Reversibility of epithelial-mesenchymal transition (EMT) induced in breast cancer cells by activation of urokinase receptor-dependent cell signaling.
Hypoxia induces expression of the urokinase receptor (uPAR) and activates uPAR-dependent cell signaling in cancer cells. This process promotes epithelial-mesenchymal transition (EMT). uPAR overexpression in cancer cells also promotes EMT. In this study, we tested whether uPAR may be targeted to reverse cancer cell EMT. When MDA-MB 468 breast cancer cells were cultured in 1% O(2), uPAR expression increased, as anticipated. Cell-cell junctions were disrupted, vimentin expression increased, and E-cadherin was lost from cell surfaces, indicating EMT. Transferring these cells back to 21% O(2) decreased uPAR expression and reversed the signs of EMT. In uPAR-overexpressing MDA-MB 468 cells, EMT was reversed by silencing expression of endogenously produced urokinase-type plasminogen activator (uPA), which is necessary for uPAR-dependent cell signaling, or by targeting uPAR-activated cell signaling factors, including phosphatidylinositol 3-kinase, Src family kinases, and extracellular signal-regulated kinase. MDA-MB 231 breast cancer cells express high levels of uPA and uPAR and demonstrate mesenchymal cell morphology under normoxic culture conditions (21% O(2)). Silencing uPA expression in MDA-MB-231 cells decreased expression of vimentin and Snail, and induced changes in morphology characteristic of epithelial cells. These results demonstrate that uPAR-initiated cell signaling may be targeted to reverse EMT in cancer.
Jo
Minji
M
Department of Pathology, University of California, San Diego, California 92093, USA.
Lester
Robin D
RD
Montel
Valerie
V
Eastman
Boryana
B
Takimoto
Shinako
S
Gonias
Steven L
SL
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement; D002642:Chick Embryo; D002645:Chickens; D002867:Chromones / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D008648:Mesoderm / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D008856:Microscopy, Fluorescence; D009025:Morpholines / Q000494:pharmacology; D010100:Oxygen / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016133:Polymerase Chain Reaction; D034741:RNA, Small Interfering / Q000235:genetics / Q000502:physiology; D055293:Receptors, Urokinase Plasminogen Activator / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014404:Tubulin / Q000235:genetics; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000502:physiology; D014746:Vimentin / Q000235:genetics
D002867:Chromones; D005419:Flavonoids; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D034741:RNA, Small Interfering; D055293:Receptors, Urokinase Plasminogen Activator; D014404:Tubulin; D014746:Vimentin; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D014568:Urokinase-Type Plasminogen Activator; D010100:Oxygen; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one