C/EBPβ suppression by interruption of CUGBP1 resulting from a complex rearrangement of MLL

Translocations involving the mixed-lineage leukemia gene (MLL) confer a poor prognosis in acute leukemias. In t(1;11)(q21;q23) MLL is fused reciprocally with AF1q. Here we describe a t(1: 11)(q21 q23) with a secondary event involving insertion of the telomeric portion of MLL into the p arm of chromosome 11 (11 p 11). We show that this latter event interrupts the CUG triplet repeat binding protein-1 (CUGBP1)gene, a translational enhancer of CIEBP ss. We then showed that these cells have reduced expression of CUGBP1 and C/EBP beta when compared to other AML blasts. This is the first report to describe insertional disruption of the CUGBP1 gene and to suggest a role for the CUGBP1-C/EBP beta pathway in leukemogenesis. (c) 2007 Elsevier Inc. All rights reserved.