S 100A8 mediates the activation of P65/HLA- B/S 100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinogenesis

S100 calcium binding protein A8 （S100A8）, a possible novel member of NF-kappa B signal pathway in laryngeal squamous cell carcinoma （LSCC）, interacts with human leukocyte antigen B （HLA-B） which carries an NF-kappa B binding site within the enhancer A. The objective of this study was to explore the molecular mechanism of S100A8 in laryngeal carcinogenesis. RT-PCR, Western blotting and immunohistochemistry staining were applied to evaluate the expression levels of IKKα, P65, REL-B, S100A8, APAF-1 and BCL-2 genes. The signal transduction passway in which S100A8 might participate was explored by RNA interference. Flow cytometry, TUNEL assay and cell invasion in vitro were used to detect the biological behavior of Hep2 cells induced by S100A8 gene. Our results showed that high expression of S100A8 was related to tumorigenesis in LSCC and negatively correlated with the degree of differentiation, indicating that S100A8 gene could inhibit apoptosis and promote metastasis in LSCC. Additionally, the suppression of S100A8 by RNA interference down-regulated BCL-2 but not APAF-1, P65 and IKKα, while, the suppression of P65 could significantly down-regulate the expression of S100A8 gene. In conclusion, S100A8 plays an important role in P65/HLA-B/S100A8/BCL-2/Caspase-9 （-3） pathway in laryngeal carcinoma.