[Interaction between necroptosis and apoptosis in MC3T3-E1 cell death induced by dexamethasone].

OBJECTIVE: To investigate the relationship between necroptosis and apoptosis in MCET3-E1 cell death induced by glucocorticoids. METHODS: MC3T3-E1 cells were incubated with 10-6 mol/L dexamethasone followed by treatment with the apoptosis inhibitor z-VAD-fmk (40 μmol/L) or the necroptosis inhibitor necrostatin-1 (40 μmol/L) for 2 h. At 72 h after incubation with dexamethasone, the cells were harvested to determine the cell viability using WST-1 assay and the rate of necrotic cells using annexin V/PI double staining; the percentage of apoptotic cells was determined using Hoechst staining. The mitochondrial membrane potential and the level of ATP in the cells were also evaluated. Transmission electron microscopy was used to observe the microstructural changes of the cells. The expressions of RIP-1 and RIP-3 in the cells were detected by Western blotting. RESULTS: At a concentration of 10-6 mol/L, dexamethasone induced both apoptosis and necroptosis in MC3T3- E1 cells. Annexin V/PI double staining showed that inhibition of cell apoptosis caused an increase in cell necrosis manifested by such changes as mitochondrial swelling and plasma membrane disruption, as shown by electron microscopy; Hoechst staining showed that the percentage of apoptotic cells was significantly reduced. When necroptosis was inhibited by necrostatin-1, MC3T3-E1 cells showed significantly increased apoptosis as shown by both AV/PI and Hoechst staining, and such changes were accompanied by changes in mitochondrial membrane potential and ATP level in the cells. CONCLUSIONS: In the process of dexamethasone-induced cell death, necroptosis and apoptosis can transform reciprocally accompanied by functional changes of the mitochondria.