ENO1 promotes Acute Myeloid Leukemia progression through SCD1-mediated lipid metabolism reprogramming

Abstract Enhanced glycolysis and aberrant hyperactivation of glycolytic enzymes collectively contributes to tumor progression and chemoresistance development in acute myeloid leukemia (AML). Alpha-enolase (ENO1), a pivotal enzyme in the glycolytic pathway, is a potential therapeutic target for AML given its high expression in AML cells. In this study, we investigated the association between high ENO1 expression and poor AML prognosis, as well as its critical role in AML tumor progression. A total of 142 AML patients from our center from October 2013 to September 2022 were included and divided into ENO1 high group (n=46) and ENO1 low group (n=96). The event-free survival rate for patients with high ENO1 expression was lower than that for those with low ENO1 expression. Furthermore, the growth and tumor progression of ENO1-knockdown (ENO1KD) MV4-11 and Kasumi-1 cells were significantly suppressed both in vitro and in vivo. Notably, we observed that ENO1KD AML cells exhibited an increased feroptosis, and displayed heightened sensitivity to ferroptosis inducer RSL3, suggesting a role for ferroptosis regulation in ENO1-mediated tumor progression. To delineate and characterize the molecular pathways governing ENO1-mediated AML progression and ferroptosis resistance, we performed RNA sequencing (RNA-seq) on ENO1KD MV4-11 cells. The KEGG pathway enrichment analysis revealed a significant association between fatty acid metabolism and ENO1 expression level. Among the down-regulated genes, stearoyl-CoA desaturase 1 (SCD1)—a key enzyme involved in fatty acid (FA) metabolism governing monounsaturated fatty acids (MUFA) biosynthesis, were prominently ranked. Metabolomic analysis of ENO1KD MV4-11 revealed decreased activity in lipid metabolic pathways, as well as an increased PUFA/MUFA ratio in multiple types of GPs, which is a hallmark of enhanced susceptibility to membrane lipid peroxidation and ferroptosis, indicating that ENO1 directly modulates lipid metabolism via regulating SCD1 expression. Given that ENO1 was also known as a DNA-binding protein, we performed CUT&Tag in MV4-11 cells to elucidate whether ENO1 regulates SCD1 on transcription level. Analysis revealed distinct binding peaks for ENO1 in the promoter regions of SCD1, indicating a direct binding of ENO1 on the SCD1 promoter, and regulation of fatty acids metabolism by ENO1 via promoting SCD1 transcription in AML cells. This leads to increased synthesis of monounsaturated fatty acids. Moreover, the elevated monounsaturated fatty acids catalyzed by SCD1 are subsequently incorporated into the membrane phospholipids of AML cells, leading to increased resistance to lipid peroxidation and ferroptotis. Based on these results, we found that combining an SCD1 inhibitor with daunorubicin (DNR), which can induce ferroptosis in tumor cells, effectively reduced the resistance to ferroptosis in AML cells exhibiting high ENO1 expression. Overall, our study elucidates the mechanism by which ENO1 directly 8regulates SCD1, driving lipid reprogramming and alterations in membrane lipid homeostasis within AML. Additionally, it highlights the therapeutic potential of combining SCD1 inhibition with DNR for targeting AML cells characterized by elevated ENO1 expression levels.