Lubrol-RAFTs in melanoma cells: a molecular platform for tumor-promoting ephrin-B2-integrin-beta1 interaction.
Ephrins control cell motility and matrix adhesion. These functions play a pivotal role in cancer progression, for example, in malignant melanomas. We have previously shown that the ephrin-B2-tumor-promoting action is partly mediated by integrin-beta1 interaction. However, the subcellular prerequisites for molecular interaction like molecular proximity and co-compartmentalization have not been elucidated yet. Specific cholesterol-rich microdomains, termed lipid rafts (RAFTs), are known to be essential for functional ephrin-B2 signalling and integrin-mediated effects. Therefore, we addressed the question whether RAFT co-compartmentalization of both molecules could provide the molecular platform for their tumor-promoting interaction. In this study, we show that overexpressed ephrin-B2 is not only compartmentalized to classical Triton X-100 RAFTs in B16 melanoma cells, but also to the recently defined Lubrol-RAFTs. Interestingly, in the melanoma cells investigated, integrin-beta1 is also preferentially detected in such Lubrol-RAFTs. Accordingly, the presence of ephrin-B2 and integrin-beta1 in RAFTs and their function in cell migration and matrix attachment are highly sensitive to RAFT disruption by cholesterol depletion. Confocal fluorescence microscopy analyses also support the concept of a close molecular proximity and functional interplay of ephrin-B2 and integrin-beta1 in the plasma membrane. We conclude that Lubrol-RAFTs probably represent the platform for tumor-promoting ephrin-B2-integrin-beta1 interaction, which could become an interesting target for future antitumoral therapies.
Meyer
Stefanie
S
Department of Dermatology, University Hospital of Regensburg, Regensburg, Germany. stefanie.meyer@klinik.uni-regensburg.de
Orsó
Evelyn
E
Schmitz
Gerd
G
Landthaler
Michael
M
Vogt
Thomas
T
D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002471:Cell Transformation, Neoplastic; D002784:Cholesterol / Q000502:physiology; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D036388:Ephrin-B2 / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D021962:Membrane Microdomains / Q000502:physiology*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D011092:Polyethylene Glycols; D025941:Protein Interaction Mapping / Q000379:methods*; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*
D036388:Ephrin-B2; D019012:Integrin beta1; D011092:Polyethylene Glycols; C005092:lubrol; D002784:Cholesterol