Expression of focal adhesion kinase and phosphorylated focal adhesion kinase in squamous cell carcinoma of the larynx

OBJECTIVES: Focal adhesion kinase (FAK) is overexpressed in a variety of human cancers including those derived from the oral cavity. The purpose of this work is to determine the expression patterns of FAK and its activated form, FAK pY397, in squamous cell carcinoma of the larynx and to correlate FAK expression with tumor differentiation and clinical parameters. STUDY DESIGN: A retrospective study using archival tissue. METHODS: Thirty-five paraffin embedded tissue specimens of laryngeal carcinoma were obtained from the Department of Pathology at the University of Florida College of Medicine. Immunohistochemical staining of the specimens for FAK and activated phospho-FAK (FAK pY397) was performed. Intensity of staining, distribution of staining, and percentage of cells stained was determined by one pathologist. RESULTS: There was a statistically significant correlation between FAK staining intensity and tumor differentiation. Poorly differentiated tumors stained more intensely than moderately differentiated tumors (P <.001). There was no correlation between FAK pY397 staining and differentiation (P =.163). However, FAK pY397 staining was unexpectedly found in the nuclei of many specimens. FAK was present in the basal layer of cells within nontransformed squamous mucosa derived from tonsillectomy specimens and in blood vessels. A small amount of FAK pY397 was also localized to blood vessels in nontransformed squamous mucosa. CONCLUSION: FAK and phospho-FAK are overexpressed in squamous cell carcinoma of the larynx. FAK expression correlates with differentiation. Future investigations will examine the potential of FAK and FAK pY397 expression both as a prognostic indicator and a point of therapeutic inhibition.