The double life of KLF5: Opposing roles in regulation of gene-expression, cellular function, and transformation.

The mechanisms by which cells control their growth and behavioral identities are complex and require adaptability to environmental changes. Transcription factors act as master controllers of many of these pivotal points through their ability to influence the expression of many thousands of downstream genes, and increasingly research is showing that transcription factor regulation of target genes can change in response to environmental stimuli and cell type such that their function is not prescribed but rather context-dependent. Krüppel like factor 5 (KLF5) is an example of such a transcription factor, where evidence of disparate effects on cell growth and differentiation in normal and transformed tissue are clear. Here we present and discuss the literature covering the differential roles of KLF5 in particular tissues and cancer states, and the mechanisms by which these differences are effected through the regulation of KLF5 protein function in response to different cellular states and the direct effect on target gene expression.