STAT3 Inactivation and Induction of Apoptosis Associate With Fluoxetine-inhibited Epithelial-mesenchymal Transition and Growth of Triple-negative Breast Cancer In Vivo.

Abstract

Breast cancer (BC) is the most common cancer and second leading cause of death in women worldwide. Triple-negative breast cancer (TNBC) is the most aggressive type of BC, while the treatment option is limited and has long been considered as a major unmet need. Meta-analysis indicated the anti-tumor potential of anti-depressants, especially selective serotonin-reuptake inhibitors (SSRIs). The SSRI fluoxetine has been shown to suppress BC and ovarian cancer cell growth; however, whether it suppresses tumor progression in vivo is unclear. We established an 4T1 bearing animal model, an orthotopic TNBC model, to identify the mechanism and therapeutic efficacy of fluoxetine. Tumor growth evaluated by caliper and computed tomography scan demonstrated the inhibition effect by fluoxetine treatment. Immunohistochemistry showed that the expression of STAT3-mediated epithelial-to-mesenchymal transition (EMT) proteins and apoptosis-related proteins was decreased. Fluoxetine may induce an anti-TNBC effect via inactivating STAT3 signaling transduction and triggering the caspase-mediated apoptotic pathway.