Fig.1.

Invasive properties of UCB cells. (A) The TEER assay depends on a high electrically resistant MDCK-C7 cell layer, seeded upside down into a filter cup insert. UCB cells were cultivated in the upper compartment of the filter cup. Therefore, MDCK-C7 cells were physically separated from the UCB cells limiting the communication of both cell types to released molecules. Immunofluorescence staining of MDCK-C7 cells documents the formation of tight junctions. Tight junctions were detected by zonula occludens 1 specific antibodies (green). Cell nuclei were stained in blue using 4^′,6-Diamidin-2-phenylindol. Scale corresponds to 50μm. (B) The dynamic development of the trans-epithelial electrical resistance (TEER) as a function of time. The invasive potential of malignant HT1197 and T24/83 cells was compared to that of the benignant urothelial cell line UROtsa. TEER was followed for three days after challenging the MDCK-C7 epithelial layer (t = 0 h). (C) Invasion coefficients were calculated with equation 1 and invasive properties 60 h and 120 h after carcinoma cells addition were compared. HT1197 caused the strongest TEER breakdown. (D) Proliferation rate of the UCB cells was of a comparable magnitude whereas HT1197 showed the lowest cell growth and UROtsa cells had the highest cell increment. n.d.: not detectable, ^*P < 0.05 t-test.