Melanoma cell lines are responsive in vitro to lipopolysaccharide and express TLR-4

Endotoxin/lipopolysacccharide (LPS) is a potent inflammatory stimulus, which acts on tumour infiltrating leukocytes by eliciting a wide range of factors promoting invasion and metastasis. Less known is the effect of LPS directly on tumour cells. In this study, we analysed whether tumour cell lines from different origin (melanoma, ovarian carcinoma, neuroblastoma) are responsive to LPS in vitro. Results showed that only melanoma cells significantly up-regulated the production of IL-8 and cell adhesion, when triggered with LPS. These effects were associated with the constitutive expression of TLR-4 mRNA in these cells and the expression on the cell membrane of the complete LPS-binding receptor.