We set up an in vitro differentiation model of ameloblasts by using retinoic acid (RA) and dexamethasone (DEX) to induce the maturation of mouse ameloblast-like LS8 cells.
The mRNA and protein levels of two enamel matrix proteins and two enamel proteinases were downregulated and upregulated, respectively, in the RA/DEX induced cells, indicating RA/DEX induced cells possessed the characteristics of matured ameloblasts. The strengthened endocytosis function and decreased intracellular pH value inside RA/DEX treated ameloblasts confirmed the maturation inducing effect of RA/DEX on ameloblasts. Excessive fluoride inhibited cell proliferation of ameloblasts within 72 h. High amounts of fluoride also induced more apoptosis/dead cells and reduced the expression of Bcl-2, but to a different degree in the non-induced cells and RA/DEX induced cells.
We inferred that high doses of fluoride may easily target the transitional/early maturation ameloblasts and cause apoptosis or cell death. Bcl-2 might be involved in this process.