rs7986407 — FOXO1

FOXO1 rs7986407 — The Apoptosis Switch in Uterine Fibroid Cells

Uterine fibroids (leiomyomata) affect up to 70% of women by age 50 and are the leading indication for hysterectomy worldwide. Their growth depends on a fundamental imbalance: fibroid smooth muscle cells proliferate but resist dying. FOXO1 — forkhead box protein O1¹¹ forkhead box protein O1
a transcription factor that drives expression of pro-apoptotic genes including BIM, PUMA, and Fas ligand — is a central regulator of that life-or-death balance. An intronic variant in FOXO1, rs7986407, has emerged from multiple genome-wide association studies as a locus influencing both uterine leiomyoma risk and the timing of natural menopause, two phenotypes that converge on estrogen exposure duration and uterine smooth muscle cell biology.

The Mechanism

Under normal conditions, FOXO1 translocates to the nucleus and transcribes genes that initiate programmed cell death — a key brake on abnormal cell accumulation. In leiomyoma cells, however, progestins (which drive fibroid growth) rapidly activate the PI3K/AKT signaling cascade²² PI3K/AKT signaling cascade
a pro-survival kinase pathway that is constitutively elevated in many tumors. Activated AKT phosphorylates FOXO1 at Ser256, causing it to be sequestered in the cytoplasm where it cannot reach its target genes. The result: pro-death signals are silenced and fibroid cells survive and accumulate. This mechanism was directly demonstrated by Hoekstra et al. (2009), who showed that blocking AKT or forcing nuclear FOXO1 entry with Psammaplysene A restored apoptosis in leiomyoma cells³³ blocking AKT or forcing nuclear FOXO1 entry with Psammaplysene A restored apoptosis in leiomyoma cells
Hoekstra AV et al. J Clin Endocrinol Metab 2009.

The rs7986407 variant is intronic and does not alter the FOXO1 protein sequence. Its functional effect likely operates through regulatory mechanisms — altered splicing efficiency, changes in intronic enhancer activity, or linkage disequilibrium with regulatory variants in the FOXO1 locus — that may modulate FOXO1 expression levels or transcript stability in uterine smooth muscle cells. The precise molecular consequence of the G allele in this tissue remains an open research question.

FOXO1 also plays a broader role in reproductive physiology: in ovarian granulosa cells, FOXO1 and its close family member FOXO3 regulate follicular development and granulosa cell apoptosis. Selective deletion of both in mice caused complete infertility⁴⁴ caused complete infertility
Liu Z et al. Mol Endocrinol 2015, demonstrating that FOXO-family transcription factors are essential throughout the reproductive axis, not only in the uterus.

The Evidence

The locus around rs7986407 has been identified in multiple large-scale GWAS efforts. The GWAS Catalog reports two fibroid associations at this variant: one with OR 1.07 (95% CI 1.04–1.10; p = 7 × 10⁻⁸; risk allele G) from studies in European-ancestry women, and a second association in a larger meta-analysis (p = 2 × 10⁻¹³; beta 0.064) where the A allele direction diverges — reflecting the complexities of phenotypic stratification across studies. A third entry in the GWAS Catalog records an association with uterine leiomyoma specifically (OR 0.93 per A allele; p = 2 × 10⁻¹⁸), consistent with a protective role of the A allele on fibroid risk.

The same A allele is associated with later age at natural menopause⁵⁵ later age at natural menopause
later menopause means longer total estrogen exposure across the reproductive lifespan at genome-wide significance (p = 4 × 10⁻¹⁹), suggesting that the A allele promotes prolonged functional ovarian activity. The relationship between these two A-allele phenotypes (later menopause and reduced fibroid risk, or context-dependent fibroid association) likely reflects the complex role of estrogen timing in uterine tissue biology.

A case-control study of 737 UF patients and 451 controls⁶⁶ case-control study of 737 UF patients and 451 controls
Ponomareva et al. 2024 found rs7986407 appearing in multiple gene-gene interaction models alongside rs547025 (SIRT3), rs2456181 (ZNF346), rs7907606 (STN1/SLK), and rs72709458 (TERT) — suggesting that the fibroid risk associated with this locus may be amplified or modified by co-occurring variants in related pathways. The SIRT3 connection is biologically plausible: sirtuin-family deacetylases directly regulate FOXO1 nuclear localization and activity, as shown by the SIRT1–FOXO1 axis in granulosa cells⁷⁷ SIRT1–FOXO1 axis in granulosa cells
miR-181a promotes SIRT1 downregulation, FOXO1 acetylation, and granulosa cell apoptosis via this axis.

Practical Actions

For women carrying two G alleles at rs7986407, the evidence may suggest a modest but biologically grounded susceptibility to uterine fibroid development, potentially acting through reduced FOXO1-mediated apoptotic surveillance in uterine smooth muscle cells. The fibroid phenotype in GG women may be modulated by factors that influence AKT pathway activity — including progestin exposure from hormonal contraception and body composition, as adipose tissue is a source of both estrogens and progestins.

Early pelvic ultrasound surveillance is the most actionable monitoring step for GG carriers. If fibroids are identified, awareness of the AKT/FOXO1 pathway biology may be relevant to treatment considerations, particularly given ongoing research into AKT-targeted fibroid therapies.

Interactions

The gene-gene interaction data from Ponomareva et al. 2024 and 2025 suggests that rs7986407 FOXO1 interacts with rs547025 SIRT3 in the context of uterine fibroid risk. SIRT3 (sirtuin 3) is a mitochondrial deacetylase with known roles in oxidative stress resistance and cellular longevity signaling. In the 2024 study, rs547025 SIRT3 showed the strongest individual protective effect against fibroids (C allele OR 0.61), while rs7986407 FOXO1 appeared repeatedly across interaction models. The biological rationale is compelling: SIRT3-family deacetylases regulate FOXO-family transcription factor activity through deacetylation, and FOXO1 acetylation status determines whether it can enter the nucleus to trigger apoptosis. A dual variant carrier — with both reduced SIRT3 protective capacity and a FOXO1 allele associated with fibroid risk — may face a convergent impairment of apoptotic regulation in uterine smooth muscle cells. Proposed compound action: SIRT3 rs547025 + FOXO1 rs7986407 — women carrying GG at rs7986407 (FOXO1, elevated fibroid risk) combined with TT at rs547025 (SIRT3, reduced protective effect) may have a compounded impairment of the SIRT3-FOXO1 apoptotic axis in uterine smooth muscle; recommended action would be earlier pelvic surveillance and monitoring of fibroid-related symptoms (heavy menstrual bleeding, pelvic pressure), plus consideration of lifestyle and dietary factors shown to support mitochondrial SIRT3 activity such as time-restricted eating and resistance exercise.