LPS increased the expression and secretion of IL-6, IL-8 and VEGF through TLR4 in a human OSCC cell line instead of HIOEC cells. A. HIOEC and CAL-27 cells (5 × 105 ml-1) were stimulated with LPS (1 μg/ml) for 24 h, and then cytokines and chemokines in the supernatants were assayed using sandwich ELISA. Protein levels (pg/ml) are expressed as mean ± SD in three independent experiments (***p < 0.001, **p < 0.01, *p < 0.05, compared with control). B. RT-PCR analysis of IL-6, IL-8, and VEGF and TGF-β mRNA expression in HIOEC and CA-27 cells stimulated with LPS (1 μg/ml) for indicated time points. C. To determine the cytokine levels, supernatants were collected from cultured tumor cells after stimulation with LPS for 24 h with or without TLR4 siRNA transfection. Results are expressed as mean ± SD of cytokine concentrations (pg/ml) in three independent experiments (***p < 0.001, **p < 0.01, *p < 0.05, compared with the NC siRNA group). D. LPS-induced expression of IL-6, IL-8, and VEGF was inhibited by TLR4 siRNA in CAL-27 cells as determined by RT-PCR.