THE PROGESTERONE ANALOGUE, NORGESTREL, IMPAIRS TUMOR IMMUNITY AND PROMOTES METASTATIC BREAST CANCER PROGRESSION

TOMÁS DALOTTO MORENO; MENDEZ-HUERGO SANTIAGO; MARIANA SALATINO; JUAN PABLO CERLIANI; MOSES FLORENCIA; DIEGO CROCI; GABRIEL RABINOVICH

New Orleans

Congreso; AACR Annual Meeting 2016; 2016

American Association of Cancer Research

The immune system plays key roles in the elimination of most tumors. Progesterone (Pg) can shape the immune response favoring a tolerogenic rather than a pro-inammatory adaptive response. As hormonesupplement therapies have been associated with increased frequency of malignant breast neoplasias, we investigated, using the highly metastasic triple negative 4T1 breast tumor, how progestins can regulate keyimmune cell populations in the tumor microenvironment and how progestin-induced immunosuppression inuences tumor progression. Balb/c mice treated with Pg or its synthetic analog, medroxyprogesteroneacetate (MPA), showed an increased frequency of Foxp3+ regulatory T cells (Tregs) in draining lymph nodes and displayed an impaired antitumor response evidenced by a decreased production of IL-17 and IFN-by CD4+ T cells (p