Down-regulation of the apoptosis-inducing factor or Bcl-2 inhibitor of transcription by RNA interference can alleviate TAp63gamma-induced apoptosis in esophageal squamous carcinoma EC9706 cells.

In this communication, the roles of apoptosis-inducing factor (AIF) and Bcl-2 inhibitor of transcription (Bit1) in TAp63gamma-induced apoptosis were investigated in human esophageal squamous cancer EC9706 cells. Positive RNA and protein expressions of AIF and Bit1 in these cells were verified. However, no TAp63gamma could be detected. Transfection of expression vector pcDNA3.1-TAp63gamma into EC9706 resulted in TAp63gamma expression, and peak level apoptosis was observed 24 h after the transfection disclosed by DNA fragmentation assay. In addition, it was found with Western blot that AIF and Bit1 were released into cytosol from mitochondria, and AIF was further translocated into nucleus, during the stage of TAp63gamma-induced cell apoptosis. Down-regulation of either AIF or Bit1 by RNA interference could, however, alleviate TAp63gamma-induced cell apoptosis. In conclusion, TAp63gamma could induce apoptosis in human esophageal squamous cancer EC9706 cells, through at least releasing AIF and Bit1 from mitochindria into cytosol and nucleus, where apoptotic cascade takes place. These findings indicate that mitochondria-released proapoptotic proteins, AIF and Bit1, are important factors in a TAp63gamma-induced EC9706 cell apoptosis pathway.