Abstract
The activation of signal transducer and activator of transcription 3 (STAT3) has been reported in several types of cancer, where it acts as an oncogene. However, in breast cancer, the clinical role of STAT3 remains unclear. In the present study, the association between phosphorylated-STAT3 (p-STAT3) expression and clinicopathological/biological factors was examined in each subtype. p-STAT3 expression was examined in 135 cases of breast cancer by immunohistochemistry. p-STAT3 expression was not associated with clinicopathological/biological factors and prognosis in a complete cohort of breast cancer cases. However, in patients with estrogen receptor-negative (ER(−)) breast cancer and triple-negative breast cancer (TNBC), multivariate analysis showed that higher p-STAT3 expression was significantly associated with a short relapse-free survival (p = 0.029, HR 5.37, 95%CI 1.19–24.29). TNBC patients with p-STAT3 overexpression were found to have a poor prognosis (p = 0.029, HR 5.37, 95%CI 1.19–24.29). On the other hand, in ER(+) breast cancer, p-STAT3 overexpression was associated with a favorable prognosis (p = 0.034, HR 9.48, 95%CI 1.18–76.21). The present results suggested that STAT3 expression may play a different role in ER(−) and ER(+) breast cancer. In the future, the pharmacological inhibition of STAT3 expression may serve as an effective therapeutic strategy for ER(−) breast cancer, particularly TNBC.
Highlights
Signal transducers and activators of transcription (STATs) are latent cytoplasmic proteins that are activated to control gene expression through the phosphorylation of a single tyrosine when cells encounter ligands such as extracellular cytokines, growth factors and hormones [1,2,3]
Patient characteristics are presented in Table 1. p-signal transducer and activator of transcription 3 (STAT3) expression was not associated with clinicopathological/biological factors in any of the 135 cases
In the estrogen receptor (ER)(−) group, recurrence is more common in the p-STAT3 expression positive group, while in the ER(+) group, recurrence is more common in the p-STAT3 expression negative group
Summary
Signal transducers and activators of transcription (STATs) are latent cytoplasmic proteins that are activated to control gene expression through the phosphorylation of a single tyrosine when cells encounter ligands such as extracellular cytokines, growth factors and hormones [1,2,3]. Ligands bound to the Janus kinase receptor-associated tyrosine kinases are subsequently phosphorylated and activated, STATs act as a transcription factor. STATs have an SRC-homology-2 domain, through which they contact the receptor, dimerize, become phosphorylated-STATs (p-STATs) and translocate into the nucleus. STAT3 has been shown to play an important role in cancer progression and typically acts as an oncogene [4,5,6]. STAT3 regulates the expression of vascular endothelial growth factor (VEGF) and is associated with angiogenesis and tumor progression [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
