Evaluation of DNA Binding Drugs as Inhibitors of ESX, an ETS Domain Transcription Factor Associated with Breast Cancer: Effects of ESX/DNA Complex Disruption.

摘要

This work was designed to compare representative DNA-binding agents to inhibit formation of transcription factor (TF) complexes on a key gene regulatory element. This was done in an attempt to link inhibition of TF binding with decreased cellular mRNA levels. The results obtained from conventional DNA- binding agents can be used as a baseline to assess novel sequence specific ligands for improved selective inhibition of gene expression. Most sequence preference DNA-binding agents were capable of inhibiting ESX/promoter complex formation and subsequent gene expression. However, this inhibition appeared to be non-selective since general transcription was inhibited as well. Analysis of the sequence specific polyamides, on the other hand, found limited measurable activity within a cellular environment in spite of their effective inhibition of TF binding and function in cell-free systems. Analysis of a variety of fluorescently labeled PAs suggest that these novel ligands are cell permeable but perhaps vulnerable to cellular modification. This unidentified alteration results in a compound incapable of reaching or binding internuclear DNA and whose fluorescence detection within the cell is precluded. The use of solvents released the quenched and bio-unavailable forms of the PAs, which then exhibited nuclear localization for most ligands. Structure-localization studies suggest that the majority (6 of 9) of PAs localize in the nucleus in a chromatin-like pattern.