The CS1 segment of fibronectin is involved in human OSCC pathogenesis by mediating OSCC cell spreading, migration, and invasion.
BACKGROUND
The alternatively spliced V region or type III connecting segment III (IIICS) of fibronectin is important in early development, wound healing, and tumorigenesis, however, its role in oral cancer has not been fully investigated. Thus, we investigated the role of CS-1, a key site within the CSIII region of fibronectin, in human oral squamous cell carcinoma (OSCC).


METHODS
To determine the expression of CS-1 in human normal and oral SCC tissue specimens immunohistochemical analyses were performed. The expression of CS1 was then associated with clinicopathological factors. To investigate the role of CS-1 in regulating OSCC cell spreading, migration and invasion, OSCC cells were assayed for spreading and migration in the presence of a CS-1 peptide or a CS-1 blocking peptide, and for invasion using Matrigel supplemented with these peptides. In addition, integrin alpha4siRNA or a focal adhesion kinase (FAK) anti-sense oligonucleotide was transfected into OSCC cells to examine the mechanistic role of integrin alpha4 or FAK in CS1-mediated cell spreading and migration, respectively.


RESULTS
CS-1 expression levels were significantly higher in OSCC tissues compared to normal tissues (p < 0.05). Also, although, high levels of CS-1 expression were present in all OSCC tissue samples, low-grade tumors stained more intensely than high grade tumors. OSCC cell lines also expressed higher levels of CS-1 protein compared to normal human primary oral keratinocytes. There was no significant difference in total fibronectin expression between normal and OSCC tissues and cells. Inclusion of CS-1 in the in vitro assays enhanced OSCC cell spreading, migration and invasion, whereas the CS1 blocking peptide inhibited these processes. Suppression of integrin alpha4 significantly inhibited the CS1-mediated cell spreading. Furthermore, this migration was mediated by focal adhesion kinase (FAK), since FAK suppression significantly blocked the CS1-induced cell migration.


CONCLUSIONS
These data indicate that the CS-1 site of fibronectin is involved in oral cancer pathogenesis and in regulating OSCC cell spreading, migration and invasion.
Kamarajan
Pachiyappan
P
Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, Michigan 48109-1078, USA.
Garcia-Pardo
Angeles
A
D'Silva
Nisha J
NJ
Kapila
Yvonne L
YL
D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D048430:Cell Shape; D005353:Fibronectins / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D039441:Integrin alpha4 / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D015603:Keratinocytes / Q000378:metabolism* / Q000473:pathology; D009062:Mouth Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D010455:Peptides / Q000378:metabolism*; D034622:RNA Interference; D046888:Tissue Array Analysis; D014162:Transfection
D005353:Fibronectins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C076687:CS1 peptide; D039441:Integrin alpha4; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human