Discovery and characterization of a novel CCND1/MRCK gene fusion in mantle cell lymphoma

The t(11;14) translocation resulting in constitutive cyclin D1 expression is an early event in mantle cell lymphoma (MCL) transformation. Patients with a highly proliferative phenotype produce cyclin D1 transcripts with truncated 3'UTRs that evade miRNA regulation. Here, we report the recurrence of a novel gene fusion in MCL cell lines and MCL patient isolates that consists of the full protein coding region of cyclin D1 (CCND1) and a 3'UTR consisting of sequences from both the CCND1 3'UTR and myotonic dystrophy kinase-related Cdc42-binding kinase's (MRCK) intron one. The resulting CCND1/MRCK mRNA is resistant to CCND1-targeted miRNA regulation, and targeting the MRCK region of the chimeric 3'UTR with siRNA results in decreased CCND1 levels.