The trace element fluoride can be beneficial for oral health by preventing dental caries. However, fluoride is also known as an environmental pollutant. Fluoride pollution can lead to fluoride over-ingestion and can cause health issues, including dental fluorosis. Curcumin attenuated fluoride-induced toxicity in animal models, however the molecular mechanisms of how curcumin affects fluoride toxicity remain to be elucidated. We hypothesized that curcumin attenuates fluoride toxicity through modulation of Ac-p53. Here we investigated how curcumin affects the p53-p21 pathway in fluoride toxicity. LS8 cells were treated with NaF with/without curcumin. Curcumin significantly increased phosphorylation of Akt [Thr308] and attenuated fluoride-mediated caspase-3 cleavage and DNA damage marker γH2AX expression. Curcumin-mediated attenuation of caspase-3 activation was reversed by Akt inhibitor LY294002 (LY). However, LY did not alter curcumin-mediated γH2AX suppression. These results suggest that curcumin inhibited fluoride-mediated apoptosis via Akt activation, but DNA damage was suppressed by other pathways. Curcumin did not suppress/alter fluoride-mediated Ac-p53. However, curcumin itself significantly increased Ac-p53 and upregulated p21 protein levels to suppress cell proliferation in a dose-dependent manner. Curcumin suppressed fluoride-induced phosphorylation of p21 and increased p21 levels within the nuclear fraction. However, curcumin did not reverse fluoride-mediated cell growth inhibition. These results suggest that curcumin-induced Ac-p53 and p21 led to cell cycle arrest, while curcumin attenuated fluoride-mediated apoptosis via activation of Akt and suppressed fluoride-mediated DNA damage. By inhibiting DNA damage and apoptosis, curcumin may potentially alleviate health issues caused by fluoride pollution. Further studies are required to better understand the mechanism of curcumin-induced biological effects on fluoride toxicity. Capsule: Curcumin induced Ac-p53 and p21 to suppress cell proliferation and activated Akt signaling to attenuate fluoride-mediated apoptosis and DNA damage in LS8 cells.
ASJC Scopus subject areas
- Health, Toxicology and Mutagenesis