title: Localization of CD26/DPPIV in nucleus and its nuclear translocation enhanced by anti-CD26 monoclonal antibody with anti-tumor effect.
abstract: BACKGROUND
  CD26 is a type II, cell surface glycoprotein known as dipeptidyl peptidase (DPP) IV. Previous studies have revealed CD26 expression in T cell leukemia/lymphoma and malignant mesothelioma, and an inhibitory effect of anti-CD26 monoclonal antibody (mAb) against the growth of CD26+ cancer cells in vitro and in vivo. The function of CD26 in tumor development is unknown and the machinery with which the CD26 mAb induces its anti-tumor effect remains uncharacterized.
  
  
  RESULTS
  The localization of CD26 in the nucleus of T cell leukemia/lymphoma cells and mesothelioma cells was shown by biochemical and immuno-electron microscopic analysis. The DPPIV enzyme activity was revealed in the nuclear fraction of T cell leukemia/lymphoma cells. These expressions of intra-nuclear CD26 were augmented by treatment with the CD26 mAb, 1F7, with anti-tumor effect against the CD26+ T cell leukemia/lymphoma cells. In contrast, the CD26 mAb, 5F8, without anti-tumor effect, did not augment CD26 expressions in the nucleus. Biotin-labeled, cell surface CD26 translocated into the nucleus constantly, and this translocation was enhanced with 1F7 treatment but not with 5F8.
  
  
  CONCLUSIONS
  These results indicate that the intra-nuclear CD26 which moves from plasma membrane may play certain roles in cell growth of human cancer cells.
authors: Department of Pathology, Keio University School of Medicine, Tokyo, Japan. kohji@z8.keio.jp
authors: Kohji
authors: K
authors: Yamada
authors: Mutsumi
authors: M
authors: Hayashi
authors: Wenlin
authors: W
authors: Du
authors: Kei
authors: K
authors: Ohnuma
authors: Michiie
authors: M
authors: Sakamoto
authors: Chikao
authors: C
authors: Morimoto
authors: Taketo
authors: T
authors: Yamada