Effects of N‐acetylcysteine on TEGDMA‐ and HEMA‐induced suppression of osteogenic differentiation of human osteosarcoma MG63 cells

Abstract

Triethyleneglycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) are major resinous components of dental restorative materials and dentin bonding adhesives. Resin monomers are known to cause cytotoxicity in mammalian cells via oxidative stress and inhibit differentiation of dental pulp cells and osteoblasts. This study was aimed to investigate whether oxidative stress was involved in the inhibition of TEGDMA- and HEMA-induced differentiation. TEGDMA and HEMA reduced alkaline phosphatase (ALP) activity and the mRNA expression of the osteopontin (OPN) gene in MG63 cells at noncytotoxic concentrations. On the other hand, N-acetylcysteine (NAC) did not affect ALP activity at concentrations below 10 mM. Reduced ALP activity and OPN mRNA expression by TEGDMA were partially recovered via cotreatment with NAC. However, NAC did not exhibit significant effects in HEMA-treated cells. Glutathione (GSH) levels were also down-regulated by both TEGDMA and HEMA. The addition of NAC induced the partial recovery of GSH in cells treated with 0.5 mM TEGDMA. On the other hand, the levels of GSH in HEMA-treated cells were not affected by NAC. These results suggest that oxidative stress is involved in the suppression of differentiation by TEGDMA. Translocation of Nrf2 from the cytoplasm to the nucleus has been known to play a role in the suppression of osteogenic differentiation by oxidative stress. However, Nrf2 did not move into the nucleus in resin monomer-treated MG63 cells, suggesting the contribution of other signaling pathways to the suppressive effects of resin monomers.

In Vitro Effects of Lead on Gene Expression in Neural Stem Cells and Associations between Up-regulated Genes and Cognitive Scores in Children

“…Consistent with our finding that oxidative stress increases SPP1 expression, exposure of MG63 cells to the oxidative stress inhibitor n-acetylcysteine (NAC) down-regulates SPP1 expression (Kim et al 2011). In addition, SPP1-mediated signaling through Akt and ERK is suggested to affect migration in glioma cells by activation of NRF2 (Lu et al 2012), which would suggest a positive feedback loop.…”

Hesperetin Alleviates the Inhibitory Effects of High Glucose on the Osteoblastic Differentiation of Periodontal Ligament Stem Cells

“…These findings indicate that hesperetin, due to its radical scavenging ability, functions in cellular defense. Previous studies have shown that oxidative stress suppresses osteogenic differentiation in various cellular systems [35]–[37]. Indeed, regulatory transcription networks between redox-responsive elements and the OPN gene have been reported [38].…”

NAC ameliorates dental composite-induced DNA double-strand breaks and chromatin condensation

“…Furthermore, the NAC thiol compound and GSH precursor is able to significantly increase endogenous GSH levels thereby reducing oxidative damage 11,58) , with NAC in addition also having cyclooxygenase-2 (COX-2) inhibitor 59) and prostaglandin-E2 inhibitor activity 60) . COX-2 is induced by inflammatory cytokines like interleukin-1β (IL-1β) and plays an important role in various inflammatory processes.…”