Dynamic regulation of ROCK in tumor cells controls CXCR4-driven adhesion events.
CXCR4 is a chemokine receptor often found aberrantly expressed on metastatic tumor cells. To investigate CXCR4 signaling in tumor cell adhesion, we stably overexpressed CXCR4 in MCF7 breast tumor cells. Cell attachment assays demonstrate that stimulation of the receptor with its ligand, CXCL12, promotes adhesion of MCF7-CXCR4 cells to both extracellular matrix and endothelial ligands. To more closely mimic the conditions experienced by a circulating tumor cell, we performed the attachment assays under shear stress conditions. We found that CXCL12-induced tumor cell attachment is much more pronounced under flow. ROCK is a serine/threonine kinase associated with adhesion and metastasis, which is regulated by CXCR4 signaling. Thus, we investigated the contribution of ROCK activity during CXC12-induced adhesion events. Our results demonstrate a biphasic regulation of ROCK in response to adhesion. During the initial attachment, inhibition of ROCK activity is required. Subsequently, re-activation of ROCK activity is required for maturation of adhesion complexes and enhanced tumor cell migration. Interestingly, CXCL12 partially reduces the level of ROCK activity generated by attachment, which supports a model in which stimulation with CXCL12 regulates tumor cell adhesion events by providing an optimal level of ROCK activity for effective migration.
Struckhoff
Amanda P
AP
Department of Oral Biology, LSU Health Sciences Center, New Orleans, LA 70112, USA.
Vitko
Jason R
JR
Rana
Manish K
MK
Davis
Carter T
CT
Foderingham
Kamau E
KE
Liu
Chi-Hsin
CH
Vanhoy-Rhodes
Lyndsay
L
Elliot
Steven
S
Zhu
Yun
Y
Burow
Matt
M
Worthylake
Rebecca A
RA
D000577:Amides / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D011725:Pyridines / Q000494:pharmacology; D019718:Receptors, CXCR4 / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000577:Amides; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D004791:Enzyme Inhibitors; D011725:Pyridines; D019718:Receptors, CXCR4; C108830:Y 27632; D054460:rho-Associated Kinases