Abstract
Abstract *Background:* The transcription factor PAX2 regulates key developmental processes, including mediation of resistance to apoptosis. Inappropriate PAX2 expression has been implicated in facilitating tumour survival, and we have previously shown that siRNA-mediated blockade of PAX2 signalling at the transcript level in EJ bladder carcinoma cells promotes cell death. In this study, we attempted to disrupt PAX2 transcriptional activity in EJ cells by using a decoy oligodeoxynucleotide (ODN). *Results:* We could not show an interaction between PAX2 and our PAX2 decoy ODN, and in both PAX2-positive EJ and PAX2-negative HEK293 control cells, decoy and control ODN transfection resulted in a marked retardation of cell growth, irrespective of sequence, but not in COS7 and NZM4 melanoma cells. *Conclusions:* Our data indicate that decoy ODN transfection had off-target effects that inhibited cell growth in a cell line-dependent manner, and we suggest caution is required to determine the specificity of decoy ODN sequences before considering their application as a potential therapeutic agent.