Activation of canonical Wnt/β-catenin signaling inhibits H2O2-induced decreases in proliferation and differentiation of human periodontal ligament fibroblasts

• Published in: Molecular and cellular biochemistry 2016, Vol.411 (1-2), p.83-94
• Main Authors: Kook, Sung-Ho, Lee, Daewoo, Cho, Eui-Sic, Heo, Jung Sun, Poudel, Sher Bahadur, Ahn, Yu-Hyeon, Hwang, Jae-Won, Ji, Hyeok, Kim, Jong-Ghee, Lee, Jeong-Chae
• Format: Article
• Language: English
• Subjects: Adult; Alkaline Phosphatase - metabolism; beta Catenin - genetics; beta Catenin - metabolism; Biochemistry; Biomedical and Life Sciences; Cardiology; Cell Differentiation - drug effects; Cell Proliferation - drug effects; Fibroblasts - cytology; Fibroblasts - drug effects; Humans; Hydrogen Peroxide - pharmacology; Life Sciences; Male; Medical Biochemistry; Oncology; Periodontal Ligament - cytology; Periodontal Ligament - drug effects; Periodontal Ligament - enzymology; Signal Transduction; Wnt Proteins - metabolism; Young Adult
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1007/s11010-015-2570-4

Human periodontal ligament fibroblasts (hPLFs) are exposed to oxidative stress during periodontal inflammation and dental treatments. It is hypothesized that hydrogen peroxide (H 2 O 2 )-mediated oxidative stress decreases survival and osteogenic differentiation of hPLFs, whereas these decreases are prevented by activation of the Wnt pathway. However, there has been a lack of reports that define the exact roles of canonical Wnt/β-catenin signaling in H 2 O 2 -exposed hPLFs. Treatment with H 2 O 2 reduced viability and proliferation in hPLFs in a dose- and time-dependent manner and led to mitochondria-mediated apoptosis. Pretreatment with lithium chloride (LiCl) or Wnt1 inhibited the oxidative damage that occurred in H 2 O 2 -exposed hPLFs. However, knockout of β-catenin or treatment with DKK1 facilitated the H 2 O 2 -induced decreases in viability, mitochondrial membrane potential, and Bcl-2 induction. Osteoblastic differentiation of hPLFs was also inhibited by combined treatment with 100 μM H 2 O 2 , as evidenced by the decreases in alkaline phosphatase (ALP) activity and mineralization. H 2 O 2 -mediated inhibition of osteoblast differentiation in hPLFs was significantly attenuated in the presence of 500 ng/ml Wnt1 or 20 mM LiCl. In particular, H 2 O 2 stimulated the expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) at protein and mRNA levels in hPLFs, whereas the induction was almost completely suppressed in the presence of Wnt1 or LiCl. Furthermore, siRNA-mediated silencing of Nrf2 blocked H 2 O 2 -induced decreases in ALP activity and mineralization of hPLFs with the concomitant restoration of runt-related transcription factor 2 and osteocalcin mRNA expression and ALP activity. Collectively, these results suggest that activation of the Wnt/β-catenin pathway improves proliferation and mineralization in H 2 O 2 -exposed hPLFs by downregulating Nrf2.