Figure 1.

Acquired cisplatin-resistant human GC cells are sensitive to TRAIL. (a) The expression of DR4, DR5, TNFR1 and Fas in human GC cells BGC823 and SGC7901 and their cisplatin-resistant variants was determined by western blotting. (b) Left: Cell surface DR4 expression in BGC823 and SGC7901 cells and their variants was analyzed by flow cytometry. Right: Comparison of relative DR4 surface expression between different groups. Respective DR4 surface expression was estimated by examining the difference between the values (percentage of positive cells) of PE-DR4 and its corresponding IgG-PE control from at least three experiments in the same group. After 24 h of TRAIL treatments at the indicated concentrations in (c) BGC823 and its variant and (d) SGC7901 and its variant, the cell viability was determined by Cell Counting Kit-8 (CCK8) assays. After 24 h of TRAIL treatments at the indicated concentrations in (e) BGC823 and its variant and in (f) SGC7901 and its variant, cell apoptosis was determined by flow cytometry, and the quantification of apoptotic cells is indicated below. After exposure to TRAIL at the indicated concentrations and time points, the cleaved-PARP-1 and cleaved-caspase-8 and -9 levels were determined by western blotting analyses in BGC823 and its variant (g) or SGC7901 and its variant (h). The experiments were independently performed at least three times, and representative data are shown. For flow cytometry and CCK8 assays, the results are shown as the means±s.e.m., *P<0.05, **P<0.01, ***P<0.001.