Figure 3.

Influence of H₂S on cell vulnerability to PX-12-induced cell death. (A,B) Effect of H₂S on PX-12-induced HepG2 cell death. HepG2 cells were incubated with 200 μM PX-12 in the presence or absence of 2 mM BCA, 3 mM PAG, 2 mM L-cysteine or 1 mM NaHS for 12 h. Then, the cells were either stained with Calcein-AM/PI (A, magnification: × 400) or assayed for formazan formation with WST reagent (B). Data in (B) are expressed as the percentage of living cells against the untreated control (mean ± SE, n = 4; ^*P < 0.05, ^**P < 0.01 vs. control; ^#P < 0.05, ^##P < 0.01 vs. PX-12 alone). (C–E) Effect of CSE siRNA on PX-12-induced HepG2 cell injury. The HepG2 cells were transfected with control siRNA or siRNAs targeting different sequences of CSE (siCTH1 and siCTH2) as described in Method section. The cellular lysates were extracted and subjected to Western blot analysis for CSE (C). The treated cells were also seeded into 96-well plate and exposed to 200 μM PX-12 for 12 h to evaluate cell viability through Calcein-AM/PI staining (D, magnification: × 400) and WST assay (E). Data in (E) are expressed as the percentage of living cells against the untreated siControl (mean ± SE, n = 4; ^*P < 0.05 vs. untreated siControl; ^#P < 0.05 vs. PX-12-treated siControl).