The protrusive phase and full development of integrin-dependent adhesions in colon epithelial cells require FAK- and ERK-mediated actin spike formation: deregulation in cancer cells.
Integrins play an important role in tumour progression by influencing cellular responses and matrix-dependent adhesion. However, the regulation of matrix-dependent adhesion assembly in epithelial cells is poorly understood. We have investigated the integrin and signalling requirements of cell-matrix adhesion assembly in colon carcinoma cells after plating on fibronectin. Adhesion assembly in these, and in the adenoma cells from which they were derived, was largely dependent on alpha v beta 6 integrin and required phosphorylation of FAK on tyrosine-397. The rate of fibronectin-induced adhesion assembly and the expression of both alpha v beta 6 integrin and FAK were increased during the adenoma-to-carcinoma transition. The matrix-dependent adhesion assembly process, particularly the final stages of complex protrusion that is required for optimal cell spreading, required the activity of extracellular signal-regulated kinase (ERK). Furthermore, phosphorylated ERK was targeted to newly forming cell--matrix adhesions in the carcinoma cells but not the adenoma cells, and inhibition of FAK--tyrosine-397 phosphorylation or MEK suppressed the appearance of phosphorylated ERK at peripheral sites. In addition, inhibition of MEK--ERK activation blocked the formation of peripheral actin microspikes that were necessary for the protrusive phase of cell-matrix adhesion assembly. Thus, MEK--ERK--dependent peripheral actin re-organization is required for the full development of integrin-induced adhesions and this pathway is stimulated in an in vitro model of colon cancer progression.
Brunton
V G
VG
Beatson Institute for Cancer Research, CRC Beatson Laboratories, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK. v.brunton@beatson.gla.ac.uk
Fincham
V J
VJ
McLean
G W
GW
Winder
S J
SJ
Paraskeva
C
C
Marshall
J F
JF
Frame
M C
MC
D000199:Actins / Q000378:metabolism; D000236:Adenoma / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules / Q000378:metabolism / Q000502:physiology*; D002461:Cell Line, Transformed; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D018450:Disease Progression; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology*; D005353:Fibronectins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions / Q000502:physiology; D006801:Humans; D016023:Integrins / Q000378:metabolism / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D008819:Mice, Nude; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism / Q000502:physiology*; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism / Q000502:physiology*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D000199:Actins; D000951:Antigens, Neoplasm; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D016023:Integrins; C073878:integrin alphavbeta6; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases