Serum Amyloid A1 Mediates Paclitaxel Resistance via MD2‐Dependent Pathways in Triple‐Negative Breast Cancer

Triple-negative breast cancer (TNBC) is difficult to treat due to the lack of clear therapeutic targets. Paclitaxel (PTX) is commonly used to treat TNBC, but drug resistance limits its effectiveness. Myeloid differentiation protein 2 (MD2) and serum amyloid A1 (SAA1) are involved in various diseases, including infections, inflammatory diseases, and cancer. We investigated their role in PTX resistance to identify potential anti-TNBC drugs. In this study, we investigated the changes of SAA1 in TNBC tissues and its role in PTX-induced TNBC cells. Our study revealed SAA1 expressed in the human TNBC subtype and TNBC cells. PTX and CIS induce SAA1 in TNBC cells, and PTX induces inflammatory response via SAA1 in TNBC cells. MD2 blockade increased the sensitivity of TNBC cells to PTX, which was related to the expression of SAA1 during PTX-caused damage of TNBC cells. In further research, SAA1 binds to MD2, promotes the combination of TLR4/MD2 and TLR4/MyD88, activates the NF-κB signaling pathway, and creates the inflammatory microenvironment for cancer cells. Our study reports for the first time that the PTX/SAA1/MD2 axis exists in the PTX-resistance process, which could be a potential treatment target of PTX-resistance.