Uterine Fibroids (UFs), or leiomyomas, represent the most frequent pelvic tumor in reproductive-aged
women. Although of benign origin, UFs decrease fertility and cause significant reproductive dysfunctions. Compared
to normal myometrium, UFs are characterized by a clinical and molecular heterogeneity as demonstrated by
the presence of multiple genetic alterations and altered signaling pathways. Recently, selective progesteronereceptor
modulators (SPRM), as ulipristal acetate (UPA), have demonstrated their clinical benefits by reducing
tumor growth and extracellular matrix deposition. For these reasons, UPA is used in the clinical practice as an
intermittent treatment for women symptomatic for UFs or, sometimes, before a myomectomy. However, drug
effects on signaling pathways frequently upregulated in UFs remain largely unknown. In fact, the mechanisms of
action of the UPA on UFs and on the surrounding areas are not yet understood. To learn more about UPA molecular
mechanisms, UF samples were treated ex vivo with UPA and profiled for drug effects on selected markers.
During this preliminary ex vivo UPA administration, significant changes were observed in the expression levels of
proteins related to cell cycle regulation, cytoskeleton remodeling, and drug resistance. The UPA administration
reduced cofilin, Erk and Src phosphorylation, p27 and ezrin protein levels, but not Akt phosphorylation and cyclin
D1 and β-catenin levels. This preliminary ex vivo biological analysis provided new insights into the mechanism
of action of UPA in the treatment of UFs, which could better explain the biological functioning of the drug
on UFs.