Increased expression of Toll-like receptor-9 has close relation with tumour cell proliferation in oral squamous cell carcinoma

Toll-like receptor-9 (TLR-9), a new member of the interleukin-1 receptor superfamily, was recently found to have a high level of expression in many carcinoma specimens. The objective of this study was to examine the TLR-9 expression and its role in tumour cell proliferation in oral squamous cell carcinoma.

Western blot and immunohistochemistry were used to detect TLR-9 protein in oral squamous cell carcinoma (OSCC) Tca-8113 cell lines and clinical specimens (n=60). The relationship between TLR-9 expression and clinicopathologic features was analysed. Cell proliferation and inflammatory chemokines secretion were tested by MTT and ELISA methods respectively.

Results showed that TLR-9 expression level was higher in OSCC tissues than in paired adjacent normal tissues (P<0.01), and the expression level of TLR-9 was significantly associated with tumour size (P=0.001), tumour clinical stage (P=0.003) and Ki-67 expression (P<0.01). In vitro results also suggested that stimulation of Tca-8113 cells with TLR-9 agonist CpG-ODN could significantly increase tumour cell proliferation as well as subsequent IL-1α and IL-6 secretions (P<0.01), which could be partially inhibited by usage of anti-TLR-9 protein.

It was therefore hypothesized that increased expression of TLR-9 may be of great value in assessing the development of OSCC, and could be used as a new target for OSCC prevention and therapy in future.