Hydrogen sulfide inhibits cell proliferation and induces cell cycle arrest via an elevated p21 Cip1 level in Ca9-22 cells.

BACKGROUND AND OBJECTIVE

Volatile sulfur compounds such as hydrogen sulfide (H(2)S) and methyl mercaptan (CH(3)SH) are the main causes of oral mal odor. However, the physiological functions of H(2)S have not been investigated in oral tissues. The aim of this study was to evaluate the effect of H(2)S on cell proliferation and the cell cycle in oral epithelial-like cells.

MATERIAL AND METHODS

Ca9-22 cells were used in this study. Cells were cultured in 5% CO(2)/95% air with (5 or 10 ng/mL) or without H(2)S. DNA synthesis was measured using a 5-bromo-2-deoxyuridine enzyme-linked immunosorbent assay. The cell cycle was analyzed using a flow cytometer. The expressions of phosphorylated retinoblastoma protein (Rb), p21(Cip1) and p27(Kip1) were evaluated by western blotting.

RESULTS

Exposure to 5 and 10 ng/mL of H(2)S significantly decreased DNA synthesis (p < 0.05). Cell cycle analysis also showed that exposure to both concentrations of H(2)S significantly increased the proportion of cells in G(1) phase (p < 0.001) and significantly decreased the proportion of cells in S phase (p < 0.01). Western blotting showed that Rb phosphorylation was reduced and p21(Cip1) was enhanced by exposure to H(2)S.

CONCLUSION

The results indicated that H(2)S inhibits cell proliferation and induces cell cycle arrest via the expression of p21(Cip1) in Ca9-22 cells.