Disruption of STAT3 signaling leads to tumor cell invasion through alterations of homotypic cell-cell adhesion complexes.
STAT3 is frequently overexpressed and constitutively activated by tyrosine phosphorylation during malignant transformation. Despite the clear importance of STAT3 in cell proliferation and survival in diverse human cancers, its possible contribution to tumor cell adhesion, motility and invasion remains hypothetical. We therefore compared the transforming properties of STAT3wt, its constitutively activated dimeric form STAT3C, and the dominant negative mutant STAT3-Y705F in human colorectal HCT8/S11 cancer cells. Both STAT3wt and STAT3C exert a permissive action to the proinvasive activity of the scatter factor HGF in HCT8/S11 cells. In contrast, the monomeric and cytoplasmic mutant Y705F induces a constitutive invasive phenotype through Wnt/Rho-independent and EGFR/PI3-kinase-dependent pathways. Accordingly, Y705F decreases cell-cell homotypic adhesions, and increases cell motility and scattering, as well as lamellipodia-type cellular extensions. STAT3-Y705F-transfected HCT8/S11 cells display an increased tyrosine phosphorylation of the cell-cell adhesion regulator beta-catenin and its dissociation from the invasion suppressor E-cadherin at cell-cell contacts. Our data imply that both invasion promoter and repressor genes are controlled by the canonical STAT3 transcription pathways. Disruption of this cascade by Y705F reveals the proinvasive potential of altered forms of STAT3 as a persistent signaling adaptor in cytokine/transforming growth factor receptor scaffolds and oncogenic pathways.
Rivat
Christine
C
INSERM U 482, Signal Transduction and Cellular Functions in Diabetes and Digestive Cancers, Hôpital Saint-Antoine, 184 Rue du Faubourg Saint-Antoine, 75571 Paris Cedex 12, France.
De Wever
Olivier
O
Bruyneel
Erik
E
Mareel
Marc
M
Gespach
Christian
C
Attoub
Samir
S
D015820:Cadherins / Q000032:analysis / Q000502:physiology; D002448:Cell Adhesion; D002449:Cell Aggregation; D002465:Cell Movement; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000502:physiology; D004268:DNA-Binding Proteins / Q000502:physiology*; D066246:ErbB Receptors / Q000502:physiology; D006801:Humans; D051821:Lymphoid Enhancer-Binding Factor 1; D009361:Neoplasm Invasiveness; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000032:analysis / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology; D051153:Wnt Proteins; D051176:beta Catenin
C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; D011518:Proto-Oncogene Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; D019869:Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors