT5, Jnk, and Akt.