Figure 4

Increased Apoptosis in SCC9 Cells after H₂O₂ Treatment.

(A) The number of apoptotic cells was measured by staining with Annexin V-FITC and PI, and with flow cytometry techniques. The X-axis indicates the intensity of Annexin V-FITC staining and the Y-axis that of PI. Viable cells at the bottom left are FITC⁻PI⁻; early apoptotic cells at the bottom right are FITC⁺PI⁻; cells in late apoptosis at top right are FITC⁺PI⁺; and dead cells at top left are FITC⁻PI⁺. (B) Apoptotic cells were elevated after SCC9 cells were treated by 0.5 mM or 1 mM H₂O₂ for 24 hours. (control: 13 ± 1%, 0.5 mM H₂O₂: 34 ± 2%, and 1 mM H₂O₂: 72 ± 2%. n = 3). (C) After being treated for 24 hours with different concentrations of H₂O₂, expression levels of p21 and p53 in SCC9 cell line were reduced, moreover, caspases-3,-9 and bcl-2 levels also showed a down-regulation trend, all in a dose-dependent manner. (D) Quantitative results for the Western blotting of each group (n = 3). **p < 0.01; ***p < 0.001 compared with the control group.