Abstract 465: Progestin-driven regulatory T cells directly promote an aggressive and metastatic phenotype in triple-negative breast cancer

The immune system plays key roles in the recognition and elimination of most tumors. Progesterone (Pg) can shape the immune response favoring a tolerogenic rather than a pro-inflammatory adaptive response. As hormone replacement therapies, supplementation and hormone-based contraceptives have been associated with an increase of malignant breast neoplasia we decided to investigate how progestins can regulate different key immune cell populations in the tumor microenvironment and their influence to tumor progression. To address this issue we used the highly metastatic, triple-negative 4T1 breast tumor. Balb/c mice treated with Pg or its synthetic analog, medroxyprogesterone acetate, showed an increased frequency of Foxp3+ regulatory T cells (Tregs) in draining lymph nodes (DLN) and an impaired antitumor response elicited by a decreased production of IL-17 and IFN-γ by CD4+ T cells (p Citation Format: Tomas Dalotto Moreno, Juan Pablo Cerliani, Diego Omar Croci, Santiago Patricio Mendez-Huergo, Florencia Moses, Gabriel Adrian Rabinovich, Mariana Salatino. Progestin-driven regulatory T cells directly promote an aggressive and metastatic phenotype in triple-negative breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 465. doi:10.1158/1538-7445.AM2015-465