Methods: Protein and mRNA expression of TLR4 of primary (HN4, HN30) and metastatic (HN12, HN31) HNSCC cells were detected using flow cytometry and RT-PCR, respectively. The effect of LPS on TLR4 expression in tumor cells was also investigated in this study. MTT assay and chemoinvasion were used for determining the effect of LPS on tumor cell proliferation and cell invasion, respectively.
Results: Flow cytometry demonstrated that TLR4 expression in metastatic cancer cells was relatively high compared to that of primary cancer cells. E. coli LPS obviously enhance TLR4 expression in primary cancer cells. MTT assay showed that E. coli and A. actinomycetemcomitan LPS significantly stimulated proliferation of primary cancer cells. Finally, we found that E. coliLPS markedly increased the invasion of primary cancer cells.
Conclusions: Lower expression of TLR4 was observed in primary HNSCC cells. However, LPS obviously enhanced TLR4 expression, cell proliferation and invasion of primary cancer cells compared to metastatic cancer cells.