Structure-Function Relationships in STAT Proteins

Background: Through specific activation of gene expression, the family of proteins known as signal transducers and activators of transcription (STATs) converts extracellular stimuli into diverse biological responses. Beyond the normal signaling functions of STATs, recent evidence indicates that aberrant activation of STATs contributes to neoplastic transformation. Methods: Current literature pertaining to the role of STAT proteins in oncogenesis is presented. Also, the rationale for developing novel approaches to disrupt STAT signaling is discussed, and the potential of STATs as anticancer targets in treating human cancer is reviewed. Results: The discovery that certain oncoproteins constitutively activate specific STATs, coupled with observations that elevated STAT activity occurs frequently in a spectrum of human tumors, establishes a direct link between STAT activation and neoplastic transformation. Significantly, abrogation of STAT signaling blocks oncogenesis in model in vitro and in vivo systems. These results make STATs attractive targets for rational design of small molecule inhibitors and gene therapy approaches to disrupt STAT signaling. Conclusions: As a result of genetic, biochemical, and crystallographic analyses, the functional domains of STAT proteins have been well characterized. Based on these data, selective inhibitors of STAT function can be designed. Because disrupting STAT signaling has proven effective in blocking neoplastic transformation, it is proposed that STAT proteins represent promising targets for development of novel molecular therapeutics to treat human cancer.