Endothelial injury causes degradation of adjacent basement membranes and promotes their invasion by A549 carcinoma cells.
Experiments in vivo have demonstrated that endothelial cell injury promotes the local arrest of circulating, intravascular cancer cells and the subsequent formation of metastatic tumors. The experiments described here were performed to test the hypothesis that injury of the endothelium also causes damage to the adjacent vascular basement membrane, which in turn facilitates the passage of cancer cells across the vessel wall. Confluent monolayers of bovine pulmonary artery endothelial cells were incubated with 3H-2-deoxyglucose or 3H-proline to label the endothelial cells or the basement membrane, respectively. After adding H2O2 to these cultures, damage of the endothelium and basement membrane was detected by release of the isotopes into the culture medium. The kinetics and magnitude of basement membrane degradation correlated with the damage to the endothelial cells. Evidence for involvement of endothelial proteases in basement membrane injury included identification of a 63-kD gelatinase in the culture medium, inhibition of injury by protease inhibitors and the inability of H2O2 to cause 3H-proline release when applied directly to basement membranes. Scanning electron microscopy demonstrated that a greater number of A549 lung adenocarcinoma cells attached to the basement membrane and endothelium at points of endothelial retraction. However, this was not due to an increase in the adhesive properties of the basement membrane. The media from injured endothelial cultures stimulated the motility of A549 cells in a Boyden chamber assay. Furthermore, in a 24-hour invasion assay, a greater number of A549 cells migrated through injured basement membranes than through control membranes. We conclude that endothelial cell injury can cause enzymatic damage to the underlying basement membrane and postulate that this can facilitate the transvascular passage of cancer cells in vivo.
Missirlis
E
E
Department of Pharmacology, Faculty of Medicine, Patras, Greece.
Whaley
M
M
Lhotak
S
S
Orr
F W
FW
D000818:Animals; D001485:Basement Membrane / Q000187:drug effects / Q000473:pathology* / Q000502:physiology; D002417:Cattle; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008175:Lung Neoplasms / Q000473:pathology*; D009361:Neoplasm Invasiveness / Q000473:pathology*; D011480:Protease Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery; D014407:Tumor Cells, Cultured
D011480:Protease Inhibitors; D006861:Hydrogen Peroxide