TY - JOUR
T1 - Antagonism of SET using OP449 enhances the efficacy of tyrosine kinase inhibitors and overcomes drug resistance in myeloid leukemia
AU - Agarwal, Anupriya
AU - MacKenzie, Ryan J.
AU - Pippa, Raffaella
AU - Eide, Christopher A.
AU - Oddo, Jessica
AU - Tyner, Jeffrey W.
AU - Sears, Rosalie
AU - Vitek, Michael P.
AU - Odero, María D.
AU - Christensen, Dale J.
AU - Druker, Brian J.
PY - 2014/4/15
Y1 - 2014/4/15
N2 - Purpose: The SET oncoprotein, a potent inhibitor of the protein phosphatase 2A (PP2A), is overexpressed in leukemia. We evaluated the efficacy of SET antagonism in chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) cell lines, a murine leukemia model, and primary patient samples using OP449, a specific, cell-penetrating peptide that antagonizes SET's inhibition of PP2A. Experimental Design: In vitro cytotoxicity and specificity of OP449 in CML and AML cell lines and primary samples were measured using proliferation, apoptosis, and clonogenic assays. Efficacy of target inhibition by OP449 was evaluated by immunoblotting and PP2A assay. In vivo antitumor efficacy of OP449 was measured in human HL-60 xenografted murine model. Results: We observed that OP449 inhibited growth of CML cells including those from patients with blastic phase disease and patients harboring highly drug-resistant BCR-ABL1 mutations. Combined treatment with OP449 and ABL1 tyrosine kinase inhibitors was significantly more cytotoxic to K562 cells and primary CD34 CML cells. SET protein levels remained unchanged with OP449 treatment, but BCRABL1- mediated downstream signaling was significantly inhibited with the degradation of key signaling molecules such as BCR-ABL1, STAT5, and AKT. Similarly, AML cell lines and primary patient samples with various genetic lesions showed inhibition of cell growth after treatment with OP449 alone or in combination with respective kinase inhibitors. Finally, OP449 reduced the tumor burden of mice xenografted with human leukemia cells. Conclusions: We demonstrate a novel therapeutic paradigm of SET antagonism using OP449 in combination with tyrosine kinase inhibitors for the treatment of CML and AML.
AB - Purpose: The SET oncoprotein, a potent inhibitor of the protein phosphatase 2A (PP2A), is overexpressed in leukemia. We evaluated the efficacy of SET antagonism in chronic myeloid leukemia (CML) and acute myeloid leukemia (AML) cell lines, a murine leukemia model, and primary patient samples using OP449, a specific, cell-penetrating peptide that antagonizes SET's inhibition of PP2A. Experimental Design: In vitro cytotoxicity and specificity of OP449 in CML and AML cell lines and primary samples were measured using proliferation, apoptosis, and clonogenic assays. Efficacy of target inhibition by OP449 was evaluated by immunoblotting and PP2A assay. In vivo antitumor efficacy of OP449 was measured in human HL-60 xenografted murine model. Results: We observed that OP449 inhibited growth of CML cells including those from patients with blastic phase disease and patients harboring highly drug-resistant BCR-ABL1 mutations. Combined treatment with OP449 and ABL1 tyrosine kinase inhibitors was significantly more cytotoxic to K562 cells and primary CD34 CML cells. SET protein levels remained unchanged with OP449 treatment, but BCRABL1- mediated downstream signaling was significantly inhibited with the degradation of key signaling molecules such as BCR-ABL1, STAT5, and AKT. Similarly, AML cell lines and primary patient samples with various genetic lesions showed inhibition of cell growth after treatment with OP449 alone or in combination with respective kinase inhibitors. Finally, OP449 reduced the tumor burden of mice xenografted with human leukemia cells. Conclusions: We demonstrate a novel therapeutic paradigm of SET antagonism using OP449 in combination with tyrosine kinase inhibitors for the treatment of CML and AML.
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U2 - 10.1158/1078-0432.CCR-13-2575
DO - 10.1158/1078-0432.CCR-13-2575
M3 - Article
C2 - 24436473
AN - SCOPUS:84898936320
SN - 1078-0432
VL - 20
SP - 2092
EP - 2103
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 8
ER -