Abstract
PURPOSE: Aberrant fibroblast growth factor receptor (FGFR) expression is thought to contribute to the development of many types of cancer. As yet, however, their impact on the course and prognosis of head and neck cancer remains to be determined. Here, we aimed to investigate the effects of expression of the FGFR family members FGFR1 and FGFR3, as well as their downstream PI3K/AKT signal-regulated kinases, on the aggressiveness and prognosis of laryngeal cancer. METHODS: In total 137 surgically removed squamous cell laryngeal cancer (SCLC) and 100 matched non-cancerous laryngeal mucosa (NCLM) samples were assessed for mRNA expression using quantitative real-time PCR. The corresponding proteins were analyzed by Western blotting. SLUG expression was assessed by immunohistochemistry. The expression data were subsequently related to tumor front grading (TFG), local/nodal recurrences, prognosis and overall survival. RESULTS: The FGFR1, FGFR3 and PI3K/AKT kinase mRNA and protein levels were found to be significantly higher in the SCLC than the NCLM samples (p < 0.05). A high FGFR1 mRNA/protein expression level was found to be associated with an increased invasion rate, according to TFG scale and SLUG level, a high local/nodal recurrence rate and a poor prognosis (p < 0.05). Similarly, we found that a high FGFR3 mRNA/protein expression level was associated with a shorter survival time (p < 0.05). In addition, we found that high PI3K/AKT kinase mRNA/protein levels were associated with a high TFG (p < 0.05). We also found that FGFR1/3 mRNA and FGFR1 protein levels were inversely associated with overall survival (log-rank test: FGFR1 mRNA p = 0.03, FGFR3 mRNA p = 0.04, FGFR1 protein p = 0.03). Subsequent multivariate analyses revealed that high FGFR3 mRNA expression may serve as an independent poor prognostic factor (HR 2.32, 95% CI 1.03-6.59; p = 0.04). We also found that the p-PI3K regulatory kinase protein level was significantly associated with survival in the cohort studied (HR 1.78, 95% CI 0.64-8.53; p = 0.03). CONCLUSIONS: From our data we conclude that FGFR1 and FGFR3, as well as its downstream regulatory PI3K/AKT kinases, may serve as potential biomarkers for the invasiveness and prognosis of laryngeal cancer. The expression of FGFR1/3-PI3K/AKT regulatory pathway members may be instrumental for the identification of patients at risk for an unfavorable clinical outcome.