Identification of Regulators of Polyploidization Presents Therapeutic Targets for Treatment of AMKL

Abstract

Summary The mechanism by which cells decide to skip mitosis to become polyploid is largely undefined. Here we used a high-content image-based screen to identify small-molecule probes that induce polyploidization of megakaryocytic leukemia cells and serve as perturbagens to help understand this process. We found that dimethylfasudil (diMF, H-1152P) selectively increased polyploidization, mature cell-surface marker expression, and apoptosis of malignant megakaryocytes. A broadly applicable, highly integrated target identification approach employing proteomic and shRNA screening revealed that a major target of diMF is Aurora A kinase (AURKA), which has not been studied extensively in megakaryocytes. Moreover, we discovered that MLN8237 (Alisertib), a selective inhibitor of AURKA, induced polyploidization and expression of mature megakaryocyte markers in AMKL blasts and displayed potent anti-AMKL activity in vivo. This research provides the rationale to support clinical trials of MLN8237 and other inducers of polyploidization in AMKL. Finally, we have identified five networks of kinases that regulate the switch to polyploidy.

Novel function of PITH domain-containing 1 as an activator of internal ribosomal entry site to enhance RUNX1 expression and promote megakaryocyte differentiation

“…Indeed, differentiation therapy is so successful in acute promyeloid leukemia (APL) that combinatory application of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) synergistically causes terminal differentiation of APL cells and achieves complete clinic remission in APL patients [1,2]. Recent study identified Aurora kinase A as a therapeutic target of MLN8237 to promote polyploidization and differentiation in acute megakaryoblastic leukemia (AMKL) [3]. Unfortunately, differentiation therapy is not well defined in other subtypes of myeloid leukemia possibly due to heterogeneous etiology with different molecular genetic aberrations.…”

L’ETO se resserre sur les leucémies aiguës mégacaryoblastiques

“…Le principe du criblage de nouvelles molécules pour le traitement des LAM7 repose sur la capacité de ces molécules à induire la polyploïdisation et la maturation d'une lignée de LAM7. Le dimé-thylfasudil (DiMF), un inhibiteur de la kinase Aurora A, a ainsi été identifié [12]. C. (Figure 1) [8].…”

The Hippo-p53 pathway in megakaryopoiesis

“…5 The firstin-class inhibitor of Bruton's tyrosine kinase (BTK), ibrutinib, was welcomed in 2013 as a new paradigm for the treatment of relapsed or refractory CLL, as it produced responses in 71% of the cases in a heavily pre-treated patient population who had few, if any, alternative treatment options. 6,7 After a median observation of 3 years, 8 exceptional overall survival (OS) and progression-free survival (PFS) rates were reported (79% and 69%, respectively), along with a low (12%) discontinuation rate due to adverse events. Following the publication of excellent efficacy data in patients with 17p deletion (del(17p)) or TP53 mutations, 9,10 high expectations were generated in the belief that this drug was able to produce durable responses in the majority of patients, irrespective of the presence of unfavorable prognostic factors.…”

“…Following the publication of excellent efficacy data in patients with 17p deletion (del(17p)) or TP53 mutations, 9,10 high expectations were generated in the belief that this drug was able to produce durable responses in the majority of patients, irrespective of the presence of unfavorable prognostic factors. 11 However, the median age of the patients in the trials was 64 years 8 and only 32% of them had a Cumulative Illness Rating Scale (CIRS) score of >6. 12 This reflects the inclusion criteria in the clinical trials, which required that the patients had an Eastern Cooperative Oncology Group (ECOG) performance status of less than 2, with adequate liver and kidney function, no significant neutropenia or thrombocytopenia and who did not require warfarin or strong CYP3A4/5 inhibitors.…”

“…7 Evidence in support of a critical role of the RhoA and its effector Rho kinase (ROCK) in the regulation of the switch to polyploidy includes the finding that its inhibition or knockdown leads to increased polyploidy of megakaryocytes. [7][8][9][10] Moreover, megakaryocyte-specific deletion of RhoA in mice resulted in macrothrombocytopenia due to premature release of platelets. 11 Interestingly, the megakaryocytes in the animals were larger and more highly polyploidy, consistent with the inhibitor data.…”