Areca nut extracts modulated expression of alkaline phosphatase and receptor activator of nuclear factor kappaB ligand in osteoblasts.

OBJECTIVE

Areca chewers have a higher prevalence of periodontal diseases than non-chewers. This study was to determine the possible effects of ripe areca nut extracts (rANE) on viability and gene expression of alkaline phosphatase (ALP), receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) in human osteoblasts.

METHODS

The effects of rANE on cell viability of osteoblast-like MG63 cells were determined using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) that measures metabolic activity. Gene expression of ALP, RANKL and OPG was examined using reverse transcription-polymerase chain reaction. ALP activity and RANKL protein were further examined using substrate assay and confocal laser scanning microscopy, respectively.

RESULTS

Relative viability was reduced to approximately 50% when 25 microg/ml of rANE was used. The expression of OPG mRNA in MG63 cells was not altered by rANE. However, decreased levels of mRNA and enzyme activity of ALP were observed. Moreover, the expressions of mRNA and protein of RANKL were stimulated by rANE in a dose-dependent manner.

CONCLUSIONS

The rANE affected morphology and viability of osteoblasts. We also present novel evidence demonstrating that areca nut may compromise the periodontal health of areca chewers by suppression of ALP gene expression and elevation of RANKL gene expression in osteoblasts.