Aurora kinases in childhood acute leukemia: the promise of aurora B as therapeutic target

Abstract

We investigated the effects of targeting the mitotic regulators aurora kinase A and B in pediatric acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Aurora protein expression levels in pediatric ALL and AML patient samples were determined by western blot and reverse phase protein array. Both kinases were overexpressed in ALL and AML patients (P<0.0002), especially in E2A-PBX1-translocated ALL cases (P<0.002), compared with normal bone-marrow mononuclear cells. Aurora kinase expression was silenced in leukemic cell lines using short hairpin RNAs and locked nucleic acid-based mRNA antagonists. Aurora B knockdown resulted in proliferation arrest and apoptosis, whereas aurora A knockdown caused no or only minor growth delay. Most tested cell lines were highly sensitive to the AURKB-selective inhibitor barasertib–hydroxyquinazoline–pyrazol–anilide (AZD1152-HQPA) in the nanomolar range, as tested with an MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. But most importantly, primary ALL cells with a high aurora B protein expression, especially E2A-PBX1-positive cases, were sensitive as well. In adult AML early clinical trials, clear responses are observed with barasertib. Here we show that inhibition of aurora B, more than aurora A, has an antiproliferative and pro-apoptotic effect on acute leukemia cells, indicating that particularly targeting aurora B may offer a new strategy to treat pediatric ALL and AML.

Inhibiting Polo-like kinase 1 causes growth reduction and apoptosis in pediatric acute lymphoblastic leukemia cells

“…However, PLK1 expression was relatively high in all cell lines (data not shown), probably due to their proliferative capacity, and factors like transfection efficiency and rate of protein knockdown differ between PLK1 in childhood acute lymphoblastic leukemia haematologica | 2013; 98 (10) 1543 We have previously shown that AURKB protein expression is up-regulated in pediatric ALL and correlates with sensitivity to an AURKB inhibitor. 31 It has been shown that PLK1 is required for activation of AURKB and vice versa, 41 but this does not explain the correlation between PLK1 and AURKB protein expression that we observed in ALL patients. Rather than a direct connection between the two, the cross-talk between PLK1 and AURKB and their shared functions in mitotic processes make it more likely that there is a common factor regulating the expression of PLK1, AURKB and possibly other proteins involved in the same pathway.…”

“…HEK293T cells were transfected as described before 31 with psPAX2 (Addgene plasmid 12260) and pMD2.G (Addgene plasmid 12259), and a pLKO.1 Mission® vector (Sigma-Aldrich, Zwijndrecht, The Netherlands) containing a puromycin selection marker and a short hairpin RNA (shRNA) against PLK1 (TRCN0000121222) or eGFP (SHC005) as a non-targeting control (NTC). After 24 h, transduced cells were selected on puromycin (Sigma-Aldrich).…”

“…31 Antibodies were from Cell Signaling Technology (PLK1 (208G4), #4513; cleaved Poly (ADP-ribose) polymerase (PARP), #9541; Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), #2118) and Abcam (Cambridge, UK) (β-actin, ab6276).…”

“…Cell viability after NMS-P937 (Nerviano Medical Sciences, Nerviano, Italy) exposure was determined by MTS assay as described previously, 31 and calculated as a percentage of untreated controls. GI50 values represent drug doses inhibiting cell growth by 50% within 72 h.…”

“…We previously observed that Aurora kinase B expression was elevated in TCF3-rearranged patients, 31 which prompted us to investigate whether there is a correlation between PLK1 and Aurora kinase expression. In our patient cohort, PLK1 protein expression was indeed correlated to expression of Aurora kinase B (r s =0.53 and P<0.0001), and to a lesser extent to Aurora kinase A (r s =0.32 and P<0.0001) ( Figure 1C and D, respectively).…”