miR-21 Reduces Hydrogen Peroxide-Induced Apoptosis in c-kit⁺ Cardiac Stem Cells In Vitro through PTEN/PI3K/Akt Signaling

Figure 6

PTEN/PI3K/Akt pathway’s contribution to H₂O₂-induced apoptosis in c-kit⁺ CSCs. Cultured CSCs were treated with miR-21 mimics or inhibitor for 48 h before being subjected to 2 h H₂O₂ insult. PTEN and PI3K were inhibited with Phen or LY294002, respectively, before H₂O₂ insult. (a) Flow cytometry was employed to detect necrosis and early apoptosis in CSCs that underwent different treatments. PI: propidium iodide. (b) Statistics of Annexin V-FITC/PI staining assay result in (a). When PTEN was inhibited by Phen, there was notably a decrease of necrosis and apoptosis in CSCs compared with H₂O₂ group. When PI3K was inhibited by LY294002, there was notably an increase of necrosis and apoptosis in mimics + LY294002 + H₂O₂ group compared with mimics + H₂O₂ group in CSCs. compared with H₂O₂ group; compared with miR-21 mimics group. This trend was further confirmed by caspase-3 immunofluorescence tests (c) and caspase-3, Bax, and Bcl-2 immunoblotting tests (d-e). LY294002 reversed miR-21 mimics’ effect on caspase-3, Bax, and Bcl-2, which is evidenced by the increase of caspase-3 (c–e) and Bax and the decrease of Bcl-2 (d-e). compared with H₂O₂ group. in each group. Bar = 50 μm. PI: propidium iodide.

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