title: Down-regulation of BOB.1/OBF.1 and Oct2 in classical Hodgkin disease but not in lymphocyte predominant Hodgkin disease correlates with immunoglobulin transcription.
abstract: In contrast to the tumor cells (L&H cells) of lymphocyte predominant Hodgkin disease (LPHD), Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin disease (cHD) are unable to transcribe immunoglobulin, despite the presence of rearranged immunoglobulin genes. Although initial studies have suggested crippling immunoglobulin gene mutations to be the cause of absent immunoglobulin expression in cHD, recent work of our group has demonstrated an impaired activation of the immunoglobulin promoter as a superior mechanism. As immunoglobulin transcription is mainly regulated by the B-cell transcription factors Oct2 and BOB.1/OBF.1, we analyzed 35 cases of LPHD, 32 cases of cHD, and 2 Hodgkin disease cell lines for the expression of these transcription factors and also in parallel for immunoglobulin expression. Our results demonstrate an absence of Oct2 and/or BOB.1/OBF.1 in cHD and a striking overexpression of Oct2 in LPHD. Immunoglobulin expression was lacking in cHD but present in LPHD. Furthermore, the reintroduction of BOB.1/OBF.1 and Oct2 into cultured HRS cells restored the activity of cotransduced immunoglobulin promoter constructs. Our findings dismiss the concept that the different immunoglobulin expression in cHD and LPHD is due to disrupting mutations of immunoglobulin V genes in cHD but is most likely due to a down-regulation of Oct2 and/or BOB.1/OBF.1. This study further revealed Oct2 as a new and valuable marker for the identification of L&H cells and their distinction from HRS cells. The impairment of immunoglobulin transcription with a down-regulated synthesis of Oct2 and BOB.1/OBF.1 is the first established general recurrent defect found in HRS cells.
authors.affiliation: Institute of Pathology, Consultation and Reference Centre for Lymph Node Pathology and Haematopathology, University Hospital Benjamin Franklin, Free University, Berlin, Germany. stein@ukbf.fu-berlin.de
authors.forename: H
authors.initials: H
authors.lastname: Stein
authors.forename: T
authors.initials: T
authors.lastname: Marafioti
authors.forename: H D
authors.initials: HD
authors.lastname: Foss
authors.forename: H
authors.initials: H
authors.lastname: Laumen
authors.forename: M
authors.initials: M
authors.lastname: Hummel
authors.forename: I
authors.initials: I
authors.lastname: Anagnostopoulos
authors.forename: T
authors.initials: T
authors.lastname: Wirth
authors.forename: G
authors.initials: G
authors.lastname: Demel
authors.forename: B
authors.initials: B
authors.lastname: Falini
mesh_terms: D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation / Q000235:genetics; D006689:Hodgkin Disease / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007132:Immunoglobulin Isotypes / Q000378:metabolism; D007136:Immunoglobulins / Q000235:genetics* / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008214:Lymphocytes / Q000473:pathology*; D008224:Lymphoma, Follicular / Q000473:pathology; D050813:Octamer Transcription Factor-2; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D007132:Immunoglobulin Isotypes; D007136:Immunoglobulins; D050813:Octamer Transcription Factor-2; C091546:POU2AF1 protein, human; C058435:POU2F2 protein, human; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors