Syndecan-2 regulation of morphology in breast carcinoma cells is dependent on RhoGTPases.
BACKGROUND
While syndecan-2 is usually considered a mesenchymal transmembrane proteoglycan, it can be upregulated in some tumour cells, such as the malignant breast carcinoma cell line, MDA-MB231. Depletion of this syndecan by siRNA, but not other syndecans, has a marked effect on cell morphology, increasing spreading, microfilament bundle and focal adhesion formation, with reduced cell migration.


METHODS
A combination of siRNA transfection, immunofluorescence microscopy, phosphoprotein analysis and migration assays was used to determine how syndecan-2 may influence the cytoskeleton.


RESULTS
The altered adhesion upon syndecan-2 depletion was dependent on the RhoGTPases. p190ARhoGAP relocated to the margins of spreading cells, where it codistributed with syndecan-4 and active β1-integrin. This was accompanied by increased RhoGAP tyrosine phosphorylation, indicative of activity and RhoGTPase suppression. Consistent with this, GTP-RhoA was strongly present at the edges of control cells, but lost after syndecan-2 reduction by siRNA treatments. Further, RhoA, but not RhoC was shown to be essential for the anchored phenotype of these breast carcinoma cells that accompanied siRNA-mediated loss of syndecan-2.


CONCLUSIONS
Syndecan-2 has a key role in promoting the invasive activity of these cells, in part by regulating the RhoGTPases.


CONCLUSIONS
Syndecan-2, as a cell surface receptor is accessible for targeting to determine whether breast tumour progression is altered. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.
Department of Biomedical Sciences, University of Copenhagen, Denmark.
Hooi Ching
HC
Lim
Department of Biomedical Sciences, University of Copenhagen, Denmark. Electronic address: john.couchman@bric.ku.dk.
John R
JR
Couchman
D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D048430:Cell Shape; D005260:Female; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism; D053669:Syndecan-2 / Q000378:metabolism*; D053671:Syndecan-4 / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism; D000075024:rhoC GTP-Binding Protein; D019061:src-Family Kinases / Q000378:metabolism
C074560:ARHGAP35 protein, human; D020662:Guanine Nucleotide Exchange Factors; D019012:Integrin beta1; D012097:Repressor Proteins; D053671:Syndecan-4; D053669:Syndecan-2; D019061:src-Family Kinases; C066690:RHOC protein, human; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D000075024:rhoC GTP-Binding Protein
Cell adhesion; Cytoskeleton; Heparan sulfate; Proteoglycan; RhoGAP; RhoGTPases