Molecular features of a new human lymphoma cell line carrying both BCL2 and BCL6 gene rearrangements

Abstract

Chromosomal translocations and/or their molecular equivalents involving the BCL6 gene on 3q27 band have been suggested to be involved in the development of nonHodgkin's lymphoma of B-cell type (B-NHL). The rearrangement of BCL6 sometimes coexists with other translocations speci®c to B-NHL. Here, we report a novel B-cell lymphoma cell line, YM, established from a patient with di use large cell lymphoma. The YM cells expressed B-cell-associated antigens in addition to md/k monoclonal immunoglobulin. Southern blot analysis of DNA from YM cells demonstrated rearrangement of the BCL2 gene within the 5'¯anking region (5'-BCL2). Polymerase chain reaction (PCR) using primer pairs for the BCL2 exons 1 and 2, and for the constant region of the immunoglobulin k light chain gene (IGk) revealed PCR products encompassing the 5'-BCL2/IGk fusion, indicating that the YM cells had a t(2;18)(p11;q21) translocation. The BCL6 gene was rearranged at a point within the ®rst intron, and cloning of the rearranged BCL6 revealed unidenti®ed sequences juxtaposed to the 5' side of the gene. The isolated clones were mapped to 16p11.2 by high resolution¯uorescence in situ chromosomal hybridization. Thus, the YM cells carried a 3q27 translocation involving 16p11.2 as a partner. Chromosome painting of metaphase spreads con®rmed that the YM cells had both t(2;18) and t(3;16). Northern blot analysis using a fragment immediately adjacent to the breakpoint on 16p11.2 revealed transcriptional activity within this locus. The YM cells expressed abundant transcripts with aberrant sizes from BCL2 and BCL6, indicating deregulated overexpression of the two genes resulting from the t(2;18) and t(3;16). The YM cell line will therefore be useful to study whether BCL2 and BCL6 genes collaborate in the pathogenesis of B-NHL.

The gene for interleukin-21 receptor is the partner of BCL6 in t(3;16)(q27;p11), which is recurrently observed in diffuse large B-cell lymphoma

“…1012 had t(3;16) as the sole chromosome abnormality, indicating that the translocation was the primary genetic abnormality in this particular case (Ichinohasama et al, 1998). In contrast, YM cells carried a t(2;18)(p11;q21) leading to the fusion between BCL2 and the IG k-light chain gene (Yonetani et al, 1998), raising the possibility that the t(3;16) was a secondary change that developed in a prelymphomatous B-cell with BCL2 translocation and was related to progression to¯orid lymphoma. However, recombination activation genes (RAG) 1/2 have been shown to be reactivated in the germinal center (Han et al, 1997), therefore, oncogene/IG translocation mediated by V(D)J recombination may not be restricted to B-cell precursors in the bone marrow but can occur in the peripheral lymphoid organs.…”

“…Cytogenetic and molecular analysis of YM cells revealed that the cells carried t(3;16)(q27;p11) and t(2;18)(p11;q21) involving BCL6 and BCL2, respectively (Yonetani et al, 1998 (Ichinohasama et al, 1998). The cell lines used in the present study were cultured in RPMI 1640 medium supplemented with 10% fetal calf serum (FCS) under the standard culture conditions.…”

“…To identify the gene directly aected Figure 1 Molecular anatomy of t(3;16)(q27;p11) aecting BCL6 and IL-21R genes. (a) Comparative map encompassing the YM breakpoints (Yonetani et al, 1998). The breakpoints of no.…”

“…We previously cloned and sequenced the t(3;16) breakpoint on 16p11 of YM cells (Figure 1a) (Yonetani et al, 1998). The breakpoint of case no.…”

Detection of translocations affecting the BCL6 locus in B cell non-Hodgkin's lymphoma by interphase fluorescence in situ hybridization

“…34 DNA was digested with add(5)(p12),del(6)(q13q25),der(9)t(4;9)(q21;p22)del(4)(q31q33),der(10)t(5;10)(p12;q11), der(14)t(2;14)(q31;q32),der(18)t(14;18)(q32;q21),+22,der (22) der(9)del(9)(p22)t(1;9)(q13;q34),−13,−14 [30] 22 DLBCL PB 49,XX,+X,t(1;3)(p34;q27),der(6)t(6;7)(q13;q22),der (7) 32 LDI-PCR from the IGHJ segments and from 5Ј S to amplify the derivative partner chromosome was performed as described. 35,36 LDI-PCR products were cloned into pTOPO (Invitrogen, San Diego, CA, USA) and sequenced.…”