BSCI-04. Tumor-educated platelets promote breast cancer brain metastasis and therapeutic resistance

Platelets have been shown to play an important role in systemic and local tumor modulation. Once encountered by tumor cells, platelets are educated to collect and release pro-tumor factors in the tumor/microenvironment, serving as a guiding partner for metastasis. This educational program, however, is not well understood. Here, we show that tumor-educated platelets (TEPs) acquire tumor promoting functions and drive breast cancer progression, metastasis to distal sites including the brain, as well as therapeutic resistance. Importantly, TEPs promoted an increased pro-tumorigenic effect on metastatic breast cancer, compared to their wild-type counterpart, leading to epithelial to mesenchymal transition through NF-κB/STAT3 signaling axis via C/EBPβ transcription factor. Our findings point to the important role of TEPs in breast cancer brain metastasis and therapeutic resistance, which could have a major implication in other tumor types, endorsing TEPs as a potential therapeutic target.