Pim kinase inhibitor co-treatment decreases alternative non-homologous end-joining DNA repair and genomic instability induced by topoisomerase 2 inhibitors in cells with FLT3 internal tandem duplication

Mario Scarpa; Shivani Kapoor; Eric S Tvedte; Kshama A Doshi; Ying S Zou; Prerna Singh; Jonelle K Lee; Aditi Chatterjee; Moaath K Mustafa Ali; Robin E Bromley; Julie C Dunning Hotopp; Feyruz V Rassool; Maria R Baer

doi:10.18632/oncotarget.28042

Pim kinase inhibitor co-treatment decreases alternative non-homologous end-joining DNA repair and genomic instability induced by topoisomerase 2 inhibitors in cells with FLT3 internal tandem duplication

Oncotarget. 2021 Aug 31;12(18):1763-1779. doi: 10.18632/oncotarget.28042.

Authors

Mario Scarpa^{1

2}, Shivani Kapoor¹, Eric S Tvedte³, Kshama A Doshi¹, Ying S Zou^{1

4}, Prerna Singh¹, Jonelle K Lee¹, Aditi Chatterjee^{1

2}, Moaath K Mustafa Ali^{1

2}, Robin E Bromley³, Julie C Dunning Hotopp^{1

3

5}, Feyruz V Rassool^{1

6}, Maria R Baer^{1

2

7}

Affiliations

¹ University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA.
² Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
³ Institute for Genome Sciences, Baltimore, MD, USA.
⁴ Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA.
⁵ Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.
⁶ Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.
⁷ Veterans Affairs Medical Center, Baltimore, MD, USA.

Abstract

Acute myeloid leukemia (AML) with fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) relapses with new chromosome abnormalities following chemotherapy, implicating genomic instability. Error-prone alternative non-homologous end-joining (Alt-NHEJ) DNA double-strand break (DSB) repair is upregulated in FLT3-ITD-expresssing cells, driven by c-Myc. The serine/threonine kinase Pim-1 is upregulated downstream of FLT3-ITD, and inhibiting Pim increases topoisomerase 2 (TOP2) inhibitor chemotherapy drug induction of DNA DSBs and apoptosis. We hypothesized that Pim inhibition increases DNA DSBs by downregulating Alt-NHEJ, also decreasing genomic instability. Alt-NHEJ activity, measured with a green fluorescent reporter construct, increased in FLT3-ITD-transfected Ba/F3-ITD cells treated with TOP2 inhibitors, and this increase was abrogated by Pim kinase inhibitor AZD1208 co-treatment. TOP2 inhibitor and AZD1208 co-treatment downregulated cellular and nuclear expression of c-Myc and Alt-NHEJ repair pathway proteins DNA polymerase θ, DNA ligase 3 and XRCC1 in FLT3-ITD cell lines and AML patient blasts. ALT-NHEJ protein downregulation was preceded by c-Myc downregulation, inhibited by c-Myc overexpression and induced by c-Myc knockdown or inhibition. TOP2 inhibitor treatment increased chromosome breaks in metaphase spreads in FLT3-ITD-expressing cells, and AZD1208 co-treatment abrogated these increases. Thus Pim kinase inhibitor co-treatment both enhances TOP2 inhibitor cytotoxicity and decreases TOP2 inhibitor-induced genomic instability in cells with FLT3-ITD.

Keywords: FLT3 internal tandem duplication; Pim kinase; alternative non-homologous end-joining DNA repair; genomic instability; topoisomerase 2 inhibitors.

Abstract

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