Targeting CDK1 promotes FLT3-activated acute myeloid leukemia differentiation through C/EBPα
Hanna S. Radomska, Meritxell Alberich-Jordà, Britta Will, David Gonzalez, Ruud Delwel, Daniel G. Tenen
Hanna S. Radomska, Meritxell Alberich-Jordà, Britta Will, David Gonzalez, Ruud Delwel, Daniel G. Tenen
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Research Article Oncology

Targeting CDK1 promotes FLT3-activated acute myeloid leukemia differentiation through C/EBPα

Abstract

Mutations that activate the fms-like tyrosine kinase 3 (FLT3) receptor are among the most prevalent mutations in acute myeloid leukemias. The oncogenic role of FLT3 mutants has been attributed to the abnormal activation of several downstream signaling pathways, such as STAT3, STAT5, ERK1/2, and AKT. Here, we discovered that the cyclin-dependent kinase 1 (CDK1) pathway is also affected by internal tandem duplication mutations in FLT3. Moreover, we also identified C/EBPα, a granulopoiesis-promoting transcription factor, as a substrate for CDK1. We further demonstrated that CDK1 phosphorylates C/EBPα on serine 21, which inhibits its differentiation-inducing function. Importantly, we found that inhibition of CDK1 activity relieves the differentiation block in cell lines with mutated FLT3 as well as in primary patient–derived peripheral blood samples. Clinical trials with CDK1 inhibitors are currently under way for various malignancies. Our data strongly suggest that targeting the CDK1 pathway might be applied in the treatment of FLT3ITD mutant leukemias, especially those resistant to FLT3 inhibitor therapies.

Authors

Hanna S. Radomska, Meritxell Alberich-Jordà, Britta Will, David Gonzalez, Ruud Delwel, Daniel G. Tenen

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Figure 8

Granulocytic differentiation of FLT3ITD cells after inhibition of CDK1 activity.

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Granulocytic differentiation of FLT3ITD cells after inhibition of CDK1 a...
(A) Inhibition of CDK1 in patient samples with FLT3ITD induces granulocytic differentiation. Blood specimens from FLT3ITD AML patients (patient A and patient B; same as shown in Figure 7) were cultured in the presence of 0.1% DMSO or 10 mM NU6102 for 7 days. Cell aliquots were stained with anti-CD11c, anti-CD15, anti-CD14, anti-CD11b, anti-CD16, anti–G-CSF-R, anti-CD33, anti-CD133, anti-CD34, and anti-CD38 antibodies and analyzed by flow cytometry. The y axes indicate the percentage of positive cells. (B) Patient samples were treated as in A for 5 days and analyzed for mRNA expression of granulocytic cell-surface markers by quantitative RT-PCR. The y axes indicate relative expression to GAPDH. (C) CD15+ cells with granulocytic-like morphology are viable. CD15 expression on FLT3ITD AML patient A sample treated with DMSO (gray) or 5 mM NU6102 (white) during 10 days (left panel). Number indicates the percentage of CD15+ cells upon NU6102 treatment. CD15+ cells were sorted, cytocentrifuged, and stained with Wright-Giemsa method (middle panel). Original magnification, ×40. CD15+ cells were also stained with annexin V and PI to determine the extent of their viability (right panel). The numbers in each quadrant indicate percentages of viable (lower left), early apoptotic (lower right), late apoptotic (upper right), and necrotic cells (upper left).