Abstract 2611: Activated pentose phosphate pathway mediated by FBP1 upregulation supports progression of acute myeloid leukemia with high EVI1 expression
Authors: Mizuno Hideaki , Kagoya Yuki , Chiba Akira , Koya Junji , Masamoto Yosuke , Kurokawa Mineo 
Published: August 2019

Abstract
EVI1 (ecotropic viral integration site 1) is a transcription factor essential for the development and progression of acute myeloid leukemia (AML). Since high EVI1 expression, seen in approximately 10% of AML patients (EVI1high AML), is associated with poor clinical outcome, development of a novel therapeutic strategy is required. In this study, we investigated key molecules that are induced by aberrant EVI1 expression and modulate the metabolomics of leukemia cells. We conducted whole transcriptome analysis by RNA-sequencing in murine leukemia cells induced by retroviral transduction with EVI1 followed by transplantation into irradiated mice. We identified 45 genes with more than 10-fold expression in EVI1-transduced bone marrow cells compared to those with the mock vector at both pre-leukemic phase and leukemia phase. Intriguingly, the fructose bisphosphatase 1 gene (Fbp1), which encodes a key enzyme of gluconeogenesis was highly upregulated in EVI1-induced AML cells. We confirmed that FBP1 mRNA expression is quickly upregulated by ectopic expression of EVI1 in murine LSK (Linneg, c-Kitpos, Sca-1pos) cells. Moreover, we observed an enrichment of EVI1 in the promoter and enhancer region of Fbp1 by chromatin immunoprecipitation followed by qPCR analysis in murine hematopoietic cells, suggesting that Fbp1 expression is directly regulated by EVI1. Although high FBP1 expression suppresses glycolytic metabolism and negatively affects cellular proliferation in various types of solid tumor, its role in AML has not been investigated. In contrast to the results previously reported in other types of cancers, pharmacologic inhibition or short hairpin RNA (shRNA)-mediated knockdown of FBP1 significantly decreased colony-forming cell (CFC) capacity in EVI1-transduced murine LSK cells and significantly delayed progression of leukemia in the mice secondarily transplanted with EVI1-induced AML cells in vivo. These results suggest that aberrant expression of FBP1 is important for progression of EVI1high AML. While high FBP1 enzymatic activity negatively affects the glycolytic pathway, it in turn enhances the pentose phosphate pathway (PPP) through elevating the fructose-6-phosphate level. Activated PPP results in enhanced nucleotide synthesis essential for rapidly dividing cells. Importantly, individual knockdown of main PPP enzymes (G6pd, Pgd, Rpia) by shRNA transduction significantly decreased the CFC capacity of EVI1 transduced murine LSK cells, further confirming an important role of PPP in driving proliferation of EVI1high leukemia cells. Collectively, these results indicate that the activated PPP through transcriptional upregulation of FBP1 is crucial for progression of EVI1-driven leukemia. Since inhibition of FBP-1 did not compromise normal hematopoiesis, targeting the enzyme can be a promising therapeutic approach for the EVI1high AML.
Citation Format: Hideaki Mizuno, Yuki Kagoya, Akira Chiba, Junji Koya, Yosuke Masamoto, Mineo Kurokawa. Activated pentose phosphate pathway mediated by FBP1 upregulation supports progression of acute myeloid leukemia with high EVI1 expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2611.