Arsenic trioxide induces apoptosis in human gastric cancer cells through up‐regulation of P53 and activation of caspase‐3

Arsenic trioxide (As2O3) can induce clinical remission in patients suffering from acute promyelocytic leukemia, through induction of apoptosis and activation of caspases. We investigated the potential use of As2O3 in human gastric cancer and its possible mechanisms. Human gastric cancer cell lines AGS and MKN-28 were treated with various concentrations (0.1 to 100 μM) of As2O3 for 24 to 72 hr. Apoptosis was determined by acridine orange staining, flow cytometry and DNA fragmentation. Protein levels of p53, p21waf1/cip1, c-myc, bcl-2 and bax were detected by Western blotting. Effects of As2O3 on caspase-3 protease activity, its protein concentration and cleavage of poly(ADP)-ribose polymerase (PARP) were also studied. As2O3 inhibited cell growth and induced apoptosis in both cell lines, though AGS cells were more sensitive. As2O3 induced apoptosis in AGS cells in a concentration- and time-dependent manner. Treatment resulted in a marked increase in p53 protein levels as early as 4 hr. Co-incubation with p53 anti-sense oligo-nucleotide suppressed As2O3-induced intracellular p53 over-expression and apoptosis. As2O3 increased the activity of caspase-3, with appearance of its 17 kDa peptide fragment, and cleavage of PARP, with appearance of the 85 kDa cleavage product, both in parallel with the induction of apoptosis. Both the tripeptide caspase inhibitor zVAD-fmk and the specific caspase-3 inhibitor DEVD-fmk partially suppressed As2O3-induced caspase-3 activation and apoptosis. As2O3 inhibits cell growth and induces apoptosis in gastric cancer cells, involving p53 over-expression and activation of caspase-3. The potential use of this compound in the treatment of gastric cancer is worth further investigation. © 2001 Wiley-Liss, Inc.