Molecular Regulation of FOXO1 and Its Pathophysiological Significance in Endometriosis: A Narrative Review

Endometriosis is a chronic inflammatory disorder that affects approximately 10% of women of reproductive age and exhibits tumor-like characteristics such as invasion, recurrence, and hormone-dependent proliferation despite its benign nature. Its pathogenesis is thought to involve hormonal imbalance, oxidative stress, hypoxia, immune dysregulation, and epigenetic alterations. This review summarizes how these factors contribute to lesion formation through intracellular signaling pathways, with a particular focus on the role of the stress-responsive transcription factor Forkhead box O (FOXO1).

A comprehensive literature search was conducted using PubMed and Google Scholar without temporal restriction.

FOXO1 is a transcription factor that integratively regulates decidualization, cellular senescence, autophagy, and apoptosis. In the normal endometrium, under mild stress or hormonal stimulation, FOXO1 induces decidualization-associated genes (PRL, IGFBP1) and antioxidant enzymes, thereby promoting differentiation and survival. In contrast, in endometriosis, activation of the PI3K/AKT signaling pathway and an estrogen-dominant environment suppress the nuclear activity of FOXO1, leading to apoptosis resistance, accumulation of senescent cells, and chronic inflammation through the senescence-associated secretory phenotype (SASP). Moreover, depending on the intensity and duration of oxidative, metabolic, and environmental stress, FOXO1 drives distinct cellular fates-including decidualization, senescence, and apoptosis-thus contributing to the persistence and progression of endometriotic lesions.

Dysregulation of the FOXO1-dependent cellular fate-control network plays a central role in the development of endometriosis. Elucidating the molecular mechanisms governing FOXO1 activity and its nuclear dynamics will be crucial for a comprehensive understanding of disease progression and for the development of novel therapeutic strategies.