TY - JOUR
T1 - Sorafenib induces apoptosis of AML cells via Bim-mediated activation of the intrinsic apoptotic pathway
AU - Zhang, W.
AU - Konopleva, M.
AU - Ruvolo, V. R.
AU - McQueen, T.
AU - Evans, R. L.
AU - Bornmann, W. G.
AU - McCubrey, J.
AU - Cortes, J.
AU - Andreeff, M.
N1 - Funding Information:
We thank Ms Wenjing Chen for valued assistance in the collection of the patient clinical information and Ms Betty L Notzon for critical review of this paper. This work supported in part by grants from the National Institutes of Health CA55164 and CA100632 (to MA and MK) and a Leukemia SPORE (CA100632) Career Development Award (to WZ).
PY - 2008/4
Y1 - 2008/4
N2 - Raf/MEK/Erk signaling is activated in the majority of acute myeloid leukemias (AMLs), providing rationale for targeting this pathway with therapeutic intent. We investigated growth-inhibitory and proapoptotic effects of sorafenib in AML. Our studies demonstrated that sorafenib significantly inhibited the phosphorylation levels of Raf downstream target proteins MEK1/2 and Erk, induced apoptosis and inhibited colony formation in AML cell lines and in primary AML samples. Mechanistically, treatment with sorafenib resulted in upregulation of proapoptotic Bim, accompanied by an increase in Bad, Bax and Bak protein levels and decreased Mcl-1, X-linked inhibitor of apoptosis and surviving levels, which mainly led to the activation of the intrinsic apoptotic pathway. Silencing of Bim protein expression significantly abrogated sorafenib-induced apoptosis, suggesting a critical function of Bim in the activation of the intrinsic mitochondrial pathway induced by sorafenib. Importantly, sorafenib also modulated phospho-Erk, Bim, Bax and Mcl-1 levels in samples procured from patients in an ongoing Phase I clinical trial of sorafenib in AML. Combination of sorafenib with cytarabine or the novel small molecule Bcl-2 inhibitor ABT-737 synergistically induced cell death in AML cell lines. Our results strongly suggest potential activity of sorafenib as a novel mechanism-based therapeutic agent in AML.
AB - Raf/MEK/Erk signaling is activated in the majority of acute myeloid leukemias (AMLs), providing rationale for targeting this pathway with therapeutic intent. We investigated growth-inhibitory and proapoptotic effects of sorafenib in AML. Our studies demonstrated that sorafenib significantly inhibited the phosphorylation levels of Raf downstream target proteins MEK1/2 and Erk, induced apoptosis and inhibited colony formation in AML cell lines and in primary AML samples. Mechanistically, treatment with sorafenib resulted in upregulation of proapoptotic Bim, accompanied by an increase in Bad, Bax and Bak protein levels and decreased Mcl-1, X-linked inhibitor of apoptosis and surviving levels, which mainly led to the activation of the intrinsic apoptotic pathway. Silencing of Bim protein expression significantly abrogated sorafenib-induced apoptosis, suggesting a critical function of Bim in the activation of the intrinsic mitochondrial pathway induced by sorafenib. Importantly, sorafenib also modulated phospho-Erk, Bim, Bax and Mcl-1 levels in samples procured from patients in an ongoing Phase I clinical trial of sorafenib in AML. Combination of sorafenib with cytarabine or the novel small molecule Bcl-2 inhibitor ABT-737 synergistically induced cell death in AML cell lines. Our results strongly suggest potential activity of sorafenib as a novel mechanism-based therapeutic agent in AML.
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U2 - 10.1038/sj.leu.2405098
DO - 10.1038/sj.leu.2405098
M3 - Article
C2 - 18200035
AN - SCOPUS:42349087045
SN - 0887-6924
VL - 22
SP - 808
EP - 818
JO - Leukemia
JF - Leukemia
IS - 4
ER -