LAUSR

Over the past decade, several inhibitors of key metabolic dependencies have been shown to be active in AML (Acute Myeloid Leukemia), suggesting that targeting cellular metabolism is a promising therapeutic strategy for this disease. Specific inhibitors of the TCA cycle isoenzymes IDH1 and 2, mutated in approximately 20% of AML cases, abrogate the myeloid differentiation block and restore normal granulocytic/neutrophilic differentiation of IDH1/2mutated AML blasts [1, 2]. Moreover, lonidamine and 2deoxy-D-glucose, two small molecules that inhibit the first rate-limiting step of glycolysis, have been demonstated to have potent anti-leukemic activities in AML cells in preclinial studies and are now being tested in early phase clinical trials [3, 4]. While the inhibition of metabolic enzymes alters metabolite steady-state levels, it also impacts the activity of other downstream signaling pathways. For instance, glycolysis inhibition by lonidamine is associated with activation of the MEK/ERK pathway, which in the context of AML, could counteract the anti-leukemic effect of glycolysis inhibition [3]. This example suggests that it is essential to identify both the favorable effects and the potential liabilities of metabolic perturbations on downstream signaling pathways in order to (i) prevent potential resistance mechanisms to inhibition of the metabolic targets and (ii) nominate combination therapies that may synergize with metabolic inhibitors. We recently identified the mitochondrial creatine kinase, CKMT1, involved in arginine-creatine metabolism, as a new metabolic vulnerability in the molecular subset of AML driven by the proto-oncogene EVI1 [5]. We determined that suppression of arginine-creatine metabolism by CKMT1-directed shRNAs or by the small molecule cyclocreatine selectively altered the mitochondrial respiration and ATP production of EVI1-positive AML cells, thereby reducing their growth. In an effort to identify relevant signaling pathways that may be dysregulated by alteration of arginine-creatine metabolism, we interrogated by Gene Set Enrichment Analysis (GSEA) our transcriptional data generated through RNA-sequencing in three EVI1-positive AML cell lines, TF-1, UT-7, and UCSD-AML1, treated for 24 h with cyclocreatine (GSE86151). This open-ended enrichment analysis revealed that gene sets related to the GSK3 and WNT pathways were among those most enriched in genes whose expression was suppressed by cyclocreatine (Fig. 1a, b, odds ratio= 4.10, P value= 0.017; odds ratio = 10.24, P value= 0.004 for WNT and GSK3 respectively, based on two-tailed Fisher exact test). Creatine These authors contributed equally: Kimberly Stegmaier, Alexandre Puissant.