Epstein−Barr virus reactivation induces MYC‐IGH spatial proximity and t(8;14) in B cells

Abstract

Burkitt lymphoma (BL) is a B cell malignancy associated with the Epstein−Barr virus (EBV). Most BL cases are characterized by a t(8;14) chromosomal translocation involving the MYC oncogene and the immunoglobulin heavy chain gene (IGH). The role of EBV in promoting this translocation remains largely unknown. Here we provide the experimental evidence that EBV reactivation from latency leads to an increase in the proximity between the MYC and IGH loci, otherwise located far away in the nuclear space both in B-lymphoblastoid cell lines and in patients' B-cells. Specific DNA damage within the MYC locus, followed by the MRE11-dependent DNA repair plays a role in this process. Using a CRISPR/Cas9-based B cell model to induce specific DNA double strand breaks in MYC and IGH loci, we have shown that the MYC-IGH proximity induced by EBV reactivation leads to an increased t(8;14) translocation frequency.

Specificity of cancer-related chromosomal translocations is linked to proximity after the DNA double-strand break and subsequent selection

“…Several studies addressed this question before. They found that genes that are proximally positioned in the nuclear space, have a higher transcriptional activity or have an accessible chromatin configuration tend to have a higher propensity to form translocations in a specific cell type ( 22 , 44–52 ). Initial studies on chromosomal translocation formation utilized naturally occurring chromosomal translocations, as in the case of B-cell lymphomas, and then correlated their formation with the nuclear spatial position and transcription activity of the involved genes in normal cells ( 44 , 45 ).…”

“…This is supported by the occurrence of chromosomal translocations involving gene loci that were already proximal, such as RET and H4 ( 56 ), ABL and BCR ( 57 ), and PML and RARA ( 58 ) loci, or gene loci that have moved closer to each other before the chromosomal breakage occurred, e.g. MYC and IGH loci upon B-lymphocyte activation ( 18 , 22 , 44 , 45 , 59 ). The ‘breakage-first’ model postulates that broken chromosomal ends can freely move around the nuclear space and that the meeting of the two ends may lead to translocation formation.…”

Chronic HIV‐1 Tat action induces HLA‐DR downregulation in B cells: A mechanism for lymphoma immune escape in people living with HIV

“…Western blot analysis with whole cell extracts was performed as previously described 16 . For cytoplasmic and nuclear extracts, NE‐PER nuclear and cytoplasmic extraction reagents were employed following the manufacturer's instructions.…”

“…Western blot analysis with whole cell extracts was performed as previously described. 16 For cytoplasmic and nuclear extracts, NE-PER nuclear and cytoplasmic extraction reagents were employed following the manufacturer's instructions. Proteins were resolved on 4%−12% polyacrylamide gels, transferred onto a polyvinylidene fluoride membrane, blocked and probed with the primary antibodies.…”

Hub genes and their key effects on prognosis of Burkitt lymphoma

“…Three distinct clinical subtypes of BL have been identified: Namely endemic (African), sporadic (non-endemic), and immunodeficiency-associated. Notably, chronic Epstein-Barr virus infection plays a pivotal role in the pathogenesis of BL, particularly in the endemic subtype[ 2 ]. Endemic BL is primarily found in countries located near the equator in Africa.…”