Expression profile of isolated lymphoblasts from mice treated with vehicle or SAHM1

NOTCH proteins regulate signaling pathways involved in cellular differentiation, proliferation and death. Overactive Notch signaling as been observed in numerous cancers and has been extensively studied in the context of T-cell acute lymphoblastic leukemia (T-ALL) where more than 50% of pateints harbour mutant NOTCH1. Small molecule modulators of these proteins would be important for understanding the role of NOTCH proteins in malignant and normal biological processes. We were interested to measure the global gene expression changes in leukemic cells isolated from mice harbouring a NOTCH1-driven genetically engineered T-cell leukemia after treatment with SAHM1, a synthetically stabilized α-helical peptide derived from the MAML1 co-activator protein. A genetically engineered murine model of NOTCH1-driven T-ALL was developed by retroviral transduction of murine bone marrow with a mutant NOTCH1 allele commonly observed in human T-ALL patients. Transplantation of transduced cells gave rise to T-ALL that was quantifiable by bio-luminescence in our model. After established leukemia was evident by continually increased tumor burden (luminescence) mice were either treated with vehicle alone (5% DMSO in Hank's buffered saline solution) or SAHM1 (30 mg/kg, twice daily, intraperitoneal injection). After five days of treatment, mice receiving SAHM1 had a significant decrease in tumor growth. To measure a pharmacodynamic effect on Notch signaling, circulating lymphoblasts were collected from vehicle- (n=3) and SAHM1-treated (n=3) mice and gene expression profiles were generated.