Selective targeting of NAMPT by KPT-9274 in acute myeloid leukemia.

Treatment options for acute myeloid leukemia (AML) remain extremely limited and associated with significant toxicity. Nicotinamide phosphoribosyltransferase (NAMPT) is involved in the generation of NAD+ and a potential therapeutic target in AML. We evaluated the effect of KPT-9274, a p21-activated kinase 4/NAMPT inhibitor that possesses a unique NAMPT-binding profile based on in silico modeling compared with earlier compounds pursued against this target. KPT-9274 elicited loss of mitochondrial respiration and glycolysis and induced apoptosis in AML subtypes independent of mutations and genomic abnormalities. These actions occurred mainly through the depletion of NAD+, whereas genetic knockdown of p21-activated kinase 4 did not induce cytotoxicity in AML cell lines or influence the cytotoxic effect of KPT-9274. KPT-9274 exposure reduced colony formation, increased blast differentiation, and diminished the frequency of leukemia-initiating cells from primary AML samples; KPT-9274 was minimally cytotoxic toward normal hematopoietic or immune cells. In addition, KPT-9274 improved overall survival in vivo in 2 different mouse models of AML and reduced tumor development in a patient-derived xenograft model of AML. Overall, KPT-9274 exhibited broad preclinical activity across a variety of AML subtypes and warrants further investigation as a potential therapeutic agent for AML.

Validation of ZAP-70 methylation and its relative significance in predicting outcome in chronic lymphocytic leukemia.

ZAP-70 methylation 223 nucleotides downstream of transcription start (CpG+223) predicts outcome in chronic lymphocytic leukemia (CLL), but its impact relative to CD38 and ZAP-70 expression or immunoglobulin heavy chain variable region (IGHV) status is uncertain. Additionally, standardizing ZAP-70 expression analysis has been unsuccessful. CpG+223 methylation was quantitatively determined in 295 untreated CLL cases using MassARRAY. Impact on clinical outcome vs CD38 and ZAP-70 expression and IGHV status was evaluated. Cases with low methylation (<20%) had significantly shortened time to first treatment (TT) and overall survival (OS) (P < .0001). For TT, low methylation defined a large subset of ZAP-70 protein-negative cases with significantly shortened TT (median, 8.0 vs 3.9 years for high vs low methylation; hazard ratio [HR] = 0.43; 95% confidence interval [CI], 0.25-0.74). Conversely, 16 ZAP-70 protein-positive cases with high methylation had poor outcome (median, 1.1 vs 2.3 years for high vs low methylation; HR = 1.62; 95% CI, 0.87-3.03). For OS, ZAP-70 methylation was the strongest risk factor; CD38 and ZAP-70 expression or IGHV status did not significantly improve OS prediction. A pyrosequencing assay was established that reproduced the MassARRAY data (κ coefficient > 0.90). Thus, ZAP-70 CpG+223 methylation represents a superior biomarker for TT and OS that can be feasibly measured, supporting its use in risk-stratifying CLL.

Consumption of glucose drinks slows sensorimotor processing: double-blind placebo-controlled studies with the Eriksen flanker task.

Modulations of blood glucose concentration (BGC) in the normal range are known to facilitate performance in memory and other cognitive tasks but few studies have investigated the effects of BGC variations on complex sensorimotor task so far. The present study aimed to examine glucose effects with the Eriksen flanker task. This task was chosen because it can dissociate between the effects of BGC on sensorimotor processing and cognitive control by assessing congruency effects. In two linked double-blind placebo-controlled experiments BGC was elevated within the normal BGC range (4-7 mmol/l) by approx. 1.5 mmol/l with glucose drinks and compared to a placebo drink condition while a flanker task with either strong or weak stimulus-response (SR) mapping was performed. Modulation of the performance in the flanker task by glucose was linked to the strength of the SR mapping but not congruency effects. Under weak SR mapping, reaction times (RTs) were slowed in the glucose condition compared to placebo while error rates remained unchanged, whereas cognitive control was not affected by glucose. When SR mapping was strong, no differences were found between glucose and placebo. Enhanced glucose levels differentially affect behavior. Whereas the literature mainly reports facilitating characteristics of enhanced glucose levels in the normal range, the present study shows that higher glucose levels can slow RTs. This suggests that glucose does not have a uniform effect on cognition and that it might be differential depending on the cognitive domain.

Silencing of the inhibitor of DNA binding protein 4 (ID4) contributes to the pathogenesis of mouse and human CLL.

Inhibitor of DNA binding protein 4 (ID4) is a member of the dominant-negative basic helix-loop-helix transcription factor family that lacks DNA binding activity and has tumor suppressor function. ID4 promoter methylation has been reported in acute myeloid leukemia and chronic lymphocytic leukemia (CLL), although the expression, function, and clinical relevance of this gene have not been characterized in either disease. We demonstrate that the promoter of ID4 is consistently methylated to various degrees in CLL cells, and increased promoter methylation in a univariable analysis correlates with shortened patient survival. However, ID4 mRNA and protein expression is uniformly silenced in CLL cells irrespective of the degree of promoter methylation. The crossing of ID4(+/-) mice with Eµ-TCL1 mice triggers a more aggressive murine CLL as measured by lymphocyte count and inferior survival. Hemizygous loss of ID4 in nontransformed TCL1-positive B cells enhances cell proliferation triggered by CpG oligonucleotides and decreases sensitivity to dexamethasone-mediated apoptosis. Collectively, this study confirms the importance of the silencing of ID4 in murine and human CLL pathogenesis.

Epigenetic changes during disease progression in a murine model of human chronic lymphocytic leukemia.

Epigenetic alterations, including gain or loss of DNA methylation, are a hallmark of nearly every malignancy. Changes in DNA methylation can impact expression of cancer-related genes including apoptosis regulators and tumor suppressors. Because such epigenetic changes are reversible, they are being aggressively investigated as potential therapeutic targets. Here we use the Emu-TCL1 transgenic mouse model of chronic lymphocytic leukemia (CLL) to determine the timing and patterns of aberrant DNA methylation, and to investigate the mechanisms that lead to aberrant DNA methylation. We show that CLL cells from Emu-TCL1 mice at various stages recapitulate epigenetic alterations seen in human CLL. Aberrant methylation of promoter sequences is observed as early as 3 months of age in these animals, well before disease onset. Abnormally methylated promoter regions include binding sites for the transcription factor FOXD3. We show that loss of Foxd3 expression due to an NF-kappaB p50/p50:HDAC1 repressor complex occurs in TCL1-positive B cells before methylation. Therefore, specific transcriptional repression is an early event leading to epigenetic silencing of target genes in murine and human CLL. These results provide strong rationale for the development of strategies to target NF-kappaB components in CLL and potentially other B-cell malignancies.