Human esophageal cancer cell death mediated by apoptosis-inducing nucleosides from CD57+HLA-DRbright natural suppressor cell line.

We approached the induction of apoptosis in human esophageal cancer cells (T.Tn) by apoptosis-inducing nucleosides (AINs) from CD57+HLA-DRbright-natural suppressor (57.DR-NS) cell line originated in decidua. The 57.DR-NS cells generated apoptosis in T.Tn cells by AINs released into the cultures. We isolated a series of AINs by high performance liquid chromatography (HPLC) from 57.DR-NS cell culture fluids. Each AIN and its mixture induced apoptotic cell death in T.Tn cells, detected by DNA fragmentation in agarose gels, terminal deoxynucleotide transferase mediated dUTP-nick end labeling (TUNEL) method and accumulation of sub-G1 DNA content with flow cytometry. Furthermore, we found the occurrence of DNA strand breaks followed by the activation of caspase-3 during AINs-induced apoptosis in T.Tn cells. Thus, we validated that AINs could induce apoptosis in T.Tn cells mediated through DNA strand breaks and activation of caspase-3.