title: Clinical and oncologic implications in epigenetic down-regulation of CD26/dipeptidyl peptidase IV in adult T-cell leukemia cells.
abstract: CD26/dipeptidyl peptidase IV (DPPIV), a T-cell-activation antigen, is a 110-kD type II surface glycoprotein expressed on various types of normal cells. CD26/DPPIV is considered a multifunction housekeeping protein. Malignant cells often show altered CD26/DPPIV expression or no CD26/DPPIV expression, thus suggesting a useful marker for assessing some T-cell malignancies. In this study, cell surface protein and messenger RNA expression profiles for CD26/DPPIV were examined in 49 patients with adult T-cell leukemia (ATL), 10 carriers of human T-lymphotropic virus I (HTLV-I), and 4 HTLV-I-infected cell lines to assess the utility of CD26/DPPIV expression as a useful molecular marker for ATL pathology. In contrast to normal lymphocytes, ATL cells and HTLV-I-infected cell lines apparently down-regulated or completely lost the CD26/DPPIV antigen. Furthermore, the positive rate and antigen density for CD26/DPPIV in ATL cells gradually declined along with the advancement of ATL stage. Analysis of genomic DNA and the CD26/DPPIV transcript showed that CD26- ATL cells possessed faintly detected transcripts of the gene that were aberrantly methylated at the CpG islands within the promoter region in parallel with the advancement of ATL, a finding supported by a rescue experiment for transcript reexpression using 5-azacytidine as demethylation agent. Moreover, there was no relationship between loss of CD26/DPPIV and HTLV-I tax expression. These results indicate that ATL cells down-regulate CD26 antigens by means of epigenetic machinery and that this antigen abnormality is a useful molecular marker for the pathology of ATL.
authors.affiliation: Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Tsuji
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Sugahara
authors.forename: Kazuto
authors.initials: K
authors.lastname: Tsuruda
authors.forename: Akiko
authors.initials: A
authors.lastname: Uemura
authors.forename: Hitomi
authors.initials: H
authors.lastname: Harasawa
authors.forename: Hiroo
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hamaguchi
authors.forename: Masao
authors.initials: M
authors.lastname: Tomonaga
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Yamada
authors.forename: Shimeru
authors.initials: S
authors.lastname: Kamihira
mesh_terms: D015415:Biomarkers; D016022:Case-Control Studies; D018899:CpG Islands; D019175:DNA Methylation; D018819:Dipeptidyl Peptidase 4 / Q000032:analysis / Q000235:genetics*; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000175:diagnosis / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012313:RNA / Q000032:analysis
chemical_list: D015415:Biomarkers; D012313:RNA; D018819:Dipeptidyl Peptidase 4