The electrical resistance breakdown assay determines the role of proteinases in tumor cell invasion.
The electrical resistance breakdown of the Madin-Darby canine kidney (MDCK) cell monolayer provides a continuous assay system for cancer invasion that detects functional changes before morphological alterations. In this study, we address the question of whether physical contact between tumor cell and epithelial monolayer is a prerequisite for tumor cell invasion. When human melanoma cells were seeded directly (i.e., physical contact) on top of an electrically tight epithelial cell layer (5,800 +/- 106 Omega x cm2), electrical monolayer leakage led to an 18 +/- 3% reduction of transepithelial electrical resistance within 24 h. However, when melanoma cells were seeded close to the basolateral surface of the epithelial cell monolayer but separated by a filter membrane (i.e., no physical contact), electrical leakage occurred even more quickly (42 +/- 3% reduction in 24 h). Atomic force microscopy detected discrete structural changes between cells. Electrical leakage was effectively blocked by alpha2-macroglobulin or ilomastat, inhibitors of matrix metalloproteinases. We conclude that exocytosis of soluble proteases causes electrical breakdown of the MDCK monolayer, independently of physical contact between tumor cells and the monolayer.
Institute of Physiology, University of Münster, D-48149 Münster, Germany.
Thomas
T
Ludwig
Rainer
R
Ossig
Susanne
S
Graessel
Marianne
M
Wilhelmi
Hans
H
Oberleithner
Stefan W
SW
Schneider
D000818:Animals; D001485:Basement Membrane / Q000201:enzymology; D002474:Cell-Free System; D018920:Coculture Techniques; D017364:Collagenases / Q000378:metabolism; D017097:Electric Impedance; D005089:Exocytosis / Q000502:physiology; D006801:Humans; D006877:Hydroxamic Acids; D007211:Indoles / Q000494:pharmacology; D007668:Kidney / Q000166:cytology*; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008545:Melanoma; D009361:Neoplasm Invasiveness; D011480:Protease Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000201:enzymology / Q000473:pathology
D006877:Hydroxamic Acids; D007211:Indoles; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D017364:Collagenases; D020782:Matrix Metalloproteinases; C119203:ilomastat