Aberrant ERG expression associates with downregulation of miR‐4638‐5p and selected genomic alterations in a subset of diffuse large B‐cell lymphoma

Abstract

ERG (avian v‐ets erythroblastosis virus E26 oncogene homolog), an oncoprotein in prostate carcinoma and Ewing's sarcoma is associated with poor prognosis in patients with acute myeloid leukemia and T lymphoblastic leukemia. However little is known about ERG in lymphoma. Here we studied ERG in diffuse large B‐cell lymphoma (DLBCL) by immunohistochemistry, fluorescence in situ hybridization (FISH), genome‐wide microRNA (miRNA) expression profiling, real‐time reverse‐transcriptase polymerase chain reaction (RT‐PCR) and whole exome sequencing (WES). Approximately 30% of de novo DLBCLs (37 of 118) expressed ERG (ERG+). ERG expression showed no significant correlation with DLBCL cell‐of‐origin classification, patient's age, sex, nodal, or extranodal disease status, tumor expression of p53 or p63. There was no ERG rearrangement in 10 randomly selected ERG+ DLBCLs by FISH. Forty‐three miRNAs showed significant differential expression between ERG+ and ERG− DLBCLs. Downregulation of miR‐4638‐5p was confirmed by real‐time RT‐PCR. WES not only confirmed known gene mutations in DLBCLs but also revealed multiple novel gene mutations in POLA1, E2F1, PSMD8, AXIN1, GAB2, and GNB2L1, which occur more frequently in ERG+ DLBCLs. In conclusion, our studies demonstrated aberrant ERG expression in a subset of DLBCL, which is associated with downregulation of miR‐4638‐5p. In comparison with ERG‐negative DLBCL, ERG+ DLBCL more likely harbors mutations in genes important in cell cycle control, B‐cell receptor‐mediated signaling and degradation of β‐catenin. Further clinicopathological correlation and functional studies of ERG‐related miRNAs and pathways may provide new insight into the pathogenesis of DLBCL and reveal novel targets for better management of patients with DLBCL.