Cytoplasmic c-ros oncogene 1 receptor tyrosine kinase expression may be associated with the development of human oral squamous cell carcinoma.

The c-ros oncogene 1 receptor tyrosine kinase (ROS1) gene encodes a proto-oncogenic protein that has been demonstrated to be involved in the pathogenesis of several types of cancer. The present study aimed to analyze the expression of ROS1 in human oral squamous cell carcinomas (OSCCs), and investigate the association between its expression and the clinicopathological parameters of patients with OSCC. Paraffin-embedded OSCC tissues from 31 patients were obtained and the expression of ROS1 was analyzed by immunohistochemistry. The cellular location of ROS1 was determined by immunofluorescence in human oral cancer CAL-27 cells. The association of clinicopathological characteristics and survival rates with ROS1 expression were assessed. The results revealed that ROS1 was exclusively localized in the cytoplasm of the OSCC tissues (24/30, 80.0%), and in the cytoplasm of adjacent dysplastic epithelial tissues (2/15, 13.3%) (P<0.001). The moderate to strong expression of ROS1 in the cytoplasm was higher in OSCC tissues than in the normal epithelial tissues adjacent to the tumor (67.7 vs. 0%, P=0.001). The results of the Kaplan-Meier analysis and multivariate Cox regression analysis indicated that there was no association between the 5-year survival rate of patients and the cytoplasmic (P=0.28 and P=0.60, respectively) or nuclear expression (P=0.90 and P=0.31, respectively) of ROS1. These results suggest that the cytoplasmic expression level of ROS1 may be associated with the development of OSCC.