title: Aspirin induces apoptosis in mesenchymal stem cells requiring Wnt/beta-catenin pathway.
abstract: OBJECTIVE
  Mesenchymal stem cells (MSC) are multipotent progenitor cells that are have found use in regenerative medicine. We have previously observed that aspirin, a widely used anti-inflammatory drug, inhibits MSC proliferation. Here we have aimed to elucidate whether aspirin induces MSC apoptosis and whether this is modulated through the Wnt/beta-catenin pathway.
  
  
  METHODS
  Apoptosis of MSCs was assessed using Hoechst 33342 dye and an Annexin V-FITC/PI Apoptosis Kit. Expression of protein and protein phosphorylation were investigated using Western blot analysis. Caspase-3 activity was detected by applying a caspase-3/CPP32 Colorimetric Assay Kit.
  
  
  RESULTS
  In these MSCs, aspirin induced morphological changes characteristic of apoptosis, cytochrome c release from mitochondria, and caspase-3 activation. Stimulating the Wnt/beta-catenin pathway by both Wnt 3a and GSK-3beta inhibitors (LiCl and SB 216763), blocked aspirin-induced apoptosis and protected mitochondrial function, as demonstrated by decreased cytochrome c release and caspase-3 activity. Aspirin initially caused a time-dependent decrease in COX-2 expression but subsequently, and unexpectedly, elevated the latter. Stimulation of COX-2 expression by aspirin was further enhanced following stimulation of the Wnt/beta-catenin pathway. Application of the COX-2 inhibitor NS-398 suppressed elevated COX-2 expression and promoted aspirin-induced apoptosis.
  
  
  CONCLUSIONS
  These results demonstrate that the Wnt/beta-catenin pathway is a key modulator of aspirin-induced apoptosis in MSCs by regulation of mitochrondrial/caspase-3 function. More importantly, our findings suggest that aspirin may influence MSC survival under certain conditions; therefore, it should be used with caution when considering regenerative MSC transplantation in patients with concomitant chronic inflammatory diseases such as arthritis.
authors.affiliation: Research Center for Cardiovascular Regenerative Medicine, Ministry of Health, Cardiovascular Institute & Fu Wai Hospital, Chinese Academy of Medical Science & Peking Union Medicine College, Beijing 100037, China.
authors.forename: L
authors.initials: L
authors.lastname: Deng
authors.forename: S
authors.initials: S
authors.lastname: Hu
authors.forename: A R
authors.initials: AR
authors.lastname: Baydoun
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: X
authors.initials: X
authors.lastname: Cong
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001241:Aspirin / Q000494:pharmacology*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation; D005434:Flow Cytometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D016861:Cyclooxygenase Inhibitors; D051153:Wnt Proteins; D051176:beta Catenin; D011451:Prostaglandin-Endoperoxide Synthases; D053148:Caspase 3; D001241:Aspirin
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