Identification of genes induced by NOTCH1 in a chronic lymphocytic leukaemia (CLL) cell line and tracking of these genes in primary CLL patients

NOTCH1 is mutationally activated in ~15% of cases of chronic lymphocytic leukaemia (CLL), but its role in B-cell development and leukemogenesis is not known. Here, we report that the active intracellular portion of NOTCH1 (ICN1) is detectable in ~50% of peripheral blood CLL cases lacking gene mutations. We identify a 'NOTCH1 CLL gene expression signature' in CLL cells, and show that this signature is significantly enriched in primary CLL cases expressing ICN1, independent of NOTCH1 mutation. NOTCH1 target genes include key regulators of B-cell proliferation, survival and signal transduction physiology. In particular, we show that MYC is a direct target of NOTCH1 via B-cell specific distal regulatory elements, thus implicating this oncogene in the pathogenesis of the disease. Overall design: RNA-Seq analysis