The vacuolar-type ATPase inhibitor archazolid increases tumor cell adhesion to endothelial cells by accumulating extracellular collagen
HUVECs were transfected with a plasmid containing human cathepsin B (catB) or the empty vector (pcDNA3.1(-)delta MCS). After 48 h cells were treated with 1 nM archazolid (arch) or DMSO (co) for 24 h. (A) The expression of cathepsin B was determined by western blot analysis. One representative blot out of three independently performed experiments is shown. Actin served as loading control. (B) Untreated MDA-MB-231 cells were labeled with CellTracker Green CMFDA Dye, added to the HUVEC monolayer and were allowed to adhere for 10 min. Non-adherent MDA-MB-231 cells were washed off. The adhesion was quantified by measuring the fluorescence signal using a plate reader. Data are expressed as mean ± SEM (n = 7). *p ≤ 0.05 versus DMSO (control transfection). #p ≤ 0.05 versus 1 nM archazolid (control transfection).