Immunohistochemical analysis of phosphotyrosine signal transducer and activator of transcription 3 and epidermal growth factor receptor autocrine signaling pathways in head and neck cancers and metastatic lymph nodes

Purpose: To determine the effect of tyrosine-phosphorylated signal transducer and activator of transcription 3 (pSTAT3) immunoexpression on survival in two independent cohorts of patients with squamous cell carcinoma of the head and neck (SCCHN) and to evaluate pSTAT3, transforming growth factor-α (TGF-α), epidermal growth factor receptor (EGFR), and gastrin-releasing peptide receptor (GRPR) expression in matched tumor and lymph node metastases in one of these cohorts. Experimental Technique: Immunostaining for pSTAT3, TGF-α, EGFR, and GRPR was done in two SCCHN cohorts (cohort 1, 61 tumors; cohort 2, 69 paired primary tumors and lymph node metastases). Semiquantitative scores derived from the product of staining intensity (scale 0-3) score and percentage of positive tumor cells were correlated with clinical outcome. Results: Immunoexpression of pSTAT3 did not correlate with clinical outcome in either cohort (cohort 1, P = 0.914; cohort 2, P = 0.312). In cohort 2, TGF-α and EGFR expression in the primary tumors showed some association with decreased disease-free survival (P = 0.0306 and P = 0.0985, respectively). Both pSTAT3 and EGFR showed a correlation of expression between tumor and matched lymph node metastasis (P < 0.0001 and P = 0.0046, respectively). In addition, the expression of EGFR and GRPR in the primary tumors correlated with TGF-α expression in paired nodal metastases (P = 0.0043 and P = 0.0268, respectively). In the nodal metastases, TGF-α expression correlated with EGFR expression (P = 0.0069). In primary tumors, GRPR expression correlated with TGF-α and EGFR expression (P = 0.0378 and P = 0.0026, respectively). Conclusions: These findings support an autocrine signaling pathway involving TGF-α, EGFR, and pSTAT3 in metastatic SCCHN as well as transactivation of EGFR by GRPR via TGF-α, but fails to identify an independent prognostic role for pSTAT3 immunoexpression.