Albero, Robert

Abstract Early T-cell acute lymphoblastic leukemia (ETP-ALL) is an aggressive hematologic malignancy associated with early relapse and poor prognosis that is genetically, immunophenotypically, and transcriptionally distinct from more mature T-cell acute lymphoblastic leukemia (T-ALL) tumors. Here, we leveraged global metabolomic and transcriptomic profiling of primary ETP- and T-ALL leukemia samples to identify specific metabolic circuitries differentially active in this high-risk leukemia group. ETP-ALLs showed increased biosynthesis of phospholipids and sphingolipids and were specifically sensitive to inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase, the rate-limiting enzyme in the mevalonate pathway. Mechanistically, inhibition of cholesterol synthesis inhibited oncogenic AKT1 signaling and suppressed MYC expression via loss of chromatin accessibility at a leukemia stem cell–specific long-range MYC enhancer. In all, these results identify the mevalonate pathway as a druggable novel vulnerability in high-risk ETP-ALL cells and uncover an unanticipated critical role for cholesterol biosynthesis in signal transduction and epigenetic circuitries driving leukemia cell growth and survival. Significance: Overtly distinct cell metabolic pathways operate in ETP- and T-ALL pointing to specific metabolic vulnerabilities. Inhibition of mevalonate biosynthesis selectively blocks oncogenic AKT–MYC signaling in ETP-ALL and suppresses leukemia cell growth. Ultimately, these results will inform the development of novel tailored and more effective treatments for patients with high-risk ETP-ALL. This article is highlighted in the In This Issue feature, p. 587

Abstract Purpose: Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32) translocation leading to cyclin D1 overexpression. Cyclin D1 is a major cell-cycle regulator and also regulates transcription, but the impact of cyclin D1–mediated transcriptional dysregulation on MCL pathogenesis remains poorly understood. The aim of this study was to define a cyclin D1–dependent gene expression program and analyze its prognostic value. Experimental Design: We integrated genome-wide expression analysis of cyclin D1–silenced and overexpressing cells with cyclin D1 chromatin-binding profiles to identify a cyclin D1–dependent transcriptional program in MCL cells. We analyzed this gene program in two MCL series of peripheral blood samples (n = 53) and lymphoid tissues (n = 106) to determine its biological and clinical relevance. We then obtained a simplified signature of this program and evaluated a third series of peripheral blood MCL samples (n = 81) by NanoString gene expression profiling to validate our findings. Results: We identified a cyclin D1–dependent transcriptional program composed of 295 genes that were mainly involved in cell-cycle control. The cyclin D1–dependent gene program was overexpressed in MCL tumors directly proportional to cyclin D1 levels. High expression of this program conferred an adverse prognosis with significant shorter overall survival of the patients. These observations were validated in an independent cohort of patients using a simplified 37-gene cyclin D1 signature. The cyclin D1–dependent transcriptional program was also present in multiple myeloma and breast tumors with cyclin D1 overexpression. Conclusions: We identified a cyclin D1–dependent transcriptional program that is overexpressed in MCL and predicts clinical outcome.