title: Expression of TCL1 in hematologic disorders.
abstract: OBJECTIVE
  TCL1, MTCP1 and TCL1b are three members of a new family of oncogenes that are expressed in T cell leukemias of ataxia telangiectasia patients (T-PLL, T-CLL). TCL1 is located at 14q32.1 and activated by juxtaposition to the alpha/delta-locus at 14q11 or beta-locus at 7q35 of the T cell receptor during the reciprocal translocations t(14;14)(q11;q32), t(7;14)(q35;q32), or inversion inv(14)(q11;q32). TCL1 encodes a predominantly cytoplasmic protein of 114 aa (14 kD) of unknown function. Recent studies suggest that TCL1 promotes cell survival rather than stimulating cell proliferation, as previously proposed.
  
  
  METHODS
  In an attempt to clarify the contexts in which TCL1 is expressed, we investigated TCL1 expression in 114 lymphoma and leukemia patients by Northern blot, RT-PCR and immunohistochemistry.
  
  
  RESULTS
  TCL1 expression is restricted to lymphoid cells, and is found in neoplastic (T and B cell neoplasms, and Hodgkin's disease) and nonneoplastic proliferations (reactive lesions). Out of 114 cases, 18 neoplasms of myeloid and 4 cases of epithelial origin were TCL1-negative. In lesions of the lymphoid system, both low- and high-grade lymphomas were found to express TCL1.
  
  
  CONCLUSIONS
  We propose that TCL1 expression especially in high-grade B cell non-Hodgkin's lymphomas might interfere with B cell differentiation and promote the transition from low- to high-grade lymphoma.
authors.affiliation: Institute of Pathology, University of Berne, Berne, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Roos
authors.forename: I
authors.initials: I
authors.lastname: Hennig
authors.forename: J
authors.initials: J
authors.lastname: Schwaller
authors.forename: J
authors.initials: J
authors.lastname: Zbären
authors.forename: R
authors.initials: R
authors.lastname: Dummer
authors.forename: G
authors.initials: G
authors.lastname: Burg
authors.forename: A
authors.initials: A
authors.lastname: Tobler
authors.forename: L
authors.initials: L
authors.lastname: Virgilio
authors.forename: C M
authors.initials: CM
authors.lastname: Croce
authors.forename: M F
authors.initials: MF
authors.lastname: Fey
authors.forename: B
authors.initials: B
authors.lastname: Borisch
mesh_terms: D015152:Blotting, Northern; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000097:blood; D006801:Humans; D007150:Immunohistochemistry; D007938:Leukemia / Q000097:blood / Q000378:metabolism* / Q000473:pathology; D008223:Lymphoma / Q000097:blood / Q000378:metabolism* / Q000473:pathology; D011518:Proto-Oncogene Proteins; D012334:RNA, Neoplasm / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000096:biosynthesis* / Q000097:blood; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D012334:RNA, Neoplasm; C090851:TCL1A protein, human; D014157:Transcription Factors