Diffuse large B-cell lymphoma with combinedTP53mutation andMIR34Amethylation: Another “double hit” lymphoma with very poor outcome?

// Fazila Asmar 1,* , Christoffer Hother 1,* , Gorjan Kulosman 1 , Marianne Bach Treppendahl 1 , Helene Myrtue Nielsen 1 , Ulrik Ralfkiaer 1,2 , Anja Pedersen 1 , Michael Boe Møller 3 , Elisabeth Ralfkiaer 2 , Peter de Nully Brown 1, and Kirsten Grønbæk 1 1 Department of Hematology, Rigshospitalet, Copenhagen, Denmark, 2 Department of Pathology, Rigshospitalet, Copenhagen, Denmark, 3 Department of Pathology, Odense University Hospital, Odense, Denmark. * These authors contributed equally to the paper Correspondence: Kirsten Grønbæk, email: // Keywords : Epigenetic changes, DNA methylation, microRNA, Tumor suppressors, non-Hodgkin lymphoma Received : February 9, 2014 Accepted : March 30, 2014 Published : March 31, 2014 Abstract MiR34A, B and C have been implicated in lymphomagenesis, but information on their role in normal CD19+ B-cells (PBL-B) and de novo diffuse large B-cell lymphoma (DLBCL) is limited. We show that in normal and activated B-cells miR34A-5p plays a dominant role compared to other miR34 family members. Only miR34A-5p is expressed in PBL-B, and significantly induced in activated B-cells and reactive lymph nodes. In PBL-B, the MIR34A and MIR34B/C promoters are unmethylated, but the latter shows enrichment for the H3K4me3/H3K27me3 silencing mark. Nine de novo DLBCL cases (n=150) carry both TP53 mutation and MIR34A methylation (“double hit”) and these patients have an exceedingly poor prognosis with a median survival of 9.4 months ( P <0.0001), while neither TP53 mutation, MIR34A or MIR34B/C promoter methylation alone (“single hit”) influence on survival. The TP53/MIR34A “double-hit” is an independent negative prognostic factor for survival ( P =0.0002). In 2 DLBCL-cell lines with both TP53 mutation and promoter methylation of MIR34A, miR34A-5p is upregulated by 5-aza-2’deoxycytidine. Thus, the TP53/MIR34A “double hit” characterizes a very aggressive subgroup of DLBCL, which may be treatable with epigenetic therapy prior to or in combination with conventional immunochemotherapy.