Correlation of protease-activated receptor-1 with differentiation markers in squamous cell carcinoma of the head and neck and its implication in lymph node metastasis.
OBJECTIVE
Protease-activated receptor-1 (PAR-1) is a G-protein-coupled receptor that contributes to multiple signal transduction pathways. Although the functions of PAR-1 in many normal cells, such as platelets and astrocytes, have been well studied, its roles in cancer progression and metastasis have not been fully elucidated, and studies to date appear contradictory.


METHODS
To clarify the function of PAR-1 in metastasis of squamous cell carcinoma of the head and neck (SCCHN), we examined PAR-1 expression in clinical specimens by immunohistochemistry and in SCCHN cell lines by immunoblotting. Furthermore, par-1 cDNA-transfected SCCHN cell lines were also used to verify PAR-1-mediated pathway.


RESULTS
The metastatic tumors showed a lower percentage of PAR-1-positive cells (46%) and lower levels of PAR-1 expression (median weight index = 10) than node negative primary tumors (80% and median weight index = 60, respectively). In addition, expression level of PAR-1 positively correlated with levels of keratinocyte differentiation markers keratin-1, -10, and -11. Additional studies using sense and antisense par-1 cDNA-transfected SCCHN cell lines illustrated that the presence of PAR-1 was required for the expression of involucrin, a keratinocyte differentiation marker. PAR-1 expression also contributes to activation of the mitogen-activated protein kinase (MAPK) pathway. Blocking MAPK activation by a mitogen-activated protein/extracellular signal-regulated kinase inhibitor, not by a phosphatidylinositol 3'-kinase inhibitor, reduced level of involucrin, suggesting that regulation of involucrin by PAR-1 is partially through the MAPK signaling pathway.


CONCLUSIONS
Our study suggests that PAR-1 signaling induces differentiation markers in SCCHN cells, and its expression is conversely correlated with cervical lymph node metastasis.
Zhang
Xin
X
Department of Hematology-Oncology, Emory University Winship Cancer Institute, Atlanta, Georgia 30322, USA.
Hunt
Jennifer L
JL
Landsittel
Doug P
DP
Muller
Susan
S
Adler-Storthz
Karen
K
Ferris
Robert L
RL
Shin
Dong M
DM
Chen
Zhuo Georgia
ZG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000378:metabolism; D002454:Cell Differentiation; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D018450:Disease Progression; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D015603:Keratinocytes / Q000378:metabolism; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011498:Protein Precursors / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
D014408:Biomarkers, Tumor; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011498:Protein Precursors; D044463:Receptor, PAR-1; C032253:involucrin