title: Tumor Necrosis Factor Alpha Stimulates Proliferation of Dental Pulp Stem Cells via Akt/Glycogen Synthase Kinase-3β/Cyclin D1 Signaling Pathway.
abstract: BACKGROUND
  It has been widely accepted that dental pulp stem cells (DPSCs), which are a class of self-renewal and differentiation potential of adult stem cells, play an important role in the repair procession of pulp's inflammation. We investigated whether tumor necrosis factor alpha (TNF-α) could induce the proliferation of DPSCs and clarified the potential mechanism of this proliferation.
  
  
  METHODS
  Cell Counting Kit-8 assay (Dojindo Laboratories, Mashiki-machi, Kumamoto, Japan) and 5-ethynyl-2'-deoxyuridine-based proliferation assays were determined to investigate various concentrations or hours of TNF-α inducing a cell number change of DPSCs. Next, flow cytometry analysis was performed to investigate the main cell cycle phase process of DPSCs. Furthermore, the signaling pathway of TNF-α-induced proliferation of DPSCs was analyzed using Western blot analysis. Then, inhibitors were added to confirm the mechanism of this signaling pathway.
  
  
  RESULTS
  TNF-α induced the proliferation of DPSCs in a dose- and time-dependent manner. Cyclin D1, which controlled the cell cycle process from the G1 to the S phase, was up-regulated by TNF-α in a time-dependent manner, whereas its overexpression alone increased DPSC proliferation. Furthermore, TNF-α was capable of inducing Akt/GSK-3β signaling pathway activation. Blockage of phosphoinositide 3-kinase/Akt by their kinase or genetic inhibitors could significantly reduce TNF-α-induced proliferation of DPSCs.
  
  
  CONCLUSIONS
  This study confirmed that TNF-α induced the proliferation of DPSCs by regulating the Akt/GSK-3β/cyclin D1 signaling pathway and then provided a suitable number for the requirements of cell differentiation.
authors.affiliation: Department of Stomatology, Zoucheng People's Hospital, Zoucheng, Shandong, People's Republic of China.
authors.forename: Zhenjie
authors.initials: Z
authors.lastname: Qin
authors.affiliation: Office of Management of Hospital Infection, Jining No. 1 People's Hospital, Jining City, Shandong, People's Republic of China.
authors.forename: Yuanye
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Pharmacy, Zoucheng People's Hospital, Zoucheng, Shandong, People's Republic of China.
authors.forename: Yuanteng
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Obstetrics and Gynecology, Zoucheng People's Hospital, Zoucheng, Shandong, People's Republic of China. Electronic address: zcskqkqzj@163.com.
authors.forename: Guangyun
authors.initials: G
authors.lastname: Liu
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D019938:Cyclin D1 / Q000378:metabolism*; D003782:Dental Pulp / Q000166:cytology* / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism*; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: C530104:CCND1 protein, human; D014409:Tumor Necrosis Factor-alpha; D019938:Cyclin D1; D019869:Phosphatidylinositol 3-Kinases; D000071679:Glycogen Synthase Kinase 3 beta
keywords: Akt; cyclin D1; dental pulp stem cells; glycogen synthase kinase-3β; proliferation; tumor necrosis factor-alpha