title: CD26/DPPIV expression and 8-azaguanine response in T-acute lymphoblastic leukaemia cell lines in culture.
abstract: Dipeptidyl peptidase IV, a cell membrane surface protease also known as CD26 (CD26/DPPIV), is known to play multiple functions in human organism, where it is largely expressed, for instance, in the development of human cancer and metastasis as well as in chemotherapy response. The objective of this work was to study the CD26 membrane expression and DPPIV activity in T-acute leukaemia cell lines (CEM and MOLT3) in culture, in order to observe the modification of its expression under the 8-azaguanine treatment. Cell line samples were incubated, some without different azaguanine concentration and others with, ranging from 10 to 100muM. Cell surface CD26 expression has been identified by flow cytometry and DPPIV activity, in cultured medium, was fluorimetrically measured. Results we have observed showed that 8-azaguanine induced a decrease in cell viability in a dose, time and cell type dependent manner with MOLT3 cells being the most sensitive to 8-azaguanine citotoxic effects (24h IC50: +/-10muM) when compared with CEM cells (24h IC50: +/-100muM). In the same experimental conditions, MOLT3 cell treated with 8-azaguanine shows an increase in CD26 expression (MIF) compared with that of CEM cell submitted to the same conditions (65.4+/-1.3 versus 18.7+/-1.7). DPPIV activity in culture medium supernatant of CEM versus MOLT3 controls cells (1.91+/-0.43 versus 2.06+/-0.50) and of CEM versus MOLT3 treated cells (2.10+/-0.16 versus 1.89+/-0.04) did not show a significant difference. These preliminary results suggest that 8-azaguanine stimulates CD26 expression which may be related to cellular sensitivity to 8-azaguanine.
authors.affiliation: Institute of General Pathology, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal; Discipline of Pathophysiology of Dental Medicine, Faculty of Medicine, University of Coimbra, Rua Larga, 3004-504 Coimbra, Portugal.
authors.forename: Marília
authors.initials: M
authors.lastname: Dourado
authors.forename: Ana Bela
authors.initials: AB
authors.lastname: Sarmento
authors.forename: Sofia Vale
authors.initials: SV
authors.lastname: Pereira
authors.forename: Vera
authors.initials: V
authors.lastname: Alves
authors.forename: Teresa
authors.initials: T
authors.lastname: Silva
authors.forename: Anabela Mota
authors.initials: AM
authors.lastname: Pinto
authors.forename: Manuel Santos
authors.initials: MS
authors.lastname: Rosa