Clonality Analysis of Immunoglobulin Gene Rearrangement by Next-Generation Sequencing in Endemic Burkitt Lymphoma Suggests Antigen Drive Activation of BCR as Opposed to Sporadic Burkitt Lymphoma

Abstract

Objectives: Recent studies using next-generation sequencing (NGS) analysis disclosed the importance of the intrinsic activation of the B-cell receptor (BCR) pathway in the pathogenesis of sporadic Burkitt lymphoma (sBL) due to mutations of TCF3/ID3 genes. Since no definitive data are available on the genetic landscape of endemic Burkitt (eBL), we first assessed the mutation frequency of TCF3/ID3 in eBL compared with sBL and subsequently the somatic hypermutation status of the BCR to answer whether an extrinsic activation of BCR signaling could also be demonstrated in Burkitt lymphoma.Methods: We assessed the mutations of TCF3/ID3 by RNAseq and the BCR status by NGS analysis of the immunoglobulin genes (IGs).Results: We detected mutations of TCF3/ID3 in about 30% of the eBL cases. This rate is significantly lower than that detected in sBL (64%). The NGS analysis of IGs revealed intraclonal diversity, suggesting an active targeted somatic hypermutation process in eBL compared with sBL.Conclusions: These findings support the view that the antigenic pressure plays a key role in the pathogenetic pathways of eBL, which may be partially distinct from those driving sBL development.

High-throughput sequencing of the B-cell receptor in African Burkitt lymphoma reveals clues to pathogenesis

“…This study demonstrates that Ig gene rearrangements in African BL tumors are characterized by far more molecular heterogeneity than suggested by previous studies, most [6][7][8][9][10][11]31 but not all 24 of which were performed using capillary sequencing. HTS of the Ig loci in gDNA from BL tumors identified at least 1 clonal locus in 90% (46/51) of tumors.…”

“…In addition, we examined the IGHV usage in 40 endemic and 33 sporadic tumor-associated BCRs of BL cases reported in the literature. [24][25][26] We also used a novel computational method to identify IGHV utilization in RNAseq data from 28 sporadic BL tumors. 25 Combining the 30 evaluable cases from our 2 BL cohorts with these independent tumor BSCL2 COL6A3 FOXO1 ZNF587 ATAD3C HK3 TFAP4 SEPSECS TBC1D10B PAX5 ABCD4 BMPR2 POMC SMARCA4 ACTR10 RRM2 TP53 ID3 Sequence frequency (%) Figure 4B).…”

“…No significant differences, however, were seen in the expression of BCR signaling pathway genes in tumors with and without a dominant, productive IGH rearrangement. RNAseq variant analysis revealed sequence variants in genes previously reported to be mutated in BL, including ID3, TP53, SMARCA4, ZNF587, and FOXO1, 24,25,[28][29][30] as well as 14 genes that are mutated in other cancers, including NOTCH1, PAX5, and TFAP4 ( Figure 1D; supplemental Table 2). Two tumors with a polyclonal IGH repertoire and a clonal IGK/IGL rearrangement by HTS of gDNA carried mutations in several genes mutated in other BL tumors, including TP53, POMC, COL6A3, and BSCL2, supporting the diagnosis of BL in these cases.…”

The cell of origin of Burkitt lymphoma: germinal centre or not germinal centre?

“…post-germinal centre/ memory B cells. 4 This is in line with the fact that in healthy carriers, EBV resides in memory immunoglobulin (Ig)M-positive B cells that re-enter the GC reaction following antigen stimulation. 5 In fact, activation of the B cell receptor by malaria infection and/or other pathogens induces the clonal expansion of memory B cells that express Epstein-Barr nuclear antigen 1 (EBNA-1) (latency I) and activation-induced cytidine deaminase (AID) when they divide.…”

“…Conversely, it has been hypothesized that endemic and human immunodeficiency virus (HIV)‐related BL cases, which are associated commonly with Epstein–Barr virus (EBV) infection, may derive from a later developmental stage of B cells than sporadic BL, i.e. post‐germinal centre/memory B cells . This is in line with the fact that in healthy carriers, EBV resides in memory immunoglobulin (Ig)M‐positive B cells that re‐enter the GC reaction following antigen stimulation .…”