Predictive role of toll-like receptors 2, 4, and 9 in oral tongue squamous cell carcinoma

Objectives: The clinical behavior of oral tongue squamous cell carcinoma (OTSCC) can be unpredictable, and even small tumors may behave aggressively. Toll-like receptors (TLRs) are pattern-recognition molecules involved in innate immunity, and they are also expressed in many types of cancer. TLRs play an apparently pivotal role in some cancers related to tumor progression and, conversely, cancer inhibition, however their role in oral cancer is unclear. We therefore studied the expression of TLR-2, -4, -5, -7, and -9 in early-stage OTSCC. Materials and methods: Tissue microarray technique and immunohistochemistry was employed to define the expression of TLRs from the tumors of 73 consecutive patients with Stage I-II OTSCC. Immunoexpression scores were compared with patient and tumor related characteristics and survival. Results: All TLRs were expressed in OTSCC tissue. High/strong TLR-2, -4, and -9 expression correlated with deeper tumor invasion. Cytoplasmic TLR-2 and -4 also correlated significantly with higher tumor grade, whereas high TLR-5 expression associated with lower tumor grade. High expression of TLR-9 correlated with advanced tumor size. Negative or mild TLR-5 expression predicted poor disease-specific survival. Conclusion: All the studied TLRs showed high expression in early-stage OTSCC. More importantly, TLR-2, -4, and -9 seemed to predict invasive tumor growth. (C) 2014 Elsevier Ltd. All rights reserved.