Objective: To explore the correlation between expression of PAR-1 and metastasis of human lung carcinoma.
Methods: Expression levels of PAR-1 were examined in surgically resected lung carcinoma specimens and corresponding lymph nodes by RT-PCR and immunohistochemistry, combined with morphometric methodology and clinicopathologic profiles.
Results: Strong PAR-1 staining was detected in the periphery of carcinoma nests, adenocarcinomatous emboli, foci of atypical adenomatous hyperplasia adjacent to the adenocarcinoma and atypical proliferation of duct epithelium of bronchial mucous glands. The expression rates of PAR-1 were 73.8% (59/80) and 63.9% (23/36) by immunohistochemistry and RT-PCR respectively. The percentage of PAR-1 protein expression cells was significantly higher in tumors with metastasis (85.7%, 48/56) than those without (45.8%, 11/24). Morphometric study demonstrated that there were significant differences of PAR-1 protein expression levels between tumors with metastatic and those without, primary and metastatic carcinomas, primary carcinomas and benign lung tissues adjacent to the carcinoma. No significant correlation was found between PAR-1 expression level and tumor size, histological types and tumor grades. The positive rate of PAR-1 mRNA expression in the metastatic group was significantly higher than that of the non-metastatic group (78.3%, 18/23 v.s. 38.5%, 5/13).
Conclusion: PAR-1 expression may play an important role in determining the malignant phenotypes of lung cancers and significantly contribute to their initiation, progression and metastasis.