Signal Transducer and Activator of Transcription as a Potential Therapeutic Target in Breast Cancer

Signal transducer and activator of transcription (STAT) signaling pathway, connected upstream with Janus kinases (JAK) proteins, is known to be capable of the integration of inputs from various signaling pathways. Each family member exerts a particular role in signal transduction and is hence crucial to mediate different cellular responses to cytokines. STAT proteins especially STAT3 and STAT 5 are widely investigated and known to be involved in breast cancer progression. On the other hand, STAT1 and STAT4 exert opposite roles through suppression of breast tumor growth. Persistent activation of STAT3/5 can promote chronic inflammation, increasing healthy cells susceptibility to carcinogenesis. In this chapter, we discuss the structure, functional development, and activation of STAT family members. We also summarize the roles of different STAT proteins in breast cancer and its different subtypes. We also discuss STAT signaling pathway inhibitors used to treat breast cancer.