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Waldenstrom's Macroglobulinemia patients: expression and aCGH data

ABSTRACT: Waldenström’s macroglobulinemia (WM) is a distinct clinicobiological entity defined as a B-cell neoplasm characterized by a lymphoplasmacytic infiltrate in the bone marrow and immunoglobulin M paraprotein production. Cytogenetic analysis is limited by the difficulty in obtaining tumor metaphases and the genetic basis of the disease remains poorly defined. We performed a comprehensive analysis in 42 WM patients by using high-resolution array-based comparative genomic hybridization with the Human Genome 244A microarray. Overall, 83% of samples have chromosomal abnormalities, with a median of three abnormalities per patient (range 0 to 27). The most common abnormality was 6q deletion (40%) and four non-overlapped minimal deleted regions (MDR) were identified. Gain of 6p was the second most common abnormality (17%) and its presence was always concomitant with 6q loss. An interstitial MDR was delineated at 13q14 including MIRN15A and MIRN16-1 in 10% of patients. Other recurrent deletions were 7q22, 8p, 11q22-q23, 11q23-q24 and 17p11-p13 (7% each). Copy gains were identified in chromosomes 18 (17%), 4 (12%), 3 (10%), 8q (10%) and Xq27.1-q28 (10%). To note, we reported biallelic deletions and/or inactivating mutations with uniparental disomy in TRAF3 and TNFAIP3, two negative regulators of the NF-kB signaling pathway. Furthermore, we confirmed the association between TRAF3 inactivation and increased transcriptional activity of NF-kB target genes. Mutational activation of the NF-kB pathway, which is normally activated by ligand-receptor interactions within the bone marrow microenvironment, highlight its biologic importance, and suggest a therapeutic role for inhibitors of NF-KB pathway activation in the treatment of Waldenström’s macroglobulinemia. Keywords: gene expression profiling; array comparative genomic hybridization

ORGANISM(S): Homo sapiens

PROVIDER: GSE12668 | GEO | 2009/08/24

SECONDARY ACCESSION(S): PRJNA112739

REPOSITORIES: GEO

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Project description:A highly recurrent, somatic L265P mutation in the TIR domain of the signaling adapter MYD88 constitutively activates NF-kB. It occurs in nearly all human patients with Waldenström’s macroglobulinemia (WM), a B cell malignancy caused by IgM-expressing cells. Here we introduced an inducible leucine to proline point mutation into the mouse Myd88 locus, at the orthologous position L252P. When the mutation was introduced early during B cell development, B cells developed normally. However, IgM-expressing plasma cells accumulated with age in spleen and bone, leading to more than 20-fold elevated serum IgM titers. When introduced into germinal center B cells in the context of an immunization, the Myd88L252P mutation caused prolonged persistence of antigen-specific serum IgM and elevated numbers of antigen-specific IgM plasma cells. Myd88L252P-expressing B cells switched normally, but plasma cells expressing other immunoglobulin isotypes did not increase in numbers, implying that IgM expression may be required for the observed cellular expansion. In order to test whether the Myd88L252P mutation can cause clonal expansions, we introduced it into a small fraction of CD19-positive B cells. In this scenario, five out of five mice developed monoclonal IgM serum paraproteins accompanied by an expansion of clonally related plasma cells that expressed mostly hypermutated VDJ regions. Taken together, our data suggest that the Myd88L252P mutation is sufficient to promote aberrant survival and expansion of IgM-expressing plasma cells which in turn can cause IgM monoclonal gammopathy of undetermined significance (MGUS), the premalignant condition that precedes WM. References: 1. Shevchenko A, Tomas H, Havli J, Olsen JV, Mann M. In-gel digestion for mass spectrometric characterization of proteins and proteomes. Nat Protoc (2006) 1:2856–2860. doi:10.1038/nprot.2006.468, 2. Rappsilber J, Mann M, Ishihama Y. Protocol for micro-purification, enrichment, pre-fractionation and storage of peptides for proteomics using StageTips. Nat Protoc (2007) 2:1896–1906. doi:10.1038/nprot.2007.261, 3. Cox J, Neuhauser N, Michalski A, Scheltema RA, Olsen JV, Mann M. Andromeda: A Peptide Search Engine Integrated into the MaxQuant Environment. J Proteome Res (2011) 10:1794–1805. doi:10.1021/pr101065j, 4. Cox J, Mann M. MaxQuant enables high peptide identification rates, individualized p.p.b.-range mass accuracies and proteome-wide protein quantification. Nat Biotechnol (2008) 26:1367–1372. doi:10.1038/nbt.1511.

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Waldenstrom's Macroglobulinemia patients: expression and aCGH data

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