Therapeutic targeting of the NOTCH1 and neddylation pathways in T cell acute lymphoblastic leukemia

Gamma Secretase Inhibitors (GSIs) effectively block the activation of oncogenic protein Notch homolog-1 (NOTCH1), a frequent event in T-cell Acute Lymphoblastic Leukemia (T-ALL). However, their clinical application is hampered by severe gastrointestinal toxicity due to the inhibition of NOTCH1 signaling and subsequent increase in goblet cell differentiation in the gut. Genome-wide CRISPR loss-of-function (LOF) screen in the colon cancer cell line LS174T identified the neddylation pathway as a main regulator of goblet cell differentiation upon NOTCH1 inhibition. Consistently, genetic deletion or pharmacologic inhibition of the neddylation pathway with the small molecule inhibitor MLN4924 rescued GSI-induced differentiation and cell death in LS174T cells. Mechanistically, neddylation inhibition by MLN4924 increases the protein stability of Hairy and enhancer of split-1 (HES1), a known NOTCH1 target and a regulator of absorptive and secretory cell fate decisions. Combined treatment with GSI and MLN4924 in murine Notch1-induced model of T-ALL showed leukemia regression and improved overall survival without any associated gut toxicity. Overall, these results substantiate the potential of targeting NOTCH1 and neddylation pathway in the treatment of NOTCH1-induced T-ALL. We used microarray to profile the gene expression in mouse intestinal stem cells upon NOTCH1 inhibition through GSI (DBZ treatment). This will allow us to explore the mechanisms of NOTCH1 inhibition in intestinal cell fate in vivo. We collected mouse intestinal stem cells by sorting GFPhigh cells from Lgr5-EGFP-IRES-creERT2 mice treated with vehicle (DMSO) or DBZ (30 mol kg-1) for 24 hours for RNA extraction and hybridization to Affymetrix arrays (n=3 per treatment). Gene expression profiling was analyzed to identify gene expression signatures inhibition of NOTCH1 by gamma secretase inhibitor (DBZ) in mouse intestine.