Identification of 2 DNA methylation subtypes of Waldenström macroglobulinemia with plasma and memory B-cell features

Journal article

Epigenetic changes during B-cell differentiation generate distinct DNA methylation signatures specific for B-cell subsets, including memory B cells (MBCs) and plasma cells (PCs). Waldenström macroglobulinemia (WM) is a B-cell malignancy uniquely comprising a mixture of lymphocytic and plasmacytic phenotypes. Here, we integrated genome-wide DNA methylation, transcriptome, mutation, and phenotypic features of tumor cells from 35 MYD88-mutated WM patients in relation to normal plasma and B-cell subsets. Patients naturally segregate into 2 groups according to DNA methylation patterns, related to normal MBC and PC profiles, and reminiscent of other memory and PC-derived malignancies. Concurrent analysis of DNA methylation changes in normal and WM development captured tumor-specific events, highlighting a selective reprogramming of enhancer regions in MBC-like WM and repressed and heterochromatic regions in PC-like WM. MBC-like WM hypomethylation was enriched in motifs belonging to PU.1, TCF3, and OCT2 transcription factors and involved elevated MYD88/TLR pathway activity. PC-like WM displayed marked global hypomethylation and selective overexpression of histone genes. Finally, WM subtypes exhibited differential genetic, phenotypic, and clinical features. MBC-like WM harbored significantly more clonal CXCR4 mutations (P = .015), deletion 13q (P = .006), splenomegaly (P = .02), and thrombocytopenia (P = .004), whereas PC-like WM harbored more deletion 6q (P = .012), gain 6p (P = .033), had increased frequencies of IGHV3 genes (P = .002), CD38 expression (P = 4.1e-5), and plasmacytic differentiation features (P = .008). Together, our findings illustrate a novel approach to subclassify WM patients using DNA methylation and reveal divergent molecular signatures among WM patients.

Authors: Roos-Weil, D; Giacopelli, B; Armand, M; Della-Valle, V; Ghamlouch, H

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Society of Hematology
• Journal: Blood
• Volume: 136
• Issue: 5
• Pages: 585-595
• Publication date: 2020-07-30
• Acceptance date: 2020-03-26
• DOI: 10.1182/blood.2020005081
• EISSN: 1528-0020
• ISSN: 0006-4971
• Pmid: 32457988
• Language: English
• Keywords: FFR