Abstract 59: 14-3-3zeta overexpressing breast cancer cells promote fibroblast senescence and CAF-like phenotype

Abstract

Abstract 14-3-3ζ overexpression in breast cancer is associated with accelerated cancer progression and poor clinical outcome in patients. Our previous study revealed that 14-3-3ζ overexpression promotes epithelial mesenchymal transition (EMT) of breast cancer cells, which facilitates progression of ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC). However, the impact of 14-3-3ζ overexpressing breast cancer cells on tumor microenvironment (TME) and the underlying mechanisms have not been explored. We found dramatically increased cancer associated fibroblast (CAF) signatures in patients' matched IDC lesions compared to their DCIS lesions, suggesting that activated fibroblasts may be involved in DCIS to IDC transition. Global gene expression profiling uncovered increased expression of pro-inflammatory cytokines/chemokines, including IL6 and IL8, in 14-3-3ζ AND ErbB2 co-overexpressed 10A.ErbB2.1433ζ cells compared to ErbB2 overexpressed 10A.ErbB2 cells. This finding was further confirmed by ELISA and validated in other breast cancer cell lines. We tested whether increased pro-inflammatory cytokines in the conditional medium (CM) from 14-3-3ζ overexpressed cancer cells promotes CAF-like phenotype. Indeed, CM from 14-3-3ζ overexpressed cancer cells significantly increased SMA+ activated fibroblast cells compared to controls. Additionally, up-regulation of β-galactosidase and reduced cell proliferation, hallmarks of senescence cells, were detected in fibroblast cells cultured in CM from 14-3-3ζ overexpressed cancer cells. Next, we explored potential mechanism of how 14-3-3ζ overexpression in cancer cells leads to up-regulation of pro-inflammatory cytokines/chemokines. Since NF-kappaB is one of the master upstream regulator of IL-6 and IL-8, we next investigated the NF-kappaB signaling activation in 14-3-3ζ overexpressed vs control cancer cells. 14-3-3ζ overexpressing cancer cells had hyperactive canonical NF-kappaB responses, including accelerated IκBα degradation, p65 phosphorylation, as well as nuclear translocation compared to 14-3-3ζ low cancer cells. Prolonged NF-kappaB signaling activation upon pro-inflammatory cytokine stimulation was also detected in 14-3-3ζ overexpressing cancer cells. These results suggest that 14-3-3ζ overexpressing cancer cells may promote fibroblast cell senescence and CAF-like phenotype by creating by a chronic inflammatory microenvironment, which ultimately enhances DCIS to IDC transition. Citation Format: Hongzhong Li, Yi Xiao, Xiangliang Yuan, Wenling Kuo, Ping Li, Dihua Yu. 14-3-3zeta overexpressing breast cancer cells promote fibroblast senescence and CAF-like phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 59.