Deficient E-cadherin adhesion in C57BL/6J-Min/+ mice is associated with increased tyrosine kinase activity and RhoA-dependent actomyosin contractility.
The Min/+ mouse is a model for APC-dependent colorectal cancer (CRC). We showed that tumorigenesis in this animal was associated with decreased E-cadherin adhesion and increased epidermal growth factor receptor (Egfr) activity in the non-tumor intestinal mucosa. Here, we tested whether these abnormalities correlated with changes in the actin cytoskeleton due to increased Rho-ROCK signaling. We treated Apc+/+ (WT) littermate small intestine with EGTA, an inhibitor of E-cadherin, and with LPA, an RhoA activator; both induced effects on adhesion and kinase activity that mimicked the Min/+ phenotype. GTP-bound Rho was increased in Min/+ enterocytes relative to WT. Since RhoA activity is associated with actomyosin contractility, markers of this signaling cascade were assessed including phosphorylated myosin light chain (MLC), cofilin, Pyk2, Src, and MAPK kinases. The increased actomyosin contractility characterizing Min/+ intestinal tissue was suppressed by the ROCK inhibitor, Y27632, but was inducible in the WT by EGTA or LPA. Finally, ultrastructural imaging revealed changes consistent with actomyosin contractility in Min/+ enterocytes. Thus, the positive regulation of E-cadherin adhesion provided by Apc+ in vivo allows proper negative regulation of Egfr, Src, Pyk2, and MAPK, as well as RhoA activities.
Carothers
Adelaide M
AM
Department of Surgery, Carrie Hall, Room 116, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA. acarothers@partners.org
Javid
Sara H
SH
Moran
Amy E
AE
Hunt
Daniel H
DH
Redston
Mark
M
Bertagnolli
Monica M
MM
D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism*; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000502:physiology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000172:deficiency; D024722:Cardiac Myosins / Q000378:metabolism; D000068579:Celecoxib; D002448:Cell Adhesion / Q000187:drug effects; D004533:Egtazic Acid / Q000494:pharmacology; D020895:Enterocytes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D066246:ErbB Receptors / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism; D051418:Focal Adhesion Kinase 2 / Q000378:metabolism; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000378:metabolism; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000502:physiology; D008246:Lysophospholipids / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D046529:Microscopy, Electron, Transmission; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D018994:Myosin Light Chains / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011799:Quinazolines; D013449:Sulfonamides / Q000494:pharmacology; D020032:Tyrphostins / Q000494:pharmacology; D015854:Up-Regulation; D051176:beta Catenin / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000819:agonists / Q000378:metabolism*
D051339:Actin Depolymerizing Factors; D025601:Adenomatous Polyposis Coli Protein; D000577:Amides; D000894:Anti-Inflammatory Agents, Non-Steroidal; D015820:Cadherins; D008246:Lysophospholipids; D009125:Muscle Relaxants, Central; D018994:Myosin Light Chains; D011720:Pyrazoles; D011725:Pyridines; D011799:Quinazolines; D013449:Sulfonamides; D020032:Tyrphostins; D051176:beta Catenin; C107184:myosin light chain 2; C108830:Y 27632; C101044:RTKI cpd; D004533:Egtazic Acid; D000205:Actomyosin; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496053:Ptk2b protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D024722:Cardiac Myosins; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D000068579:Celecoxib; C032881:lysophosphatidic acid; D002118:Calcium