Augmented Adriamycin Sensitivity in Cells Transduced with an Antisense Tumor Necrosis Factor Gene Is Mediated by Caspase‐3 Downstream from Reactive Oxygen Species

While transduction of an antisense tumor necrosis factor (TNF) gene sequence can augment the cytotoxicity of adriamycin (ADM) in human cancer cells, the specific effect of introducing this sequence on the signal transduction pathway leading to cell death remains unclear. In ADM‐resistant pancreatic carcinoma (PANC‐1) cells, both the antioxidant N‐acetyl‐L‐cysteine (NAC) and the caspase‐3 inhibitor acetyl‐L‐aspartyl‐L‐methionyl‐L‐glutaminyl‐L‐aspartyl‐aldehyde (Ac‐DMQD‐CHO) prevented ADM‐induced cytotoxicity. NAC additionally inhibited caspase‐3 activity induced by ADM treatment, while Ac‐DMQD‐CHO showed no suppressive effect on reactive oxygen species (ROS). Stable antisense‐TNF transfectants showed higher ADM sensitivity and greater ADM‐induced ROS production and caspase‐3 activity than mock transfectant or parent cells. These results indicate that increased caspase‐3 activity downstream from ROS production is among the mechanisms by which transduction of the antisense TNF sequence of augments ADM sensitivity of pancreatic carcinoma cells.