title: EZH2 codon 641 mutations are common in BCL2-rearranged germinal center B cell lymphomas.
abstract: Mutations at codon 641 of EZH2 are recurrent in germinal center B cell lymphomas, and the most common variants lead to altered EZH2 enzymatic activity and enhanced tri-methylation of histone H3 at lysine 27, a repressive chromatin modification. As an initial step toward screening patients for cancer genotype-directed therapy, we developed a screening assay for EZH2 codon 641 mutations amenable for testing formalin-fixed clinical specimens, based on the sensitive SNaPshot single nucleotide extension technology. We detected EZH2 mutations in 12/55 (22%) follicular lymphomas (FL), 5/35 (14%) diffuse large B cell lymphomas with a germinal center immunophenotype (GCB-DLBCL), and 2/11 (18%) high grade B cell lymphomas with concurrent rearrangements of BCL2 and MYC. No EZH2 mutations were detected in cases of Burkitt lymphoma (0/23). EZH2 mutations were frequently associated with the presence of BCL2 rearrangement (BCL2-R) in both the FL (28% of BCL-R cases versus 0% of BCL2-WT cases, p<0.05) and GCB-DLBCL groups (33% of BCL2-R cases versus 4% of BCL2-WT cases, p<0.04), and across all lymphoma types excluding BL (27% of BCL2-R cases versus 3% of BCL2-WT cases, p<0.003). We confirmed gain-of-function activity for all previously reported EZH2 codon 641 mutation variants. Our findings suggest that EZH2 mutations constitute an additional genetic "hit" in many BCL2-rearranged germinal center B cell lymphomas. Our work may be helpful in the selection of lymphoma patients for future trials of pharmacologic agents targeting EZH2 and EZH2-regulated pathways.
authors.affiliation: Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, United States of America. Ryan.Russell@mgh.harvard.edu
authors.forename: Russell J H
authors.initials: RJ
authors.lastname: Ryan
authors.forename: Mai
authors.initials: M
authors.lastname: Nitta
authors.forename: Darrell
authors.initials: D
authors.lastname: Borger
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Zukerberg
authors.forename: Judith A
authors.initials: JA
authors.lastname: Ferry
authors.forename: Nancy Lee
authors.initials: NL
authors.lastname: Harris
authors.forename: A John
authors.initials: AJ
authors.lastname: Iafrate
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Bernstein
authors.forename: Aliyah R
authors.initials: AR
authors.lastname: Sohani
authors.forename: Long Phi
authors.initials: LP
authors.lastname: Le
mesh_terms: D000818:Animals; D015153:Blotting, Western; D003062:Codon / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D000071221:Enhancer of Zeste Homolog 2 Protein; D005347:Fibroblasts / Q000378:metabolism; D015321:Gene Rearrangement / Q000235:genetics*; D018858:Germinal Center / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D016393:Lymphoma, B-Cell / Q000235:genetics*; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D041681:NIH 3T3 Cells; D063151:Polycomb Repressive Complex 2; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D003062:Codon; D004268:DNA-Binding Proteins; D050505:Mutant Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014157:Transcription Factors; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2