Expression of focal adhesion kinase in small-cell lung carcinoma

BACKGROUND:

The focal adhesion kinase (FAK) is a non‐receptor tyrosine kinase linked to tumor growth, invasion, and metastasis. FAK is overexpressed and associated with prognosis in many cancers, but its prognostic value in small‐cell lung carcinoma (SCLC) is unknown and was the focus of this study.

METHODS:

Total FAK expression was analyzed via immunohistochemistry in tissue microarrays consisting of formalin‐fixed, paraffin‐embedded SCLC specimens from 85 patients. FAK staining scores were tested for correlations with pathological characteristics and clinical outcomes. Phospho‐paxillin was also tested in 35 of the 85 specimens to evaluate whether FAK expression was associated with downstream signaling.

RESULTS:

Specific FAK expression was localized to the cytoplasm of 78/85 (92%) SCLCs. FAK expression was scored low in 11 (13%), moderate in 17 (20%), and high in 50 (59%) SCLCs. FAK staining scores treated as continuous variables did not correlate with SCLC disease stage, response to therapy, recurrence/progression‐free survival, or overall survival. Moreover, total FAK expression did not correlate with phospho‐paxillin Tyr¹¹⁸ expression.

CONCLUSIONS:

Total FAK is strongly expressed in a majority of SCLC tumors. However, the expression evaluated via immunohistochemistry is not a prognostic factor in patients with SCLC. Cancer 2012;. © 2011 American Cancer Society.