OSU-03012 sensitizes TIB-196 myeloma cells to imatinib mesylate via AMP-activated protein kinase and STAT3 pathways.

Although c-Kit is expressed on the surface of myeloma cells in one-third of myeloma patients, the efficacy of imatinib mesylate for patients with myeloma is still controversial. To investigate the combinatorial effect of OSU-03012 and imatinib mesylate, we treated a c-Kit-expressing myeloma cell line, TIB-196, with DMSO, OSU-03012 alone, imatinib mesylate alone and OSU-03012 plus imatinib mesylate. OSU-03012 sensitized TIB-196 cells to imatinib mesylate cytotoxicity. p-STAT3 (Tyr705), as well as down-stream cyclin D1 and Mcl-1, was down regulated. Additionally, there was markedly increased p-AMPK (Thr172) and down-regulation of p-p70S6K (Thr386) in the combination group. Combined treatments targeting c-Kit, AMPK and STAT3 may be a potential strategy for treating patients with myeloma. Copyright 2009 Elsevier Ltd. All rights reserved.