DOCK10-mediated Cdc42 activation is necessary for amoeboid invasion of melanoma cells.
BACKGROUND
Tumor cells can move in a three-dimensional (3D) environment in either mesenchymal-type or amoeboid modes. In mesenchymal-type movement, cells have an elongated morphology with Rac-induced protrusions at the leading edge. Amoeboid cells have high levels of actomyosin contractility, and movement is associated with deformation of the cell body through the matrix without proteolysis. Because signaling pathways that control the activation of GTPases for amoeboid movement are poorly understood, we sought to identify regulators of amoeboid movement by screening an siRNA library targeting guanine nucleotide exchange factors (GEFs) for Rho-family GTPases.


RESULTS
We identified DOCK10, a Cdc42 GEF, as a key player in amoeboid migration; accordingly, we find that expression of activated Cdc42 induces a mesenchymal-amoeboid transition and increases cell invasion. Silencing DOCK10 expression promotes conversion to mesenchymal migration and is associated with decreased MLC2 phosphorylation and increased Rac1 activation. Consequently, abrogating DOCK10 and Rac1 expression suppresses both amoeboid and mesenchymal migration and results in decreased invasion. We show that the Cdc42 effectors N-WASP and Pak2 are required for the maintenance of the rounded-amoeboid phenotype. Blocking Cdc42 results in loss of mesenchymal morphology, arguing that Cdc42 is also involved in mesenchymal morphology through different activation and effector pathways.


CONCLUSIONS
Previous work has identified roles of Rho and Rac signaling in tumor cell movement, and we now elucidate novel roles of Cdc42 signaling in amoeboid and mesenchymal movement and tumor cell invasion.
Gadea
Gilles
G
Cancer Research UK Centre for Cell and Molecular Biology, Institute of Cancer Research, London, United Kingdom.
Sanz-Moreno
Victoria
V
Self
Annette
A
Godi
Anna
A
Marshall
Christopher J
CJ
D045744:Cell Line, Tumor; D002465:Cell Movement; D048430:Cell Shape; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D009361:Neoplasm Invasiveness; D015398:Signal Transduction; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D054462:p21-Activated Kinases / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D020662:Guanine Nucleotide Exchange Factors; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D020764:cdc42 GTP-Binding Protein; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein; C530992:DOCK10 protein, human; C495771:WASL protein, human; C515907:PAK2 protein, human