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The lack of curative therapies for acute myeloid leukaemia (AML) remains an ongoing challenge despite recent advances in the understanding of the molecular basis of the disease. Here we identify the WNK1-OXSR1/STK39 pathway as a previously uncharacterised dependency in AML. We show that genetic depletion and pharmacological inhibition of WNK1 or its downstream phosphorylation targets OXSR1 and STK39 strongly reduce cell proliferation and induce apoptosis in leukaemia cells in vitro and in vivo. Furthermore, we show that the WNK1-OXSR1/STK39 pathway controls mTORC1 signalling via regulating amino acid uptake through a mechanism involving the phosphorylation of amino acid transporters, such as SLC38A2. Our findings underscore an important role of the WNK1-OXSR1/STK39 pathway in regulating amino acid uptake and driving AML progression. With-No-lysine?(K) kinase 1 (WNK1) is an atypical serine-threonine kinase that has been implicated in ion transport. Here, the authors show that WNK1 regulates amino acid transport and mTORC1 activity, and that the axis is a vulnerability for acute myeloid leukemia

Multiplex gene-edited chimeric antigen receptor (CAR) T-cell therapies face significant challenges, including potential oncogenic risks associated with double-strand DNA breaks. Targeted microRNAs (miRNAs) may provide a safer, functional, and tunable alternative for gene silencing without the need for DNA editing. As a proof of concept for multiplex gene silencing, we employed an optimized miRNA backbone and gene architecture to silence T-cell receptor (TCR) and major histocompatibility complex class I (MHC-I) in mesothelin-directed CAR (M5CAR) T cells. The efficacy of this approach was compared to CD3¦Æ and ¦Â2-microglobulin (¦Â2M) CRISPR/Cas9 knockout (KO) cells. miRNA-expressing cassettes were incorporated into M5CAR lentiviral vectors, enabling combined gene silencing and CAR expression. Antitumor activity was evaluated using in vitro assays and in vivo pancreatic ductal adenocarcinoma models. Silenced (S) M5CAR T cells retained antitumor functionality comparable to, and in some cases exceeding, that of KO cells. In vivo , S M5CAR T cells achieved tumor control with higher persistence and superior metastasis prevention. In vitro assays demonstrated enhanced resistance to alloreactive natural killer (NK) cells and peripheral blood mononuclear cells (PBMCs). Titratable multiplex gene silencing via targeted miRNAs offers an alternative to gene editing for CAR T cells, with potential advantages in potency, persistence, metastasis prevention, and immune evasion for allogeneic products. This strategy may overcome tumor-induced immunosuppression while avoiding the risks associated with DNA double-strand breaks.