Stereotyped B cell receptors in B cell leukemias and lymphomas.

2013

Darzentas N, Stamatopoulos K.

Source

Medical Genomics Research Group, Molecular Medicine Program, CEITEC/Central European Institute of Technology, Masaryk University, Brno, Czech Republic.

Abstract

Recent research has revealed the existence of subsets (clusters) of patients with different types of B-cell lymphomas and leukemias with restricted, "stereotyped" immunoglobulin (IG) variable heavy complementarity-determining region 3 (VH CDR3) sequences within their B cell receptors (BcR), suggesting selection by common epitopes or classes of structurally similar epitopes. BcR stereotypy was initially described in chronic lymphocytic leukemia (CLL), where it constitutes a remarkably frequent feature of the IG repertoire, and subsequently identified in other malignancies, including mantle cell lymphoma and splenic marginal-zone lymphoma. Of note, at least in CLL, emerging evidence indicates that the grouping of cases into distinct clusters with stereotyped BcR is functionally and prognostically relevant. Hence, the reliable identification of BcR stereotypy may assist in the investigation of the nature of the selecting antigens and immune pathways leading to lymphom adevelopment, and also potentially pave the way for tailored treatment strategies applicable to each major stereotyped subset. In this chapter, we provide an overview of BcR stereotypy in human B-cell malignancies, and outline previous and current methodological approaches used for its identification.

PubMed

MCL1 is deregulated in subgroups of diffuse large B-cell lymphoma.

Dec 21, 2012

Wenzel SS, Grau M, Mavis C, Hailfinger S, Wolf A, Madle H, Deeb G, Dörken B, Thome M, Lenz P, Dirnhofer S,Hernandez-Ilizaliturri FJ, Tzankov A, Lenz G.

Source

Department of Hematology, Oncology and Tumor Immunology, Molecular Cancer Research Center, Charité - Universitätsmedizin Berlin, Germany.

Abstract

Keywords: 

MCL1, diffuse large B-cell lymphoma, aCGH, apoptosis, therapy resistance

MCL1 is an anti-apoptotic member of the BCL2 family that is deregulated in various solid and hematological malignancies. However, its role in the molecular pathogenesis of diffuse large B-cell lymphoma (DLBCL) is unclear. We analyzed gene expression profiling data from 350 DLBCL patient samples and detected that activated B-cell-like (ABC) DLBCLs express MCL1 at significantly higher levels compared to germinal center B-cell-like (GCB) DLBCL patient samples (p=2.7 x 10(-10)). Immunohistochemistry confirmed high MCL1 protein expression predominantly in ABC DLBCL in an independent patient cohort (n=249; p=0.001). To elucidate molecular mechanisms leading to aberrant MCL1 expression, we analyzed array comparative genomic hybridization (aCGH) data of 203 DLBCL samples and identified recurrent chromosomal gains/amplifications of the MCL1 locus that occurred in 26% of ABC DLBCLs. In addition, aberrant STAT3 signaling contributed to high MCL1 expression in this subtype. Knockdown of MCL1 as well as treatment with the BH3-mimetic obatoclax induced apoptotic cell death in MCL1 positive DLBCL cell lines. In summary, MCL1 is deregulated in a significant fraction of ABC DLBCLs and contributes to therapy resistance. These data suggest that specific inhibition of MCL1 might be utilized therapeutically in a subset of DLBCLs.Leukemia accepted article preview online, 21 December 2012; doi:10.1038/leu.2012.367.

Nature.com