Aspirin induces apoptosis in mesenchymal stem cells requiring Wnt/β-catenin pathway

• Published in: Cell proliferation 2009-12, Vol.42 (6), p.721-730
• Main Authors: Deng, L., Hu, S., Baydoun, A. R., Chen, J., Chen, X., Cong, X.
• Format: Article
• Language: English
• Subjects: Apoptosis - drug effects; Aspirin - pharmacology; beta Catenin - metabolism; Blotting, Western; Caspase 3 - metabolism; Cells, Cultured; Cyclooxygenase Inhibitors - pharmacology; Enzyme Activation; Flow Cytometry; Gene Expression Regulation, Enzymologic - drug effects; Humans; Mesenchymal Stem Cells - cytology; Mesenchymal Stem Cells - drug effects; Original; Prostaglandin-Endoperoxide Synthases - genetics; Prostaglandin-Endoperoxide Synthases - metabolism; Wnt Proteins - metabolism
• ISSN: 0960-7722; 1365-2184
• DOI: 10.1111/j.1365-2184.2009.00639.x

Background and Objectives:  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/β‐catenin pathway. Materials and 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/β‐catenin pathway by both Wnt 3a and GSK‐3β 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/β‐catenin pathway. Application of the COX‐2 inhibitor NS‐398 suppressed elevated COX‐2 expression and promoted aspirin‐induced apoptosis. Conclusion:  These results demonstrate that the Wnt/β‐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.