Dipeptidyl peptidase IV in two human glioma cell lines

There is growing evidence that dipeptidyl peptidase IV [DPP-IV, EC 3.4.14.5 ] takes part in the metabolism of biologically active peptides participatin g in the regulation of growth and transformation of glial cells. However, t he knowledge on the DPP-IV expression in human glial and glioma cells is st ill, very limited. In this study, using histochemical and biochemical techn iques, the DPP-IV activity was demonstrated in two commercially available h uman glioma cell lines of different transformation degree, as represented b y U373 astrocytoma (Grade III) and U87 glioblastoma multiforme (Grade IV) l ines. Higher total activity of the enzyme, as well as its preferential loca lisation in the plasma membrane, was observed in U87 cells. Compared to U37 3 population, U87 cells were morphologically more pleiomorphic, they were c ycling at lower rate and expressing less Glial Fibrillary Acidic Protein. T he data revealed positive correlation between the degree of transformation of cells and activity of DPP-IV. Great difference in expression of this enz yme, together with the phenotypic differences of cells, makes these lines a suitable standard model for further studies of function of this enzyme in human glioma cells.