RNA helicase DHX15 exemplifies a unique dependency in acute leukemia

Abstract

RNA-binding proteins (RBPs) have emerged as essential regulators to control gene expression and modulate multiple cancer traits. T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy derived from transformation of T-cell progenitors that normally undergo discrete steps of differentiation in the thymus. Yet implications of essential RBPs during T-cell neoplastic transformation remain largely unclear. Systematic evaluation of RBPs identifies RNA helicase DHX15, which facilitates the disassembly of spliceosome and release of lariat introns, as a T-ALL dependency factor. Functional analysis using multiple murine T-ALL models demonstrates the essential importance of DHX15 in tumor cell survival and leukemogenesis. Moreover, single-cell transcriptomics reveals that DHX15 depletion in T-cell progenitors hinders burst proliferation during CD4-CD8-(DN)-to-CD4+CD8+(DP) transition. Mechanistically, abrogation of DHX15 perturbs RNA splicing and leads to diminished levels of SLC7A6 and SLC38A5 transcripts due to intron retention, thereby suppressing glutamine import and mTORC1 activity. We further propose a DHX15 signature modulator drug ciclopirox and demonstrate prominent anti-T-ALL efficacy. Collectively, we here highlight the functional contribution of DHX15 to leukemogenesis through regulation of established oncogenic pathways. These findings also suggest a promising therapeutic approach that splicing perturbation by targeting spliceosome disassembly may achieve considerable anti-tumor efficacy.