Expression Of Protease-activated Receptor-1 In Nasopharyngeal Carcinoma Cells And Its Significance

Objective: To examine the expression of protease-activated receptor-1 (PAR1) in nasopharyngeal carcinoma (NPC) cell lines, and explore its role in the malignant behavior of NPC cells, such as in proliferation, adhesion and invasion.Methods: Five representative NPC cell lines were selected for our research. CNE1 is a well differentiated cell line. CNE1-LMP1 is a cell line which was stably transfected with the gene of latent membrane protein-1 (LMP1), and it has been confirmed to be more invasive and metastatic than CNE1 cell line. CNE2 is a poorly differentiated cell line. SUNE1-5-8F cell line has highly tumorigenic and metastatic potential. And SUNE1-6-10B cell line is tumorigenic but showing no metastatic capability. Real time PCR and Western blot were used to detect the expression of mRNA and protein of PAR1 in the five NPC cell lines. Subcellular localization of PAR1 was investigated by immunofluorescence technique. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, adhesion assay and transwell chamber assay were used to investigate the effect of PAR1 specific activating peptide SFLLRN and thrombin on proliferation, adhesion and in vitro invasion of CNE1-LMP1 cells. The activities of MMP2 and MMP9 in the supernatant of CNE1-LMP1 cells treated by SFLLRN and thrombin were measured by gelatin zymography.Results: PAR1 was expressed in all of the five NPC cell lines, and it was mainly distributed in the cell membrane and cytoplasm. The expression levels of PAR1 in CNE1-LMP1 and SUNE1-5-8F were higher than in CNE1, CNE2 and SUNE1-6-10B. And CNE1-LMP1 expressed the highest PAR1 in all of the five cell lines. SFLLRN could promote proliferation, adhesion and in vitro invasion of CNE1-LMP1 cells. Thrombin also increased the ability of adhesion and in vitro invasion of CNE1-LMP1 cells, but it had a dual effect on cells proliferation. Concentrations of thrombin in the range of 0.1~0.5U/ml promoted cell growth, but concentrations higher than 0.5U/ml inhibited cell growth. The activities of MMP2 and MMP9 in the supernatant of CNE1-LMP1 cells rised significantly following cells incubated with thrombin for 24 hours. In comparison with thrombin, SFLLRN only enhanced the activity of MMP2 slightly, and it had little effect on the activity of MMP9 in CNE1-LMP1 cells.Conclusions: The expression of PAR1 is correlated with the invasive and metastatic potential of NPC cells. PAR1 activation could increase the ability of proliferation, adhesion and invasion, and enhance secrection of gelatinase to some extent in NPC cells.