Effects of Oral Squamous Cell Carcinoma-derived TGF-β1 on CD26/DPPIV Expression in T Cells

Background: Enzymatic activity levels of serum CD26/ dipeptidylpeptidase (DPP) IV in oral cancer patients are lower than those in healthy subjects. However, the mechanism for this decrease is not yet fully understood. Materials and Methods: The influence of malignant cell- derived cytokines on cell surface CD26/DPP IV expression in human T cells was analyzed using an oral squamous cell carcinoma (SCC) cell line, KB, and peripheral blood T cells. Results: Tumor growth factor (TGF)-‚1 in KB-conditioned medium (KBCM) down-regulated CD26/DPPIV expression in T cells, which was responsible for the decreased DPPIV activities in the cultured supernatant. Expression p27 kip in T cells was maintained in addition to G1 arrest when cultured