Transcription factors (TFs) are proteins that can dramatically alter the DNA transcription rate to RNA upon binding to a specific DNA sequence. TFs contain the characteristic DNA-binding domains that bind to the promoter or regulatory sequences, such as promoters or silencers, usually binding 6 to 10 base pairs. Some transcription factors bind to the promoter region near the transcription start site to help form the transcription initiation complex. Others bind to the enhancer sequence, which may be found upstream or downstream of the gene, and lead to enhanced or repressed transcription, partly by simply occupying the recognition site. Transcriptional regulation is the easiest way for a cell to control its gene expression. Transcription factors are vital in allowing the specific regulation of genes in each cell type and during development.
However, TFs’ specificity, efficiency and velocity in finding the transcription site to result in appropriate transcription events are still being understood. Extensive work on eukaryotic TFs such as Drosophila melanogaster Engrailed has provided insights into the roles played by these conserved proteins. The conservation of TFs allows work in a wide array of model organisms to help understand their role in the development and progression of cancer. TFs are often called tumour suppressors or oncogenes due to mutations in their sequence or dysregulation, which often results in cancer. In humans, the TFs linked to cancer are broadly categorised into 3 groups the NF-kappaB and AP-1 families, the STAT family and the steroid receptors.