Transendothelial migration of melanoma cells involves N-cadherin-mediated adhesion and activation of the beta-catenin signaling pathway.
Cancer metastasis is a multistep process involving many types of cell-cell interactions, but little is known about the adhesive interactions and signaling events during extravasation of cancer cells. Transendothelial migration of cancer cells was investigated using an in vitro assay, in which melanoma cells were seeded on top of a monolayer of endothelial cells. Attachment of melanoma cells on the endothelium induced a twofold increase in N-cadherin expression in melanoma cells and the redistribution of N-cadherin to the heterotypic contacts. Transendothelial migration was inhibited when N-cadherin expression was repressed by antisense RNA, indicating a key role played by N-cadherin. Whereas N-cadherin and beta-catenin colocalized in the contact regions between melanoma cells and endothelial cells during the initial stages of attachment, beta-catenin disappeared from the heterotypic contacts during transmigration of melanoma cells. Immunolocalization and immunoprecipitation studies indicate that N-cadherin became tyrosine-phosphorylated, resulting in the dissociation of beta-catenin from these contact regions. Concomitantly, an increase in the nuclear level of beta-catenin occurred in melanoma cells, together with a sixfold increase in beta-catenin-dependent transcription. Transendothelial migration was compromised in cells expressing a dominant-negative form of beta-catenin, thus supporting a regulatory role of beta-catenin signaling in this process.
Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada.
Jianfei
J
Qi
Ning
N
Chen
Junfu
J
Wang
Chi-Hung
CH
Siu
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D015703:Antigens, CD; D015820:Cadherins; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000037:antagonists & inhibitors / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D006801:Humans; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology*; D010766:Phosphorylation; D021381:Protein Transport / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology; D051176:beta Catenin / Q000378:metabolism / Q000502:physiology*
D015703:Antigens, CD; C050361:CDH2 protein, human; D015820:Cadherins; D015815:Cell Adhesion Molecules; D051176:beta Catenin; D014443:Tyrosine