Extracellular mechanical forces and ferroptosis in triple negative breast cancer (TNBC): Targeting of aurora kinase A (AURKA).

Abstract

e13086 Background: The mechanics of tumor microenvironment, primarily induced by extracellular matrix (ECM), function to regulate cell biological behaviors. However, it is unclear if and how triple negative breast cancer (TNBC) cells adapt their biological characteristics to variable extracellular mechanical forces. Methods: TNBC tissues of different stiffness from patients were harvested for untargeted metabolomics to investigate the potential effects of mechanical forces on metabolism. TNBC cells were cultured within gels of different type I collagen (Col-I) densities, which were the major component of ECM, to simulate the effects of extracellular mechanical forces on cells. The metabolic changes of TNBC cells were also examined by using untargeted metabolomics. TNBC cells bathed in different Col-I densities were injected subcutaneously into the breast pad of nude mice. Ferroptosis indicators were evaluated between different groups of mechanical force both in vitro and in vivo. Real-time quantitative polymerase chain reaction (RT-qPCR) and western blot were carried out to examine the expression of ferroptosis-related genes and proteins between different groups of mechanical force. Results: Untargeted metabolomics studies showed significant differences in ferroptosis-related metabolites between TNBC tissues with different stiffness, which were also verified in TNBC cells subjected to different extracellular mechanical forces. In vitro experiment suggested that TNBC cells cultured within high Col-I density (strong extracellular forces) exhibited higher levels of lipid peroxidation, reactive oxygen accumulation, mitochondria membrane potential and iron concentration, and lower levels of total glutathione and reduced glutathione concentration, compared with low Col-I density (weak extracellular forces). In addition, mitochondria in high Col-I density group appeared to have volume decrease, fracture and fuzzy cristae. The above results indicated that extracellular mechanical force significantly induced ferroptosis in TNBC. RT-qPCR and western blot of ferroptosis-related genes and protein showed that both mRNA and protein levels of aurora kinase A (AURKA) were significantly decreased in TNBC cells with strong extracellular mechanical force. In addition, overexpression of AURKA inhibited ferroptosis caused by mechanical forces. Furthermore, this cause and effect among mechanical force, AURKA and ferroptosis was also evident in vivo experiments. Conclusions: Our data clarified the role of extracellular mechanical forces in TNBC and showed that the extracellular mechanical forces induced ferroptosis through decreasing the expression of AURKA.