Antagonism of SET using OP449 enhances the efficacy of tyrosine kinase inhibitors and overcomes drug resistance in myeloid leukemia.

Abstract

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 BCR-ABL1-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.

• Authors: Anupriya Agarwal, Ryan J MacKenzie, Raffaella Pippa, Christopher A Eide, Jessica Oddo, Jeffrey W Tyner, Rosalie Sears, Michael P Vitek, María D Odero, Dale J Christensen, Brian J Druker
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 20 Issue 8 Pg. 2092-103 (Apr 15 2014) ISSN: 1557-3265 [Electronic] United States
• PMID: 24436473 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2014 AACR.

Chemical References

• DNA-Binding Proteins
• Histone Chaperones
• OP449 peptide
• Peptides
• Protein Kinase Inhibitors
• SET protein, human
• Transcription Factors
• Fusion Proteins, bcr-abl
• Protein Phosphatase 2

Topics

• Aged
• Amino Acid Sequence
• Animals
• Cell Line, Tumor
• Cell Proliferation (drug effects)
• Cell Survival (drug effects)
• DNA-Binding Proteins
• Drug Resistance, Neoplasm (drug effects)
• Drug Synergism
• Fusion Proteins, bcr-abl (metabolism)
• HL-60 Cells
• Histone Chaperones (antagonists & inhibitors, metabolism)
• Humans
• Immunoblotting
• K562 Cells
• Leukemia, Myeloid (drug therapy, metabolism, pathology)
• Male
• Mice, Knockout
• Middle Aged
• Molecular Sequence Data
• Peptides (pharmacology)
• Protein Kinase Inhibitors (pharmacology)
• Protein Phosphatase 2 (metabolism)
• Signal Transduction (drug effects)
• Transcription Factors (antagonists & inhibitors, metabolism)
• Tumor Burden (drug effects)
• Xenograft Model Antitumor Assays