Expression and clinical significance of FAK and Src proteins in human endometrial adenocarcinoma

Focal Adhesion Kinase (FAK) is a protein tyrosine kinase, localised in the focal adhesions, which, upon activation interacts with Src, another tyrosine kinase, regulating several cellular signalling pathways. Both enzymes have been implicated in malignant transformation and disease progression. The aim of the present study was to evaluate the clinical significance of FAK and Src expression in cases of endometrial adenocarcinoma. The total (t) and the activated, phosphorylated (p) forms of FAK and Src proteins were assessed immunohistochemically in tumour specimens obtained from 43 endometrial adenocarcinoma patients and were statistically analyzed in relation to various clinicopathological parameters and tumour proliferative capacity, reflected by Ki-67 labelling index. t-FAK positivity was significantly correlated with FIGO disease stage (p = 0.031), and t-FAK overexpression with patients' age (p = 0.015). No statistically significant correlation was identified between t-FAK staining intensity, t-Src positivity, overexpression or staining intensity and any of the clinicopathological parameters tested. No significant correlation was found between neither the positivity nor the intensity of staining of either p-FAk or p-Src with any of the parameters under study. Nonetheless, important, but non-significant, trends were identified between t-FAK staining intensity, t-Src positivity and overexpression and patients' survival (log rank, p = 0.122, p = 0.090 and p = 0.057 respectively). Similarly, p-FAK and p-Src staining characteristics seemed to correlate, even though non-significantly, with patients' survival (log rank, p = 0.051 and p = 0.070 for p-FAK and p-Src expression, respectively; log rank, p = 0.134 and p = 0.110 for p-FAK and p-Src staining intensity, respectively). These results support an important potential role of FAK-Src signalling in endometrial malignant disease progress and render further research in this field a necessity.