Survivin is a 16.5 kDa protein highly expressed in centrosomes, where it controls proper sister chromatid separation. In addition to its function in mitosis, survivin is also involved in apoptosis. Overexpression of survivin in many cancer types makes it a suitable target for cancer therapy. Western blotting and confocal microscopy were used to characterize the effect of chemotherapy on acute myeloid leukemia (AML) cells. We found enhanced survivin expression in a panel of AML cell lines treated with cytarabine (Ara-C), which is part of a first-line induction regimen for AML therapy. Simultaneously, Ara-C caused growth arrest and depletion of the mitotic cell fraction. Subsequently, the effect of a second component of standard therapy protocol, idarubicin, and of a known survivin inhibitor, YM-155, on cell viability and survivin expression and localization in AML cells was investigated. Idarubicin reversed Ara-C-induced survivin upregulation in the majority of AML cell lines. YM-155 caused survivin deregulation together with a viability decrease in cells resistant to idarubicin treatment, suggesting that YM-155 might be efficient in a specific subset of AML patients. Expression levels of other apoptosis-related proteins, in particular X-linked inhibitor of apoptosis (XIAP), Mcl-1, and p53, and of the cell-cycle inhibitor p21 considerably changed in almost all cases, confirming the off-target effects of YM-155.
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