Differences between BCL2-break positive and negative follicular lymphoma unraveled by whole-exome sequencing

Leukemia. 2018 Mar;32(3):685-693. doi: 10.1038/leu.2017.270. Epub 2017 Aug 21.

Abstract

Depending on disease stage follicular lymphoma (FL) lack the t(14;18) in ~15-~50% of cases. Nevertheless, most of these cases express BCL2. To elucidate mechanisms triggering BCL2 expression and promoting pathogenesis in t(14;18)-negative FL, exonic single-nucleotide variant (SNV) profiles of 28 t(14;18)-positive and 13 t(14;18)-negative FL were analyzed, followed by the integration of copy-number changes, copy-neutral LOH and published gene-expression data as well as the assessment of immunoglobulin N-glycosylation sites. Typical FL mutations also affected t(14;18)-negative FL. Curated gene set/pathway annotation of genes mutated in either t(14;18)-positive or t(14;18)-negative FL revealed a strong enrichment of same or similar gene sets but also a more prominent or exclusive enrichment of immune response and N-glycosylation signatures in t(14;18)-negative FL. Mutated genes showed high BCL2 association in both subgroups. Among the genes mutated in t(14;18)-negative FL 555 were affected by copy-number alterations and/or copy-neutral LOH and 96 were differently expressed between t(14;18)-positive and t(14;18)-negative FL (P<0.01). N-glycosylation sites were detected considerably less frequently in t(14;18)-negative FL. These results suggest a diverse portfolio of genetic alterations that may induce or regulate BCL2 expression or promote pathogenesis of t(14;18)-negative FL as well as a less specific but increased crosstalk with the microenvironment that may compensate for the lack of N-glycosylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers, Tumor*
  • Chromosomes, Human, Pair 14
  • Chromosomes, Human, Pair 18
  • Computational Biology / methods
  • DNA Copy Number Variations
  • Exome Sequencing
  • Glycosylation
  • Humans
  • Immunoglobulin Variable Region / genetics
  • Lymphoma, Follicular / genetics*
  • Lymphoma, Follicular / metabolism
  • Mutation
  • Polymorphism, Single Nucleotide
  • Proto-Oncogene Proteins c-bcl-2 / genetics*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Translocation, Genetic

Substances

  • Biomarkers, Tumor
  • Immunoglobulin Variable Region
  • Proto-Oncogene Proteins c-bcl-2