Figure 4.

Effect of LMWP-SOD1 on H₂O₂-induced activation of the p53-p21^cip/WAF1 pathway in human DPSCs. DPSCs were pretreated with SOD1 (2 μM) or LMWP-SOD1 (2 μM) for 3 hours before 2 hours of incubation with H₂O₂. After removal of H₂O₂, the cells were continuously cultured for an additional 3 days. (A) The p53 and p21Cip1/WAF1 genes were detected by reverse transcriptase polymerase chain reaction. (B) Transcription levels of p53 and p21Cip1/WAF1 were quantified. GAPDH was detected as a loading control. ■ p53, □ p21 Cip1/WAF1. (C) Phosphorylated p53, p53, and p21Cip1/WAF1 proteins were detected by Western blotting. (D) Protein levels of phosphorylated p53/p53 and p21Cip1/WAF1 were quantified. β-actin was detected as a loading control. ■ p-p53/p53, □ p21 Cip1/WAF1. DPSCs were pretreated with SOD1 (2 μM) or LMWP-SOD1 (2 μM) for 3 hours before 2 hours of incubation with H₂O₂. After removal of H₂O₂, the cells were continuously cultured for an additional 3 days. (E) Levels of SOD1 protein were detected by Western blotting. (F) The SOD1 expression level was quantified and normalized with β-actin.

Notes: Each bar represents the mean ± standard error of the mean obtained from four experiments. Four independent experiments were performed in duplicate, and significant differences are denoted by symbols: (B, D) *P < 0.05 versus the H₂O₂- and SOD1-treated group; ^#P < 0.05 versus the H₂O₂- and SOD1-treated group. (B) *P = 0.012; ^#P = 0.04; (D) *P = 0.023; ^#P = 0.02; (F) *P < 0.05 versus the SODI-treated group; ^#P < 0.05 versus the H₂O₂- and SODI-treated group. (F) ^*P = 0.018; ^#P = 0.03.

Abbreviations: LMWP, low molecular weight protamine; SOD1, superoxide dismutase; DPSCs, human dental pulp stem cells.