Identification of Target Gene at 2p15 Amplification in DLBCL Using Contig Array CGH.

Genomic amplification of the 2p arm has been identified as a recurrent alteration in classical Hodgkin lymphoma, follicular lymphoma, primary mediastinal large B cell lymphoma and diffuse large B-cell lymphoma (DLBCL). We previously reported that 2p15 was gained in 25 out of 100 DLBCL patients by use of a genome-wide array-comparative genomic hybridization (array-CGH). In DLBCL with 2p amplification, genomic co-amplification of REL and BCL11A has been observed. Recent studies suggest that REL amplification is infrequently associated with nuclear REL expression and NFkB activation. In an attempt to identify the target gene at 2p15 amplification, we made BAC contig array CGH glasses for 2p15 region with 33 BAC clones covering 4.5Mb, and found that seven samples of the DLBCL with 2p amplification displayed alterations. REL and BCL11A were located within majority of the gained regions. The minimal common region of amplification was mapped to 0.5 Mb and we found that this region did not include BCL11A. To investigate the relationship between genomic gains and gene expression, we performed real-time quantitative polymerase chain reaction (RQ-PCR) analysis. The results indicated that REL, rather than BCL11A, is the target of 2p15 alterations in DLBCL.