Effects of monocyte conditioning medium induced by Porphyromonas gingivalis lipopolysaccharides on proliferation, invasion and apoptosis of head and neck cancer cell lines

Abstract

Introduction: The purpose of this study is to investigate the effect of lipopolysaccharide from periodontal pathogen Porphyromonas gingivais on proliferation, invasion and apoptosis of head and neck cancer cells.
Methods: Human monocytic cells (THP-1) were activated by P. gingivalis lipopolysaccharides (250-1,000 ng/ml) for 24 hours, then the conditioning media of the activated THP-1 were collected, and co-cultured with head and neck cancer cell lines (primary cancer cell line: HN18 and metastatic cancer cell line: HN17). Cell proliferation, invasion and apoptosis were analyzed by MTT assay,
modified Boyden chamber assay and flow cytometry Annexin V- FITC assay, respectively.
Results: The head and neck cancer cell lines when co-cultured with conditioning media of P. gingivalis LPS activated THP-1 cells showed the significant increase of cell proliferation and invasion in
dose dependent manner. In addition, the conditioning media could inhibit apoptosis in both primary and metastatic cell lines.
Conclusion: These results suggested that activated monocytes by P. gingivalis LPS can enhance aggressiveness in both primary and metastatic head and neck cancer cell lines