Focal adhesion kinase表現於口腔鱗狀細胞癌之預後價值

Abstract

Focal adhesion kinase (FAK) has been considered as a key player of the signal transduction in cell adhesion. Studies have demonstrated that motility and proliferation of tumor cells are associated with increased expression of FAK, both at mRNA and protein levels. However, the relationship between FAK expression and various clinical parameters of oral squamous cell carcinoma (OSCC) remains controversial. Furthermore, most of the previous studies examined only total FAK, but FAK becomes activated only after phosphorylation at the position of tyrosine 397. In this study, the expressions of total FAK and FAK pY397 and their prognostic values were examined in 76 OSCC specimens. Twenty-one cases of normal oral mucosa were used as control. The relation between FAK expression and clinical parameters was analyzed by Fisher’s exact test and Kaplan-Meier method was employed to examine the influence of FAK expression on survival. Results showed that normal mucosa was negative for immunostaining of total FAK and FAK pY397. In OSCC specimens, the rates of negative, weakly positive and strongly positive staining for total FAK were respectively 48.7%, 23.7% and 27.6%, and for FAK pY397 were respectively 34.3%, 28.9% and 36.8%. Expression of total FAK was significantly related to the size of primary tumor (0.002), nodal metastasis status (0.003) and clinical stage (0.001). A higher rate of total FAK expression was found in tumors of smaller size and those without lymph node metastasis. Larger tumors and cases with metastasis node had lower expression of total FAK. Early stage diseases had stronger expression of total FAK than cases of late stage. Therefore, expression of total FAK was negatively related to survival (0.007). Lower expression of total FAK was also found in patients with longer history of alcohol drinking (0.013). As for FAK pY397, both cytoplasmic and nuclear stains were found but no significant relationship between immunostaining and various clinical parameters was noted. In conclusion, the study demonstrated that overexpression of total FAK tended to occur in early stage OSCC and denoted a better prognosis. The role of FAK pY397 expression in tumor growth was unclear and need further investigation.